A multi-criteria targeting approach to neutral grassland conservation
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Transcript of A multi-criteria targeting approach to neutral grassland conservation
A multi-criteria targeting approach to neutral grassland conservation
Julian Bayliss*, Alice Helyar, John T. Lee, Stewart Thompson
Department of Biological and Molecular Sciences Geographical Information Systems and Habitats Research Group, Oxford Brookes University,
Gipsy Lane Campus, Headington, Oxford OX3 0BP, UK
Received 16 August 2002; accepted 6 September 2002
Abstract
Resources for creating and managing rare habitats are limited, and a targeting approach aimed at identifying the most viable sites for
habitat conservation is therefore desirable. This study developed a multi-criteria targeting approach to site conservation for two rare
grassland types, based on a suite of biotic and abiotic factors managed within a Geographical Information System. A number of biotic and
abiotic criteria were assessed to evaluate the biodiversity status of grassland sites. Biotic factors included species diversity, species richness
and species rarity; and abiotic factors included patch area, position in the ecological unit and the influence of surrounding land use. Each
criterion was given equal weighting and a final biodiversity value for each patch was calculated; the patch with the highest cumulative rank
score was deemed the patch with the greatest biodiversity. Each site was then examined in relation to agricultural land under the existing
management prescriptions of the Upper Thames Tributaries Environmentally Sensitive Area (UTTESA). Sites identified with high
biodiversity potential, but currently not included under management prescriptions, were targeted for future inclusion in the ESA scheme. The
targeting approach demonstrated how the national Lowland Meadows habitat action plan creation target of 500 ha could be achieved in the
UTTESA. The fact that this target figure was so easily attained within this study area highlighted the possible underestimation of national
habitat creation targets.
q 2002 Elsevier Science Ltd. All rights reserved.
Keywords: ESA; GIS; Habitat action plans; Mesotrophic grasslands
1. Introduction
This research is undertaken as a contribution to the
growing interest in the conservation of neutral grasslands
in the UK. Although the discussions may at times be
technical the issues are straightforward: how do we choose
those grassland sites to which our limited resources should
be allocated, and are more ambitious conservation targets
achievable within those resources. A targeting approach
has been developed with an existing agri-environment
scheme in mind as the funding mechanism. This is the
environmentally sensitive area (ESA) scheme which is
managed by the Department for Environment, Farming,
and Rural Affairs (DEFRA) in the UK. The work is
supported by the GIS and Habitats Research Group at
Oxford Brookes University, UK.
2. Situation
Lowland mesotrophic ‘neutral’ grasslands are rare and
threatened habitats, specifically the lowland flood meadows
Alopecurus pratensis–Sanguisorba officinalis (hereafter
referred to as type MG4) and old grazed hay meadows
Cynosurus cristatus–Centaurea nigra (hereafter referred to
as type MG5) (Rodwell, 1998). These habitats are listed
under Annex 1 of the European Union’s Directive 92/43/
EEC on the Conservation of Natural Habitats and of Wild
Fauna and Flora (EEC, 1992), commonly known as the
‘Habitats Directive’, as priority habitat requiring special
conservation measures. In the UK these habitats are covered
by a habitat action plan (HAP) with a commitment to
conserve and enhance their distribution in response to
dramatic declines in former ranges (Fuller, 1987; Hopkins,
1990; Jefferson and Robertson, 1996; Young, 2000). For
example, the Lowland Meadows HAP sets a target of 500 ha
of lowland hay meadow to be re-established by 2010 on
carefully targeted sites (Wynne et al., 1995; UK Biodiver-
sity Steering Group, 1999). It is estimated that in the UK
0301-4797/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0301-4797(02)00202-5
Journal of Environmental Management 67 (2003) 145–160
www.elsevier.com/locate/jenvman
* Corresponding author. Tel.: þ44-1865-483269; fax: þ44-1865-
483242.
E-mail address: [email protected] (J. Bayliss).
there has been a loss of 97% of semi-natural lowland
meadow sites between 1938 and 1984, with further national
declines of between 2 and 10% per annum (UK Biodiversity
Steering Group, 1999). These losses are largely due to
agricultural intensification and drainage. The HAP esti-
mates that MG5 grassland currently covers between 5000
and 10 000 ha in England and Wales, whilst MG4 has a total
cover of less than 1500 ha; 10% of which can be found in
Oxfordshire (Stevenson and Liwicki, 1999).
3. Problem statement
This neutral grassland resource is highly fragmented,
being characterised by a number of small isolated patches
and it is generally considered desirable to reduce these
levels of fragmentation with judicious spatial targeting of
both conservation and expansion measures.
4. Goals, targets, hypotheses
If this is to occur it is important first to identify those sites
of high conservation potential (in terms of biodiversity
assessment criteria) to include within the reserve network;
and second, to target expansion around these sites to
encourage re-generation accompanied by appropriate in-site
management. As the majority of lowland neutral grassland
is located in some of the most intensively farmed country-
side in the UK it is logical to enlist the support of land
managers to help achieve the UK HAP targets of the Upper
Thames Tributaries Environmentally Sensitive Area
(UTTESA). This study will consider how much of this
national target can be realistically achieved within the study
area, taking into account the individual requirements of the
biodiversity action plan (BAP) species associated with the
habitat.
5. Materials and methods
5.1. Study area
Introduced in 1987 the ESA scheme aims to protect
countryside of high landscape, wildlife or historic value (i.e.
land that is deemed ‘sensitive’). The ESA initiative is one of
several agri-environment schemes that are designed to
encourage sympathetic agricultural practices; farmers enter
land under specific management prescriptions and receive
payments for farming in an environmentally friendly
manner. There are currently a total of 22 ESA schemes in
England covering 10% of all agricultural land, of which
532 000 ha were under management prescriptions in 2000
(DEFRA, 2001).
