Scoping study: ecosystem services and natural capital

Scoping study: ecosystem services and natural capital costs of Invasive Non-Native Species (INNS) in the UK Final Report

Defra

14 May 2019

Final | 4.0 | 14 May 2019 Atkins | Defra Natural Capital and INNS FINAL ISSUE Page 2 of 54

Notice

This document and its contents have been prepared and are intended solely as information for Defra and use in relation to Ecosystem services and natural capital costs of INNS in the UK scoping study.

Atkins Limited assumes no responsibility to any other party in respect of or arising out of or in connection with this document and/or its contents.

This document has 54 pages including the cover.

Document history

Rev Purpose description Originated Checked Reviewed Authorised Date

1.0 Initial draft, to be updated following stakeholder workshop

W Wainwright, M Barker

M Barker S Smith S Smith 27/03/2019

2.0 Draft for client review W Wainwright, M Barker

M Barker S Smith

D Aldridge

S Smith 05/04/2019

3.0 Re-draft based on client and Environment Agency comments

W Wainwright M Barker S Smith S Smith 26/04/2019

4.0 Final version for issue W Wainwright M Barker S Smith S Smith 14/05/2019


Contents

Chapter Page

Executive Summary 5

Introduction 5

Approach 5

Conclusions and recommendations 5

1. Introduction 7

1.1. Objectives 7

2. Approach 8

2.1. Overview 8

2.2. Quick Scoping Review 8

2.3. Review and scoping of approaches for valuation of ecosystem services impacts 10

2.4. Stakeholder workshop 10

2.5. Scoping the implementation of a natural capital approach 10

3. Results of the QSR 11

3.1. Overview of studies 11

3.2. Species and impacts 12

3.3. Economic impacts 15

3.4. Targeting current actions to minimise current and future costs 21

3.5. Knowledge gaps 21

4. Stakeholder workshop 23

4.1. Overview 23

4.2. Ecosystem services impacts 23

4.3. Methodological approaches, priorities and data sources 23

4.4. Consideration of whether the natural capital framework is useful in the context of INNS24

5. Scoping the implementation of the natural capital approach 26

5.1. Review of potential approaches 26

5.2. Recommendations for undertaking a natural capital assessment 35

6. Conclusions and recommendations 38

7. References 40

Appendices 42

Appendix A. Literature review and QSR 43

Appendix B. Information from workshop discussions 47

Appendix C. Costing a two-phase approach 52

Tables Table 1-1 - Main ecosystem impacts arising from most frequently noted INNS in the QSR 6

Table 2-1 - Keywords to be used in the literature search (noting ‘and’ qualifiers where considered important to focus search) 9

Table 3-1 - Study attributes and count 12

Table 3-2 - Example of direct and indirect market impacts of the zebra mussel 19

Table 3-3 - Economic impacts of INNS in UK from the review sources (n=7) ordered by the total annual economic impact. Note P=provisioning; R = regulating, C=cultural and S=supporting services. 20


Table 5-1 – Overview of potential monetisation approaches for various ecosystem services and economic impacts with relation to INNS 27

Table A-1 - Search terms used in the QSR corresponding to each database 43

Table A-2 - Description of ecosystem service categories 44

Table A-3 – Valuation methods for ecosystem services 46

Table B-1 - Natural capital assets and service provision for UK woodland 47

Table B-2 - Natural capital assets and service provision for UK freshwater 48

Table B-3 - Natural capital assets and service provision for UK farmland 49

Table B-4 - Natural capital assets and service provision for UK urban area 50

Table B-5 - Organisations and areas of expertise present at the stakeholder workshop 51

Table C-1 - Indicative cost estimate for implementing the recommendations for a natural capital two-phase approach 52

Figures Figure 3-1 - Number of records associated with the various QSR stages. Note only the first 80 articles

(sorted by relevance) from each search engine / database were taken through to the filtering round. 11

Figure 3-2 - Geographical distribution of all studies in the review (n=24). 12

Figure 3-3 - Top 20 INNS species most mentioned in the review (n=24). 13

Figure 3-4 – Frequency ecological impacts are noted in the review (exc. non-European studies). Note, INNS ecological impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16). 13

Figure 3-5 - Frequency ecosystem service impacts are noted in the literature (exc. non-European studies). Note, INNS ecosystem service higher-level impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16). 14

Figure 3-6 - Frequency ecosystem services impacts are noted in the review (exc. non-European studies). Note, INNS ecosystem service lower-level impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16). 15

Figure 3-7 - Different economic valuation techniques and their association with total economic value. Source: (Defra, 2011) 16

Figure 3-8 – Frequency of economic costing approaches to capture INNS economic impacts noted in the review. Note, the economic costing approach was documented for each article that specifically denotes the economic impact of INNS (n=9). 17

Figure 3-9 - Frequency with which different sectors are noted across the studies. Note, sectors were documented for all articles reviewed (n=24). 17

Figure 3-10 - Frequency of economic impacts noted for INNS (exc. non-European studies). Note, economic impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16). 18

Figure 5-1 - Schematic approach to documenting the long-term natural capital impacts of INNS35


Executive Summary

Introduction Invasive non-native species (INNS) represent a significant and growing risk to the health of ecosystems in the UK and their presence results in adverse economic impacts on a wide range of sectors (e.g. agriculture, transport and utilities). Previous UK analysis of INNS economic impacts CABI by Williams et al. (2010) focused on the financial control costs and market-related impacts of INNS. This report gave a robust estimate but did not attempt to capture the non-market impacts of INNS, acknowledging a lack of data on the wider economic costs of INNS, such as lost non-use value benefits. The use of a natural capital approach as a tool for managing land more sustainably is a key tenet of the 25 Year Environment Plan (25 YEP) and this study seeks to explore the viability of undertaking a full assessment of the costs of INNS through an ecosystem services and natural capital lens. This is important because a partial synthesis of cost information hinders our understanding of the impacts of INNS on societal welfare.

Approach Four principal stages were used as part of this scoping study:

Stage 1: Quick Scoping Review (QSR) – the aim of this was to assess the current evidence base on the ecosystem service and natural capital impacts of INNS relevant to the UK.

Stage 2: Literature review of methodological approaches for valuing INNS ecosystem service impacts.

Stage 3: A stakeholder workshop to document the noteworthy impacts of INNS on UK natural capital assets and to map out approaches to document the full economic impact of INNS through an ecosystem services and natural capital approach.

Stage 4: The findings from the first three stages were synthesised to inform the scoping of the implementation of a full natural capital assessment as part of further work.

Conclusions and recommendations The main findings from Stage 1 (the QSR) are as follows:

1. The main INNS ecosystem impacts of relevance to the UK arise from alteration / damage to habitat and

out-competing other species. The most frequently noted INNS from the QSR were the coypu, Canada

goose, zebra mussel and American mink. Some ecosystem impacts for these INNS are denoted in

Table 1-1 (below)1.

2. The most frequently noted ecosystem service impacts of relevance to the UK relate to supporting and

cultural services, which most frequently refer to maintenance of genetic diversity and aesthetic values.

3. Most economic studies document the economic impacts of INNS as a function of direct market cost.

The sectors most impacted by INNS are agriculture, recreation, nature conservation and forestry.

4. The main economic impacts of INNS identified in the review correspond to landscape and amenity

impacts; damage to infrastructure and damage to fisheries/aquaculture.

5. Findings from the QSR suggest the economic impacts for the top 14 most impactful INNS in the UK

range from £920 million (European rabbit) to £1 million per annum (signal crayfish)2. These impacts are

almost exclusively valued through production function approaches or damage cost avoidance.

6. Control costs are generally much lower than the economic impacts of INNS, suggesting controls are

perhaps cost-effective. This is apart from signal crayfish, where control costs represent 880% of the

reported economic impacts (control costs are also proportionally very high for Japanese knotweed).

7. Overall, a range of knowledge gaps were identified including the need to measure non-market and

indirect impacts of INNS to capture the full spectrum of economic impacts; the benefits of taking a

natural capital approach that facilitates rationalisation of control efforts for INNS and finally the need to

measure public willingness-to-pay (WTP) for INNS control that could be used to validate current

spending on control strategies.

1 These species may not fully represent the known species and extent of impacts that arise from INNS in the UK. For instance, this species

list does not reflect the impact invasive plants have on carbon sequestration and soil mycorrhizal quality. 2 Note that the figure of £920 million is from work by Pimentel et al. (2001), which has now been updated to £263 million by CABI (Williams

et al., 2010).


Table 1-1 - Main ecosystem impacts arising from most frequently noted INNS in the QSR

Species Ecosystem impacts Distribution

Coypu3 Alteration of erosion rates and sediment regimes

Agricultural pest

Destruction of marshland habitats

East of England

Canada goose Competition with local species

Hybridisation with local species

Damage to agricultural land

UK wide

Zebra mussel Alteration of ecosystem functioning (e.g. through feeding regimes)

Water quality changes

Reduced food and oxygen for native fauna

Central and Southern England

American mink Competition with local species

Transmission of disease

Predation on native species

UK wide

The main recommendations from Stages 2-4 are as follows:

1. We suggest that undertaking a natural capital approach to account for INNS impacts would be

beneficial and will address multiple gaps in the literature concerning marginal changes to human

welfare and regional variation. Attendees at the workshop broadly shared this recommendation. There

are significant indirect and non-market impacts that are not currently visible to decision-makers,

meaning the allocation of resources for control measures may be sub-optimal.

2. Across the different ecosystem services, the relative feasibility and resources needed to

monetise the impacts of INNS varies considerably. Data are generally well documented for

provisioning services and should focus on provision of freshwater. For regulating services, the picture

is somewhat more complex. Quantification of regulating services may be achieved most efficiently by

focusing on carbon sequestration and waste water treatment (i.e. water quality). For cultural services,

the impact of pathways and associated changes to marginal welfare are less well understood. We

therefore suggest focusing on recreation and tourism services, where the feasibility of documenting

monetary estimates is greatest.

3. Implementation of a natural capital assessment should be developed in two phases. Phase 1

could identify case study projects to trial the schematic approach we have outlined. To complement the

25 YEP, this could focus on the four Pioneer projects (Cumbria, North Devon, Greater Manchester and

Marine Pioneers) that are already using natural capital approaches to inform land management

strategies. Phase 2 could draw on the analysis in Phase 1, undertaking a scaled-up national natural

capital assessment of INNS impacts that complements work undertaken by the ONS on constructing

National Natural Capital Accounts. We have costed this two-phase approach in Table C-1.

4. Undertaking a natural capital assessment as a vehicle to prioritise investments in INNS control

strategies. Taking the approach outlined here means such investments can be disaggregated

regionally and across the relevant natural capital assets where cost-effectiveness can be measured.

5. Complementing the natural capital baseline assessment with further scenario analysis will

deliver added value. Climate change is emerging as a key factor in INNS spread and distribution that

is influenced by strategic control efforts. Developing a broader conceptual understanding of the natural

capital impacts of INNS through future scenario planning will promote proactive rather than reactive

management strategies that can be optimised relative to societal welfare.

3 This species has been eradicated in the UK since 1998


1. Introduction Invasive non-native species (INNS) represent a significant and growing risk to the health of ecosystems in the UK and their presence results in adverse economic impacts on a wide range of sectors (e.g. agriculture, transport and utilities). The CABI report by Williams et al. (2010) provided a robust national estimate of the market-based and financial costs of controlling INNS. The CABI report employed a sector-based approach and suggested the annual economic impact of INNS to the British economy is £1.7 billion (£1.3 billion in England, £0.25 billion in Scotland and £0.13 billion in Wales). The CABI report focused on the financial control costs and market-related impacts of INNS but did not capture the non-market impacts of INNS, acknowledging a lack of data, most notably lost non-use values and indirect use values that are hard to measure but not arbitrary. This has led to concern that there have been significant underestimates regarding the full economic impact of INNS. The wider economic impacts can be appreciated through a total economic value (TEV) framework that captures both market and non-market values in decision-making.

