12
HALES WOOD, SAFFRON WALDEN - A National Vegetation Classification Survey
In the summer of 1993, the members of BirkbeckCollege's Ecology and Conservation
Studies Society visited Hales Wood, just east of Saffron Walden, both to have a look at
the wood, and to practice the use of the new National Vegetation Classification (NVC)
survey technique.
The wood is a National Nature Reserve, although there is no right of public access, but
this can be arranged by obtaining a permit from the Area Office of English Nature. There
is documentary evidence for the existence of this woodland in 1251, and although
reduced in size over the centuries, and partly converted to conifer plantation within the
last 30 years, one section remains as an example of the ancient coppice woods of Essex,
which were a valuable resource before the age of plastic and fossil fuels, supplying wood
for fences, tool handles, thatching spars and house building, and wood for burning. It is
still managed today, by the British Trust for Conservation Volunteers, who aim to
continue the coppice rotation on an eight year cycle, coping with modern problems like
the large numbers of Fallow and Muntjac deer which are resident locally, and which have
to be kept out of the re-growing coppice by fences, to prevent them from severely
damaging both the regrowth of the coppice stools of Hazel and Ash, as well as the
attractive ground flora.
The NVC scheme is a system which classifies all British vegetation as a description of the
present state of affairs, but also as a practical tool for identifying vegetation types,
describing and mapping sites and providing a basis for further study. A set of volumes
have been published by Cambridge University Press as British Plant Communities by J.
Rodwell, but they are expensive at £70.00 or more each. The books are a comprehensive
description of each recognisable vegetation stand; a tract of vegetation which is
homogeneous in its composition. The survey method involves taking a number of
samples within a stand, and use of NVC keys can match a survey to the NVC type. The
system is based on two concepts, frequency and abundance.
Frequency is used to describe how often a species is encountered in samples of the
vegetation type, irrespective of how much is present in each sample. Five samples are
taken, using quadrat sizes which are standardised for each type of habitat, for example
short woodland field layers are sampled with 4m x 4m quadrats. For each species, you
decide which of the following frequencies is appropriate:
I 1-20% frequency (i.e. 1 stand in 5) -scarce
II 21-40% -occasional
III 41-60% -frequent
IV 61-80%
V 81-100% constant
Abundance is used to describe how much of a species is present in a stand or sample,
irrespective of how frequently it is encountered from one sample to another. The survey
records percentage cover using a 10 point DOM1N scale: