262 THE WILTSHIRE ARCHAEOLOGICAL AND NATURAL HISTORY MAGAZINE 
2 a 
Tussock Sedge in winter (© WWT — Steve Day) 
more dramatic change to a late stage of fenland 
succession: willow and alder carr surrounding an 
earlier stage of as yet ungrazed Tussock Sedge fen. 
Part of this section has been fenced with the 
intention of grazing it in the near future. 
As mentioned above, the carr extends north- 
westwards into the wet flushes and around the two 
ponds, making a total area of five hectares in all. 
The area around the ponds [G] and bordering the 
Avon [D] have been woodland for many years, but 
aerial photographs show that the carr between them 
[B and C] is comparatively recent in origin. Here in 
1946 there were no trees or bushes except in the 
hedgelines; by 1958 a scatter of trees had appeared 
and by 1972 these were larger but still scattered, 
with none of the closed canopy that we have today. 
The open fen is dominated by Great Horsetail 
Equisetum telmateia, Reed Sweet-grass G. maxima 
and Meadowsweet Fi ulmaria. Along one of the 
streams are several Greater Reedmace T° latifolia, 
and in another is Lesser Water-parsnip Berula 
erecta, which is rare in Wiltshire, particularly in the 
southern vice-county. Other typical fen plants 
found here are Common Valerian V. officinalis, 
Marsh Valerian V. dioica and Square-stalked St. 
John’s-wort Hypericum tetrapterum. There are 
impressively large Greater Tussock-sedge Carex 
paniculata, especially along the edges of the streams, 
which together with the primeval Horsetails give 
the area a very special character. Tussock Sedge is 
now very rare in Wiltshire, being found in only 1% 
of the kilometre squares but was once ‘locally 
plentiful particularly in the Vale of Pewsey’ (Grose 
1957, 589). The central fen is also the best part of 
the reserve for the extremely rare Desmoulin’s 
Whorl-snail Vertigo moulinsiana, a Red Data Book 
species that is common on the reserve. 
The principal trees in the carr are Alder 
A. glutinosa, Grey Willow Salix cinerea and Crack 
Willow S. fragilis. In the drier places there are a few 
Pedunculate Oak Quercus robur and Ash Fraxinus 
excelsior. The shrubs include Hawthorn C. monogyna 
and Elder Sambucus nigra with a few Guelder-rose 
Viburnum opulus in open areas. The herb layer 
within the carr is principally Lesser Pond-sedge 
C. acutiformis, Yellow Iris I. pseudacorus — which 
Great Horsetail 
A tall exotic conifer was to have been felled as 
an unwanted alien, until it was realised that it was a 
favourite nest site for Sparrowhawks Accipiter nisus. 
There are several tall dead trees both standing and 
fallen, some with big root plates. Along the edge of 
the northern spur of the carr several willows have 
been pollarded and the resulting large logs left in 
piles. All this provides excellent habitats, 
particularly for bees and beetles. 
Important plants on the northern edges of the 
carr, both along a path and where it merges into 
open fen, include Hemp-agrimony Eupatorium 
cannabinum, Wild Angelica A. sylvestris and 
Common Comfrey S. officinale. On the edge of the 
path itself can be found Southern Marsh-orchid D. 