The use of a natural capital approach as a tool for managing land more sustainably is a key tenet of the 25 Year Environment Plan (25 YEP), which was published in January 2018. Natural capital extends the concept of asset management to the natural environment (e.g. soil, air, water), recognising that human wellbeing is highly dependent on the health of these assets and the ecosystem services (ES) they provide.

This study seeks to explore the viability of undertaking a full assessment of the costs of INNS through an ecosystem services and natural capital lens. This is important to ensure that investments in management and control strategies can be targeted most efficiently and effectively, because a partial synthesis of cost information hinders our full understanding of the impacts of INNS on societal welfare.

The report is structured as follows:

Section 2 outlines the approach, including a Quick Scoping Review (QSR) and stakeholder workshop.

Section 3 provides a summary of the findings from the QSR and Section 4 provides the outputs from the workshop. These are used to inform an assessment of the feasibility and approaches for undertaking a full natural capital assessment, as documented in Section 5.

Finally, Section 6 provides conclusions from the study and recommendations for further work.

1.1. Objectives The aim of this study is to document current evidence in relation to the ecosystem service impacts of INNS in the UK and to scope the feasibility of estimating the full costs of INNS through a natural capital/ecosystem services lens. The objectives are as follows:

Assess the main impacts of INNS on natural capital assets and associated ES flows;

Highlight gaps in the evidence of impacts of INNS on natural capital;

Assess whether the current available evidence can be used for better targeting of current actions to minimise or avoid future costs (e.g. particular taxonomic groups, pathways, locations, sectors or ecosystems);

Assess the feasibility of estimating the full cost to human welfare from INNS using a natural capital framework that considers both market and non-market costs;

Scope the methodological approaches and resource requirements for undertaking a full assessment of the human welfare cost of INNS.

Consider whether the natural capital and ecosystem services frameworks are appropriate for assessing INNS impacts.


2. Approach

2.1. Overview The approach used for this scoping study was divided into two parts with four principal stages in total, as follows:

Part 1

Stage 1: Quick Scoping Review – the aim of this was to assess the current evidence base on the

ecosystem service and natural capital impacts of INNS relevant to the UK.

Part 2

Stage 2: Review of methodological approaches for valuing the ecosystem services impacts of INNS.

Stage 3: A stakeholder workshop to document the noteworthy impacts of INNS on UK natural capital assets and to map out approaches to document the full economic impact of INNS through an ecosystem services approach.

Stage 4: The findings from the first three stages were synthesised to inform the scoping of the implementation of a full natural capital assessment as part of further work.

The approaches used are described below in the following sections.

2.2. Quick Scoping Review

2.2.1. Objective and question The objective of this element of the study was to collate and summarise the scale and scope of current research in response to the primary research question:

What is the full economic cost to human welfare of INNS in the UK viewed through an ecosystem services lens?

The aim, scope and primary question of the QSR was discussed and agreed with the Project Steering Group at the project inception meeting. This was central to identifying the focus of the QSR and the search terms that would be employed to identify the relevant literature. This QSR approach is advantageous because bias and subjectivity are minimised while any conclusions can clearly be linked back to the underpinning evidence and scope of the review. The method used in the development of this QSR was based on Defra guidance for the production of QSRs (Collins et al., 2015). The three steps employed in this work were:

1. Searching for evidence;

2. Screening;

3. Filtering and extracting information.

This was followed by a stakeholder workshop to discuss key findings and gaps. These steps are set out in the sections below.

2.2.2. Search strategy, terms and sources An initial scoping search was performed to validate the search keywords and methodology. Search terms were formulated by the review team in consultation with the Steering Group. These terms were tested for specificity and sensitivity using a structured search within Web on Knowledge. The volume of relevant literature was used to gauge the effectiveness of each of the search terms and their syntax in the search string. The primary question was constructed as a closed question containing the relevant Population, Intervention, Control and Outcome (PICO) elements. Identifying the PICO elements follows guidance documented by Collins et al. (2015) to ensure that the question was clear and focused.

Table 2-1 lists search terms that were used for the QSR in the PICO framing. A wildcard (*) was used where appropriate to pick up multiple word endings, alongside other Boolean operators (e.g. AND, OR, NOT). The specific search terms used for each search engine / database are provided in Table A-1 in Appendix A.


Table 2-1 - Keywords to be used in the literature search (noting ‘and’ qualifiers where considered important to focus search)

Population Intervention Control Outcomes

Ecosystem services Invasive species n/a Costs

Natural AND capital Alien species Consequences

Ecosystem impacts Invasive non-native species / INNS

Benefits

Ecosystem service value Non-native species Impacts

Socio-economic impact

Economic impact

UK, Europe

The following study inclusion criteria were also applied:

Geographical reference: Search terms focused on UK and Europe but not a restrictive clause.

Language: English

Date: Studies published from 1990

Article type: Any

Multiple sources were searched to capture the range of both peer-reviewed and grey literature that may inform the primary research question. These were:

Web of Science

Science Direct

Scopus

Google Scholar

This was complemented by searches drawing on similar keywords in databases specific to the topic including:

Conservation evidence database

Centre for Agriculture and Bioscience International (CABI) compendium database

GB Non-Native Species Secretariat website

The results of each search were processed in Excel and duplicates removed. A record of each search was made to enable a re-run of the search if needed. The following data were recorded: date the search was conducted; database name; search term; number of hits; notes.

2.2.3. Filtering and data extraction Following the database searches, the literature was subject to a filtering and data extraction process to retain a non-biased approach to the literature review. The filtering consisted of the following steps:

1. A first pass filter, where studies were retained or excluded based on the article title only. The records were marked either ‘clearly relevant’, ‘uncertain; or ‘not relevant’.

2. A second pass was employed in which the abstracts of all articles classified as either ‘clearly relevant’, or ‘uncertain’ in the first pass filter were read. Upon reading the abstract, the articles were then classified as either ‘relevant’ or ‘not relevant’. These classifications were subsequently blind-checked by a colleague and any discrepancies were discussed and either removed or retained through consensus.

3. A final record of literature was then derived and used in the data extraction process.

The data extraction process featured a review of each article and was accompanied by a data extraction template where key information from each article pertaining to the primary research question was documented. This information included:

type of evidence;

geographical context;

relevance of the article to the primary question (PQ);

INNS ecosystem impacts;


INNS species;

ecosystem services assessed;

economic impacts;

economic costing approach;

sectors considered;

evidence and conclusions pertaining to the PQ;

limitations / further work;

other notes.

2.3. Review and scoping of approaches for valuation of ecosystem services impacts

The second stage in the study was to identify potential methodological approaches and data sources that could be used to quantify and monetise the costs of INNS through an ecosystem services framework. This was based on a review of the approaches employed in the literature sources identified within the QSR and other relevant references noted within these. An initial assessment of the feasibility and resource requirements of undertaking a full assessment by ecosystem services category was completed, which was refined following the stakeholder workshop.

2.4. Stakeholder workshop The workshop provided an important contribution to the study, with expert stakeholders sharing their views and perspectives on a range of factors surrounding invasive species ecological and ecosystem service impacts. The workshop also explored the impacts of INNS on ecosystem services provision; potential methodological approaches for quantifying ecosystem service and other economic impacts; and the feasibility and resource requirements of employing such approaches.

Further information on the workshop and outcomes is provided in Section 4.

2.5. Scoping the implementation of a natural capital approach The final stage in the study drew together the initial review of approaches and findings of the workshop to identify:

Approaches that could be used to quantify impacts in relation to each ecosystem services category;

The feasibility and resource requirements of quantifying the impacts in each category;

Priorities based on findings from the QSR and stakeholder views;

Recommendations for a more detailed study (setting out the ways in which this might be undertaken);

Whether the natural capital framework is suitable for assessing the wider costs of INNS and what this might look like.


3. Results of the QSR

3.1. Overview of studies The total search hits from the review of peer-review literature are shown in Figure 3-1. The combined search hits amounted to 26,746 articles, although a search cap ensured only the top 80 most relevant articles (as identified by the search engines) were taken through to the filtering stage from each search engine. This meant (after duplicate removal) only 300 records were taken through into the filtering stage due. Following the title filtering (first pass) 47 articles were remaining. The abstract filtering (second pass) reduced this number to 24 articles, all of which were reviewed fully.

Figure 3-1 - Number of records associated with the various QSR stages. Note only the first 80 articles

(sorted by relevance) from each search engine / database were taken through to the filtering round.

The geographical distribution of the reviewed studies was mainly centred around Europe (n=7) and the UK (n=5) reflecting the search terms employed in the QSR (Figure 3-2). Studies from outside Europe were also included in the review because a key feature of the QSR was to capture variations in methodological application corresponding to the PQ, which does not need to be geographically or taxonomically specific.


Figure 3-2 - Geographical distribution of all studies in the review (n=24).

The primary evidence base of reviewed articles was academic papers (n=19) while the remaining sources were either technical reports or book chapters (n=5), see Table 3-1. Most studies were of limited relevance to the PQ (n=10), while 7 were moderately relevant and 7 were highly relevant.

Table 3-1 - Study attributes and count

Attribute Count

Evidence base

Academic paper - review 10

Academic paper - empirical 9

Technical report 3

Book chapter 2

Relevance of study

Highly relevant 7

Moderately relevant 7

Limited relevance 10

3.2. Species and impacts

3.2.1. Species Over fifty INNS were mentioned in the review. The coypu (n=10); Canada goose (n=9); zebra mussel (n=8); American mink (n=7) and Japanese knotweed (n=6) were most frequently mentioned in the review (Figure 3-3). Of course, the frequency a species is mentioned may be a function of several factors, including economic impacts, scientific understanding, societal/political sensitivity, cost of control and geographical and temporal factors. The latter is particularly important because focusing exclusively on highly publicised INNS that are widely established may ignore emerging threats that could be exacerbated by climate change (Hellmann et al., 2008). Nevertheless, it does reveal the broad focus of research and understanding in the field of INNS control and economic accounting.

0

1

2

3

4

5

6

7

8

European UK USA Spain Ireland /NorthernIreland

Multiple None

Count

Country focus of studies


Figure 3-3 - Top 20 INNS species most mentioned in the review (n=24).

3.2.2. Ecological impacts In addition to species specific factors, a range of ecological impacts were also noted (and can be mapped to damages to natural capital assets). These impacts have been categorised under five broad headings and their frequencies documented (Figure 3-4). The most frequently mentioned impacts were ‘alteration/damage to habitat’ (n=25) and ‘out-competing other species’ (n=22). Much less is documented on other ecological impacts of invasive species, suggesting either a gap in the literature or the consolidation of INNS impacts across these categories.

Figure 3-4 – Frequency ecological impacts are noted in the review (exc. non-European studies). Note, INNS ecological impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16).

0

2

4

6

8

10

12N

um

ber

of

mentions in r

evie

w

INNS common name


3.2.3. Impacts on ecosystem services Ecosystem services are the benefits people obtain from ecosystems. An overview of the high-level ecosystem service categories is documented in Box 3-1, where high-level represents the broad categorisations of services that can be disaggregated into further individual or ‘lower level’ services.

The ecosystem service impacts (see Table A-2 for a full description of ecosystem service categories) most frequently documented were supporting (n=29) and cultural services (n=27) – see Figure 3-5. Monetisation of cultural service impacts is challenging because these values are usually not captured in conventional economic markets, meaning the creation of (hypothetical) surrogate markets is often necessary to capture these values (discussed further in Section 3.3.1). Provisioning services were not the most mentioned (n=16), despite the fact they are often easier to account for since the impacts can be mapped directly to goods and services supplied in conventional markets. It is important to note that supporting services are typically valued through the other ecosystem service categories and so while there is merit in acknowledging these impacts, they ultimately will not complement monetary valuation (Defra, 2011).

