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Final Report
January 2016
This project is supported by the Rural Development Programme for England, for which Defra is the
Managing Authority, part financed by the European Agricultural Fund for Rural Development:
Europe investing in rural areas
Environmental Stewardship Monitoring and Evaluation Programme
Moorland Habitat Monitoring: A Resurvey of Selected Moorland Agri-environment
Agreement Sites
Natural England Contract reference ECM6214
C. Nigel R. Critchley1
James Towers2
Naomi E. Jones3
1ADAS UK Ltd., c/o Newcastle University, NEFG Offices, Nafferton Farm, Stocksfield,
Northumberland NE43 7XD 2ADAS UK Ltd., 16 Eastway Business Village, Olivers Place, Fulwood, Preston PR2 9WT 3 The Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, UK
2
Contents Executive summary ............................................................................................................................. 3
Introduction ........................................................................................................................................ 5
Methods .............................................................................................................................................. 7
Field survey ..................................................................................................................................... 7
Laboratory assessment of Calluna .................................................................................................. 7
Data handling .................................................................................................................................. 7
Data analysis ................................................................................................................................... 8
Content of individual site reports ................................................................................................... 9
Results ............................................................................................................................................... 12
Current condition of habitats........................................................................................................ 12
Changes in vegetation variables ................................................................................................... 13
Discussion.......................................................................................................................................... 19
Habitat condition .......................................................................................................................... 19
Changes and timescales ................................................................................................................ 21
Methodology ................................................................................................................................. 21
Future work ................................................................................................................................... 22
Acknowledgements ........................................................................................................................... 23
References ........................................................................................................................................ 24
3
Executive summary Upland habitats including dry and wet heath, blanket bog, flushes, fens and swamps and calcareous
grassland are Priority Habitats under the UK Biodiversity Action Plan and the UK Post-2010
Biodiversity Framework. Many sites in England which include these habitats have been subjected to
long-term monitoring to assess the outcomes on habitat condition of reducing grazing intensity and
other management, including altered burning regimes, under agri-environment schemes and
Environmental Cross Compliance regulations. The information is required to guide both the
development of agri-environment prescriptions and guidance, and management practices at
individual sites.
A resurvey was carried out of 20 moorland case study sites during March – April 2014 (16 sites) and
February 2015 (4 sites), using standardised methods to record a range of variables associated with
grazing intensity and habitat condition. Change in habitat condition at individual sites was
determined by formal statistical analysis or, where sampling methods were not compatible with
previous surveys, by reference to data and conclusions from previous site reports. A series of
individual site reports was produced, each providing summary statistics and a descriptive overview
of the results.
All sites were in Higher Level Stewardship (HLS) agreements, and had previously been managed
under other agri-environment scheme agreements or overgrazing Environmental Cross Compliance
(ECC) grazing prescriptions. In total, these restrictions had been in place for periods ranging from six
to 22 years. The commonest vegetation types on the sites were heather heath, blanket bog,
fragmented heath, rough acid grassland and bent-fescue grassland.
Across the sample of sites, none of the habitats assessed for condition (dry heath, mires, wet heath
and calcareous grassland), were above all the favourable condition thresholds relating to species
composition (i.e. the frequency of indicator species or relative abundance of key species). Re-
establishment of the complete plant community simply by reducing grazing is clearly difficult, and
might be inhibited by dominant graminoids or heather, poor species dispersal, inappropriate burning
or external factors such as nitrogen deposition. In dry heath and mires there were high failure rates
for current levels of browsing on dwarf shrubs, and current levels of grazing were not optimum on
the two calcareous grassland sites. However, grazing intensity was variable within sites, indicating
some localised concentration of heavy grazing and potentially acceptable levels of grazing across
other areas. The range of heather growth stages was lacking in dry heath habitat at many sites,
primarily due to a shortage of degenerate heather, but also sometimes pioneer or mature stages.
This suggests grazing levels or burning frequency have been too high, at least historically, to allow
heather to develop. Most, but not all mire sites achieved condition thresholds for burning and
erosion. Severe disturbance, undergrazing, drainage and invasive species were not an issue in any
habitat across the sample of sites.
Significant changes in grazing related variables were detected at the sites that could be analysed,
although there were no consistent trends among these sites. However, most of the 20 sites in the
whole sample showed at least some long-term reduction in grazing intensity or improvement in
condition. Some sites had shown an initial improvement in condition up to around 10 years ago, but
with less change since then, which might be the result of more recent increases in stocking densities
under HLS. The dry heath habitat was closest to being in good condition in six sites that had been
under agri-environment scheme agreements for the longest periods (19 – 22 years). In contrast, the
mires habitat was below the favourable condition threshold for several attributes even in sites with
4
the longest periods of grazing restrictions (17 – 22 years), suggesting longer periods or more
intervention is needed to achieve good condition in this habitat.
The variability among sites in current condition and trends over time will be partly due to variation in
vegetation types and starting condition, geographic locations and timescales. Grazing and other
prescriptions also varied widely among sites and over time, presenting a complex set of individual
scenarios. It is therefore difficult to reach firm conclusions about general responses to particular
management regimes and the timescales over which they are likely to occur. The case studies will be
useful for guiding management on individual sites and, in combination with wider national surveys,
for continual assessment of the outcomes of agri-environment scheme agreements.
5
Introduction Upland habitats including dry and wet heath, blanket bog and calcareous grassland are Priority
Habitats under the UK Biodiversity Action Plan and the UK Post-2010 Biodiversity Framework. A
significant proportion of sites in England containing these habitats have been managed under agri-
environment scheme agreements for up to two decades or more, and some were also formerly
subject to grazing restrictions under Environmental Cross Compliance (ECC) regulations. Natural
England (NE) and its predecessors has carried out a series of monitoring programmes on many of
these sites, focussing initially on the condition of heather (Calluna vulgaris) in relation to grazing
pressure, and latterly also on the overall condition of the vegetation across the range of habitats
present on a site.
A recent review of moorland grazing highlighted the need for more information on timescales and
trajectories of vegetation change for achieving favourable condition, when in the process of
recovering from degradation attributable to high grazing intensity and its interaction with other
practices including burning (Martin et al., 2013). This information is needed to inform management
prescriptions and Indicators of Success in agri-environment schemes. Whilst this information is
required to guide generalised prescriptions at the scheme level, it is also needed to ensure that
management practices are tailored to the needs of individual sites, which are known to vary in their
response to management according to various factors and their interactions. These factors include
geographic location, the identity, spatial distribution and condition of different vegetation types,
management history, topography and soils. As part of the evidence base in support of agri-
environment schemes, long term monitoring programmes have the potential to provide information
on the variation in response of vegetation to reduced grazing intensity, both in terms of its current
condition and change in condition over different timescales.
