ASSESSMENT OF POTENTIAL EFFECTS OF DIFFERENT
GRAZING REGIMES IN WOOTTON COPPICE AND HOLMSLEY
INCLOSURES
Dr.Jonty Denton Bsc (Hons) D(Phil) FRES (Consultant Ecologist)
Pentire, 29 Yarnhams Close, Four Marks, Hampshire, GU34 5DH
phone/fax 01420 563228 email:Jonty [email protected]
ASSESSMENT OF POTENTIAL EFFECTS OF DIFFERENT GRAZING REGIMES IN
WOOTTON COPPICE AND HOLMSLEY INCLOSURES
CONTENTS
1.1
BACKGROUND
1.2 Aims and Objectives
1.3 Baseline
1.4 Potential Effects
2.0
Inclosure Evaluation
2.1 Wootton Coppice: Existing Baseline information
2.2 Assessment of Effects of Implementation of options 1-4.
2.3 Holmsley Inclosure: Existing Baseline information
2.3.1 Existing grazing pressure
2.3.2. Recent restoration Work
2.4 Assessment of Effects of Implementation of options 1-4.
3.0
CONCLUSIONS
3.1 Wootton Inclosure
3.2 Holmsley Inclosure
4.0
ACKNOWLEDGENTS
5.0
REFERENCES
6.0
APPENDIX 1- SPECIES LIST
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1.1 Background
Over the last 6 years in the New Forest, the Forestry Commission (FC) has been working closely
with stakeholders to agree the management the Inclosures. The Forest Design Plans produced in
1999 (now under review after a 5 year period of implementation) identify a number of inclosures
for which grazing by open forest livestock would benefit the habitats present/restored.
Many of the Forest Inclosures proposed to be thrown open are recent in origin (1960’s) and are
located on former heathland. As such, there are widespread benefits to the re-introduction of
grazing to this land as part of the heathland restoration initiative. However, there has been
significant discussion with respect to allowing livestock into more established Inclosures where
there would be some benefits to open habitats along stream corridors and other wetland features.
The FC is currently engaged in the LIFE 3 Project, restoring wetland habitats throughout selected
catchments in the New Forest. As part of this initiative the FC has resources available to implement
changes to the existing grazing regime in several Inclosures in these catchments. As such, further
information is required about the potential effects of any such changes in Inclosures thought to be
ecologically sensitive.
1.2 AIMS AND OBJECTIVES
To determine what the potential effects of allowing open forest livestock into the following
Inclosures:
Holmsley Inclosure (SU223 003 – enclosed in 1811)
Wootton Coppice Inclosure (SZ 249 996 – enclosed in 1808)
Fig. 1. Location of Inclosures (left =Holmsley/ right =Wootton Coppice)
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1.2 Baseline
Holmsley & Wootton Inclosures are fenced to prevent access by livestock, and have been fenced
for the vast majority of their 200 year history. Historically the Inclosures were fenced to protect the
regeneration/stocking of young trees from grazing by livestock. Over time the fences have allowed
the ecological interests of Inclosures to change, and these two Inclosures are prime examples of
such change. The botanical and entomological value of these Inclosures has long been known, and
is attributable to the relatively low grazing pressure when compared with levels found on the Open
Forest. Occasionally livestock do gain access to Inclosures, either due to gates accidentally being
left open or fallen trees collapsing the fenceline. Such livestock are removed on a regular basis to
ensure that grazing pressure in the Inclosures does not become detrimental to the ecological
interests they support. The Inclosures are not without grazing pressure due to deer, and deer
numbers have fluctuated enormously over the last 200 years. However, today deer numbers are
closely managed.
In the context of the New Forest, the plant and invertebrate value of these two enclosed areas is
well known. Some survey records and reports are available to support this position.
From this information and necessary site visits the FC would like an assessment of the value of the
invertebrate fauna to be made. Consideration of invertebrate communities and interest species will
be required. This assessment will need to consider the New Forest, Hampshire and National
contexts. In addition, an assessment of the associated vegetation structure under current grazing
levels is necessary.
1.4 Potential effects
There is the potential to manipulate the grazing system in these Inclosures, although mechanisms
for this are limited. The FC considers that the following 4 options are possible:
1. Complete removal the Inclosures fencelines, thereby allowing livestock grazing in the Inclosure
at the same density as experienced on the Open Forest.