Figure 3-5 - Frequency ecosystem service impacts are noted in the literature (exc. non-European studies). Note, INNS ecosystem service higher-level impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16).

0

5

10

15

20

25

30

35

Supporting Cultural Provisioning Regulating

Count

Ecosystem service (high-level)

Box 3-1 – Description of ‘high-level’ ecosystem service categories

Provisioning: The material benefits people obtain from ecosystems; for example, supply of food, water,

fibre, wood and fuels.

Regulating: The benefits obtained from the regulation of ecosystem processes; for example, the

regulation of air quality and soil fertility, control of floods and crop pollination.

Cultural: The non-material benefits people gain from ecosystems; for example, aesthetic inspiration,

cultural identity, sense of place and spiritual experience related to the natural environment. Typically,

opportunities for tourism and for recreation are also considered within this group.

Supporting: Services necessary for the production of all other ecosystem services; for example, by

providing plants and animals with living spaces, allowing for diversity of species, and maintaining genetic

diversity.


Aside from the higher-level ecosystem services, the QSR also documented the frequency that several lower-level service categories (derived from UN FAO (2019)) were noted in the literature. The most commonly noted lower level services from European studies only were maintaining genetic diversity (n=24); aesthetics (n=19); food (n=17); erosion prevention and maintenance of soil fertility (n=17) and biological control (n=10). Relatively little was documented for freshwater provision and tourism or recreation, despite the wide-ranging impacts INNS are known to have on these sectors.

Figure 3-6 - Frequency ecosystem services impacts are noted in the review (exc. non-European studies). Note, INNS ecosystem service lower-level impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16).

A matrix of species-specific impacts from INNS in Europe is documented in the information review spreadsheet that accompanies this report.

3.3. Economic impacts

3.3.1. Methodological approaches There are a range of ecological drivers that result in changes to ecosystem services provision and, ultimately, a reduction in societal benefits arising from ecosystem services. However, most economic analyses only consider the direct (market) cost of INNS and largely ignore the indirect and non-market costs associated with invasive species. McLaughlan et al. (2014) suggest that a surprisingly small proportion of papers relate INNS impacts (both in the UK and globally) to ecosystem services and human wellbeing. Most of the evidence of such impacts is currently in the form of technical reports, which often rely on expert consultation and generally extrapolate the ecological and economic costs of invaders across broad geographies.

The main valuation methods to estimate public preferences for changes in ecosystem services are revealed preference (RP) and stated preference (SP) methods. These approaches capture different elements of Total Economic Value (TEV) as denoted in Figure 3-7.

RP methods rely on data from conventional and surrogate markets regarding individuals’ preferences for marketable goods and services which include environmental attributes. For instance, people’s willingness to pay (WTP) for recreation sites can be approximated by the distance and time they are willing to spend to travel


to a site. RP methods include market prices, production function approaches, averting behaviour, hedonic pricing, travel cost method, and random utility modelling (Defra, 2011). Production function approaches have been widely applied in the field of INNS to value changes in provisioning services. At its simplest, this approach works by measuring the change in marketable output of goods and services (e.g. crop yield) as a result of environmental change (e.g. through the impact of invasive species). Damage cost avoidance represents a proxy method of estimating direct use values by appreciating the additional expenditures needed on items such as pesticides, herbicides or physical barriers.

SP methods use surveys to elicit individuals’ preferences, or WTP, for a given change in a natural resource or attribute through the construction of hypothetical markets. It is also possible to value individuals’ willingness to accept (WTA) compensation for changes in environmental quality. SP methods can be applied in a wide range of contexts and are the only methods that can estimate non-use values which can be a significant component of overall TEV for some natural resources. The main options in this approach are contingent valuation and choice modelling (Adamowicz et al., 1998).

Figure 3-7 - Different economic valuation techniques and their association with total economic value. Source: (Defra, 2011)

Importantly, Figure 3-7 shows that all these different valuation approaches can be used in benefits transfer. Benefits transfer is an approach for taking evidence on the value of benefits or damages from one context (the ‘study site’) and transferring it to another context (the ‘policy site’). The attraction of this process is to avoid conducting a primary study (which may be both time consuming and costly), if it is deemed robust enough to apply in the given policy context (Defra, 2011). An overview of valuation methods for ecosystem services is provided in Table A-3.

3.3.2. QSR results There has been limited work in the literature documenting the economic impacts of INNS (i.e. the costs to human welfare). Where there have been attempts, these focus almost exclusively on either direct market costs (n=3) or direct market and control costs (n=3) – see Figure 3-8. This reflects the difficulty inherent in approaches that aim to capture either indirect market costs or non-market costs (i.e. costs that impact welfare but do not affect goods and services sold in conventional economic markets).


Figure 3-8 – Frequency of economic costing approaches to capture INNS economic impacts noted in the review. Note, the economic costing approach was documented for each article that specifically denotes the economic impact of INNS (n=9).

A range of INNS ecosystem service impacts were identified in Section 3.2 and these can be mapped to different sectors (see Figure 3-9). The most commonly noted sector impacts were for agriculture (n=7); recreation (n=6); nature conservation (n=5); forestry (n=5) and tourism (n=4). This corresponds to the ecosystem service impacts most frequently noted in Figure 3-6. Identifying the sectoral impacts is important because it is the sectors that partially (and sometimes fully) bear the costs of invasive species impacts and need to implement mitigation measures to limit the damages arising from species establishment. Interactions across sectors may be an important consideration for understanding the costs and benefits of control measures.

Figure 3-9 - Frequency with which different sectors are noted across the studies. Note, sectors were documented for all articles reviewed (n=24).

A range of economic impacts were noted for INNS in Europe. Most frequently noted were landscape and amenity impacts (n=15); damage to infrastructure (n=9) and damage to fisheries and aquaculture (n=9). It is important to note that landscape and amenity impacts are mostly associated with cultural ecosystem services and these services mostly, though not exclusively, require valuation techniques that can capture both market

0

1

2

3

4

Direct marketcosts

Direct marketcosts and control

costs

Control costs Stated preferencesurvey

Count

Economic costing method

0

2

4

6

8

10

12

14

Count

Sector


and non-market values. The latter requires the application of more complex stated preference techniques. It is surprising that damage to agriculture was relatively infrequently mentioned, given that Williams et al. (2010) found INNS economic impacts in the agricultural and horticultural sector to be the most significant.

Figure 3-10 - Frequency of economic impacts noted for INNS (exc. non-European studies). Note, economic impacts were noted from each article for multiple INNS, hence the total count exceeds the number of papers reviewed (n=16).

3.3.2.1. Market impacts (use values)

Most studies exploring the economic impact of INNS focus on valuing direct market impacts, since direct impacts are generally much more obvious to the analyst (see Table 3-2 for an example of market and non-market impacts for the zebra mussel). Work by Williams et al. (2010) estimated the total current annual cost of INNS to the British economy at £1.7 billion. The work suggests INNS have by far the largest effect on the agricultural and horticultural sector, amounting to just under two thirds of the total estimated cost. A key limitation of this work is that the only costs that could be quantified in most instances are the direct market costs, such as the money spent on control measures or the reduction in productivity due to the presence of an INNS. Indirect costs constitute less than 1% of their total estimate. More work is therefore necessary to document these indirect and non-market costs which is important for evidence-based policy setting.

Findings from the QSR suggest the reported economic impacts for the top 14 most impactful INNS in the UK (and one example from Germany) range from £920 million (European rabbit) to £1 million per annum (signal crayfish) - see Table 3-3. These impacts are almost exclusively valued through production function approaches or damage cost avoidance. The valuations may reflect an element of accounting bias (i.e. the ease at which the direct economic impacts can be mapped and valued). Mapping these impacts to the respective ecosystem services is important to identify how the functionality of natural capital assets may be depleted as a result of INNS.

Many of the species documented in Table 3-3 are well-established invaders and little is documented on projected impacts over time, in addition to how the distribution of these impacts may vary i) regionally and ii) across different natural capital assets. This is important to optimise control efforts. Control efforts themselves are generally much less than the economic impacts of INNS4, suggesting controls are perhaps cost-effective. This is with the exception of signal crayfish, where control costs represent 880% of the reported economic impacts (control costs are also proportionally very high for Japanese knotweed). Where control costs are high this suggests a prioritisation exercise may be necessary to allocate resources regionally or sectorally (e.g. by taking a strategy of reducing the impacts on high value assets, where affordable). This could also be measured through the reduction in lost benefits that occur because of INNS.

4 It is unclear, however, whether the economic impacts refer to ‘unmitigated’ costs – i.e. what the costs would be under zero controls or whether they represent the residual costs under current control approaches.

0

2

4

6

8

10

12

14

16

Landscapeand amenity

impacts

Damage toinfrastructure

Damage tofisheries /

aquaculture

Damage toforestry

Damage toagriculture

Damage towater sector

Healthimpacts

Count

Economic impacts of INNS noted in review


Table 3-2 - Example of direct and indirect market impacts of the zebra mussel

Impact Examples References

Direct market impacts:

(−/+) They are efficient filter feeders and remove algae and microorganisms from the water. Some of the most common (man-made) systems in which they occur are reservoirs and water treatment works, where their presence has a direct effect on the water being supplied to the local population. The effect of the filtration directly on the water is to increase clarity and therefore improve water quality.

(−) Increased possibility of cyanobacterial algal blooms, caused by selective feeding pressure by zebra mussels. (−) Fouling of hard structures often affects water treatment infrastructure, as zebra mussels colonise anything from pipelines to filtration beds.

Reeders and Bij de Vaate (1990); Macisaac (1996); Higgins and Vander Zanden (2010); Lindahl et al. (2005); Orlova et al. (2004)

Direct non-market impacts:

(−) Competition with native species: Adverse effects on unionid molluscs through competition for space and food. Zebra mussels will grow directly on unionids and gradually kill them by preventing feeding and eventually causing them to sink into the sediment.

(+) Zebra mussels also represent a food source, for some waterfowl, fish and crayfish.

Aldridge et al. (2004); Sousa et al. (2011), Macisaac (1996)

Indirect market impacts:

(+) Zebra mussels cause major shifts in ecosystem function through selective and efficient feeding on phytoplankton, moving nitrogen and phosphorus from the pelagic zone. Several studies have addressed the idea of harnessing this quality in a positive manner for the bioremediation of eutrophic freshwaters.

(+) Zebra mussels could be harnessed to improve water quality in areas where algal blooms have reduced the aesthetic appeal and biodiversity of a water body.

(−) Large numbers of sharp shells could cause injury and impact on the amenity value of recreational areas. Cyanobacterial blooms can cause recreational areas to become unusable.

Goedkoop et al. (2010); Mackie and Wright (1994); Stybel et al. (2009); Antsulevich (1994)

Indirect non-market impacts:

(−/+) Ecosystem engineers: zebra mussels change the benthic habitat through biodeposition of organic material (pseudofaeces) and increase the surface area and complexity of the habitat with their shells. Some species of invertebrate benefit from the increased habitat/food source created whereas others show a decrease in diversity or abundance.

