A study of habitats and ground flora in broadleaved

woodlands planted by Moor Trees in the Dartmoor National

Park and surrounding area

Summary Report

Woodland near Scorriton

Authors: Bethan Stagg and Dr Maria Donkin

With thanks to: Mark Millard and the many volunteers that took part in survey work

Contacts

Bethan Stagg (OPAL Community Scientist), Moor Trees, The Old School Centre, Totnes Road, South Brent, TQ10 9BP

email - bethan@moortrees.org, tel. 07866 149773,

Dr Maria Donkin (Project leader OPAL South West), University of Plymouth, School of Biological and Biomedical Sciences,

University of Plymouth, Drake Circus, Plymouth PL4 8AA , email - m.donkin@plymouth.ac.uk, tel - 01752584619,

Dr Bea Campbell (Trustee of Moor Trees), Moor Trees, The Old School Centre, Totnes Road, South Brent, TQ10,

email - bea@moortrees.org, tel - 0845 4569803

Introduction

Moor Trees is a woodland restoration and conservation volunteering charity

established in 1999. Each year the charity works with hundreds of volunteers to plant

woodlands in and around the Dartmoor National Park, using trees grown from locally

collected seed in the charity’s tree nurseries. Moor Trees has now planted sixteen

woodlands, with an average size of 2.3 hectares, which the charity hopes will mature

into woodland habitats comparable to the adjacent mature woodland (figure 1).

In 2008 Moor Trees formed a partnership with the University of Plymouth as part of

OPAL, a national initiative engaging people in monitoring their local environment.

This summary report presents an overview of a baseline ground flora survey carried

out by OPAL in eight of the woodland sites. The aim is to replicate the ground flora

survey on a three-yearly basis, to investigate whether these woodlands in time

develop a characteristic woodland ground flora. An accompanying instruction manual

is provided to enable this and provides an ideal student field project, with practical

assistance from Moor Trees.

The field sites and the surveysFigure 1. Woodland planted at Wedlake site (left) and ground flora in mature woodland

adjacent to Scorriton Down site

OPAL selected eight Moor Trees woodland sites that were as comparable as

possible in previous land-use (semi-improved pasture), size and tree species

composition but diverse in altitude and planting age, from 2002 to 2008 (figure 2).

Student volunteers carried out Phase 1 Habitat surveys of the eight sites and

surrounding landscapes May - June 2008 (figures 3 - 4 and see instruction manual).

Figure 2 – Selected woodland sites

12 3

4

5

7

6

Figure 3.

Student

volunteers

carrying out a

Phase 1

habitat survey

at Courtgate

Orchard

Figure 4. Phase 1

habitat survey map of

Courtgate Orchard (see

instruction manual for

maps of all sites)

Moor Trees volunteers installed ten permanent sampling points in each field site

(numbered stakes) and ten temporary points in each neighbouring pasture and

mature woodland habitat. Volunteer groups carried out vegetation surveys at all

points using 0.25m2 grid quadrats July – Sept. 2008 (figures 5 & 6). Since sites could

not be sampled prior to planting, the pasture provided a reference point for origins of

the ground flora, whilst the mature woodland provided an aspiration of what the

planted woodland might become. In other words the sampling aimed to capture a

picture of the ‘past, present and future’ of the planted woodland.

Figure 5. Moor Trees volunteers locating

sampling points with GPS and conducting

quadrat survey at Wedlake Farm.

Figure 6. Map of sampling points in planted

woodland and neighbouring pasture and

mature woodland at Hillyfield Farm.

Figure 7. From top left:

Volunteer from

Groundwork takes a

break during a survey at

Scorriton.