2. Retain Inclosure fencelines but remove the gates, thereby allowing free movement of livestock
from the Open Forest into the Inclosure. This system is thought to reduce the grazing density
compared with the Open Forest.
3. Retain Inclosure fencelines but remove the gates seasonally. The period of that season would
need to be decided but would be likely to avoid key periods for identified invertebrate/botanical
interests.
4. Maintain the existing situation. Ie. On a regular basis the keepers will continue to remove
livestock that have gained access to these Inclosures. In addition, Maarten Ledeboer (Beat
Keeper) will continue to manage the local populations of deer in accordance with the agreed
Deer Management Plan. Both of these activities will maintain the low levels of grazing activity
that currently occur in these Inclosures to the benefit of entomological/botanical interests
present.
From the baseline assessment the FC requires informed predictions of the potential effects of
allowing livestock into these Inclosures as prescribed in the first three options above. This will need
to consider changes in vegetation structure and the potential effects on invertebrate communities
and species of interest.
2.0 INCLOSURE EVALUATION
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2.1 WOOTTON COPPICE: Existing Baseline information
The list of invertebrate species recorded in the inclosure is listed in Appendix 1. the Rare and Nationally
Scarce Taxa recorded from Wootton Coppice Inclosure are summarised below;Table 1. Rare and Nationally Scarce Taxa recorded from Wootton Coppice Inclosure
Nationally Scarce B/Notable
Coenagriidae
Coenagrion mercuriale
Tettigoniidae
Conocephalus dorsalis
Acriidae
Omocestus rufipes
Gryllidae
Nemobius sylvestris
Nymphalidae
Euphydryas aurinia
Geometridae
Lampropteryx otregiata
Geometridae
Cepphis advenaria
Geometridae
Cleora cinctaria
Geometridae
Clostera pigra
Noctuidae
Elaphria venustula
Mutillidae
Mutilla europaea
Conopidae
Conops strigatus
Conopidae
Conops versicularis
Southern Damselfly
Short-winged Conehead
Woodland Grasshopper
Wood Cricket
Marsh Fritillary
Devon Carpet
Little Thorn
Ringed Carpet
Small Chocolate-tip
Rosy Marbled
Velvet Ant
a conopid fly
a conopid fly
The information for this inclosure is very poor, given the variety of habitats. Species such as the wood ant
Formica rufa occur and support a wide rage of Rare and Notable guest speices, none of which have been
recorded.
Fig 2. Wood Ant Formica rufa nest.
2.2 ASSESSMENT OF EFFECTS OF IMPLEMENTATION OF OPTIONS
Option 1. The effect of removing the inclosure fence is graphically illustrated in fig 3. The effect on spider,
orthopteran diversity would be devastating. There is a clear consensus amongst invertebrate ecologists that
the overall effects of overgrazing is highly detrimental to overall diversity (Pinchen, 2000). The structure in
the open areas of the inclosures is also optimal for the commoner reptiles, no reptiles could survive in the
open habitats present in adjacent grazed areas.
Nationally Scarce Taxa present include the Little Thorn moth Cepphis advenaria which feeds on bramble
and bilberry, and the Rosy marbled Elaphria venustula, which is associated with bracken clad open
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woodland where it’s host plant Tormentil Potentilla erecta grows (Goater & Norriss, 2001). The Small
Chocolate Tip Clostera pigra feeds on Creeping Willow Salix repens. All these moths would be threatened
with extinction if this option was implemented. Similarly, scarce orthopterans including the Short winged
Conehead Conocephalus dorsalis and Woodland Grasshopper Omocestus rufipes would be very vulnerable
as they require structured habitats.
Option 2. This is a very unsatisfactory option, as even the medium term effects cannot be predicted, as the
density of animals invading the inclosures cannot be regulated. However given the over-grazing of the open
heath/ pasture woodland areas, it seems likely that the structure would be rapidly devastated, to the detriment
of overall biodiversity. As previously stated the inclosures support populations of scarce taxa which are
absent from the grazed forest, and thus have an intrinsic importance as islands in a sea of increasingly
impoverished invertebrate habitat.
Fig 3. Detail of northern edge of Inclosure. Left of fence Wootton Coppice inclosure, well structured
habitat, right open overgrazed area with heavily poached ditch, no structure, but with open pools with some
macrophyte development.