(−) Bioaccumulation of pollutants: zebra mussels can magnify organochlorine and metal contaminants through their filter feeding activities. As they can serve as a food source for fish and waterfowl, this could mean transfer of pollutants to higher trophic levels. Changes in zooplankton populations: Zooplankton may be adversely affected either directly or indirectly by D. polymorpha establishment. Small organisms such as rotifers and protozoans can show declines in population, although it is hard to disentangle the effects of direct consumption and suppression through competition for food. This may have a knock-on effect on food availability for some planktivorous fish. (−) Cyanobacterial blooms can be a risk to human and animal health

(+) Shift to a clear water state: A primary effect of this species is their tendency to drive systems to a clear-water, macrophyte-dominated state by reducing turbidity and allowing macrophytes to grow. Once macrophytes are present again this creates habitat for benthic invertebrates, and zebra mussel faeces provides food, completing the shift from pelagic to benthic food webs.

Stewart and Haynes (1994); Silver Botts et al. (1996); Nalepa et al. (2003); Reeders and Bij de Vaate (1992); Mersch and Pihan (1993); Chorus et al. (2000); Briand et al. (2003)


Table 3-3 - Economic impacts of INNS in UK from the review sources (n=7) ordered by the total annual economic impact. Note P=provisioning; R = regulating, C=cultural and S=supporting services.

INNS Ecosystem service impacts Monetised ecosystem service impacts

UK total annual market impact

Valuation method UK Annual Control Costs

Sources

P R C S P R C S

European rabbit x

£920 million

£920 million Market damages £188 million 3,4

Japanese knotweed

x

£166 million Market damages and control costs

£151 million 4,1

Potato cyst nematodes

x


4

Floating pennywort

x x x

£23.5 million

£23.5 million Market based costs to the

tourism sector £1.8 million 4,4

Zebra mussel x x Market based damages and control costs

£18.7 million 2

House mouse


4

Grey squirrel x

x x £10 million

£10 million Market damages £5 million 1,1

Rhododendron

x x

£8.6 million Market damages 4

Slipper limpet x

£5.5 million Market damages and control costs

4

American mink

x


4

Green spruce aphid x


4

Giant hogweed x £2.3 million Market damages and control costs

4

Signal crayfish

x x

£1 million

£1 million Direct market impacts to angling

£8.8 million 4,2

References: (1European Environment Agency, 2012; 2Oreska and Aldridge, 2011; 3Pimentel et al., 2001; 4Williams et al., 2010)


3.3.2.2. Non-market impacts (use and non-use values)

The non-market costs of INNS can be high in comparison to market costs (Colautti et al., 2006). Yet, few studies have documented these costs and Holmes et al. (2009) notes a large literature gap in accounting for non-market values of INNS control in decision-making.

García-Llorente et al. (2011) used a contingent valuation survey to document people’s WTP for INNS management under two management regimes (eradication and prevention) in Spain. Results indicated that respondents were willing to pay more for eradication than prevention programmes, and public support for invasive alien species management was influenced by an individual’s knowledge and perception of invasive alien species, active interest in nature, and socio-demographic attributes. The primary findings of this work included elucidating the different public motivations that influence support for different INNS management strategies and social factors underlying the WTP estimates. Building on this work in a UK context may provide important evidence concerning the public’s WTP for invasive species control and the policy outcomes most valued by society (e.g. reduced abundance of INNS in public amenity areas).

3.3.2.3. Control costs

Reported control costs in our review for the top 14 INNS in the UK (based on economic impact) range from £188 million (European rabbit) to £1.8 million per annum (floating pennywort) - see Table 3-3. Across some studies (e.g. Oreska and Aldridge, 2011; Williams et al., 2010) control costs are combined with market impacts, meaning the various components of ‘value’ and ‘cost’ require disaggregating. Control costs are of course species specific and the benefits of control will not only depend on the full economic impact of the invasive species in question, but also the scope and scale of future impacts (Holmes et al., 2009). Our review highlights a lack of literature documenting the estimated future economic impacts and associated control costs of INNS - an area that may be of growing importance given globalisation and climate change. The latter may be particularly important because climate projection models suggest range shifts are likely for various invasive species (Gallardo et al., 2017).

3.4. Targeting current actions to minimise current and future costs Resource allocation toward a given species relies on its relative invasiveness and the marginal cost of control. In this review, surprisingly little was documented concerning methods and models to identify optimal resource allocations for targeting controls. Site prioritisation is therefore an important area for further work. This includes deciding where and when to implement invasive species controls considering budget constraints and species interdependencies (Courtois et al., 2018). This includes work on early versus late eradication and the relative merits of each.

Work by Courtois et al. (2018) suggests funding should be allocated based on cost-effective strategies targeting species with a low rate of satellite colony generation and low propagule pressure5, with a focus on control rather than exclusion. For INNS control, the objective of the decision-maker can be to conserve the maximum number of native species, the most diverse set of species, the value of ecosystem services, the minimisation of economic impacts caused by invasive species, or a combination of these factors. The authors suggest prioritisation should be informed by the relative harmfulness of invasive species by accounting for indirect benefits and damages arising from species interactions. They note that optimal management of INNS consists of assessing the benefit–cost ratio of each invasion and identifying the invasive species with the highest ratios as priority management targets. Another important factor is the cost of the control option and the likelihood of success6.

3.5. Knowledge gaps This review suggests the calculation of INNS damages tends to focus on the loss of (market) use values, overlooking the impacts on non-market and non-use values. Although such values remain hard to evaluate, reduction in non-use values caused by INNS is likely to outweigh loss of use values by a considerable margin (Jackson, 2015). The following knowledge gaps are most prevalent in the literature:

Few studies in UK or Europe have employed the impact pathway approach (Defra, 2011) to identify the ecosystem services impacts of INNS and likewise the appraisal of different policy options to control

5 Propagule pressure (also termed 'introduction effort') is a composite measure of the number of individuals released into a region to which they are not native (Lockwood et al., 2005). 6 Work by Professor Bill Sutherland’s team at Conservation Evidence is starting to provide a very useful resource for informed management-decisions for INNS control (see www.conservationevidence.com).


INNS. This would provide an important first step towards taking an ecosystems approach to INNS control.

Climate change is emerging as a key driver of species range shifts. This may impact INNS prevalence in the UK and the economic costs and benefits of implementing control strategies. Employing scenario analysis to document how species range shifts may affect the ecosystem service provision and associated INNS control costs is an area for further work.

The costs of controlling INNS are poorly documented for future costs. Further work should explore how these costs might change temporally and regionally to guide future investments in INNS control.

The monetary valuation of INNS impacts through an ecosystem services approach is currently lacking. Most approaches to date have focused on sectors rather than services. More attention to services is needed to consider the full range of control benefits.

Most economic valuation to date has focused on direct, market costs and largely ignores the non-market welfare costs of INNS. This is important because the non-market benefits of INNS control (e.g. recreation) may be much greater than the direct market cost. Methodological valuation approaches that capture both use and non-use values that span the TEV spectrum are needed.

Natural capital takes an asset-based approach to managing natural resources. Yet, there is little mention in the literature of how INNS may impact natural capital (but rather a focus on ecosystem services almost exclusively). Arguably, the sector approach documented by Williams et al. (2010) goes some way to doing this but further work is needed to develop asset and risk registers for the UK’s natural assets that include consideration of INNS impacts. These can then be related to the ecosystem service impacts and values.

The benefits and effectiveness of implementing control strategies should be used in decision-making concerning prioritisation and resourcing. A potential methodological approach for rationalising investments in INNS control is documented by Courtois et al., (2018). Further work in this area that considers both temporal and regional differences would be consistent with the approach documented in the 25 Year Environment Plan (Defra, 2018).

There is little work currently documenting public WTP for invasive species control and associated preferences for control strategies (e.g. geographical scope and measures). Building on stated preference work by García-Llorente et al. (2011) in a UK context may provide important evidence concerning WTP for invasive species control that considers both use and non-use values.


4. Stakeholder workshop

4.1. Overview The aim of the workshop was to document stakeholder views and perspectives on a range of factors surrounding invasive species ecological and ecosystem service impacts. The workshop explored how these impacts affect the UK’s natural capital assets in the context of the Office for National Statistics (ONS) national natural capital accounts (ONS, 2019). Participants were split into two sector-based groups for each workshop activity:

Activity 1: Experts were asked to discuss the impacts of INNS in terms of four high-level natural capital assets. These high-level assets included freshwater, woodland, farmland and urban areas, as these represent the broad categories underpinning the ONS Natural Capital Accounts.

Activity 2: Experts discussed future priorities for documenting the market and non-market impacts of INNS through an ecosystem services approach. Additional information was gathered concerning methodological approaches for monetising these impacts and relevant sources (if any) that may be useful for informing further work.

In total, 12 experts attended the workshop with an interdisciplinary mix of expertise (see Table B-5 in Appendix B).

4.2. Ecosystem services impacts The workshop identified a range of ecosystem service impacts arising from INNS according to different natural capital assets (see Appendix B for a full overview). The main findings for the natural capital assets were:

Plantation forests: Main ecosystem service impacts are focused on a reduction in provisioning services that impact the forestry sector. The notable INNS include non-native deer, tree health pests, grey squirrel and rhododendron.

Semi-natural forests: Main ecosystem service impacts are on regulating and cultural services that impact the forestry, farming and recreation sector. The notable INNS include non-native deer, grey squirrel, edible dormouse, rhododendron, Himalayan balsam and tree pests.

Wetlands: Main ecosystem service impacts are on regulating and cultural services that impact the water and agricultural sectors. The notable INNS include riparian plants, swamp stonecrop and American mink.

Open water: Main ecosystem service impacts are on provisioning and cultural services that impact the water, recreation and tourism sectors. The notable INNS include floating pennywort, zebra mussels, quagga mussels, signal crayfish, American mink and Canada geese.

Arable, horticultural and improved grassland: Main ecosystem service impacts are on provisioning and regulating services that impact the agricultural sector. The notable INNS include non-native deer, grey squirrel, rabbits, parakeets, non-native weeds and nematodes.

Rough grazing: Main ecosystem service impacts include provisioning, regulating and cultural services that impact the agricultural and recreation sectors. The notable INNS include rhododendron and gunnera.

Urban areas: Main ecosystem service impacts are on provisioning, regulating and cultural services impacting the construction and transport sectors. The notable INNS include Japanese knotweed, buddleia, rats, grey squirrel, tree of heaven, parakeets, racoon dog, terrapins and eucalyptus.

4.3. Methodological approaches, priorities and data sources During the second activity participants were divided into the same two groups and discussed methodological approaches, priorities and data sources for undertaking a full natural capital assessment of INNS impacts. The sections below summarise the key points raised by the workshop participants.

4.3.1. Provisioning services Impacts on some aspects of provisioning services (e.g. agricultural production) are relatively well-

understood compared to others (e.g. aquaculture and fisheries).


Water companies have undertaken a large amount of research on the natural capital value of water which could be used to inform a natural capital assessment. Water companies are also affected as landowners as well as in their role in supplying water and wastewater services.

4.3.2. Regulating services Reporting on project outcomes for projects supported by EU funding (e.g. Moors for the Future and

their work on rhododendron clearance) may provide some data relating to the carbon sequestration impact of INNS control activities.

The impact of events such as storms and Foot and Mouth disease could be used to infer the impact of INNS in monetary terms.

There is a need to focus valuation approaches on erosion regulation and regulation of water flows, where much less is documented.

4.3.3. Cultural services The Environment Agency’s National Water Environment Benefits Survey (NWEBS) benefit values per

kilometre for each catchment have been used by the water industry to look at scenarios for ecological status change of catchments and could be used for valuing of INNS impacts on the water environment.

Recreational value could be captured using existing datasets (e.g. on the value of trees and Natural England’s MENE datasets7) and assuming a loss of value.

Imperial College has undertaken research on the loss of trees due to INNS in France.

4.3.4. Supporting services It would be challenging to extract the value of protecting particular species from INNS impacts based

on conservation funding levels.

What about indirect ecosystem impacts of INNS on genetic diversity? E.g. the impact of rat infestations

on remote islands that now impact bird colonisation in the UK.