BTCV participant in

Plymouth selecting plant

species for extracting

plant dyes

Devon Wildlife Trust

participant at Lydford

selecting plant species

for hedgerow basketry

A variety of volunteer groups carried out vegetation quadrat surveys, including

children from two primary schools, excluded young people from regeneration

charities Groundwork and BTCV, long-term unemployed, retired and student adults

from Moor Trees and employees of a university institute taking part in a team-

building event. Nearly all volunteers were botanical novices and a variety of methods

were used to assist the volunteers with plant identification, including ‘photo ID’

sheets (see instruction manual), naming games in which the volunteers would

develop their own memorable names for unfamiliar species, specimen trays and craft

activities that developed botanical skills (figure 7)

Results of ground flora survey

Species diversity comparisons

Plant species diversity is a measure of the number of plant species in a sample and

how rare or common those species are in the sample. The plant species diversity

measures in this report do not include grass species because these proved too

difficult for the volunteers to identify in grazed pastures. A statistical model called a

General Linear Model was applied to the data in the computer application SPSS

(version 17) to investigate the influence of planting site age, size, altitude, aspect,

slope, proximity of mature woodland and plant species diversity of neighbouring

woodland and pasture on the plant species diversity of planted woodland. Altitude,

slope and aspect data were derived from ArcGIS. There were no significant

relationships identified between any of these above predictor variables and species

diversity (Shannon Weiner measure) of planted woodland sites in the subsequent

ANOVA statistical test (R2 = 0.589, degrees of freedom = 7, p = 0.108). In other

words, we can say fairly confidently that none of the above factors have much

influence on the species diversity of the planted woodlands at this point in time.

Plant community analysis

A plant community is simply the collection of different plant species growing together

in a habitat. The computer application PRIMER (version 6) allows us to compare the

plant communities in different habitats, to see the extent to which they overlap in the

species they contain. Figure 8 depicts the plant communities in the planted

woodland, mature woodland and pasture habitats. The figure suggests that the three

plant communities are distinctly different; a statistical analysis confirms that these

three communities are indeed significantly different from each other.

Ancient Woodland Indicators

Ancient woodland indicators were identified in the vegetation data using the

Wildflower Key by Rose (2006). Figure 9 indicates that all one of the vegetation

samples that featured ancient woodland indicators were located in mature woodland.

The phase 1 plant species lists reveal that ancient woodland indicators were

occasionally present in the other habitats but clearly the sampling was not at

sufficiently frequent intervals to capture this information.

Discussion of survey techniques and results

The results from the first year of the study have not provided much new information

but this is not surprising as the main purpose of the study is to monitor vegetation

changes over time. This study’s main achievements so far are to pilot and explore

the use of novice volunteers for botanical surveying and establish a study protocol

that will both inform the woodland restoration work of Moor Trees and provide a

resource for vocational student undergraduate and postgraduate field projects.

It is very encouraging that the plant communities of mature woodland, planted

woodland and pasture are already distinctly different. This will make it easier to

monitor the anticipated transition of newly and recently planted woodland sites to a

mature woodland community. The prevalence of ancient woodland indicators in the

mature woodland plant community provides the opportunity to monitor whether these

species are able to establish in planted woodlands. Distance of planted woodland

from mature woodland is an important factor since such species are typically poor

colonisers (Brunet, 2007). It is also important to identify ancient woodland indicator

species in other neighbouring habitats, as these were sometimes present in

hedgerows (Hillyfield) and in some cases were already present in the planting site

(Dean Burn). A study of ancient woodland indicators should be carried out in spring

as many of these species are geophytes (bulbous plants) and there may be no

visible above-ground growth by mid summer.

It is disappointing that the species data does not include grasses as this means the

study will be unable to monitor how species diversity is affected by the conversion of

the habitat from grassland to woodland. The vegetation survey originally aimed to

focus on a number of easily identifiable grassland and woodland indicator species

but there was no time to carry out the preparatory work required for this prior to the

survey season and group bookings. In 2009 OPAL trialled an indicator species

approach in a series of grassland assessments carried out in partnership with

Plymouth City Council and this method proved very effective.

Due to limited capacity and heavy rain OPAL was unable to carry out light canopy

readings or tree composition and density within a defined radius of sampling points.

Moor Trees plants the saplings at variable densities across the planting site to mimic

the patterns in natural woodland. These densities will affect light intensity, as will the

age and vigour of trees around the sampling point. These variables could have a

significant influence on ground flora composition and development and should be

included in replicates of the ground flora survey. It is also worth noting that an easier

way of marking permanent sampling points would have been to tie a coloured plastic

ribbon to a tree; that way the quadrat would have been positioned a set distance

from a tree, rather than from a wooden stake. In 2009 our volunteers carried out soil

nutrient testing (NPK profiles) and OPAL’s Soil and Earthworm survey on the study

sites but there was insufficient data collected for analysis (see instruction manual). In

2009 and 2010 we aim to carry out the OPAL National Air Survey, which uses lichen

species as biomonitors of nitrogen pollution.