A number of sites distributed throughout the English uplands have been subjected to baseline and in
many cases repeated surveys to assess vegetation condition, and provide an opportunity to
determine changes over relatively long periods of time. The reasons for the original surveys varied;
some were part of Environmentally Sensitive Area (ESA) Scheme monitoring, whereas others were
subject to Environmental Cross Compliance controls. The aim of this project was to re-survey a
selection of these sites using standardised methods, and to provide a series of individual site reports
describing their current and changing habitat condition, along with a separate overview of the
findings from the complete set of sites. Data from the surveys have also been provided to NE to
allow more detailed examination of individual sites to help guide local management inputs. The
objectives as set out by NE were to:
Resurvey a number of long-term monitoring sites to identify change in vegetation
parameters, and explore the relationship of these changes to management factors, including
grazing.
Agree with Natural England a standard survey protocol that is compatible with previous
surveys but will incorporate the range of variables required to report on current condition
and to draw comparisons with other surveys.
Describe current condition, and change since previous surveys, at the site level and across
the sample as a whole. Present these in terms of Common Standards Monitoring classes and
empirical measurements.
6
Expand and improve the baseline against which future change can be assessed, by adding
new agri-environment agreement sites and assessing condition against a consistent range of
variables.
Add to the evidence base on the influence of land management factors, including grazing,
burning and drainage modification, on vegetation change and the timescale over which this
takes place. This will inform future management guidance for the implementation of land
management schemes and the management of designated sites.
The individual site reports from the project are provided in Appendix 1, with the overview of the
approaches and findings in the following sections.
7
Methods Sites were selected subjectively by NE, based on length of time in management schemes, the
existence of baseline survey data and in order to achieve a geographical spread, and were therefore
treated as individual case studies, rather than a representative sample from a statistical population
of sites. Each site comprised a whole moorland grazing unit and encompassed a range of vegetation
types. The aim was to survey 20 sites; from an initial list of 21 sites, 16 were surveyed during the
period 18 March – 30 April 2014 and the remaining four during 12 – 27 February 2015 (Table 1). One
moorland area (Crosby Ravensworth Fell) was surveyed as two separate units (West and East), which
are treated as two individual sites but included in a single report.
Field survey
A range of variables was recorded at 100 randomly located sample points in each site. Sample points
were located using hand-held GPS and variables were recorded directly on to Excel templates on
rugged tablets. Variables to be recorded were agreed with NE prior to the survey, to assess heather
grazing and the condition of key habitats. The methodology was based on a modified version of the
Natural England overgrazing surveillance methodology (Nisbet, 2006) and the Common Standards
Monitoring Guidance for Upland Habitats (JNCC, 2009). The field protocol, including variables
recorded and field form templates, is in Appendix 2.
The vegetation type present at each sample location (Table 2) was identified using a key developed
by NE (see Appendix 2). Overgrazing surveillance variables were recorded in all vegetation types
apart from the ‘non-productive’ type (e.g. rock, scree, limestone pavement, road, water body, dense
scrub, woodland, etc.). Variables were recorded from a single 1 m x 1 m quadrat at each location and
included peat depth, cover and height of key species, variables relating to grazing, burning and
condition of Calluna and presence of livestock droppings. In the target vegetation types (Priority
Habitats) only, a range of condition assessment variables appropriate to the habitat was also
recorded, either from the 1 m x 1 m quadrat (calcareous grassland), or from a 2 m x 2 m quadrat
which had the 1 m x 1 m quadrat located in a corner (other habitats). In addition, some condition
assessment variables were recorded for the habitat at the whole site level on completion of the
survey.
The overgrazing surveillance method includes calculation of a heather Grazing Index (GI). Full details
of the field and laboratory method are described in Nisbet (2006) (see also Appendix 2). At all
sample locations where Calluna was present in the 1 m x 1 m quadrat, up to four Calluna stems were
collected and transferred to a freezer for subsequent laboratory assessment.
Laboratory assessment of Calluna
Each Calluna stem was cut 4 cm from the leading tip or, in old or contorted Calluna, a 4 cm zone
around the crown, to yield a sample of 4 – 100 shoots per sample location, depending on the growth
form. Dead shoots and those less than 1 cm long were discarded. All remaining shoots were then
assessed for evidence of sheep grazing and classified as grazed, ungrazed or indeterminate (the
latter where the cause of loss of a shoot tip was unclear). Shoots were classified as grazed only if the
removal of the tip was judged to have taken place after the majority of summer shoot production.
Data handling
Field data were backed up daily to a memory stick and checked by the field team leader. Where
internet access was available, all data files (field forms and digital photos) were copied to a central
Sharepoint Site. Multiple field forms for each site (from different surveyors) were combined to a
8
single form per site. All data were then stored on an Access database, with separate tables for the
dry heath, wet heath, mires and non-target habitats.
Data analysis
The GI was calculated for each sampling point with heather present as:
Formal statistical analysis of change in overgrazing surveillance variables could only be carried out
where the sampling method from previous surveys conducted by NE was the same as the current
method (i.e. a random sample of 1 m x 1 m quadrats across the site). Where other sampling
methods had been used (e.g. on a grid or transect, limited to a vegetation type, or using a different
quadrat size) then a subjective assessment of change was made instead, taking into account the
values of the surveillance variables and the conclusions from the previous reports.
Where formal analysis was possible, change in heather grazing indices from previous surveys was
analysed using one-way analysis of variance on arcsine(√x) transformed data. For sites with more
than two years’ data, differences between individual years were tested using unequal N HSD post-
hoc tests. To assess the overall change in the key vegetation variables (cover, height and detached
vegetation), multivariate one-way analysis of variance was applied, along with corresponding
univariate tests on the individual variables. Prior to analysis, cover variables were transformed to
arcsine(√x), heights to log(x+1) and detached vegetation to √(x+0.5). Variables with too few data for
analysis at individual sites were omitted. Change in frequencies of livestock droppings, heavily
grazed features and recent burning were analysed using chi-square tests of independence. Statistical
analyses were carried out using Statistica v.11 software (Statsoft, Inc., 2012).