Impacts of INNS on the food web. Species such as signal crayfish, demon shrimp and killer shrimp

appear to remove key components of the invertebrate food web and some authors have speculated

that this is likely to affect the ability of river ecosystems to process organic matter (and reduce their

capacity to act as a sink for organic pollution).

4.3.5. Control and maintenance costs There is a need to determine what we should be paying for INNS control rather than what we are

paying. This includes public preferences, or WTP, for INNS control. Current spending on INNS is driven by affordability but not necessarily the optimised investment in INNS control relative to the loss of benefits that occur because of colonisation. Measuring what should be spent (including public preferences for spending on INNS control) may therefore be desirable.

4.4. Consideration of whether the natural capital framework is useful in the context of INNS

The broad consensus among delegates was that applying a natural capital framework to value INNS impacts is useful for the following reasons:

To determine how much INNS control is desirable / necessary and where (regionally) control strategies would be most cost-effective.

To complement the natural capital and ecosystem services approach that underpins the 25 YEP.

Concerns were raised surrounding the following factors:

7 Monitor of Engagement with the Natural Environment; see https://www.gov.uk/government/collections/monitor-of-engagement-with-the-natural-environment-survey-purpose-and-results [Accessed April 2019]

https://www.gov.uk/government/collections/monitor-of-engagement-with-the-natural-environment-survey-purpose-and-results

https://www.gov.uk/government/collections/monitor-of-engagement-with-the-natural-environment-survey-purpose-and-results


Stated versus revealed preferences? The mechanics of valuation approaches are important and need

to be transparently reported. For instance, studies that suggest people are usually WTA more in

compensation than they are WTP to prevent damages.

Indirect ecosystem service impacts are important but difficult to measure. This will likely lead to an under estimate of the natural capital impacts, e.g. cultural value.


5. Scoping the implementation of the natural capital approach

5.1. Review of potential approaches A review of potential approaches to monetise the impacts of INNS is documented in Table 5-1. The table suggests the most noteworthy monetising approaches, input datasets (where applicable) and the expected resource requirement for each approach based on expert judgement. Example references in the table are based on a review of the approaches employed in the literature sources identified within the QSR and other relevant references noted within these.

There may be complementary overlap across monetising approaches and where applicable this could reduce the resource requirement, particularly where the relevant input datasets are also mirrored. Generally, revealed preference (RP) valuation methods feature a lower resource need in contrast to stated preference (SP) methods. As formerly noted, provisioning services are perhaps simplest to account for and monetise, while regulating, cultural and supporting services are technically more challenging. While this table documents supporting services, we do not recommend such services are monetised given general consensus across the economic community that highlights a range of issues surrounding monetisation, including double counting (TEEB, 2010).


Table 5-1 – Overview of potential monetisation approaches for various ecosystem services and economic impacts with relation to INNS

Ecosystem service affected

Most impacted sector

Noteworthy monetising approach

Example references that have

used a similar approach

Already done at the UK

level?

Example input datasets

Resources required (H/M/L)

Priority for further work?

Provisioning services

Food Agriculture

Production function - Estimated reduction in yields to agriculture, horticulture and aquaculture –

literature search with some primary data collection (e.g.

questionnaire/surveys).

Averting behaviour - Control costs (e.g. due to higher pesticide

or herbicide use) would be captured under ‘other economic

impacts’ below.

Williams et al. (2010) – CABI

report

Pimentel et al. (2001)

✔

Defra farming statistics (2018)

Agriculture in the United Kingdom (2017) dataset

M – INNS impacts on agricultural

production are relatively well

defined. Valuation relies

on adjusted market prices.

-

Raw materials Forestry

Production function - Estimated reduction in yields or value of timber – literature search with

some primary data collection (e.g. questionnaire/surveys)


report

Pimentel et al. (2001)

✔

Forestry Statistics and

Forestry Facts & Figures from

Forest Research (2018)

M – INNS impacts on

forestry production are relatively well

defined. Valuation relies

on adjusted market prices.

-

Freshwater Water Market prices - Cost of

replacement of water Zavaleta (2000)

✖

Water quality and abstraction

statistics (2013)

L – Direct market prices can be used to

proximate impact.

++

Medicinal resources

Unknown

Replacement costs - Costs of

artificial production of resource.

Cost of alternatives - Health

cost due to lack of resource.

None found ✖ n/a

H – relatively little is known concerning

INNS impacts

-

https://www.gov.uk/government/collections/food-farming-and-bio-security-statistics


https://www.gov.uk/government/collections/agriculture-in-the-united-kingdom



https://www.forestresearch.gov.uk/tools-and-resources/statistics/forestry-statistics/






https://www.gov.uk/government/collections/water-quality-and-abstraction-statistics










level?




on medicinal resources.

Regulating and maintenance services

Local air quality Health

Dose response - Estimate of reduction in air quality pollution mitigation due to damage to or

loss of trees and other vegetation.

None found ✖

Air quality and emissions statistics

Defra air quality damage costs

M – The impacts of

INNS on air quality are

poorly documented.

-

Carbon sequestration and storage

UK Public

Damage costs - Estimate of reduction in carbon sequestration and storage due to damage to or loss of trees and other vegetation

(non-market value).

None found ✖

UK greenhouse gas emissions

national statistics 2018

Non-traded price of carbon (BEIS)

L – There is an established traded and non-traded

price for carbon in the EU and

UK respectively but INNS

impacts on sequestration are less well documented.

++

Moderation of extreme events

See regulation of water flow for example for storms and flooding.

Wastewater treatment

Water

Averting behaviour - Additional costs of water treatment by water

companies.

Random utility / discrete choice models - Recreational impacts from changes in water quality

None found ✖ Water industry

research

H – Data is not readily

available and would rely on respondent surveys and

++

https://www.gov.uk/government/collections/air-quality-and-emissions-statistics



https://www.gov.uk/government/statistics/provisional-uk-greenhouse-gas-emissions-national-statistics-2018




https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/48184/3136-guide-carbon-valuation-methodology.pdf

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/48184/3136-guide-carbon-valuation-methodology.pdf








level?




captured through cultural services.

econometric modelling.

Erosion prevention and maintenance of

soil fertility

Agriculture

Contingent valuation / choice modelling - Reduction in

landslips and unstable riverine habitat that degrades ecosystems

(aesthetic values).

Production function - Estimated reduction in crop yields due to

reduction in soil fertility.

None found ✖

n/a



H – little is currently known

concerning these impacts and valuation methods are technically

difficult.

+

Pollination Agriculture Production function - Estimated

reduction in crop yields due to loss of native pollinators.

None found ✖



L – economic valuation of

pollination on provisioning services is

relatively well documented.

However, data availability for disaggregating impacts due to

INNS is uncertain.

+

Biological control

Agriculture

Cost of alternatives - Estimated cost of pest control measures due

to presence of INNS outcompeting native pest control

species (i.e. not direct control costs which would be captured under ‘other economic impacts’

None found ✖ n/a

M – Little is currently known concerning the

cost of biological

control impacts of INNS. The

-


















level?




below), or loss of agricultural yields

impacts themselves are

also challenging to

monetise.

Regulation of water flow

Infrastructure

Damage costs avoided - Estimate of flood damages

caused by presence of INNS (predominantly market cost)

Zavaleta (2000)

✖ n/a

M – Impacts of INNS on water regulation are

scarcely documented. Additionally,

(flood) tipping points are not well known.

+

Supporting services

Habitat for species /

Maintenance of genetic

diversity8

Conservation sector

Contingent valuation / choice modelling - Assess WTP to

protect an ecosystem or species from INNS or WTA damages.

Mentioned in Jackson

(2015) but does not

contain any values.

Contains arguments

against using this approach.

✖ n/a

H – construction of

hypothetical market and

survey is time consuming.

Choice modelling is challenging.

++

Value transfer - Using WTP studies from a different context

but that can be adapted.

Referenced in Williams et al.

(2010) but data available found

✖

Environmental Valuation Reference Inventory

L – Identifying a suitable

transfer value can be

++

8 Although this service is included under supporting services within the FAO ecosystem services framework used here, in some other frameworks biodiversity/non-use or existence value is included as a cultural service, and it is often included within valuation studies.

https://www.evri.ca/











level?




to be very limited

challenging but the approach is

relatively simple when impacts are well defined.

Averting behaviour - Funding spent on conservation –

assuming this reflects the benefits of protecting a particular species.

Sinden et al (2004)

✖ n/a

M – Identifying direct and

indirect economic

spend related to INNS and countryside

conservation is likely to be

challenging. Workshops / focus groups

would likely be necessary.

+

Cultural services

Recreation and tourism

Tourism and recreation

Market prices - Estimate of lost revenues (market costs, e.g.

relating to angling) using literature search and/or primary data

collection.


report

✔

L – Market prices are well established for

various recreation and

tourism activities.

-

Value transfer - Estimate of lost use values (i.e. non-market

impacts) relating to recreation.

Williams et al. (2010) – CABI report, floating

✖

Environmental Valuation Reference Inventory

L – Identifying a suitable

transfer value can be

challenging but

++












level?




pennywort example

Outdoor Recreation

Valuation Tool (ORVal)

the approach is relatively

simple when impacts are well defined.

Contingent valuation / choice modelling - Estimate of lost use values (i.e. non-market impacts)

relating to recreation.

None found ✖ n/a

H – construction of

hypothetical market and

survey is time consuming.

Choice modelling is challenging.

-

Aesthetics Tourism and

recreation

See recreation and tourism. May be challenging to distinguish

costs and benefits from closely related cultural services.

Hedonic pricing - Impacts on aesthetic value surrounding

housing could be captured using a hedonic pricing approach –

either using primary or secondary data.

n/a ✖

Office for National

Statistics - Hedonic Pricing Method (HPM) methodology

note

M – Hedonic pricing is a

well-established

methodological approach but defining the

relevant impacts on

property prices may be

challenging.

-

Sense of place Tourism and

recreation

See recreation and tourism. May be challenging to distinguish

costs and benefits from closely related cultural services.

n/a ✖ n/a n/a -

Other economic impacts

https://www.leep.exeter.ac.uk/orval/




https://www.ons.gov.uk/economy/environmentalaccounts/methodologies/valueofnatureimplicitinpropertypriceshedonicpricingmethodhpmmethodologynote














level?




Direct control, prevention and maintenance

costs

Multiple sectors

Market prices - Literature search

Williams et al. (2010) – CABI report took a

sectoral approach.

Oreska and Aldridge

(2011) look at financial

impacts of freshwater invasive species.

Range of other studies from the literature

✔ n/a

L – A rapid literature

search may identify suitable

control costs rapidly, though this depends

on the scope of the search.

-

Multiple sectors

Market prices - Questionnaire and interviews with key

organisations to calculate costs for individual species, followed by

expert review


report used this approach

✔ n/a

M - Implementing stakeholder

surveys is likely to be time

consuming.

-

Housing devaluation

UK Public Market prices - Literature search

and/or primary data collection



✔ n/a

L – Identifying impacts and aggregating over affected population.

-

Cost of collisions

(damage and delay costs);

e.g. bird strikes,

Transportation Market prices - Literature search




✔ n/a


search may identify suitable costs rapidly,

-








level?




collisions of vehicles with

non-native deer species, non-native trees

falling on power lines, leaves

falling on rails

though this depends on the

scope of the search.

Constraining development

(e.g. delayed/refused

planning applications

due to presence of

INNS)9

Infrastructure Market prices - Literature search


Approach mentioned by Williams et al. (2010) but no data available

✖ n/a


search may identify suitable costs, though this depends

on the scope of the search.

-

Human health costs

(excluding ecosystem

service costs above),

including individual

impacts and NHS costs10

Health Damage costs - Literature search and/or primary data

collection



✔ n/a


search may identify suitable costs rapidly, though this

depends on the scope of the

search.