The UTTESA, created in 1994, was the last ESA to be
designated in the UK. It covers an area of 27 000 ha and
incorporates the five main tributaries of the Upper Thames
river. These are the rivers Windrush, Evenlode, Glyme,
Cherwell, and Ray (Fig. 1). The majority of the UTTESA is
located within Oxfordshire although parts are also found in
Buckinghamshire, Gloucestershire, and Northamptonshire
(ADAS, 1997, 1998). Generally the land within the
UTTESA is a mosaic of agricultural lands, principally
arable land and improved grasslands, with isolated pockets
of lowland flood meadows (MG4) and old grazed hay
meadows (MG5). The respective land management pre-
scriptions undertaken in the UTTESA are managed through
the Department for Environment, Food and Rural Affairs
(DEFRA).
There are five types of management prescriptions
(known as ‘tiers’) available to farmers in the UTTESA
and these generally relate to the initial state of the habitat.
Tier 1A has to be managed under a permanent grassland
management plan with restrictions on grazing and fertiliser
use. Tier 1B has all the management prescriptions of Tier
1A plus certain restrictions on harvesting dates and stocking
rates. Tier 2 has all the management prescriptions of Tier 1
plus requirements on the maintenance of water levels. Tier
3A prescriptions relate the reversion of arable land to
extensive permanent grassland, and Tier 3B relates to the
reversion of arable land to lowland wet grassland. As of
December 1997 there were 226 land management agree-
ments in the UTTESA (ADAS, 1998).
5.2. GIS and ecology
With a fragmented rural matrix composed of a mosaic of
habitat patches, as is commonly the case in the UK, a spatial
targeting approach to site conservation is desirable. This
approach not only takes into account the biodiversity but
also the spatial dynamics of the focal habitat. To assess the
spatial dynamics of habitats and species within the study
area a geographical information system (GIS) was devel-
oped. GIS are increasingly used as tools to assist in policy
formulation for both inventory purposes and in addressing
wider strategic issues, such as screening of ESA agreement
applications to maximise environmental benefits from
limited financial resources (Swetnam et al., 1998). GIS
development, specifically to identify and target sites for
habitat and species conservation, is increasingly being
employed as a conservation management tool (Pereira and
Itami, 1991; Potter et al., 1993; Veitch et al., 1995; Cook
and Norman, 1996; Bian and West, 1997; Brown et al.,
1998; Lee et al., 2001; Lurz et al., 2001).
6. Methods
The habitat ranking scheme of neutral grassland patch
quality in the UTTESA required the assessment of seven
biotic and abiotic factors (Table 1) incorporated within five
criterion. Four of the main criteria were based on the Ratcliffe
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160146
(1977) criteria of habitat assessment: patch size, diversity
(floral and faunal, and species richness), rarity, and position in
the ecological unit. The fifth criterion, restoration potential,
was developed to assess the feasibility of expanding the site
based on a factor due to surrounding land use.
Species were chosen on the basis of their association
with MG4 and MG5 habitat types (Rodwell, 1998), as well
as their status in the UK BAP and the local biodiversity
action plan (LBAP) (Dodds et al., 1995; ONCF, 1998) in
which they are listed as threatened and have declining
populations. The nine species chosen were skylark (Alauda
arvensis), curlew (Numenius arquata), lapwing (Vanellus
vanellus), reed bunting (Emberiza schoeniclus), reed
warbler (Acrocephalus scirpaceus), snipe (Gallinago
Fig. 1. Location of the UTTESA in the UK.
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160 147
gallinago), redshank (Tringa totanus), yellowhammer
(Emberiza citrinella), and water vole (Arvicola terrestris).
For ease of reference, the 79 neutral grassland sites were
numbered and named according to their location in each
tributary branch listed in numerical order. The branches
were numbered 1–7
1. River Thames A (Buscot GR: SU 230 980 to Newbridge
GR: SP 404 014, at the confluence of the Windrush and
Thames)
2. River Windrush (Bourton-on-the-water GR: SP 173 200
to Newbridge GR: SP 404 014)
3. River Evenlode (Bledington GR: SP 268 205 to
Cassington GR: SP 448 100)
4. River Glyme (Old Chalford GR: SP 345 255 to Bladon
GR: SP 430 142)
5. River Cherwell (Hinton GR: SP 537 524 to Iffley GR: SP
524 028)
6. River Ray (Edgcott GR: SP 680 215 to Islip GR: SP 523
137)
7. River Thames B (Newbridge GR: SP 404 014 to Iffley
GR: SP 524 028).
For example, site 6.10 represents the 10th site on the
River Ray (tributary 6).
6.1. Biotic criteria
6.1.1. Floral diversity
National vegetation classification (NVC) surveys were
obtained for the neutral grassland sites from English Nature
and the local wildlife trust. The vegetation survey data were
then analysed using the MATCH programme (Malloch,
1999), which assesses the similarity between pairs of
vegetation communities. MATCH calculated the simi-
larities between sample data and NVC communities by
means of the Czekanowski similarity coefficient, which
assesses similarity between pairs of communities in terms of
their species composition. MATCH lists the NVC commu-
nities and sub-communities that are most similar to the data
collected. The output was used to assess quality of the
vegetation community in relation to the expected species
composition in the NVC classification system for MG4 and
MG5 communities. Sites were ranked twice, once according
to the NVC MATCH coefficient for type MG4 and again for
type MG5. The site with the highest MATCH similarity
coefficient was ranked highest. Tied scores were not
resolved.