The JNCC method for condition assessment of upland habitats specifies targets for a range of
attributes in each habitat (JNCC, 2009). A formal assessment of the overall condition of the site was
not possible because the agreed field protocol did not include the full set of JNCC attributes (such as
cover of all indicator species) due to time limitations. The JNCC method specifies that all condition
targets should be passed at 90% of sample points to achieve favourable condition so an assessment
based on an incomplete set of attributes could be biased and potentially misleading (although a
site’s condition could justifiably be assessed as unfavourable if one or more attributes failed to
achieve their target at more than 10% of sample points). Instead, each attribute was assessed
individually, and if the JNCC target was achieved at 90% or more of sample points, the habitat was
deemed to have surpassed the condition threshold for that attribute. Habitats with a small sample
size (fewer than ten sample points on a site) could not be assessed accurately and were excluded
from this assessment. The fragmented heath vegetation type could be derived from either dry or
wet heath. These were differentiated on the same basis as the dry and wet heath vegetation types,
i.e. peat depth and species composition (details in Appendix 2). Sample points in fragmented heath
were therefore included in the condition assessments of dry or wet heath habitats, according to the
respective habitat from which they were derived. Attributes assessed at the scale of ‘feature extent’
were recorded once as a ‘pass’ or ‘fail’ for each habitat, on completion of the site survey.
9
Content of individual site reports
The report for each site contains summary statistics, outputs of statistical analyses (where
appropriate) and a descriptive overview of the results, using the following structure:
Introduction
Background, aims, scope and an outline of methods used in the project.
Overview
A general description of the site, based on observations during field survey, along with the
frequency distribution of the vegetation types present, Calluna growth stages and dominant
graminoid species
Site management, including past and current AES agreements and ECC grazing prescriptions,
past and current information on stocking levels and any burning management
Current condition of the vegetation and grazing pressure, based on evidence from the
indicators of grazing, burning and other drivers such as heather beetle damage, along with a
summary of the condition assessment outputs
Changes since previous surveys including an assessment of management outcomes, the
conclusions from previous site reports, and a statement about the success of the agri-
environment agreements
Outputs from statistical analyses of change (if appropriate)
Plots showing summary statistics of the surveillance variables at whole site level.
Maps showing the values of a selection of grazing-related variables, including GI, at each
survey point, from additional analysis by NE.
Summary statistics by target vegetation type
Summary statistics of the surveillance variables are presented in tabular form for each target
vegetation type. Vegetation types with small samples (fewer than ten sample points) are combined,
and statistics presented if the combined sample is ten or more samples points.
Condition assessment
Outputs of the condition assessment variables in tabular form, showing percentage of points passed
and an overall pass / fail assessment for each variable. Variables recorded at ‘feature extent’ scale
are presented for all target habitats present on the site.
10
Table 1 Sites surveyed with main vegetation types, summary of schemes applied and period over which changed management has been implemented. CSS – Countryside Stewardship Scheme; ECC – Environmental Cross Compliance; ESA – Environmentally Sensitive Area; HLS – Higher Level Stewardship; WES – Wildlife Enhancement Scheme.
Site Location Area (ha) Target vegetation types*
Non-target vegetation types*
Schemes1 Year surveyed
Period (years)
Arnfield Moor North Peak 832 HH, BB - North Peak ESA, HLS 2015 22
Birkbeck Commons Cumbria 714 BB, FFS, FH RAG ECC, Lake District ESA,
HLS 2015 17
Broomhead Moor North Peak 1714 HH, BB - North Peak ESA, HLS 2014 20
Burnmoor Lancs/Bowland 537 HH, FH RAG, BFG CSS, HLS 2014 13
Caldbeck Common North Lakes 3300 BB, HH RAG, BFG WES, HLS 2014 62
Crosby Ravensworth Fell (East) Cumbria 471 CG, HH, FH RAG ECC, CSS, HLS 2015 20
Crosby Ravensworth Fell (West) Cumbria 1532 HH, WEH RAG, BFG ECC, CSS, HLS 2015 20
Dozmary Downs Bodmin Moor 35 FH, HH RAG, BFG ECC, HLS 2014 11
Ennerdale West Lakes 400 HH, WEH - Lake District ESA, HLS 2014 21
Ingleborough North Yorkshire 1500 BB, CG RAG ECC, HLS 2014 ?
Kearton Pasture North Yorkshire 186 HH, BB BFG, RAG ECC, WES, HLS 2014 17
Long Mynd Shropshire Hills 2230 HH, FH BFG, BK ECC, Shropshire Hills
ESA, HLS 2014 15
Manor & Trehudreth Common Bodmin Moor 360 FH, WSH BFG, RAG CSS, HLS 2014 14
Molland Moor Exmoor 706 HH, FH RAG, BFG Exmoor ESA, HLS 2014 21
Okehampton Common Dartmoor 1300 FH, BB RAG, BFG ECC, Dartmoor ESA,
WES, HLS 2014 14
Ousby Moor Cumbria 1450 BB, FFS RAG CSS, HLS 2014 12
Reeth Low Moor North Yorkshire 500 HH RAG CSS, HLS 2014 14
Thornton Moor South Pennines 91 BB, HH RAG ECC, HLS 2014 19
Ugborough & Harford Commons Dartmoor 1700 FH, WSH, BB BFG, RAG ECC, Dartmoor ESA,
HLS 2014 16
Winsford Allotment Exmoor 108 HH, FH BK, BFG, MG Exmoor ESA, HLS 2014 21 1 information extracted from reports supplied by NE and might not be complete for some sites. Most sites are also protected under statutory designations 2 stocking first reduced in 2001 (13 years) due to foot & mouth disease
* >= 10% frequency
See Table 2 for vegetation type codes.
