A management tool for monitoring the botanical condition of
Essex Wildlife Trust grassland nature reserves
ANDREW MAY
Consen'ation Manager, Essex Wildlife Trust, Abbotts Hall Farm, Great Wigborough, Essex CO5 7RZ
Abstract
There is an urgent need to monitor the wildlife value of grasslands and effectiveness of management
Grasslands are a priority habitat due to their fragility within succession. If they are not managed
properly they will change their characteristics and floristic diversity very quickly. It has been recognised
that certain species indicate floristic diversity whilst others indicate either a positive or negative
effect of management and these species could be used to monitor sites.
Introduction
The vegetation of Britain has undergone major changes as a consequence of modern land use and
certain plant species have declined within the last 50 years. Essex Wildlife Trust protects over 7,000
acres of land through the management of 89 nature reserves. Many of these reserves contain grassland
habitats. To effectively manage all of these sites requires vasl resources, both human and financial,
and it is therefore important to focus the Trust resources on sites that require urgent action. As
conservation resources are limited the method for monitoring Essex Wildlife Trust reserves is very
similar to English Nature's rapid assessment method (Robertson & Jefferson 2000).
A problem with management is getting the balance right. From an ecological viewpoint, grassland
management should maximise the opportunities for plants to flower, set seed, and for as wide range
of invertebrates as possible to establish viable populations on the site. At the same time it should
prevent the grassland from changing into scrub or woodland. However, small amounts of scrub can
be of interest depending on the conservation objectives for the site. On most grasslands, culling
once a year in autumn would match most requirements, but this could be less frequent on sub-soils
where growth is slow and sparse. Such late cutting has the added advantage of giving the least time
for re-growth over winter, and thus starting with an open sward in the spring in which the annuals
can establish. Cutting earlier, as when a hay crop is taken in July will reduce the potential for
invertebrates and small mammals, and give a longer period of re-growth during the grow ing season.
In such situations, further cuts with the material removed or grazing will be needed. There will be a
loss of botanical species if hay cutting in July is not followed by grazing or culling.
If stock is unavailable, another alternative is to take an early cut with the material removed. However,
this may need to precede the breeding season if birds of conservation importance may be benefiting
from the grassland. This early cut can reduce grass vigour for up to 2 months, and two early cuts in
April - if ground nesting birds are not an issue - may reduce sward height and vigour significantly.
The main function of removing cut material is to avoid the development of a thick thatch that effectively
smothers weaker, smaller plants and to create colonising gaps. On the other hand, leaving some
grassland uncut, perhaps around the edge of the site would benefit invertebrates, such as meadow
brown butterflies and small mammals.
Botanical richness and diversity will suffer for sites and therefore the data collected should enable
analysis to reflect the current status of the grassland and allow comparisons from year to year. In
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Essex Naturalist (New Series) 20 (2003)