6.1.2. Species richness—fauna
The presence/absence of 9 LBAP target species (Table 2)
on each site were assessed using known distribution records
of individuals between 1995 and 2001. The nine species
were chosen as they are both highly dependent upon the
MG4 and MG5 habitat types for feeding and breeding areas,
and there are nationally agreed targets for their population
expansion (Wynne et al., 1995; UK Biodiversity Steering
Group, 1999). Vector data map layers were created from six
figure UK national grid references accurate to the nearest
100 m, and four figure grid reference points accurate to the
nearest 1000 m, the latter centred in the middle of the grid
square to account for the coarse resolution. Species
distribution on the grassland sites was then scored using
the GIS software package ArcVieww and the number of
species present within the boundaries of each neutral
grassland site recorded to assess the suitability of each
patch to support a range of species. Sites with the most
species were ranked highest. Tied scores were not resolved.
6.1.3. Faunal diversity
In order to assess the species diversity of the neutral
grassland sites the abundance data of each species present
on the patch was used to calculate the Shannon–Wiener
Index of Diversity (Fowler and Cohen, 1995; Sutherland,
1997). Species abundance at each site was calculated as the
mean abundance per year over the number of years the
species had been recorded at the site. If several observations
existed for each site, the mean abundance for each
observation was calculated to give the total abundance on
site. Sites with high species diversity were ranked highest.
Tied scores were not resolved.
6.1.4. Species rarity
Using the species richness data for each site, the rarity of
the species present was scored according to their listing in
the UKBAP and the LBAP, which included the rate of
decline, local rarity, and local distinctiveness. All data were
collected annually in accordance with nation wide agreed
survey techniques, e.g. the British Trust for Ornithology
Table 1
Criteria included in the analysis
Data type Specific Criteria used in
selecting sites
Biotic Species diversity Floral diversity according to
lowland floodplains (code MG4)
and old grazed hay
meadows (code MG5) community
characteristics
Species richness (fauna) of
selected LBAP species
Species diversity (fauna)
Rarity Species rarity (fauna) according
to listings in the
UK BAP and LBAP,
rates of decline, local
rarity and local distinctiveness
Abiotic Patch size Patch area (ha)
Position in the ecological
unit
Minimum nearest neighbour distance
(minNN), edge to edge
Degree of landscape fragmentation
Potential to expand A factor due to
surrounding land use
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160148
(BTO) Breeding Bird Survey (BBS) (Bibby et al., 2000).
The species were ranked according to their final rarity score
(Table 2). Local (Oxfordshire) rate of decline over the last
25 years was scored according to species whose range or
numbers were rapidly declining (50–100%), declining (25–
49%), or ‘stable’ (24% decline or a 24% increase) following
the assessment criteria outlined in Oxfordshire’s LBAP
(ONCF, 1998). Local rarity was also assessed on a tetrad
scale (2 km2) in terms of those species that were rare
(occurring in 0.6% tetrads or less in Oxfordshire), those that
were scarce (occurring in 0.6–4.0% of tetrads in Oxford-
shire), and those that were common (occurring in more than
4.0% tetrads in Oxfordshire). Local distinctiveness was
scored according to flagship species (high profile species),
keystone species (ecologically important species), and
typical species (species characteristic within Oxfordshire).
Each site was then scored according to the sum of the
ranked species present; for example, species present may
include curlew (ranked 2), snipe (ranked 8) and water vole
(ranked 9), scoring a total of 19 for this site (refer to
Table 2). Sites were then ranked according to their total
species rarity; those with the greatest cumulative species
rarity were ranked highest. Tied scores were not resolved.
6.2. Abiotic criteria
6.2.1. Patch size
Sites were ranked according to their area, which was
recorded from the attribute database from the vector data
map layer of the neutral grassland sites in the GIS. Landuse
information was obtained from DEFRA. The largest patches
were ranked highest. Tied scores were not resolved.
6.2.2. Position in the ecological unit
Contiguous sites are much more likely to be of greater
conservation value than fragmented sites (Ratcliffe, 1977).
The connectivity of the neutral grassland habitats and their
position in the ecological landscape were assessed using the
spatial analyst programme FRAGSTATSArc (McGarigal
and Marks, 1995). This calculated the minimum nearest
neighbour distance (minNND) of the neutral grassland
patches in the UTTESA. MinNND is defined as the distance
from one patch to another based on edge-to-edge distance
(McGarigal and Marks, 1995). Patches with the highest
minNND, i.e. the most remote patches, were ranked lowest.
Tied scores were not resolved. It was assumed that there
were no suitable habitats between the patches and that patch
colonisation was dependent on the minimum nearest
neighbour distance (Beier and Noss, 1998; Harrison and
Bruna, 1999). For this reason, more isolated patches were
assumed to be less diverse than contiguous patches.
6.2.3. Surrounding land use
Surrounding land use types were assessed for restoration
potential based on the suitability for habitat expansion. The
primary factors involved in this assessment were proximityTab
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J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160 149
to known resources (i.e. other neutral grassland sites), the
size of individual patches, and the degree of shared
perimeter (if any) between patches. The land use GIS
database was divided into nine categories (Table 3), which
were assigned one of four indices of their restoration
potential to neutral grassland: good (G), moderate (M), poor
(P) or impossible (I).
The surrounding land use criterion was calculated from
the length of the shared boundary between each habitat
patch and the adjacent land, and expressed as a percentage
of the total patch perimeter. Water courses were ignored if
they bordered neutral grassland patches and the next
terrestrial landuse was considered. A 100 m buffer of the
adjacent land was included in the calculation to account for
this. As waterways do not present an insurmountable barrier
to the dispersal of many of the target species, this research
assumed that it is possible to restore grassland habitats on
either side of waterways. The 100 m buffer therefore
increased the area of land over which restoration potential
was calculated, accounting for the immediate boundaries.
Each patch was then ranked four times according to the
amount of perimeter it shared with land of good, moderate,
poor or impossible restoration potential. When the patches
were ranked for good and moderate restoration potential,
patches with the greatest shared perimeter were ranked first.
Patches with the greatest shared perimeter with land of poor
or impossible restoration potential were ranked last (Lee
et al., 2001). To account for the importance of sharing a
perimeter with land of high restoration potential and reflect
the difficulty of restoring land of impossible restoration
potential, these ranks were given double weighting.