11
Table 2. Vegetation types and corresponding habitat for condition assessment (see habitat key, Appendix 2)
Vegetation Type Code Condition Assessment
Target Types Western Heath WSH Dry Heath Heather Heath HH Fragmented Heath1 FH
Wet Heath WEH Wet Heath Fragmented Heath2 FH
Blanket Bog BB Mires Flushes, Fens & Swamps FFS
Calcareous Grassland CG Upland Calcareous Grassland
Non-target Types Montane Heath MH None Bracken BK Improved Grassland IG Bent-Fescue Grassland BFG Rough Acid Grassland RAG Mesotrophic Grassland MG Non-productive NP 1 derived from heather heath or western heath 2 derived from wet heath
12
Results The commonest target vegetation types in the sample of sites were heather heath, blanket bog and
fragmented heath (Table 1). Wet heath, although present in just over half of the sites, only occurred
at 10% or more frequency on two sites (Ennerdale, 17%; Crosby Ravensworth Fell (West), 10%;
excluding fragmented heath derived from wet heath). Western heath only occurred at high
frequencies in two south-western sites (Manor & Trehudreth Common, 21%; Ugborough & Harford
Commons, 14%) reflecting the centre of its distribution. Flushes, fens and swamps was also only
recorded at high frequency at two sites (Birkbeck Commons, 16%; Ousby, 13%), whilst calcareous
grassland was only recorded at Crosby Ravensworth Fell (East) (28%) and Ingleborough (11%). The
commonest non-target vegetation types were rough acid grassland and bent-fescue grassland.
All sites were currently under Higher Level Stewardship (HLS) agreements, although these had only
been in place for 1 – 6 years. However, each site had also been in other agri-environment scheme
(AES) agreements or subjected to overgrazing ECC grazing prescriptions prior to this, which set limits
on grazing regimes and, in the case of AES agreements, other management such as burning. In total,
these agreements/prescriptions had been in place for varying lengths of time, ranging from 6 years
(Caldbeck Common) to 22 years (Arnfield Moor) (Table 1). There had been a general reduction in
overall annual stocking densities at all sites since the start of monitoring, although in a few cases the
overall stocking rates had increased slightly when the site was transferred from one scheme to the
next (Table 3). However, many of the grazing prescriptions were complex (particularly in HLS), and
most required at least some reduction of livestock in winter (sometimes limited to a particular stock
type), along with other limitations at particular times of year. All the sites were grazed by sheep at
the time of the survey (as indicated by presence of sheep droppings) and cattle or ponies were also
present on around half of the sites.
Current condition of habitats
Of the 18 sites where the dry heath habitat was present at a minimum of 10% frequency (including
fragmented heath derived from dry heath), none were above the favourable condition threshold for
presence of indicator species, although some (Ennerdale, Molland Moor and Okehampton Common)
were close to the 90% threshold (see Appendix 3 for a summary of the condition assessment
results). At three sites (Ennerdale, Thornton Moor and Winsford Allotment), this was the only
attribute failed. There was also a high failure rate for current levels of browsing on dwarf shrubs;
preferential grazing of Vaccinium myrtillis was noticed in the field by surveyors at two sites
(Broomhead Moor and Long Mynd) where it comprised a significant dwarf shrub component. Failure
rates were also high for the range of Calluna growth stages present, for which there was a shortage
of Calluna in the degenerate growth stage at all but two sites (Birkbeck Commons and Crosby
Ravensworth (East)), although in some cases pioneer or mature stages were also lacking. In contrast,
the building stage was widespread in the dry heath habitat. Only three sites did not pass the
threshold for presence of lower plants or lichens, two of which were being subjected to
inappropriate burning (Broomhead Moor and Reeth Low Moor). Three sites were below the
threshold for cover of Group (ii) dwarf shrub species, all in south western England (Dozmary Downs,
Manor & Trehudreth Common and Ugborough & Harford Commons). Ulex gallii was almost entirely
dominant in western heath at Manor & Trehudreth Common and Ugborough & Harford Commons. It
was also prominent in fragmented heath at all three sites, in which total cover of dwarf shrubs was
by definition relatively low anyway. In the dry heath habitat, favourable condition thresholds were
passed for all attributes relating to severe disturbance, weeds, rushes, non-native species, Pteridium
aquilinum and trees & scrub.
13
The mires habitat was present at 10% frequency or more on eleven of the sites. In none of these
cases was either of the thresholds passed for attributes that relate to indicator species, and the
percentages of locations where these targets were met were low at several sites. There were also
high failure rates for levels of browsing on dwarf shrubs, dominance of Eriophorum vaginatum,
Ericaceous species or Trichophorum germanicum (i.e. cover of one or more of these usually too
high), and the presence of Sphagnum species (i.e. often only S. fallax present). Smaller numbers of
sites were also below the thresholds for attributes relating to burning or to negative indicator
species (i.e. frequency of inappropriate burning or presence of negative species was often too high).
Erosion was also an issue on two sites (Broomhead Moor in the North Peak and Thornton Moor in
the North Pennines) However, thresholds were passed at all sites for attributes relating to
disturbance or drainage, damage to Sphagnum and trees & scrub.
Only four sites contained the wet heath habitat at sufficient frequency (including fragmented heath
derived from wet heath) to assess habitat condition. None of the sites were above the threshold for
cover of indicator species and ericoids and all but one (Burnmoor) failed on relative covers of dwarf
shrubs and graminoids. Two sites (Burnmoor and Ennerdale) were below the threshold for presence
of Erica tetralix and two (Birkbeck Commons and Burnmoor) on dwarf shrub browsing. Burnmoor
also failed on cover of Juncus effusus. All sites were above the favourable condition thresholds
relating to Sphagnum damage, disturbance, drainage, burning, trees & scrub, Pteridium aquilinum,
non-native species and negative indicators.
The upland calcareous grassland habitat was only present at sufficient frequency to assess habitat
condition at two sites (Crosby Ravensworth (East) and Ingleborough). Neither site achieved the
threshold relating to cover of forbs or for having sufficient vegetation taller than 5 cm. However, the
survey was done outside the optimum time of year, when vegetation would be more likely to meet
these criteria. One site (Crosby Ravensworth (East)) appeared to be undergrazed, being below the
threshold for proportion of short vegetation and presence of dead plant litter. Both sites passed all
the remaining attributes.
Changes in vegetation variables
Statistical analyses
Nine sites in the sample had been surveyed previously using the same sampling method as in 2014
or 2015 and were subjected to statistical analyses (Table 4). Overall periods from the first such
survey to the 2014 or 2015 survey ranged from 7 to 11 years. Significant changes were detected on
individual sites in grazing indices, covers, heights, livestock droppings and heavily grazed features.
However, no consistent trends were evident among these sites, apart from the frequency of recent
burning, for which no change was detected at any site.
Overall changes
Taking into consideration the overall assessments of change at all 20 sites, including those subjected
to statistical analysis, few general patterns emerged in relation to timescales. However, even these
should be viewed with caution since a qualitative comparison could only be made between surveys
for the majority of sites. Most sites showed at least some long-term reduction in grazing intensity or
positive changes in the variables recorded (Table 3). For example, at Dozmary Downs the GI had
declined significantly over a 9-10 year period, with a concomitant increase in dwarf shrub cover and
vegetation heights and decline in indicators of heavy grazing (detached Calluna stems, heavily
grazed features and livestock droppings) following reductions in stocking densities under ECC and
HLS (Table 3, Table 4 and Appendix 1). At Thornton Moor, stocking densities were first reduced 19
14
years ago under ECC, and again in 2011 under HLS, including off-wintering. Previous reports
indicated a significant improvement in condition of Calluna within the first three years, and a
reduction in high grazing intensity between 2000 and 2003. Current grazing intensity on Calluna, as
indicated by the GI, appears to be lower than that recorded in 2003, although a different sampling
method was used (Table 3 and Appendix 1). Improvement in some condition attributes sometimes
coincided with a recent increase in GI (e.g. Manor & Trehudreth Common and Ugborough & Harford
Commons; Table 4). However, GI is a snapshot of recent grazing intensity on Calluna and does not
necessarily reflect past long-term change, and its increase at these sites might be due to a recent
increase in stocking densities under HLS (Table 3). In the individual site reports, GI has been
compared with the ECC thresholds1 and CSM threshold of 33% (JNCC, 2009) as an indicator of recent
grazing intensity on Calluna. GI is also highly variable within individual sites and within a given
habitat on a site (Table 3, Appendix 1).
A number of sites had shown an initial improvement in condition up to around 10 years ago, with
little further improvement apparent since then (e.g. Ousby, Reeth Low Moor and Winsford
Allotment), although none of these could be subjected to statistical analysis. At Winsford Allotment,
this might be attributable to a recent increase in stocking levels under HLS, following the earlier
reduction under ESA Tier 2 management. However, at Reeth Low Moor they were reduced under
HLS and the trends are less clear at Ousby (Table 3). Given that the initial improvement in condition
has not been sustained in the longer term, the more recent management might not be ideal and
might need to be reviewed at these sites. At many sites there were changes over time not only in
overall stocking levels but also in the particular grazing regimes (e.g. in the balance and timing of
stock types). This was particularly so when moving from overgrazing ECC prescriptions to AES
agreements, but also occasionally through adjustments to existing agreements (e.g. Manor &
Trehudreth Common) and on moving from Classic Scheme agreements to HLS (e.g. Crosby
Ravensworth Fell). As mentioned above, stocking levels actually increased under HLS at some sites
(i.e. Caldbeck Common, Manor & Trehudreth Common, Ugborough & Harford Commons and
Winsford Allotment).
Dry heath habitat passed all condition thresholds apart from indicator species at three sites that had
been under agri-environment scheme agreements, or subject to ECC stocking limits, for some of the
longest periods. These were Ennerdale and Winsford Allotment (both 21 years duration) and
Thornton Moor (19 years). Another three long-term sites additionally failed to achieve only one
other threshold. These were for levels of browsing on dwarf shrubs (Molland Moor, 21 years; Crosby
Ravensworth Fell (West), 20 years) and Calluna growth stages (Arnfield Moor, 22 years). Stocking
levels were reduced at all of these sites for at least part of this period, including reductions or
removal in winter, although they were variously under ECC, ESA Tier 1, ESA Tier 2 or CSS prior to HLS
(Table 3). This suggests that around 20 years of reduced grazing intensity might be needed to
achieve this level of condition in dry heath when starting condition is not too degraded (e.g. when
dwarf-shrub frequency is high even if cover is low) and with appropriate grazing regimes applied.
However, with evidence from only six sites this should be treated with caution, and a further long-
term site failed on three dry heath attributes (Crosby Ravensworth Fell (East)). Even on these sites
thresholds for all attributes have not yet been achieved after this length of time. Full recovery to
favourable condition will take longer and may require more intensive interventions such as the
reintroduction of indicator species where they are absent or have limited dispersal capability.
1 50% or more of quadrats having a GI ≥ 33%, or 25% or more ≥ 66%
15
Recovery of more degraded sites, or where stocking regimes are less restrictive, is likely to take even
longer.
It is difficult to speculate about timescales to achieve improved condition in the mires habitat
because it had not recovered sufficiently at any of the sites in the sample. The sites with the longest
history of grazing prescriptions (Arnfield Moor, 22 years; Broomhead Moor, 20 years; Thornton
Moor, 19 years; Kearton Pasture and Birkbeck Commons, 17 years) were all below the condition
threshold for several attributes. Prior to entry into HLS, the prescribed stocking levels at these sites
were higher than the current recommendations for either maintenance or restoration of blanket bog
(Nisbet & Glaves, 2010), although this would be offset by the fact that a significant area of the sites
comprised other vegetation types with higher recommended stocking levels. The results also suggest
that inappropriate burning practices may also be a factor at two of these sites (Broomhead and
Kearton Pasture) and an accidental wildfire was a factor at another (Arnfield Moor). A continuing
legacy of atmospheric pollution (affecting cover and diversity of Sphagnum) may also be a factor at
Arnfield Moor, Broomhead and Thornton Moor, although there is evidence of signs of slow recovery
of at least some Sphagnum species relatively widely in the Peak District and South Pennines (Carroll,
2009) and gully-blocking at Arnfield Moor was improving the condition of previously eroding peat. It
is probable that that 20 years of prescribed grazing practices is insufficient, and more time, and
possibly other interventions, including rewetting and reduction or cessation of burning, might be
needed for recovery of condition of the mires habitat.
Grazing prescriptions varied widely between individual sites and also among the different agri-
environment and ECC control schemes, presenting a very complex set of individual scenarios.
Grazing prescriptions also varied over time at most sites, and were site-specific to some extent
(especially under HLS). For these reasons, and given the variation in vegetation types within and
between sites, a much larger sample would be needed to examine the effectiveness of particular
prescriptions (e.g. stock densities, timing or species).