This study has, so far, carried out very little monitoring of the accuracy of volunteer

data collection, through the use of replicate sampling using experienced botanists.

Only one sample was replicated using an experienced botanist; the data was not

found to be significantly different from the sample collected by volunteers, which is

reassuring. Monitoring of this type was carried in the Plymouth grassland

assessments mentioned above and should be included when this study is repeated

in 2011 (figure 10). It will require a trained botanist to carry out replicates of at least

four of the vegetation quadrat surveys, on the same day as the community

volunteers carry out their surveys.

Figure 10. Groundwork

volunteers conducting

grassland assessment

in Plymouth

Background information on woodland

Broadleaved woodland has been the natural vegetation for the British Isles since the

last ice age but only 2% of its original amount remains, in the form of small isolated

fragments (Peterken, 1996). From the early 1990s a number of government

schemes have set out to encourage land owners to create native woodland,

including the current Woodland Grants Scheme, which has contributed to a number

of Moor Trees’ planting projects (Honnay et al. 2002). The habitat fragmentation

typical of most woodland leads to greater vulnerability to environmental stress and

loss of species that are dependent on closed canopy (Saunders et al. 1991; Jules &

Rathcke 1999). Habitat fragmentation is also likely to restrict the migration of

woodland species northwards or to higher altitudes, as a result of climate change.

Many of our native woodland species are already close to the Northern edge of their

distributions, particularly our two native oak species, which may not be such a

familiar sight in our future landscapes (pers. Comm. Crawford).

Packham et al. (1992) observed that whilst government schemes increase tree cover

they do not always create plant communities characteristic of the woodlands they

seek to replace. Davie et al. (1998) identified that this may be due to their isolation

from potential seed sources, poor dispersal and colonisation ability typical of

woodland ground flora species and competition from vegetation established by

previous past land use. The poor dispersal of many ground flora species has led to

them being used as ecological indicators of the presence of old growth woodland

(Peterken, 1996). Planting new woodlands adjacent to existing woodland may

promote colonisation by woodland species, even as distances of more than 200m,

although colonisation may only advance up to 3 metres a year (Brunet, 2007).

Within mature woodland, light is considered to be the most influential factor on the

composition of ground flora and light intensity is affected by seasonality, human

influence or natural processes that include tree decay and gap formation (Hooley &

Cohn, 2003). Soil fertility is also an important factor and woodland plants may be

out-competed by more vigorous weed species in high fertility soils, particularly if the

previous land-use is pasture (Endels et al. 2004). Woodland plants will usually start

to colonise a new site a few years after trees are established and become more

prevalent following canopy closure, which takes about ten years in densely planted

woodland (Brunet, 2007). Flinn & Vellend (2005) identified that the number of

woodland species in a planted woodland increases with age, with 70- year-old

woodlands in Europe and North America having a species composition comparable

with that of many ancient woodlands. So as long as the canopy remains relatively

closed, shade-tolerant woodland flora will easily colonize plantations with light

demanding tree species such as oak. There are a number of methods for speeding

up the colonisation by ground flora, including soil seed bank transferral, direct

sowing, planting, and large-scale translocation (Davy 2002). Local provenance is an

important issue as local genetic strains of species are expected to perform better in

those plant communities than imported genetic strains (Forestry Commission, 2008).

Contacts

Bethan Stagg (OPAL Community Scientist), Moor Trees, The Old School Centre, Totnes Road, South Brent, TQ10 9BP

email - bethan@moortrees.org, tel. 07866 149773,

Dr Maria Donkin (Project leader OPAL South West), University of Plymouth, School of Biological and Biomedical Sciences,

University of Plymouth, Drake Circus, Plymouth PL4 8AA , email - m.donkin@plymouth.ac.uk, tel - 01752584619,

Dr Bea Campbell (Trustee of Moor Trees), Moor Trees, The Old School Centre, Totnes Road, South Brent, TQ10,

email - bea@moortrees.org, tel - 0845 4569803