The total scores were ranked so that neutral grassland
patches adjacent to land of poor and impossible restoration
potential were ranked lowest and patches adjacent to land of
high and moderate restoration potential were ranked highest
(Lee et al., 2001 for a full explanation of the methodology).
Tied scores were not resolved. The four ranks were summed
to rank the sites in order of their overall restoration
potential.
6.3. Final ranking
The seven criteria were summed with equal weight with
the highest scoring, most diverse patch ranked first. Separate
algorithms were developed for MG4 and MG5 scores from
each patch, thereby creating two separate lists of ranked
patches, enabling targeting of sites for conservation and
enhancement based on the community composition for both
grassland types. The final patch rank was assigned based on
the following algorithm
MG4 sites¼floral diversity ðMG4Þþ species richness
þ species diversityþ species rarity
þpatch sizeþminNND
þ expansion potentialðlanduseÞ:
and
MG5 sites¼floral diversityðMG5Þþ species richness
þ species diversityþ species rarityþpatch size
þminNNDþ expansion potentialðlanduseÞ:
The results obtained from the final ranking process were
compared with a list of existing site designations to assess
the effectiveness of the overall methodology. Sites were
selected for enhancement in order of their ranked biodi-
versity value, with the highest ranked site selected first.
Land immediately adjacent to the top ranked sites was
assessed for the suitability of expansion through two
criteria. Firstly the expansion potential based on proximity
to known resources, the size of individual patches, and the
degree of shared perimeter between patches; and secondly
the occurrence of adjacent land under an existing ESA
management prescription. This method identified the most
desirable MG4 and MG5 sites for habitat creation up to the
500 ha target. An algorithm was developed accordingly
(Fig. 2).
7. Results
7.1. Biotic criteria
7.1.1. Floral diversity
Fifty-nine of the 79 neutral grassland patches in the
UTTESA were included in the study as these had NVC
survey data. NVC MATCH similarity coefficients ranged
from 69.9 to 2.0% for MG4 communities and 63.9 to 4.7%
for MG5 communities. Although patches with MATCH
coefficients below 40% were deemed to be a poor goodness
of fit, they were still ranked to provide an indication of the
species composition in relation to MG4 and MG5
communities.
Table 3
Landuse database categories and relative restoration potential
Landuse type Restoration potential
Floodplain grassland Good
Floodplain arable Good
Floodplain margins Moderate
Non agricultural Impossible
Open water Impossible
Other arable Moderate
Other grassland Good
Other margins Poor
Woodland and scrub Poor
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160150
7.2. Fauna
7.2.1. Species richness
Table 4 shows the results of the patch ranking using
species richness. Sites with more than one record for each
species indicate that the species was sighted at more than
one location within the patch. Only 20 of the 59 patches
have had target species recorded within their boundaries
since 1995.
7.2.2. Species diversity
The Shannon–Wiener Index of Diversity was calculated
for each patch (Table 4). Sites with only one recorded
species scored a diversity index of 0 indicating a patch
without diversity. However, these sites were more diverse
than patches without any recorded species, which also
scored a diversity of 0. Scoring the species richness
therefore accounted for this difference.
7.2.3. Species rarity
Species rarity was scored to reflect the importance of
species present on the sites. Table 4 shows the site ranking
using species rarity scores. For example site 7.29 was
ranked as the patch with the highest occurrence of rare
species with a score of 43 (out of a possible maximum score
of 48).
7.2.4. Final patch ranking of biotic criteria
The sum of the ranks and the final patch ranking of biotic
criteria for MG4 and MG5 grassland communities are
shown in Table 4. Sites 1.2, 1.6 and 5.6 were ranked as the
top three patches with the highest scoring biotic criteria for
MG4 vegetation communities. Sites 1.2, 1.6, and 6.10 were
ranked as the top three patches with the highest scoring
biotic criteria for MG5 vegetation communities. These sites
consistently had well matched vegetation communities to
MG4 and MG5 characteristics, and high-ranking species
diversity and rarity.
7.3. Abiotic criteria
7.3.1. Patch area
Patches ranged in size from 212.2 to 0.17 ha (Table 5).
The mean patch area was 20.43 ha (Std ¼ 36.6), which is
above the national average as most grassland sites in
England are less than 10 ha (Jefferson and Robertson, 1996).
The large mean patch area was skewed due to the presence
of three extensive large areas of neutral grassland; site 6.10
(212 ha), site 7.29 (165 ha), and site 1.3 (91.7 ha). However,
as 22 additional patches were larger than 10 ha, the large
mean patch size illustrated the importance of the UTTESA
for MG4 and MG5 grasslands.
7.3.2. Position in the ecological unit
Thirty-seven patches were directly contiguous with other
neutral grassland patches and therefore had a minNND of
0 m (Table 5). These patches were treated as separate
patches due to their distinct biotic and abiotic character-
istics. The mean minNND was 649.2 m (Std ¼ 1603.1),
with a maximum of 7920.2 m. The variation in inter-patch
distance reflects the fragmented nature of neutral grassland
habitats. However, the relatively small mean distance
between patches is indicative of the high concentration of
neutral grassland habitats within the UTTESA boundary.
7.3.3. Surrounding landuse
The results of the patch ranking based on the surrounding
land use scores are shown in Table 5. The highest ranked
patch (site 6.1) had high expansion potential as it had the
greatest proportion of adjoining land of good and moderate
restoration potential, being completely surrounded by
grassland and arable land. The majority of patch boundaries
were shared with land of good restoration potential
(mean ¼ 62.2%). Patch boundaries shared with land of
impossible and moderate restoration potential were also
frequent (mean perimeter shared ¼ 22.0% and 14.5%,
respectively); however, shared boundaries with land of
Fig. 2. Algorithm to identify suitable land adjacent to grassland sites to achieve the restoration target of 500 ha.
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160 151
Table 4
Patch ranking according to biotic criteria: species richness, species diversity (2H), and species rarity
Site Sp richness Sp richness rank 2H 2H rank Sp rarity Sp rarity rank Total rank score
(MG4)
Final rank
(MG4)
Total rank score
(MG5)
Final rank
(MG5)
1.2 3 53 0.8 58 19 55 217 1 221 1
1.6 4 55 1.3 59 12 51 214 2 212 3
5.6 2 51 0.1 51 16 54 210 3 206 5
6.10 8 58 0.2 53 39 57 203 4 216 2
6.9 8 58 0.2 52 39 57 197 5 207 4
7.29 7 57 0.4 56 43 59 195 6 204 6
6.7 3 53 0.3 54 12 51 191 7 187 8
5.2 6 56 0.3 55 32 56 186 8 184 9
2.11 2 51 0.7 57 13 53 183 9 200 7
7.11 1 40 0 1 2 40 140 10 133 11
7.10 1 40 0 1 2 40 136 11 140 10
1.3 1 40 0 1 2 40 134 12 132 12
7.12 1 40 0 1 2 40 128 13 126 13
5.10 1 40 0 1 8 48 121 14 119 14
6.11 1 40 0 1 5 46 104 15 101 17
2.12 1 40 0 1 8 48 101 16 104 16
4.1 1 40 0 1 2 40 97 17 107 15
5.3 1 40 0 1 8 48 92 18 92 18
7.4 1 40 0 1 2 40 90 19 91 19
2.10 1 40 0 1 5 46 88 20 88 20
7.6 0 1 0 1 0 1 61 21 58 22
1.1 0 1 0 1 0 1 59 22 61 21
6.5 0 1 0 1 0 1 59 22 58 22
5.5 0 1 0 1 0 1 55 24 55 25
1.4 0 1 0 1 0 1 53 25 52 26
2.4 0 1 0 1 0 1 51 26 38 35
1.8 0 1 0 1 0 1 49 27 45 30
6.4 0 1 0 1 0 1 48 28 49 27
7.14 0 1 0 1 0 1 47 29 28 41
7.20 0 1 0 1 0 1 46 30 44 31
6.2 0 1 0 1 0 1 45 31 24 44
5.8 0 1 0 1 0 1 44 32 37 36
6.3 0 1 0 1 0 1 43 33 47 28
5.7 0 1 0 1 0 1 42 34 31 39
7.18 0 1 0 1 0 1 41 35 30 40
7.24 0 1 0 1 0 1 40 36 46 29
6.8 0 1 0 1 0 1 39 37 57 24
7.5 0 1 0 1 0 1 37 38 40 32
7.19 0 1 0 1 0 1 34 39 27 42
7.21 0 1 0 1 0 1 32 40 33 38
6.1 0 1 0 1 0 1 31 41 24 44
6.6 0 1 0 1 0 1 30 42 39 34
5.9 0 1 0 1 0 1 29 43 26 43
5.12 0 1 0 1 0 1 28 44 22 47
7.30 0 1 0 1 0 1 26 45 40 32
4.4 0 1 0 1 0 1 24 46 36 37
2.13 0 1 0 1 0 1 23 47 23 46
2.2 0 1 0 1 0 1 21 48 15 51
2.1 0 1 0 1 0 1 18 49 12 53
2.6 0 1 0 1 0 1 17 50 21 48
3.1 0 1 0 1 0 1 16 51 19 49
2.9 0 1 0 1 0 1 14 52 16 50
5.4 0 1 0 1 0 1 13 53 14 52
2.3 0 1 0 1 0 1 11 54 9 56
5.11 0 1 0 1 0 1 10 55 5 59
3.2 0 1 0 1 0 1 9 56 10 55
4.3 0 1 0 1 0 1 8 57 8 57
3.3 0 1 0 1 0 1 7 58 7 58
2.7 0 1 0 1 0 1 5 59 11 51
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160152
Table 5
Patch Ranking according to abiotic criteria: patch area, position in ecological unit (minNND) and a factor due to the surrounding landuse
Site Area (ha) Area rank minNND (m) minNND rank Surrounding landuse score Landuse rank Total rank score Final abiotic rank
6.10 212.2 59 0 23 55 56 138 1
6.9 40.9 52 0 23 114 44 119 2
2.2 33.0 49 0 23 107 45 117 3
1.6 31.9 48 0 23 120 42 113 4
6.3 11.7 39 0 23 84 51 113 4
6.2 7.0 32 0 23 43 58 113 4
1.3 91.7 57 1422.2 8 101 46 111 7
5.2 22.9 44 0 23 128 39 106 8
5.3 44.1 54 0 23 157 28 105 9
1.4 45.4 55 2650.5 5 117 43 103 10
7.6 5.8 26 0 23 67 54 103 10
7.5 31.3 47 0 23 148 31 101 12
2.10 12.4 40 1060.7 11 89 50 101 12
3.1 6.0 27 100 21 81 52 100 14
7.10 39.0 50 0 23 170 24 97 15
7.14 28.3 46 0 23 164 27 96 16
2.7 14.2 41 492.4 13 122 41 95 17
2.1 5.7 25 0 23 92 47 95 17
7.29 165.0 58 0 23 208 12 93 19
7.11 42.0 53 0 23 198 16 92 20
2.11 3.7 15 0 23 68 53 91 21
1.8 3.3 13 0 23 64 55 91 21
5.6 40.6 51 0 23 204 14 88 23
6.7 60.1 56 1767.1 6 174 23 85 24
1.1 10.9 38 492.4 13 148 31 82 25
7.4 4.6 21 0 23 134 36 80 26
2.4 4.5 20 4225.2 3 45 57 80 26
5.10 28.0 45 0 23 224 11 79 28
5.5 4.6 22 111.8 20 129 37 79 28
6.1 2.3 10 1110.2 10 42 59 79 28
7.19 7.1 33 0 23 186 21 77 31
4.4 5.6 24 304.1 18 137 35 77 31
6.5 6.3 28 0 23 166 25 76 33
5.7 6.6 30 427.2 17 150 29 76 33
4.3 9.8 37 304.1 18 190 20 75 35
6.4 4.2 18 0 23 141 33 74 36
2.3 8.2 34 0 23 198 16 73 37
6.11 22.9 43 602.1 12 197 18 73 37
2.13 0.3 2 0 23 90 48 73 37
4.1 6.9 31 7920.2 1 126 40 72 40
3.2 9.3 36 100 21 205 13 70 41
7.20 4.8 23 0 23 182 22 68 42
3.3 4.1 17 7800 2 90 48 67 43
5.9 6.5 29 0 23 227 10 62 44
1.2 3.0 12 492.4 13 129 37 62 44
7.12 9.1 35 0 23 264 3 61 46
6.8 4.2 19 0 23 196 19 61 46
2.12 0.4 3 0 23 149 30 56 48
7.30 15.6 42 1297.1 9 252 4 55 49
2.9 1.0 6 0 23 166 25 54 50
6.6 2.7 11 1732.8 7 141 33 51 51
7.18 3.6 14 0 23 245 6 43 52
7.21 1.3 7 0 23 228 9 39 53
5.11 2.2 9 0 23 248 5 37 54
2.6 3.9 16 492.4 13 230 8 37 54
7.24 0.8 5 0 23 244 7 35 56
5.8 0.5 4 0 23 270 2 29 57
5.4 1.6 8 3400 4 204 14 26 58
5.12 0.2 1 0 23 276 1 25 59
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160 153
poor restoration potential were infrequent (mean perimeter
shared ¼ 1.4%). It is important to note that restoration
potential criteria were selected purely on the ecological and
conservation potential of the land rather than on economic
considerations.
7.3.4. Final patch ranking for abiotic criteria
Sites 6.10, 6.9, and 2.2 were the highest ranked patches;
and sites 5.8, 5.4, and 5.12 were the lowest ranked patches,
for the abiotic criteria (Table 5). Low ranking was largely
attributed to small patch size but also to the poor restoration
potential of the surrounding land use.
7.4. Overall site ranking
Overall patch ranking scores were calculated by sum-
ming the total biotic rank scores with the total abiotic rank
scores. For example the top ten patches for MG4 and MG5
grasslands based on biodiversity criteria are listed in Table 6.
Sites 6.10 and 6.9 are collectively a nationally important
wet grassland area and were ranked first and third as neutral
grassland patches with the greatest biodiversity for both
MG4 and MG5 communities. The sites were large, had high
species richness, diversity and rarity, low minNND, and
were surrounded by land of good restoration potential. The
results of the ranking scheme developed in this investigation
confirm the nature conservation value and status of these
sites, and support the large-scale conservation work
currently being carried out on the sites. Site 1.6 was also
highly ranked (second) reflecting its importance for both
MG4 and MG5 communities.
Consistent with the integral nature of these two habitats,
the overall patch ranking for MG4 and MG5 contained the
same sites although they appeared in a slightly different
order (Table 6). The lowest overall ranking was given to site
5.4, as the patch had no recorded species present, was small,
was isolated and had poor restoration potential.
7.5. Comparison of final output with site designation
Of the top 10 ranked sites of high biodiversity, six are
Sites of Special Scientific Interest (SSSI’s) (sites 6.10,
5.6, 7.29, 5.2, 6.7, and 1.3), three are locally designated
‘Alert Map’ sites (sites 1.6, 6.9, and 2.11), and one (site
1.2) was unofficially designated as a site of nature
conservation interest by a statutory body.
Of particular note were the high ranked sites 7.29,
7.10, 7.11 and 7.6 (ranked 6, 11, 12 and 20,
respectively), which are designated candidate Special
Areas of Conservation (cSACs) under the Habitats
Directive for their high biodiversity value. Site 1.4, a
national nature reserve (NNR), was only ranked 23rd, a
low rank considering its national status. This low rank
can be attributed to a lack of species recorded within the
site boundaries, scoring poorly for species richness,
diversity and rarity.
The highest ranked undesignated patch (i.e. not officially
designated as a site of nature conservation interest) was site
1.2, ranked seventh for MG4 and 8th for MG5 vegetation
community characteristics. The top rank was due to the high
number of species recorded on the site.
7.6. Targeting sites for habitat expansion
The patches targeted for expansion (Table 7) were
selected on the basis of their biodiversity. Sites 6.10 (ranked
first) and 6.9 (ranked third) were excluded from patch
expansion targeting because they already have individual
management plans with separate targets for habitat expan-
sion and enhancement. Fig. 3 shows the areas of land
targeted for habitat enhancement bordering the highest
ranked neutral grassland patches. Site 1.6 was found to have
the largest area of surrounding land (110.4 ha) suitable for
expansion (Table 7).
Land suitable for expansion but not currently under
any ESA agreement was identified (Fig. 4). It is these
areas that are the sites to be targeted for inclusion under
ESA agreements. If they are managed accordingly they
will contribute to the neutral grassland network whilst
Table 6
The 10 highest ranked patches for MG4 and MG5 grasslands based on the
biodiversity criteria
Rank MG4 Sites MG5 Sites
1 6.10 6.10
2 1.6 1.6
3 6.9 6.9
4 5.6 7.29
5 5.2 5.6
6 7.29 2.11
7 1.2 5.2
8 6.7 1.2
9 2.11 6.7
10 1.3 1.3
Table 7
Available land adjacent to neutral grassland patches that could be targeted
for habitat restoration to achieve the UK HAP target of 500 ha
Site Expandable area (ha) Cumulative total area (ha)
1.6 110.4 110.4
5.6 15.6 126
5.2 135.6 261.6
7.29 90.4 352
1.2 90.5 442.5
6.7 34.7 477.2
2.11 27.4 504.6
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160154
meeting the UK national HAP habitat creation target of
500 ha of lowland meadow (UK Biodiversity Steering
Group, 1999). Sites 1.6, 5.6, 5.2, 7.29, 1.2, 6.7 are
patches identified for inclusion in the ESA scheme that
would fulfil this target.