16
Table 3. Overall changes in annual stocking densities1 (↑ = increase, ↓ = decrease), year of implementation and type of prescription or driver (see Table 1 for scheme codes; F&M = Foot & Mouth disease), mean Calluna grazing index (± st.dev ) in 2014/15 and summary of overall changes in grazing intensity and habitat condition at each site on their commonest target habitats.
Site Year Type Change Current GI (%) Summary
Arnfield Moor Pre-1994 1994 2013
ESA Tier 2 ESA Tier 1C HLS
↓ ↓ ?
17.9 ±14.97 Grazing and eroding peat reduced but wildfire an issue on blanket bog
Birkbeck Commons 1998 2001 2010
ECC ESA HLS
↓ ↓ ↓
19.4 ±13.94 Some beneficial changes following reduced grazing and controls on burning
Broomhead Moor 1993 1994 2013
ESA Tier 2 ESA Tier 1C HLS
↓ ↓ ↓
19.5 ±20.04 Calluna improving due to reduced stocking but burning is damaging
Burnmoor 2001 2012
CSS HLS
↓ ↓
27.4 ±19.95 Changes relatively small and grazing higher than optimum and burning still an issue
Caldbeck Common 2001 2002 2008 2011
F&M - WES HLS
↓ ↑ ↓ ↑
14.0 ±18.30 Previous improvement due to reduced stocking probably being maintained
Crosby Ravensworth Fell (East)
1995 1996 1999 2001 2009
- ECC CSS F&M HLS
↓ ↓ ↓ ↓ ↓
40.2 ±28.69 Continuing improvement in heathland despite grazing levels higher than optimum; grazing lower than optimum on calcareous grassland
Crosby Ravensworth Fell (West)
1995 1996 1999 2001 2009
- ECC CSS F&M HLS
↓ ↓ ↓ ↓ ↓
38.3 ±28.74 Small improvement in Calluna but grazing levels higher than optimum, burning an issue on wet heath and mires
Dozmary Downs 2003 2011
ECC HLS
↓ ↓
11.2 ±14.62 Grazing reduced and positive vegetation change
Ennerdale 1993 2013
ESA Tier 1 HLS
- ↓
6.2 ±8.44 Condition is likely to have improved under low grazing intensity
Ingleborough pre-2001 2001 post-2001 2010
ECC F&M - HLS
↓ ↓ ↑ ↓
n/a Grazing intensity reduced from historical levels but habitats still impoverished
17
Site Year Type Change Current GI (%) Summary
Kearton Pasture 1996 ? 2011
ECC WES HLS
↓ ? ↓
45.1 ±23.98 Current grazing levels high but possible longer term reduction over last 10 years, burning still an issue
Long Mynd 1998 1999 2001 2009
ECC ESA Tier 1 F&M HLS
↓ ↓ ↑ ↓
34.0 ±23.90 Some improvement due to reduced grazing and better burning management
Manor & Trehudreth Common
2000 2003 2010
CSS CSS HLS
↓ ↓ ↑
54.9 ±32.32 Slight improvement overall but unlikely to be maintained under current grazing intensity
Molland Moor 1993 2009
ESA Tier 1 HLS
↓ ↓
14.1 ±22.12 Some improvement although burning probably not changed
Okehampton Common
2000 2002 2004 2012
ECC ESA Tier 1 WES HLS
↓ ↓ ↓ ↓
63.2 ±36.17 Grazing intensity has increased and little improvement since deterioration reported in 2008
Ousby 2001 2002 2010
F&M CSS HLS
↓ ↑ ?
24.9 ±19.07 No change following earlier improvement due to reduced stocking but burning an issue on blanket bog
Reeth Low Moor 2000 2010
CSS HLS
? ↓
37.6 ±22.36 Only small positive changes since earlier improvement but burning probably an issue
Thornton Moor 1995 2011
ECC HLS
↓ ↓
4.9 ±9.49 Reduction in grazing successful but effects of historical damage still apparent
Ugborough & Harford Commons
1998 1999 2010
ECC ESA Tier 1 HLS
↓ ↓ ↑
77.9 ±29.24 Slight long-term improvement but grazing intensity on Calluna is very high
Winsford Allotment 1993 2010
ESA Tier 2 HLS
↓ ↑
23.2 ±25.63 Maintenance of condition following earlier significant improvement
1 change in prescribed livestock units (LU) ha-1 or actual stocking densities; information extracted from reports supplied by NE and might not be complete for some
sites. Note that calculations of LU coefficients for different livestock have varied between schemes.
18
Table 4. Direction of significant changes detected (P < 0.05) on the nine sites where comparable methods were used in previous surveys. ↑ = overall increase; ↓ = overall decrease; ↑↓ = initial increase followed by decrease; ↓↑ = initial decrease followed by increase; - = no significant change detected; () = non-significant trend (P < 0.1); id = insufficient data.
Birkbeck Commons
Burnmoor Crosby Ravensworth (East)
Crosby Ravensworth (West)
Dozmary Downs
Kearton Pasture
Manor & Trehudreth Common
Okehampton Common
Ugborough & Harford Commons
No. of previous surveys analysed
4 1 1 1 2 1 2 3 2
Time since first survey (years)
11 10 8 9 10 7 9 10 10
Time since last survey (years)
6 10 8 9 9 7 7 6 7
GI ↓ (↓) id ↑ ↓ ↑ ↑ ↑ ↑
Dwarf shrub cover - - - ↑ ↑ - ↑ ↓ ↑
Bilberry cover - ↑ - - - - - ↑ ↑
Heather cover ↓↑ - ↑ - ↑ - ↑ ↓ -
Bare ground - - - - ↓ ↓ - - -
Heather height ↓↑ ↑ - - ↓↑ ↑ ↑↓ ↓ ↑↓
Graminoid height ↓↑ - ↑ ↑ ↓↑ ↑ ↓ - ↑↓
Detached heather ↓ ↑ - - ↓ - ↓ ↓ ↓
Detached vegetation
↑↓ - - - - - ↑ ↑ -
Livestock droppings ↓ ↑ - - ↓ ↑ ↑ - ↓↑
Heavily grazed features
↓ ↓ - - ↓ ↓ ↑ - ↓↑
Burning id - id - - - - - -
19
Discussion Few consistent trends were evident across the sample of sites, which would be partly attributable to
the variation in vegetation types, distribution and starting condition, geographic locations,
management prescriptions and timescales. Productivity of upland habitats also differs from year to
year (e.g. Milne et al., 2002; Fraser et al., 2011) and this would also account for some of the variation
among sites. The variability in responses among sites to the changes in management is consistent
with findings from other studies (Martin et al., 2013), as well as more recent research that showed
no evidence of a systematic shift in vegetation responses to reduction or cessation of livestock
grazing in moorland habitats (Littlewood et al., 2014). This suggests that, since individual sites are so
different, it may be more important to understand the processes of vegetation change and how to
drive these in individual situations, rather than seeking commonalities in responses to particular
management prescriptions such as stocking densities. For example, if dwarf shrubs are only present
at low cover but dispersed frequently in the vegetation, then cover can be increased by reducing
stocking density, particularly in winter.
