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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
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