7.7. Landscape fragmentation
A comparison was made between the minNND of neutral
grassland patches in the landscape with and without the sites
targeted for enhancement. Table 8 shows the difference
between the median minNND before and after patch
enhancement. There was a significant decrease in the
median minNND between patches with and without
enhancement (Mann–Whitney U-test, P ¼ 0.003). A com-
parison was also made between the mean patch area before
and after patch enhancement (Table 8) and a significant
difference was found (two sample t-test, P ¼ 0.021).
Following enhancement the mean patch area increased,
although the data was found to be skewed and was therefore
normalized. As a result of patch enhancement, the distance
between patches decreased and the patch area increased,
decreasing the overall fragmentation of the landscape as is
expected with an increase in habitat area.
8. Discussion
8.1. Overall ranking scheme
The effectiveness of employing a ranking scheme that
incorporated both biotic and abiotic factors in identifying
Fig. 3. Neutral grassland sites showing areas targeted for restoration within the UTTESA.
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160 155
the most biologically diverse sites in the UTTESA was
clearly demonstrated. Sites 6.10 and 6.9, ranked first and
third, respectively, were well positioned in the ecological
unit being adjacent to each other and surrounded by land of
good and moderate restoration potential. As a result, sites
6.10 and 6.9 and the surrounding land should be targeted for
enhancement and habitat creation under existing ESA
management prescriptions. Expansion of these sites would
not only increase patch area and species diversity (in
accordance with the species-area relationship), but also
reduce inter-patch distances between these sites and the
neighbouring patches.
Fig. 4. Neutral grassland patches with land targeted for restoration and land currently under agreement within the UTTESA.
Table 8
Comparison between minNN (m), and Area (ha), before and after patch enhancement
Median Mean LogMean Stdev LogStdev Min Max
MinNN before 30.0 426.0 1.9 1306.0 0.7 0.0 7920.0
MinNN after 30.2 249.2 1.8 1068.5 0.6 0.0 7902.5
Area before 4.2 13.8 0.5 30.6 1.0 0.0 212.2
Area after 5.6 16.4 0.8 28.7 0.7 0.2 212.2
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160156
Consistent with the theory of island biogeography, where
species diversity increases with patch size (McAurthur and
Wilson, 1967; Schulze and Mooney, 1993; Hubbell, 2001),
the largest patches had relatively high ranking for biotic
factors. However, the highest ranked patch for biotic factors
only, site 1.2, was ranked 47th for patch area and was
therefore an exception to the species-area relationship. As
discussed by Spellerberg (1992), the species-area relation-
ship does not always apply and one must be aware of
exceptions and take note of intrinsic values (other than area)
resulting in high patch diversity. Although grassland
patches such as site 1.2 are viewed as fragmented habitat
islands, they are not surrounded by hostile habitat as
suggested by the island biogeography theory. Instead the
patches are surrounded by other grassland types (e.g. MG6
or MG7) that are also capable of supporting a diverse range
of species.
Of note was site 1.6, ranked second, which only has a
regional site designation. Further investigation may result in
a recommendation to increase the status of this patch, due to
its high biodiversity value, to a nationally important status.
Site 1.6 consistently scored highly for a number of
assessment criteria, especially for site diversity where it
was ranked highest. It was also highly ranked for patch area,
species richness and species rarity and it is adjacent to site
1.8. Sites such as 7.29, 5.6, 6.7, and 5.2, were consistently
ranked highly, as were more than 50% of the SSSI’s. All
cSAC’s ranked within the top 20 sites. Middle to low
ranking patches, however, consisted of a combination of
regionally designated sites, SSSI’s and undesignated sites.
The neutral grassland SSSI’s may have become degraded,
declined in biodiversity quality (English Nature, 2001), and
as a result were ranked low. Regional sites or undesignated
sites of high biodiversity status, as determined by the current
ranking system, have not yet been recognised for their
value. A gap in the data set, particularly of species
distribution from sites of higher designated status, indicated
the necessity for a greater number of surveys, particularly
for BAP species on these patches.
8.2. Patch targeting for habitat enhancement
Generally UK nature conservation policy has focused
on the management of sites of high conservation value
without due consideration to the state of surrounding land
and its potential for habitat expansion (Sheail et al.,
1997). Various targeting mechanisms have been used for
individual site-based evaluations including multi-criteria
methods using biotic and abiotic factors (Ratcliffe, 1977;
Margules, 1984; Rossi and Kuitunen, 1996; Clevenger
et al., 1997). Other approaches have employed iterative
habitat evaluation schemes, using heuristic algorithms or
linear programming techniques, (Kirkpatrick, 1983;
Pressey et al., 1993; Freitag et al., 1997; Csuti et al.,
1997; Sarakinos et al., 2001; Briers, 2002). These aim at
representing the study region’s entire biodiversity in as
few sites as possible to maximise conservation efforts.
Generally there have been few attempts at targeting sites
for habitat creation and even less that have considered the
implications on the wider countryside in fulfilling habitat
expansion objectives.
Land adjacent to neutral grassland patches targeted for
habitat enhancement was selected according to a number
of principles to maximise the benefits attained from the
resources available and from the biodiversity attributes
within the patch. Targeting the surrounding land also
creates buffer zones around the key patches, thus
protecting them from further edge effects and subsequent
habitat degradation, as well as effectively enhancing the
site biodiversity by providing a larger area for species
colonisation.