-

Note: Ecosystem service categories were categorised according to UN FAO (2019). Key: ++ Strategic priority for further work; + moderate priority for further work; - not a priority for further work.

9 This is an indirect cost which is ultimately an artefact of development policy. 10 Disease regulation is sometimes referred to as a regulating ecosystem service within some frameworks.


5.2. Recommendations for undertaking a natural capital assessment

5.2.1. Identifying a need Natural capital is a framework for environmental economic accounting that can be used to appreciate the value of assets and the distribution of those values. The Natural Capital Committee (2017) has identified three general decision contexts for which information on the value of natural capital and its services is useful. This is important for contextualising the overarching goal from conducting such an assessment. They are:

Determining priorities for investments in natural capital;

Determining actions affecting natural capital to (i) achieve target improvements; (ii) avoid deterioration; or (iii) compensate for losses;

Determining overall progress with objectives to protect and improve natural capital (including at the regional and aggregate level).

Within any future study it will be important to first establish the primary decision context for the assessment. A further study to assess the current natural capital impacts of INNS is most aligned with the first decision context. A scenario-type analysis exploring anticipated changes to impacts due to different management approaches would be more aligned to the second decision context. A further analysis (once a baseline had been undertaken) would be possible in line with the third decision context and aligns with Defra’s work on natural capital indicators under the 25 YEP.

5.2.2. Schematic approach Figure 5-1 maps out a potential schematic approach to document the current (baseline) impacts of INNS on natural capital assets taking a long-term approach. This is important because the timing between an impact on the stock and its translated impact on service/benefit flows could differ. The approach could be regionally focused (and potentially habitat driven) to be consistent with the 25 YEP and provides comparable value estimates on a per km2 basis. This is important to ensure that the natural capital approach can be complemented by cost-effectiveness analysis to identify the most cost-effective interventions to control / eradicate INNS while also considering restoration costs. More complex analysis may employ various scenarios to identify how a change in the abundance of some INNS (e.g. relative to climate change) may impact both natural capital and the cost of control, through a regional lens.

Figure 5-1 - Schematic approach to documenting the long-term natural capital impacts of INNS


5.2.3. Documenting a path forward Building on this scoping review, we suggest a two-phase approach that a more detailed study might focus on, through application of the schematic approach outlined in Figure 5-1. While the two phases are complementary they could also be standalone:

1. Phase 1 - Identify case study / pilot area(s) to trial the schematic approach. This should focus on geographically distinctive areas where both the impact drivers and natural capital assets face different management challenges. To complement the 25 YEP, this could focus on the four Pioneer projects that are already using natural capital approaches to inform land management strategies (Natural Capital Committee, 2019). Initially, the Phase 1 analysis could focus on a sub-set of ecosystem services thought to be most feasible and impactful (identified below) to document the baseline. In parallel, the analysis could consider work to acquire insight into the cost of controlling/eradicating relevant INNS according to each natural capital asset. The benefits could then be compared with spatially-driven assessment of control/eradication and restoration costs to identify value for money actions.

2. Phase 2 - Drawing on the analysis in Phase 1, undertake a national natural capital assessment of INNS impacts. The second phase of analysis will aggregate the findings from Phase 1 to a national scale through a high-level analysis of INNS impacts on natural capital. Importantly, this will draw on learning in Phase 1 concerning identification of impact pathways and valuation approaches to different natural capital asset types and the regional distinctiveness/importance of those assets (e.g. the economic value of rural landscapes in the Cotswolds is inherently different from rural Cambridgeshire). Again, the assessment could be complemented by work to better document the control costs of INNS.

Indicative costs are provided in Appendix C.

Phases 1 and 2 will be supported by the following actions:

A. Engage with sectors to understand the spectrum of economic impacts arising from INNS. This should include identification of datasets that can be employed to quantify the scale and magnitude of such impacts through a regional approach. Datasets for aggregating such impacts at the national level should also be identified.

B. Across the different ecosystem services, the relative feasibility and resources needed to


provisioning services, meaning a relatively simple accounting exercise is needed (i.e. adjustment of

market outputs and associated income relative to INNS impacts) and should focus on provision of

freshwater. For regulating services, the picture is somewhat more complex. Quantification of regulating

services may be achieved most efficiently by focusing on carbon sequestration and waste water

treatment (i.e. water quality). For cultural services, the impact pathways and associated changes to

marginal welfare are less well understood. We therefore suggest focusing on recreation and tourism

services, where the feasibility of documenting monetary estimates is greatest.

C. Undertake planning for scenario modelling. Scenario modelling has emerged as a powerful conceptual framework to document the likelihood and severity of future impact pathways. Work by Courtois et al. (2018) shows that optimal management of INNS should consider the benefit-cost ratio of each invasion and identify the invasive species with the highest ratios as priority management targets. Optimising the allocation of funds to control INNS through multiple invasion pathways is a key area of further work. Resource allocation toward a given species should consider its relative invasiveness and the marginal cost of control. Other factors to consider include 1) the likelihood of re-invasion, and 2) the stage in the invasion process. Combining species distribution models for current and future climate scenarios, along with comprehensive estimation of the full economic costs of INNS alongside the effectiveness of control cost for different management strategies would mark a key advancement in evidence-based management decisions for UK INNS.

5.2.4. Suitability of the natural capital framework Natural capital is emerging as the core conceptual approach for delivering the UK Government’s ambitions stated in the 25 YEP, namely “to be the first generation to leave the natural environment in a better state than it inherited”. Employing a natural capital approach to account for INNS impacts is important for the following

reasons:

1. To raise awareness of INNS impacts and the need for strong biosecurity;

2. Engaging with industry to develop proposals to drive improvements in ecosystems;


3. To identify priorities for investment in control and eradication programmes;

4. Evaluate overall progress to protect and improve natural capital with reference to INNS impacts.

We suggest undertaking a natural capital approach to account for INNS impacts is beneficial and will address multiple gaps in the literature concerning our appreciation of such impacts, and how they are distributed regionally. Most notably, there are significant indirect and non-market impacts that are not currently visible to decision-makers, meaning the allocation of resources for control measures may be sub-optimal.

Addressing this gap is consistent with Key Action 3.1 in the Great Britain Invasive Non-native Species Strategy (Defra, 2015) to “develop a robust approach to prioritising pathways based on potential impact of the species introduced and the effectiveness of pathway management”. Indeed, the optimal allocation of resources for various impact pathways is also likely to vary regionally, particularly with the impacts of climate change (Gallardo et al., 2017) that may currently be unaccounted for in decision-making.


6. Conclusions and recommendations This report provides a two-part scoping review for appraising the impacts of INNS in the UK through an ecosystem services and natural capital approach. Part 1 (Section 3) documents the evidence arising from the Quick Scoping Review (QSR) concerning our current knowledge of the ecosystem service impacts of INNS. Part 2 (Sections 4-5) scopes out the potential for implementing a natural capital approach to monetise the impacts of INNS in the UK and ultimately considers whether such an approach ‘adds value’ to decision-making concerning INNS control in the UK.

The main findings from Part 1 (the QSR) are as follows:

1. The main INNS ecosystem impacts of relevance to the UK arise from alteration / damage to habitat and out-competing other species. The most frequently noted INNS from the QSR were the coypu, Canada goose, zebra mussel, and American mink. Some ecosystem impacts for these INNS are denoted in Table 1-1 in the Executive Summary.

2. The most frequently noted ecosystem service impacts in the UK and Europe relate to supporting

and cultural services, which most frequently refer to maintenance of genetic diversity and aesthetic

values, respectively. Impacts on supporting services are generally associated with INNS impacts on

ecosystem condition/functioning.

3. The majority of economic studies document the economic impacts of INNS as a function of direct

market cost. The sectors most impacted by INNS are agriculture, recreation, nature conservation

and forestry. These correspond well with the UK’s current ONS National Natural Capital Accounts

(i.e. the translation of values would be relatively straightforward).

4. The main economic impacts of INNS identified in the review correspond to cultural (landscape and

amenity) impacts; damage to infrastructure and damage to fisheries/aquaculture.

5. Findings from the QSR suggest the economic impacts for the top 14 most impactful INNS in the UK

range from £920 million (European rabbit) to £1 million per annum (signal crayfish). These reported

impacts are almost exclusively valued through production function approaches or damage cost

avoidance.

6. Control costs are generally much less than the economic impacts of INNS, suggesting controls are

perhaps cost-effective. This is with the exception of signal crayfish, where control costs represent

880% of the economic impacts (control costs are also proportionally very high for Japanese

knotweed).

7. Overall, a range of knowledge gaps were identified including the need to measure non-market and

indirect impacts of INNS to capture the full spectrum of economic impacts; the benefits of taking a

natural capital approach that facilitates rationalisation of control efforts for INNS and finally the need

to measure public willingness-to-pay for INNS control that could be used to validate current

spending on control strategies. Additionally, very little was documented on the costs of natural

capital restoration after INNS control/eradication.

The main recommendations from Part 2 (scoping the natural capital approach) are as follows:

8. We suggest undertaking a natural capital approach to account for INNS impacts is beneficial

and will address multiple gaps in the literature concerning marginal changes to welfare arising from

INNS, and how such changes differ regionally. There are significant indirect and non-market

impacts that are not currently visible to decision-makers, meaning the allocation of resources for

control measures may be sub-optimal.

9. Across the different ecosystem services, the relative feasibility and resources needed to


provisioning services, meaning a relatively simple accounting exercise is needed (i.e. adjustment of

market outputs and associated income relative to INNS impacts) and should focus on provision of

freshwater. For regulating services, the picture is somewhat more complex. Quantification of

regulating services may be achieved most efficiently by focusing on carbon sequestration and

waste water treatment (i.e. water quality). For cultural services, the impact pathways and

associated changes to marginal welfare are less well understood. We therefore suggest focusing on

recreation and tourism services, where the feasibility of documenting monetary estimates is

greatest.

10. Implementation of a natural capital assessment could be developed in two phases. Phase 1

could identify case study projects to trial the schematic approach we have outlined (Figure 5-1). To


complement the 25 YEP, this could focus on the four Pioneer projects that are already using natural

capital approaches to inform land management strategies. Phase 2 would then draw on the

analysis in Phase 1, to undertake a scaled-up national natural capital assessment of INNS impacts

that complements work undertaken by the ONS on constructing National Natural Capital Accounts

(ONS, 2019). While both phases are complementary, they may also be undertaken as a standalone

assessment. We have costed this two-phase approach in Table C-1, which provides costs for

Phase 1, Phase 2 following completion of Phase 1, and Phase 2 as a standalone project.

11. Undertaking a natural capital assessment as a vehicle to prioritise investments in INNS

control strategies. Taking the approach outlined here means such investments can be

disaggregated regionally and across the relevant natural capital assets where cost-effectiveness of

interventions is maximised. The benefits of taking action need to be compared with the assessment

of control/eradication and restoration of natural capital assets to identify value for money.

12. Complementing the natural capital baseline assessment with further scenario analysis will

deliver added value. Climate change is emerging as a key factor in INNS spread and distribution

that is influenced by strategic control efforts. Developing a broader conceptual understanding of the

natural capital impacts of INNS through future scenario planning will promote proactive rather than

reactive management strategies that can be optimised relative to societal welfare.


7. References Adamowicz, W., Boxall, P., Williams, M., Louviere, J., 1998. Stated preference approaches for measuring

passive use values: choice experiments and contingent valuation. Am. J. Agric. Econ. 80, 64–75.

Aldridge, D.C., Elliott, P., Moggridge, G.D., 2004. The recent and rapid spread of the zebra mussel (Dreissena polymorpha) in Great Britain. Biological Conservation 119, 253-261.

Antsulevich, A.E., 1994. Artificial reefs project for improvement of water quality and environmental enhancement of Neva bay (St. Petersburg county region). Bulletin of Marine Science 55, 1189– 1192.

Briand, J-F., Jacquet, S., Bernard, C., Humbert, J-F., 2003. Health hazards for terrestrial vertebrates from toxic cyanobacteria in surface water ecosystems. Veterinary Research 34, 1–17.

Chorus I, Falconer IR, Salas HJ, Bartram J. 2000. Health caused by freshwater cyanobacteria in recreational water. Journal of Toxicology and Environmental Health 3, 323–347

Colautti, R.I., Bailey, S.A., Van Overdijk, C.D.A., Amundsen, K., MacIsaac, H.J., 2006. Characterised and projected costs of nonindigenous species in Canada. Biol. Invasions 8, 45–59.

Collins, A., Coughlin, D., Miller, J., Kirk, S., 2015. The Production of Quick Scoping Reviews and Rapid Evidence Assessments. A how to guide.

Courtois, P., Figuieres, C., Mulier, C., Weill, J., 2018. A Cost–Benefit Approach for Prioritizing Invasive Species. Ecol. Econ. 146, 607–620. https://doi.org/https://doi.org/10.1016/j.ecolecon.2017.11.037

Defra, 2018. A Green Future: Our 25 year plan to imrpove the environment. London, UK.

Defra, 2015. The Great Britain Invasive Non-native Species Stratergy.

Defra, 2011. An introductory guide to valuing ecosystem services. London, UK.

European Environment Agency, 2012. The impacts of invasive alien species in Europe.

Gallardo, B., Aldridge, D.C., González‐Moreno, P., Pergl, J., Pizarro, M., Pyšek, P., Thuiller, W., Yesson, C., Vilà, M., 2017. Protected areas offer refuge from invasive species spreading under climate change. Glob. Chang. Biol. 23, 5331–5343.

García-Llorente, M., Martín-López, B., Nunes, P.A.L.D., González, J.A., Alcorlo, P., Montes, C., 2011. Analyzing the social factors that influence willingness to pay for invasive alien species management under two different strategies: eradication and prevention. Environ. Manage. 48, 418–435.

Goedkoop, W., Naddafi, R., Grandin, U., 2011. Retention of N and P by zebra mussels (Dreissena polymorpha Pallas) and its quantitative role in the nutrient budget of eutrophic Lake Ekoln, Sweden.

Biological Invasions 13, 1077–1086.

Hellmann, J.J., Byers, J.E., Bierwagen, B.G., Dukes, J.S., 2008. Five potential consequences of climate change for invasive species. Conserv. Biol. 22, 534–543.

Higgins, S.N., Vander Zanden, M., 2010. What a difference a species makes: a meta-analysis of dreissenid mussel impacts on freshwater ecosystems. Ecological Monographs 80(2), 179–196.

Holmes, T.P., Aukema, J.E., Von Holle, B., Liebhold, A., Sills, E., 2009. Economic impacts of invasive species in forests: Past, present, and future. Ann. N. Y. Acad. Sci. https://doi.org/10.1111/j.1749-6632.2009.04446.x

Jackson, T., 2015. Addressing the economic costs of invasive alien species: Some methodological and empirical issues. Int. J. Sustain. Soc. 7, 221–240. https://doi.org/10.1504/IJSSOC.2015.071303

Lindahl, O. et al., 2005. Improving marine water quality by mussel farming: a profitable solution for Swedish society. Ambio 34(2), 131–8

Lockwood, J.L., Cassey, P., Blackburn, T., 2005. The role of propagule pressure in explaining species invasions. Trends Ecol. Evol. 20, 223–228.

Macisaac, H. J., 1996. Potential abiotic and biotic impacts of zebra mussels on the inland waters of North America. American Zoologist 299, 287-299.

Mackie, G.L., Wright, C.A., 1994. Ability of the mussel, Dreissena polymorpha, to biodeposit and remove

phosphorus and BOD from diluted activated sewage-sludge. Water Research 28(5), 1123-1130.

McLaughlan, C., Gallardo, B., Aldridge, D.C., 2014. How complete is our knowledge of the ecosystem services impacts of Europe’s top 10 invasive species? ACTA OECOLOGICA-INTERNATIONAL J. Ecol. 54, 119–130. https://doi.org/10.1016/j.actao.2013.03.005


Mersch, J., Pihan, J-C., Pihan, J., 1993. Simultaneous assessment of environmental impact on condition and trace metal availability in zebra mussels Dreissena polymorpha transplanted into the Wiltz River, Luxembourg . Comparison with the aquatic moss. Archives of Environmental Contamination and Toxicology 364, 353–364.

Nalepa, T.F. et al., 2003. Trends in the benthic macroinvertebrate community of Saginaw Bay, Lake Huron, 1987 to 1996: responses to phosphorus abatement and the zebra mussel, Dreissena polymorpha.

Journal of Great Lakes Research 29(1), 14–33

Natural Capital Committee, 2019. State of Natural Capital Annual Report 2019. Sixth Report to the Economic Affairs Committee of the Cabinet.

Natural Capital Committee, 2017. Economic valuation and its applciations in natural capital management and the Government’s 25 Year Environment Plan.

ONS, 2019. Natural Capital. An overview of the Office for National Statistics and Department for Environment, Food and Rural Affairs natural capital project and all related publications [WWW Document]. URL https://www.ons.gov.uk/economy/nationalaccounts/uksectoraccounts/methodologies/naturalcapital (accessed 4.2.19).

Oreska, M.P.J., Aldridge, D.C., 2011. Estimating the financial costs of freshwater invasive species in Great Britain: a standardized approach to invasive species costing. Biol. Invasions 13, 305–319. https://doi.org/10.1007/s10530-010-9807-7

Orlova, M. et al., 2004. Dreissena polymorpha (Bivalvia: Dreissenidae) in the Neva Estuary (eastern Gulf of

Finland, Baltic Sea): is it a biofilter or source for pollution? Marine pollution bulletin 49(3), 196–205.

Pimentel, D., McNair, S., Janecka, J., Wightman, J., Simmonds, C., O’Connell, C., Wong, E., Russel, L., Zern, J., Aquino, T., Tsomondo, T., 2001. Economic and environmental threats of alien plant, animal, and microbe invasions. Agric. Ecosyst. Environ. 84, 1–20. https://doi.org/https://doi.org/10.1016/S0167-8809(00)00178-X

Reeders, H. H., Bij de Vaate, A., 1990. Zebra mussels (Dreissena polymorpha): a new perspective for water

quality management. Hydrobiologia 200/201, 437-450.

Silver Botts, P., Patterson, B.A., Schloesser, D.W., 1996. Zebra mussel effects on benthic invertebrates: physical or biotic? Journal of the North American Benthological Society 15(2), 179–184.

Sinden, J., Jones, R., Hester, S., Odom, D., Cheryl Kalisch, R.J., Cacho, O., 2004. The economic impact of weeds in Australia.

Sousa, R., Pilotto, F., Aldridge, D.C., 2011. Fouling of European freshwater bivalves (Unionidae) by the invasive zebra mussel (Dreissena polymorpha). Freshwater Biology 56, 867-876.

Stewart, T.W., Haynes, J.M., 1994. Benthic macroinvertebrate communities of Southwestern Lake Ontario following invasion of Dreissena. Journal of Great Lakes Research 20(2), 479–493.

Stybel, N., Fenske, C., Schernewski, G., 2009. Mussel cultivation to improve water quality in the Szczecin Lagoon. Journal of Coastal Research 56, 1459–1463.

TEEB, 2010. The economics of ecosystems and biodiversity: mainstreaming the economics of nature: a synthesis of the approach, conclusions and recommendations of TEEB. TEEB.

UN FAO, 2019. Ecosystem Services & Biodiversity (ESB) [WWW Document]. URL http://www.fao.org/ecosystem-services-biodiversity/background/provisioning-services/en/ (accessed 3.18.19).

Williams, F., Eschen, R., Harris, A., Djeddour, D., Pratt, C., Shaw, R.S., Varia, S., Lamontagne-Godwin, J., Thomas, S.E., Murphy, S.T., 2010. The economic cost of invasive non-native species on Great Britain. CABI Proj No VM10066 1–99.


Appendices


Appendix A. Literature review and QSR

Table A-1 - Search terms used in the QSR corresponding to each database

Search engine

Search term Date Number of hits

Web of Science

(TS=((ecosystem service* OR Natural capital OR Ecosystem impact* OR Ecosystem service value* OR socio-economic impact* OR Economic impact*) AND (invasive species OR alien species OR invasive non native species OR non-native species) AND (cost* OR consequence* OR benefit* OR impact*)) AND CU=(UK OR United Kingdom OR Britain OR England OR Wales OR Scotland OR Northern Ireland OR Europe OR European*)) AND LANGUAGE: (English)

26/02/2019 535

Science Direct (ecosystem service OR natural capital OR socio-economic impact OR Economic impact) (invasive species OR alien species OR invasive non native species) (cost OR benefit OR impact) (United Kingdom OR England OR Wales OR Scotland OR Northern Ireland)

25/02/2019 6628

Google Scholar

(ecosystem service OR natural capital OR socio-economic impact OR economic impact) AND (invasive species OR alien species OR invasive non native species) AND (cost OR benefit OR impact) AND (United Kingdom OR England OR Wales OR Scotland)

26/02/2019 19200

Scopus TITLE-ABS-KEY(ecosystem service* OR Natural capital OR Ecosystem impact* OR Ecosystem service value* OR socio-economic impact* OR Economic impact*) AND (invasive species OR alien species OR invasive non native species OR non-native species) AND (cost* OR consequence* OR benefit* OR impact*) AND (UK OR United Kingdom OR Britain OR England OR Wales OR Scotland OR Northern Ireland OR Europe OR European*) AND LANGUAGE(english) PUBYEAR > 1990

27/02/2019 47

Conservation Evidence Database

(ecosystem service OR natural capital OR socio-economic impact OR Economic impact) AND (invasive species OR alien species OR invasive non native species)

26/02/2019 0

CABI ecosystem services AND invasive species AND Impact [Europe, English]

26/02/2019 24

GB NNS Secreteriat

n/a (not a search database, just links to publications) 26/02/2019 42


Table A-2 - Description of ecosystem service categories

High-level ecosystem service category

Low level ecosystem service category

Provisioning services

The material benefits people get from ecosystems for e.g. supply of food, water, fibres, wood and fuels.

Food:

Virtually all ecosystems provide the conditions for growing, collecting, hunting or harvesting food.

Raw materials:

Ecosystems provide a great diversity of materials including wood, biofuels, and fibres from wild or cultivated plant and animal species.

Freshwater:

Ecosystems play a vital role in providing the flow and storage of fresh water.

Medicinal resources:

Natural ecosystems provide a variety of plants and mushrooms which offer effective cures for many kinds of health problems. They are used in popular and traditional medicine, and for developing pharmaceuticals.

Regulating services

The benefits obtained from the regulation of ecosystem processes e.g. the regulation of air quality and soil fertility, control of floods or crop pollination.

Local climate air quality:

Ecosystems influence the local climate and air quality. For example, trees provide shade whilst forests influence rainfall and water availability both locally and regionally. Trees or other plants also play an important role in regulating air quality by removing pollutants from the atmosphere.

Carbon sequestration and storage:

Ecosystems regulate the global climate by storing greenhouse gases. For example, as trees and plants grow, they remove carbon dioxide from the atmosphere and effectively lock it away in their tissues.

Moderation of extreme events:

Ecosystems and living organisms create buffers against natural disasters. They reduce damage from floods, storms, tsunamis, avalanches, landslides and droughts.