Across the sample of sites, the grazing prescriptions applied are complex but generally there have
been reductions in stocking levels and requirements for more appropriate management, including
burning, based on current knowledge (Glaves et al., 2013; Martin et al., 2013). Sites have been
subjected to a range of grazing prescriptions, with objectives that have often become more
ambitious over time. For example, ECC controls are aimed at stopping deterioration, ESA Tier 1
prescriptions at maintenance, ESA Tier 2 at restoration of heather and HLS at achieving favourable
habitat condition. In general, AES prescriptions aimed at maintenance have not been successful at
restoring degraded moorland habitats, although there are some examples of successful heath
restoration under higher ESA tiers or CSS (Nisbet & Glaves, 2010). One such example from the
current case study sites might be Winsford Allotment, where a combination of Tier 2 management,
including off-wintering, appears to have been successful. Whether the more site-specific HLS
prescriptions will result in further improvement on these sites following the earlier agri-environment
schemes and overgrazing cross-compliance is probably too early to judge, since the agreements have
only been in place for a relatively short time. For example, variation in vegetation responses are to
be expected where different livestock species are included in the prescriptions, due to their
preferences and mode of grazing (e.g. Grant et al., 1987; Fraser et al., 2009) but there was no
obvious difference in the changes occurring on sites grazed by sheep alone or by sheep with cattle or
ponies. There was no evidence in the sample of sites of any recent serious damage due to
disturbance, drainage or invasive species but there was evidence of inappropriate burning on a
proportion of mire sites. Colonisation by trees or scrub, which would signify a lack of management
verging on abandonment, was not noted on any of the sites, although this is not likely to occur even
after 30 years of stock exclusion (Hill et al., 1992), depending on the proximity of colonisation
sources.
Habitat condition
It has been suggested that a GI of 40% might be a suitable level for maintaining mature Calluna
(Kirkham & Milne, 2000) and the CSM guidance is that less than 33% of the last growing season’s
shoots should be grazed (JNCC, 2009). For pioneer Calluna, the CSM threshold is 66%, although
Kirkham & Milne (2000) suggested tentatively that above 40%, growth of pioneer Calluna might be
suppressed. Four of the sites (Kearton Pasture, Manor & Trehudreth Common, Okehampton
Common and Ugborough & Harford Commons) had mean GIs well above the CSM threshold,
indicating that grazing levels on these sites might be too high. Several others also had mean GI
above the threshold level. There was also a suggestion that the grazing intensity on the upland
20
calcareous grassland habitat at Ingleborough is slightly higher than the optimum for that habitat, at
least at the time of the field survey, with anecdotal evidence of eutrophication due to long-term
heavy grazing. A shortage of degenerate Calluna was a recurring feature in the dry heath habitat,
and this might be indicative of grazing levels or burning frequency that, at least historically, have
been too high to allow it to develop. On the other hand, the building stage was widespread in dry
heath, suggesting there is a significant amount of healthy Calluna in this habitat. Undergrazing, in
contrast, was not a significant issue on any of the sites, apart from calcareous grassland at Crosby
Ravensworth (East), which appeared to be below the optimum grazing level for that habitat. The
lowest GIs were at Thornton Moor (4.9%) and Ennerdale (6.2%), where reduced stocking densities
were considered to be assisting recovery of the vegetation following previously high grazing levels.
This concurs with the national picture in England, whereby undergrazing is the cause of
unfavourable condition on less than 0.5% of upland SSSIs (Martin et al., 2013).
A lack of key indicator species was the most common cause of failure to meet condition thresholds
in the heath and mire habitats. Assuming that the species are already present on the site or within
close enough proximity to allow colonisation, re-establishment of the complete plant community
can still be difficult to achieve simply by altering the grazing regime, due to competition from the
dominant dwarf shrubs and graminoids (e.g. Anderson & Radford, 1994; Littlewood et al., 2006;
Critchley et al., 2008). The proliferation of some species might also be constrained by a lack of
propagules or limited dispersal capability. Burning can reduce bryophyte diversity on blanket bog
and can perpetuate dominance of Calluna or graminoids (Glaves et al., 2013), and might have been
responsible for the lack of lower plants or lichens in dry heath at Broomhead Moor and Reeth Low
Moor. External factors can also have an effect. For example, E. tetralix, which was below the
condition threshold in the wet heath habitat at Burnmoor and Ennerdale, is reduced by nitrogen
deposition (Damgaard et al., 2014). Nitrogen deposition can also reduce species richness of
bryophytes and vascular plants and alter species composition on moorland (Caporn et al., 2014) and
is known to interact with grazing in reducing Calluna (Hartley & Mitchell, 2005). In general, the mires
habitat was in poorer condition than dry heath, which probably reflects the sensitivity of mires to
external influences such as atmospheric pollution and hydrological changes, as well as overgrazing,
burning and drainage. Although most of these factors will be historic, the recovery of mires, and
possibly wet heath, to good condition appears to be more problematic and taking longer to achieve
than for dry heath. However, it is also possible that species recognised as key indicators might not
recently have been present at the required level of cover or frequency on a particular site, in which
case it might not be reasonable to expect a generic target to be met at least without more intensive
interventions.
Within Calluna – grass mosaics, the concentration of grazing livestock on grass patches and the
consequent vulnerability of Calluna to grazing at the edge of the patches, is a well documented
phenomenon (e.g. Palmer et al., 2003; Oom et al., 2010). The relatively high failure rate for browsing
on dwarf shrubs might have been attributable to these localised concentrations of grazing in
fragmented heath or on the fringe of heath on some sites. Similarly, the high variability of GIs within
most sites indicates that the distribution of grazing on Calluna was patchy, and not necessarily a
problem across the whole site even where the mean GI was high. For example, on Long Mynd the
areas of fragmented heath tended to be more heavily grazed than where Calluna was more
dominant. Since these vulnerable areas will be targeted by livestock even when they are present at
low densities, the use of techniques such as shepherding (which is widely required within agri-
environment scheme agreements) to distribute livestock more evenly across a site, will be
important.