Land selected for restoration around the periphery of a
neutral grassland patch aimed to minimise the edge effect.
This was achieved by creating a patch that was as large and
circular as possible. Regularly shaped patches have less
edge and larger core areas, therefore land restored around
the patch periphery aimed to restore the habitat circularity
(Laurence and Yensen, 1991). Patch expansion also aimed
to increase the levels of connectivity between patches.
Neutral grasslands are not necessarily isolated habitat
islands surrounded by a landscape of hostile habitats.
They are often linked by a network of floodplain
habitats, such as streams and reed banks, which theoretically
provide wildlife corridors between patches (Beier and Noss,
1998). There are sufficient areas of floodplain grassland
habitats in the UTTESA to potentially link a number of
adjacent patches together, e.g. sites 1.2, 1.1, 5.2, 5.3, 5.6,
and 5.5. Connecting patches reduces their isolation and
minNND as well as decreasing the landscape fragmentation
(Andren, 1994).
8.3. Landscape fragmentation
Restoration and enhancement of neutral grasslands not
only secures a greater area of habitat for associated habitat
specialists but it also protects the remaining resource from
factors such as degradation, fragmentation and edge effects.
Targeting sites for restoration in the UTTESA (Figs. 3 and
4) demonstrated the effect of patch enhancement on the
overall landscape fragmentation. There was a significant
reduction in the minNND between neutral grassland patches
in the UTTESA (Table 8), which indicated a reduction in
habitat isolation and fragmentation of the landscape.
Reducing habitat fragmentation would reverse the general
pattern of biological impoverishment and reduce the impact
of edge effects as described by Bellamy et al. (1996) and
Keyser et al. (1998).
8.4. Conclusion
Fragmentation-related studies have concluded that the
preservation of small remnant areas will not conserve
J. Bayliss et al. / Journal of Environmental Management 67 (2003) 145–160 157
species diversity (Harrison and Bruna, 1999). However,
small patches are important in promoting the conservation
of larger patches as they can provide valuable habitat,
functioning as stepping stones between larger patches,
facilitating inter patch movement (Semlitsch and Bodie,
1998), and acting as reservoirs for colonisation.
The habitat ranking scheme developed here is a
technique to aid decision makers in directing financial
resources into the conservation of neutral grasslands. The
ranking system enables resource targeting on a strategic
scale, allowing objective decisions to be made according
to the best available scientific information. Fig. 4
identifies the land units to be targeted for restoration,
which are not currently under ESA agreement, on the
basis of the ranking system. This research demonstrates
the benefits of employing a patch ranking system based on
a combination of biotic and abiotic factors for the
targeting of sites for conservation. It can be used to co-
ordinate ESA agreements in order to meet conservation
objectives, maximise environmental benefits and stream-
line resources efficiently. It is, however, recognised that
other environmental variables such as soil type, slope,
aspect could be incorporated into the patch ranking
scheme in order to further refine the process. These are
aspects likely to be in need of address in future research.
Importantly the wildlife conservation and enhancement
objectives of ESA schemes have been readily incorpor-
ated into targets for species and habitats identified as
priorities for biodiversity conservation (Ovenden et al.,
1998). Linking agri-environment schemes closely with
UK BAP processes, as demonstrated by this study, is
crucial in creating a more sustainable agricultural system
and achieving the respective species and HAP targets
(Ovenden et al., 1998). More research is required to
understand the ecological relationships between farming
systems and the requirements of the species they support,
for example interactions between predation rates and
management related changes in the habitat (English
Nature, 2000; Vickery et al., 2001). Farming systems
can then be developed through ESA schemes to maintain
and benefit the ecological characteristics of wildlife
assemblages (McCracken and Bignal, 1998).
The patch ranking scheme for neutral grassland sites in
the UTTESA provided a list of sites, identified via the
GIS in terms of their biodiversity value, for habitat
creation and enhancement to meet the specific objectives
of the UK Lowland Meadows HAP. The process of
habitat restoration inevitably requires high inputs of time
and financial resources, particularly where new habitats
are created. High expenditure on one-off operations is
often required to establish the conditions and vegetation
necessary for the initiation of natural regeneration
processes (Manchester et al., 1999). To maximise
effectiveness, resource-targeting procedures should there-
fore be based on the best information available, enabling
objective rather than subjective site selection. Objective
assessment using quantitative criteria allows comparison
between sites and enables selection of the most ecologi-
cally valuable sites. As the most biologically diverse sites
were targeted for habitat restoration and inclusion under
ESA management agreements, the targeting approach was
shown to be beneficial to conservationists and DEFRA
advisors.
The national Lowland Meadows HAP creation target
of 500 hectares was achieved within the UTTESA
without site suitability becoming a limiting factor, despite
this value referring to the UK as a whole. The actual
figure for habitat creation of lowland meadows (for both
MG4 and MG5) with in Oxfordshire is only 8 ha
(Jefferson, pers. comm.). The rationale behind the
selection of this figure would appear to be proportional
to the existing extent of the particular HAP grassland type
in the county or Natural Area. It seems that the county
figure of 8 ha is particularly low, especially as the
national target of 500 ha was achieved easily, as
demonstrated in this study. We therefore suggest that
both the national and local values, presented in HAP’s,
are in need of revision to adequately reflect the real
potential capacity for habitat restoration and creation in
agricultural landscapes.
Acknowledgements
The authors would like to thank Alistair Helliwell
(DEFRA), Cengiz Philcox (BBOWT), Dan Chamberlain
(BTO), Oxford Ornithological Society, Banbury Ornitholo-
gical Society, Craig Blackwell (Oxfordshire County Ecol-
ogist), and last but not least John Campbell (Oxon
Biological Records Centre) for all their help, support, and
the sharing of data.
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