Waste-water treatment:

Ecosystems such as wetlands filter effluents, decompose waste through the biological activity of microorganisms, and eliminate harmful pathogens.

Erosion prevention / maintenance of soil fertility:

Vegetation cover prevents soil erosion and ensures soil fertility through natural biological processes such as nitrogen fixation. Soil erosion is a key factor in the process of land degradation, loss of soil fertility and desertification, and contributes to decreased productivity of downstream fisheries.

Pollination:

Animal pollination is an ecosystem service mainly provided by insects but also by some birds and bats. In agro-ecosystems, pollinators are essential


for orchard, horticultural and forage production, as well as the production of seed for many root and fibre crops.

Biological control:

The activities of predators and parasites in ecosystems that act to control populations of potential pest and disease vector.

Regulation of water flow:

Water flow regulation is a key service provided by land cover and configuration, but its dynamics are poorly understood by most policy makers and land management organisations.

Cultural services

The non-material benefits people gain from ecosystems, for e.g. aesthetic and engineering inspiration, cultural identity and spiritual well-being.

Recreation and mental physical health:

Nature-based opportunities for recreation play an important role in maintaining mental and physical health, e.g. walking and playing sports in parks and urban green spaces.

Tourism:

Enjoyment of nature attracts millions of travellers worldwide. This cultural ecosystem service includes both benefits to visitors and income opportunities for nature tourism service providers.

Aesthetic appreciation:

Animals, plants and ecosystems have been the source of inspiration for much of our arts, culture, and design; they increasingly inspire science as well.

Spiritual existence and sense of place:

Nature is a common element in most major religions. Natural heritage, spiritual sense of belonging, traditional knowledge, and associated customs are important for creating a sense of belonging.

Supporting services

Services necessary for the production of all other ecosystem services, for e.g. by providing plants and animals with living spaces, allowing for diversity of species, and maintaining genetic diversity.

Habitat for species:

Ecosystems provide living spaces for plants and animals; they also maintain a diversity of complex processes that underpin the other ecosystem services. Some habitats have an exceptionally high number of species which makes them more genetically diverse than others; these are known as ‘biodiversity hotspots'.

Maintenance of genetic diversity:

Genetic diversity distinguishes different breeds or races from each other, providing the basis for locally well-adapted cultivars and a gene pool for developing commercial crops and livestock.

Source: Adapted from UN FAO, (2019)


Table A-3 – Valuation methods for ecosystem services

Source: Defra (2011)


Appendix B. Information from workshop discussions

Table B-1 - Natural capital assets and service provision for UK woodland

Natural capital assets INNS ecosystem impacts Notable INNS species (that cause impact)

Impacts to ecosystem services provision Sectors impacted (e.g. tourism, forestry, etc).

Plantation forests These are usually intensive areas of trees managed for timber production.

Inhibited planting of forestry

Reduction in productivity (i.e. growth rate)

Damage to final forestry product

Reduction in leaf litter / debris

All non-native deer

Tree health pests (i.e. various beetle species)

Grey squirrel

Rhododendron

Provisioning services:

Reduction in timber yield

Extension to the estimated harvest date due to reductions in productivity

Regulating services:

Reduction in carbon sequestration Cultural services:

Access issues

Positive impacts include aesthetics (i.e. seeing wildlife)

Commercial forestry

Recreation / tourism

More natural forested areas and lower density of smaller stands of trees

Biodiversity impacts (i.e. reduction in species diversity)

Reduction in ecosystem resilience

Over grazing

Out competing native species

Species health impacts

Non-native deer

Grey squirrels

Edible dormouse

Rhododendron

Himalayan balsam

Tree pests


Less timber yield & charcoal Regulating services:

Reduced natural flood management

Reduction in carbon sequestration Cultural services:

Reduction in aesthetic values

Reduced access

Education impacts

Health and safety from tree diseases Supporting

Loss of biodiversity

Forestry and farming



Table B-2 - Natural capital assets and service provision for UK freshwater



Wetlands Wetlands are defined as areas of land covered by shallow water at or near the surface level including fens, marshes, swamps and bogs.

Drying out due to evapotranspiration

Covering up

Change of species mix

Introduction of diseases/acting as vectors of diseases

Inhibiting nutrient cycling

Loss of habitat for pollinators and other species

Algal blooms

Includes SuDS as well as natural wetlands

Japanese knotweed – although may more typically affect urban and open water environments

Riparian plants

Swamp stonecrop

Crasstula helmsii

American mink

Provisioning services: Regulating services:

Pollination

Water purification

Surface water management Cultural services:

Aesthetic and recreational value

Water industry

Navigation

Nature conservation

Flood management

Agriculture

Open Water Open waters include standing and flowing waters. Standing waters consist of natural bodies such as lakes, meres and pools, as well as manmade features such as reservoirs, canals, ponds and gravel pits. Flowing waters include rivers and streams that flow into the sea or a lake.

Fouling (although mainly a coastal impact)

Creating holes in dams

Causing flooding

Preventing or hindering navigation

Changing the species mix

Affecting light filtration/water clarity

Algal blooms

Reducing oxygen availability

Blocking of valves relating to water supply

Reducing fish stocks (commercial or recreational)

Increased siltration, increasing the need for dredging

Bird strikes

Floating pennywort

Dikerogammarus villosus (DV) and Dikerogammarus haemobaphes (DH)

Zebra mussels

Quagga mussels

Signal crayfish and other invasive crayfish

Mink

Canada geese

Aquatic plants, e.g. curly waterweed and Nutalls waterweed

Chinese mitten crab

Top mouth gudgeon

Invasive pathogens


Water availability for livestock

Loss of livestock from drowning

Water taste and odour

Direct water supply impacts and indirect impacts due to regulatory restrictions on water transfers due to presence of INNS (e.g. during droughts)

Regulating services:

Erosion control Cultural services:

Aesthetic/landscape impacts


Sense of place and interaction with nature

Lack of charismatic species (e.g. due to water voles)

Water industry

Nature conservation

Agriculture and irrigation


Flood management

Navigation

Industry

Aquaculture, e.g. fish farms


Table B-3 - Natural capital assets and service provision for UK farmland



Arable and horticultural Land used to grow vegetables, fruit, mushrooms and flowers; this includes uncropped arable land. Improved grassland Grasslands altered for agricultural use both temporary and permanent.

Overgrazing of crops

Competition with crops

Health / resilience of crops and yield

Loss of biological control

Pollination of crops

Toxicity to livestock?

Non-native deer

Grey squirrel

Rabbits

Parakeets

Non-native weeds

Nematodes / insects

Diseases


Reduction in yield to crops and livestock Regulating services:

Pollination services

Carbon sequestration

Impeded drainage and flooding Cultural services:

Aesthetic benefits from seeing wildlife

Agriculture

Horticulture

Recreation (from public footpaths/bridleways)

Rough grazing Land used for low-intensity grazing of livestock.

Outcompeting native species

Loss of productivity

Health impacts to livestock

Shading streams / watercourses that impacts invertebrate populations

Rhododendron

Anontoniasta

Gunnera


Reduction in primary yield Regulating services:

Increase in surface water run-off Cultural services:

Access to areas

Agriculture

Recreation (i.e. bridleways and public footpaths)


Table B-4 - Natural capital assets and service provision for UK urban area



Natural land cover Any land cover classified as being natural in type for example, grassland, heath, scrub, orchards, coniferous trees and so on. but does not include inland water bodies.

Structural integrity of buildings

Predation or outcompeting native species (e.g. harlequin ladybirds)

Aesthetic impacts

Blocking footpaths

Vectors of disease, e.g. leptospirosis, Weil’s disease, squirrel pox

Noise nuisance (e.g. parakeets)

Impact on species mix

Japanese knotweed

Buddleia

Grey squirrel

Rats

Tree of heaven

Parakeets – monk and ringneck

Invertebrates, e.g. Asian hornet, harlequin ladybird

Eucalyptus

Terrapins

Racoon dog


Property valuation

Repair costs Regulating services:

Biological control (e.g. native ladybirds and aphids)

Noise regulation Cultural services:

Aesthetic impacts leading to higher management costs

Lost recreational value due to pathways being blocked

Local authorities

Householders

Recreational users

Waste treatment

Construction

Transport companies

Public/NHS

Animal welfare (e.g. rescue centres – racoon dogs)

Maintenance companies (will incur additional costs)

Functional green space Any green space that has a specific function in its use for example, public parks or gardens, playing fields, golf courses, allotments and so on; These spaces contain natural land cover, and can also include some blue space for example, a park that has a lake within it.

Blue space All inland water bodies for example, rivers, lakes, ponds, canals and so on.

Grey space / built environment All hard infrastructure in the build environment (e.g. roads, railways, houses, etc).


Table B-5 - Organisations and areas of expertise present at the stakeholder workshop

Delegate name Organisation Principal area of expertise relevant to the topic

Niall Moore Defra INNS expert

Rob Fraser University of Kent Economist

Sania Faizi Defra Economist

David Aldridge University of Cambridge INNS expert

Ben Aston Yorkshire Water INNS expert

Sarah Webster Defra INNS expert

John Gossage Natural Resources Wales Natural capital

Peter Birch Canal and Rivers Trust INNS expert

John Mumford Imperial College Economist and INNS expert

Matt Smith JNCC Natural capital

Alisha Anstee NFU Economist

Adrian Jowitt Natural England INNS expert


Appendix C. Costing a two-phase approach

Below we provide a set of indicative costs for undertaking the two phases of work set out in Section 5.2 above, in addition to an option to undertake the second phase as a standalone study. Costs would need to refined following development of a full scope of works.

Table C-1 - Indicative cost estimate for implementing the recommendations for a natural capital two-phase approach

Phase 1 Phase 2 Phase 2 (exc. Phase 1)

Project inception £2,250 £2,250 £2,250

Project analysis £16,450 £15,000 £21,050

Report writing £10,400 £10,800 £11,450

*Optional production of 'glossy' report* £10,000 £10,000 £10,000

Expenses & subsistence £1,250 £900 £1,350

Total12 £40,350 £38,950 £46,100

Total (inc. 25% contingency)11 - excluding VAT

£50,438 £48,688 £57,625

Several assumptions underpin the cost estimate outlined in Table C-1.

The following should be noted:

Five face-to-face meetings are assumed to be required for the two-phased approach; three face-to-face meetings are assumed to be required for the Phase 2 standalone approach.

For stakeholder engagement, a stakeholder workshop is costed for both Phase 1 and Phase 2 (exc. Phase 1).

For the analysis, data collation will rely on a literature search and access to existing data sources rather than generation of primary data.

The analysis would focus on a defined set of services and species.

Each option has a GIS analysis component included for mapping outputs from the assessment.

The expenses included are transport and subsistence for meetings and workshops (where applicable).

No time has been allowed for peer review (e.g. by an academic or specialist consultancy) and would have to be costed as an additional element.

A 25% contingency has been added to the final cost estimate to reflect uncertainty in our indicative costs.

The outputs would be a concise technical report associated with each phase. For Phase 1, this would include a case study approach, whereas Phase 2 would include a UK-level assessment. The Phase 2 (excluding Phase 1) option includes a UK-level assessment only,

11 Note this total excludes VAT.


We have assumed the learning from Phase 1 would result in a lower overall cost to undertake a Phase 2 analysis. We also suggest undertaking Phase 1 analysis would result in a more robust assessment because a lower-level application would help ‘ground-truth’ our analysis before aggregation on an England or UK-wide scale (based on the overarching conceptual framework developed in Phase 1).


Monica Barker Atkins Limited Woodcote Grove Ashley Road Epsom KT18 5BW

[email protected]

© Atkins Limited except where stated otherwise

Documents

Scoping study: ecosystem services and natural capital