21
Changes and timescales
Overall, there has been some, generally limited, improvement in condition on most of the sites since
the initial implementation of ECC or AES prescriptions. This is to be expected since reduced grazing
intensity can improve the condition of Calluna and increase structural diversity on dry and
fragmented heath, and can also improve the condition of blanket bog vegetation, including reducing
the cover of dominant Calluna (Rawes & Hobbs, 1979; Martin et al., 2013). Similarly, cessation or
reduction in frequency of burning on blanket bog can reduce the dominance of Calluna or
graminoids (Glaves et al., 2013).
The effects of long-term overgrazing or inappropriate burning can be difficult to redress, as shown
by the general shortage of indicator species on the sites, especially on mires. Change in vegetation
condition in upland habitats in response to a reduction in grazing pressure can take several decades
(Martin et al., 2013), and acid grassland for example, is particularly stable (Hulme et al., 1999). Dry
heath in three sites in the sample was closer to good condition after a period of about 20 years,
while some sites appeared to have improved in condition in the early years of reducing stocking
densities, followed by a period of much slower change. Other surveys have shown that a more
marked reduction in sheep stocking densities to around 0.5 ewes ha-1 can cause some improvement
in c. 10 years (Martin et al., 2013). However, full recovery will take much longer, as sites restored by
simply reducing or excluding grazing did not resemble target vegetation after 14-20 years
(Littlewood et al., 2014). More active management might reduce the length of time needed to
achieve favourable condition, particularly on the more degraded sites. For example, cattle alone or
in combination with sheep can reduce dominance of Molinia, which was widespread on several sites
particularly in the south west. This can create suitable conditions for regeneration of dwarf shrub
vegetation, although there was little indication of recovery after 4 years in one study on wet heath
(Critchley et al., 2008). However, disturbance in combination with seed addition can increase cover
of Calluna on acid grassland to 20-30% in 8 years, if ungrazed or grazed with cattle at low stocking
densities (Critchley et al., 2013), although other species introductions will also be necessary on most
sites. Burning on blanket bog can have both short- and long-term effects, with potential increases in
graminoids and dwarf shrubs occurring over a period of decades, and further successional changes
potentially occurring for over 80 years (Glaves et al., 2013). Burning management on blanket bog
also needs to be planned over long periods or ceased as, for example, a burning rotation of greater
than 55 years might be needed to maintain a propagule bank of Sphagnum in the surface peat (Lee
et al., 2013). Together, the results from this project and evidence from other research indicate that
change is likely to continue on the sites under the current HLS management, albeit more slowly than
in the initial years of grazing or burning controls.
Methodology
The current sample was selected subjectively by NE to provide sites with a reasonable history of
monitoring and previous surveys, and also represented a range of geographic locations, vegetation
types and management history. As a series of case studies it has provided information on the current
condition of each site, along with some general points that might have wider relevance. Habitat
condition was assessed from individual attribute targets (targets for individual attributes to be
passed at 90% of sample points) rather than the full CSM methodology, but they were applied as a
common standard across the sample, which provided a degree of consistency. Individual sites were
below the 90% threshold for favourable condition for various attributes but there was often
substantial spatial variation across the site. For example, Ousby was below the mires condition
threshold for cover of indicator species at the whole site level, but the target was actually passed at
75% of individual sample points. If all other attribute targets were also achieved at these sample
points, areas of less favourable condition might have been confined, for example, to more
22
fragmented areas subjected to localised grazing or burning. Burning in particular tends to occur
patchily on both heath and blanket bog so that recent impacts are relatively localised but with the
area affected increasing cumulatively over time as new patches are burnt, so that its extent might
have been underestimated.
The potential for detecting vegetation change on many of the sites was limited by the variation in
sampling methods used at different times. However, it was usually possible to judge from previous
surveys when substantial change was likely to have occurred, although this was by no means a
precise method. Some changes detected by formal analysis should also be treated with caution, as
several of the surveillance variables are ephemeral and more of a snapshot of current or recent
impacts, such as livestock droppings and GI.
Future work
Continued monitoring at these sites is recommended, in view of the long-term nature of change in
upland habitats. A consistent sampling method should be used in order to analyse change over time
in a robust manner and it is recommended that the method used in this survey, which was similar to
some, but not all previous surveys, should be used.
Some variables are indicative of current, or recent impacts and conditions and more frequent
recording would be desirable in order to generate a time series, instead of a number of individual
snapshots. This would obviously require a larger resource but could be done on a rolling basis, with a
sub-sample of sites surveyed each time.
The spatial distribution of grazing and burning pressures within a site will be important to
understand, in order to focus any damaging effects away from sensitive areas. It is possible that, for
example, high levels of browsing on dwarf shrubs and high GI values could be limited to certain
areas on some sites, with other, possibly substantial areas achieving good condition. An analysis of
existing data incorporating a spatial element in relation to the juxtaposition of different vegetation
types would be useful to investigate this.
Case studies are a useful tool for examining the condition and change on individual sites. In order to
obtain an accurate overview at a national level, a larger random sample of sites is required (e.g.
Critchley et al., 2011). The two approaches are complementary and repeating both at intervals
should help to inform the implementation and outcomes of management practices implemented
under agri-environment schemes and other policies.
23
Acknowledgements We are grateful to Natural England staff for their advice and assistance, particularly David Martin,
Chris Chesterton, Jonathan Bradley and David Glaves.
Field surveys were carried out by JT with Danny Ardeshir, Sonia Brunton, Simon Cope, Richard Ellis,
Emily Jackson, Heather Scott and Steve Shepherd (ADAS) and Simon Conyers, Caroline Hallam,
Alistair Huntley and Ruth Laybourn (Fera). Data handling was carried out by Wadson Makari and
Antonio Calatayud (ADAS) and Alison Riding managed the contract in its initial stages for ADAS.
24
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Appendix 1. Individual Site Reports
Appendix 2. Field Protocol with Forms and Keys to Vegetation Types
Appendix 3. Summary of Condition Assessment Results by Habitat for Each Site