Option 3. The likely outcome of the implementation of this option is also difficult to assess, but the current
regular incursion of livestock into the Inclosure is such that to all intents and purposes this option is already
in operation, and the controlled seasonal removal of gates would at most result in a slightly raised grazing
pressure for part of the year. This should be restricted to the winter months ideally October – March, but
such a strategy should be subject to regular monitoring so the period of grazing can be manipulated
appropriately. I am of the opinion based on many years of study and sampling of all the habitats present in
the enclosure, that this is the most sensible approach to management for the enclosure, where the open areas
are currently not suffering from excessive scrub invasion, and therefore low level grazing pressure should be
sufficient to maintain the status quo at least.
The open habitats within this enclosure are currently in good condition. Trespassing ponies and the local
Roe and Fallow Deer have already had a measurable effect on the vegetation structure as evidenced by the
exclusion enclosures (see fig. 4). However a slightly increased level of grazing to further diversify the
ground structure would be desirable, especially along the ditch lines.
In recent months up to 7 ponies have trespassed into the enclosure (Maarten Ledeboer pers.comm.), the
bramble and rose patches are more fragmented, to the benefit of reptiles and invertebrates (see fig. 4, above).
The Molinia dominated areas are in a well-structured condition, with a great variation in height with
scattered Tussocks, see fig.5-6, below.
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Fig. 4. Effects of trespass grazing on habitats in Inclosure.
Left exclusion plot (ungrazed), right (effect of trespass/deer grazing).
Fig 5. Variety of structure wthin Molinia dominated humid grassland
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Fig. 6. Wootton Inclosure:Localised poaching along pathways created by ponies.
The effect of the current un-planned grazing is clearly positive in maintaining diversity of structure. Over
the past 15 years I have been heavily involved in the reintroduction of grazing on Wealden and Thames basin
heaths, and such schemes have aspired to create habitats close to those present in Wootton Coppice.
Option 4. Maintaining the current regime in this enclosure would result in similar effects to an Option 3
strategy (albeit with a low level of stock incursion), if the current level of trespass grazing is (somewhat
haphazardy) maintained. The random nature of the trespass grazing is clearly beneficial, as the animals never
get enough time to clear the large open areas of nectar sources in the growing season, or cause serious
localised damage of a favoured food source. Without any trespass grazing it is unlikely that the deer alone
could maintain the current favourable conditions, and there would undoubtedly be a rapid increase in scrub
regeneration, and increased dominance of Molinia, to the detriment of the structure, and overall biodiversity.
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2.3 HOLMSLEY INCLOSURE : Existing baseline information
The list of invertebrate species recorded in the inclosure is listed in Appendix 1. The Rare and Nationally
Scarce Taxa recorded from Holmsley Inclosure are summarised below;Table 2. Rare and Nationally Scarce Taxa recorded from Holmsley Inclosure.
Nationally Scarce B
Araneae
TheridiosomatidaeTheridiosoma gemmosum (Koch)
Ray spider
Araneae
Tetragnathidae
a long-jawed orb spider
Tetragnatha pinicola
Araneae
Araneidae
Strawberry Spider
Araneus alsine
Araneae
Araneidae
an orb weaver
Zilla diodia (Walck.)
Araneae
Salticidae
a jumping spider
Evarcha arcuata
Araneae
Salticidae
a jumping spider
Myrmerachna formicaria
Orthoptera Gryllidae
Wood Cricket
Nemobius sylvestris
Orthoptera Acridiidae
Woodland Grasshopper
Omocestus rufipes
Dictyoptera Ectobiidae
Ducky Cockroach
Ectobius lapponicus
Lepidoptera Sesiidae
Synanthedon flaviventris (Staudinger) Sallow Clearwing
Lepidoptera Torticidae
a micro-moth
Pammene germmana
Lepidoptera Gelechiidae
a micro-moth
Syncopacma cinctella
Orange Footman
Lepidoptera Arctiidae
Eilema sorocuka
Lepidoptera Geometridae
Argent & Sable
Rheumaptera hastata (L.)
Lepidoptera Geometridae
Pachycnemia hippocastanaria (Hubner)Horse Chestnut
Coleoptera Dytiscidae
a diving beetle
Graptodytes granularis
Coleoptera Hydrophilidae
a hydrophilid beetle
Berosus luridus
Rare (RDB3)
Araneae
Theridiidae
Episinus maculipes a comb-footed spider
Vulnerable (RDB2)
Dytiscidae
a diving beetle
Graptodytes flavipes
Dytiscidae
A diving beetle
Agabus brunneus*
* Recorded just upstream at Stony Moors, but habitats in Inclosure are suitable for this species.
2.3.1 Existing grazing pressure
The area east fo the B-road is already subject to quite heavy grazing pressure as seen in Fig.7-8.
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Fig.7. East compartment of Holmsley Inclosure. Pony grazing in winter 2005-6.
Fig. 8. Detail of heavily grazed and poached ground adjacent to Avon Water in East compartment of
Holmsley Inclosure. Winter 2005-6.
2.3.2 Recent restoration Work
Extensive restoration of the floodplain area and the Avon Water itself have recently been completed (see
fig.9). It is likely that without some intervention the recently restored area beside the Avon Water will
rapidly revert to birch dominated woodland, unless the water table settles to a level which will deter birch.
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Fig. 9. Recently cleared woodland beside Avon Water
Without such intervention the habitats may well revert to birch dominated woodland with little value for
invertebrates (see fig.10.)
Fig. 10. Existing dense birch scrub
2.4 ASSESSMENT OF EFFECTS OF IMPLEMENTATION OF OPTIONS 1-4.
Option 1. Complete removal of the Inclosure fencelines.
The reintroduction of grazing must have a clear goal, with clearly defined targets. If the purpose is to
control scrub, then the density of grazing stock needed will rapidly destroy the well structured ride habitats
upon which the fritillaries and a great range of other species of interest depend.
As in Wootton Coppice it is inevitable that the structure would be rapidly devastated. The limited trespass
grazing of just 2-3 ponies in the winter of 2005-6 has already had a very clear effect on vegetation structure,
see fig.6.
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It is clear that unlimited grazing from even a few more animals would rapidly reduce the remaining
structure. Such a change would devastate species already known to be present such as the RDB3 spider
Episinus maculipes. This species occurs on the low canopy of trees, and bushes. It is only know from 8 sites
in Britain (Harvey et al 2002). Also Nationally Scarce spiders including Dipoena tristis, Araneus alsine,
Zilla diodia, Tetragnatha pinicola, Theridiosoma gemosum, and Evarcha arcuata, all of which require
structure in the ground / shrub layer (Merrit, 1990). Other Scarce taxa including the Woodland Grasshopper
Omocestus rufipes occur in sheltered areas with good structure, at Petworth Park in Sussex it was absent
from the open deer grazed parkscape, but frequent at the margins of the fenced off enclosures (J.Denton
unpublished).
The presence of the best remaining Small Pearl-bordered Fritillary colony in the whole of Hampshire, a
species undergoing a drastic decline nationally, should be reason enough to take a very careful approach to
the use of grazing.
Option 2. This is a very unsatisfactory option, as even the medium term effects cannot be predicted, and the
density of animals invading the enclosures cannot be regulated.
The complex of rides have already been identified as being critical for the survival of Small-Pearl-bordered
Fritillary and plants such as Bastard Balm. These would be very vulnerable to grazing pressure. In the long
term the areas recently restored along the Avon Water floodplain will require some sort of management.
However the grazing density required to control scrub regeneration in these areas would be so high as to
pose an unacceptable threat to the survival of the critical species which are currently being managed by
manual scrub and tree removal, and periodic verge maintenance using a tractor and cutter bar.
One compromise worth considering would be the subdivision of the compartment and reintroduction of
grazing (either seasonal or unrestricted) into the restored areas in the South-west.
Option 3. The compartment east of the B-road is to all intents and purposes already subject to an Option 3
management regime. Ponies were present in the compartment through much of the winter of 2005-6, and the
effects on the structure especially along the wet habitats along the Avon Water were clear (see fig.9.). The
compartment east of the road has been subject to a detailed study of the spider fauna, which includes several
very uncommon taxa dependent on structure. Theridiosoma gemosum makes webs close to the ground at
base of tussocks. Evarcha arcuata occurs on low scrub and tussocks in wet heath and bog. Any increase in
the grazing intensity is likely to be detrimental with remaining structure removed.
At present there is no evidence of any trespass grazing in the enclosure to the west of the B-road. The
effects of an option 3 regime in the western compartments is very difficult to assess. As in the eastern
compartment the ponies are likely to focus on damp areas, and could rapidly alter the existing open grassy
area, which have already been identified as critical for the surviving Small Pearl-Bordered Fritillary colony.
The likely outcome would be the loss of the fritillary and much else besides, before any positive effect was
had on the birch invasion problem. A self-defeating strategy for invertebrate conservation.
However employing limited seasonal grazing as a means to control scrub regeneration post manual
clearance would be desirable in the long term.
Option 4. Option 4. Maintaining the current regime in the eastern compartment of the enclosure would
result in similar effects to an Option 3 strategy (albeit with a low level of stock incursion), if the current level
of trespass grazing is (somewhat haphazardy) maintained. The random nature of the trespass grazing is
clearly beneficial, as the animals never get enough time to clear the large open areas of nectar sources in the
growing season, or cause serious localised damage of a favoured food source. Without any trespass grazing it
is unlikely that the deer alone could maintain the current favourable conditions, and there would undoubtedly
be a rapid increase in scrub regeneration, and increased dominance of Molinia, to the detriment of the
structure, and overall biodiversity.
At present there is very little evidence of trespass grazing in the areas west of the road, without continued
manual clearance and mechanical ride management, scrub encroachment will continue to be a serious
problem. This is clearly an unsatisfactory situation. However there is currently regular local scrub
management targeted to encourage Small Pearl-bordered Fritillary which appear to be having the desired
results with increased transect counts. Even if grazing was reintroduced this local management of key foci
for the Fritillary would still be necessary, see fig 11.
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Fig.11. Area recently manually cleared of scrub
3.0 CONCLUSIONS
The importance of Inclosures such as Holmsley and Wootton Coppice for a great many declining species
which are otherwise very rare or absent from the opne forest cannot be overstated. Increasingly the overgrazing of the open forest is depleting invertebrate communities of richness. Even suggesting that removing
the fences from around these enclosures could be appropriate, reveals an extraordinary level of ignorance
and arrogance. Doing nothing is scarcely more defendable.
The level of information available is currently limited, but any competent ecologist should be able to
provide an informed prediction balancing the needs of plants and animals. Precipitative action cannot be
justified, and limited seasonal grazing is clearly the best approach accompanied by regular monitoring so that
informed decisions can be made as to whether the density/timing needs to be modified.
3.1 Wootton Coppice Inclosure
The structured open habitats in Wootton Coppice Enclosure are currently of great importance for the
conservation of a wide variety of taxa which are increasingly rare or absent from the open heavily grazed
forest. As one of the best remaining refuges, it would be insane to open it up to unlimited grazing. However
some limited seasonal grazing (akin to the trespass grazing occurring in the winter 2005-6) would help
maintain the area in its current structurally diverse condition.
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3.2 Holmsley Inclosure
The information on the invertebrate faunas of the Inclosures is very limited, however the spider fauna has
been well studied in the eastern part of the Inclosure, and includes a wide range of Rare and Notable taxa
dependent on structure, and vulnerable to heavy grazing pressure.
Subdivision of the Inclosure to separate the critical areas from those in need of intense grazing pressure to
kerb scrub regeneration would be one compromise. This would enable a direct comparison of the effect on
different regimes on the critical species. However some limited seasonal grazing (akin to the trespass grazing
occurring in the winter 2005-6) would help maintain the area east of the road in its current structurally
diverse condition, and improve matters in the western compartment, especially if combined with increased
scrub management.
4.0 Acknowledgements
Thanks to Maarten Ledeboer for showing me around the Inclosures, and to Jennifer Newton of HBIC for
providing records.
5.0 REFERENCES
Goater, B, & Norriss, T. 2001. Moths of Hampshire and the Isle of Wight. Pisces.
Harvey, P.R., Nellist, D.R. & Telfer, M.G. (eds) 2002. Provisional Atlas of British Spiders
(Arachnida, Araneae) Volumes 1 & 2. Huntingdon: BRC.
Merrit, P. 1990. A review of the Nationally Notable Spiders of Great Britain. Peterborough, NCC.
Pinchen, B.J. 2000. Evaluation of Five Inclosures in the New Forest for Invertebrate conservation
and Potential impact of grazing. Unpublished report.
APPENDIX 1.
List of Invertebrate species recorded from Wootton Coppice and Holmsley Inclosures
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