THE WILTSHIRE WILDLIFE TRUST’S VERA JEANS NATURE RESERVE 259 
At Jones’s Mill, while still in the Vale, it is a 
considerable stream. This September, after one of 
the driest and hottest summers for many years, 
measured just above the bridge where the old 
Kepnal Drove crosses the river, it was 32 metres 
wide, about 40 centimetres deep and flowing, at the 
surface, at about half a metre per second. The 
aquifers feeding it are in the chalk, but at the bridge 
the water, with a pH of 7.5, is only weakly alkaline. 
Bullhead Cottus gobio, River Lamprey Lampetra 
fluviatilis, Brown Trout Salmo trutta have all been 
recorded, as has Rainbow Trout S. gairdneri but this 
last, fortunately, seems to have died out. There are 
records of the native White-clawed Crayfish 
Austropotamobius pallipes, but now there is a large 
population of American Signal Crayfish Pacifastacus 
leniusculus, which might have come from a known 
escape of farmed crayfish just downstream of the 
reserve in the late 70s or early 80s (Wall 1999). 
Riverside Meadows and Carr 
Although, except in extreme conditions, the 
meadows are never flooded, the soil is moist even at 
the height of summer. The area is now a mire and 
River Avon in North-East Fen 
the plant communities which have developed are 
classified as fen and carr (Rodwell, 1998a, 30 et 
sequ.; Rodwell, 1998b, 24 et sequ. and Rodwell, 2000, 
109 et sequ.). The nutrient status of the old meadows 
ranges from mesotrophic to eutrophic. The ground 
water is calcareous, but deposition of leaf litter over 
the years has created a peaty, slightly acid soil. Soil 
samples taken at both the east and west ends of the 
meadows gave a surface pH value of 6°5 and this 
remained constant down through the soil until an 
abrupt change to 7-5 at the greensand layer. The 
water in the leats had a pH of 7°5. 
The leaf litter leads to somewhat drier 
conditions with tall herbs and, ultimately, shrubs 
and trees. The earlier stages of succession support a 
much more diverse and interesting ecosystem. To 
preserve these, the meadows are now managed by 
maintaining the leats and by grazing by Belted 
Galloway cattle — a tough but gentle breed that are 
happy to be out of doors all the year round and, in 
summer, do well grazing the fen. As can be seen on 
the map, there are two main areas of fen, one in the 
north-east of the reserve [2 & 3] and the other in the 
south-west [5 & 6]. These are separated by an area 
of carr [4] which also spreads beyond the probable 
extent of the old meadows into some of the wet 
flushes at the foot of the north slope of the valley. 
The two outer sections are lightly grazed during the 
summer. This has had important effects. Selective 
eating of the dominant competitive and tall plants 
has both reduced the accumulation of leaf litter and 
allowed the under-storey to flourish. The treading 
of the cattle has opened up pockets of bare soil, so 
allowing germination. These factors combine to 
make a complex mosaic of vegetation which is by no 
means unusual for such sites: the plant 
communities found here, while not matching 
exactly, are very similar to typical fen and carr 
communities elsewhere in southern England. They 
are dominated by sedges Carex sp. of which there 
are no fewer than fourteen species on the reserve. 
Lowland mires are now rare: most have either, 
through neglect, proceeded to woodland or, 
probably more often, have been deliberately 
drained. The SSSI citation describes Jones’s Mill as 
‘the best known example of a calcareous valley mire 
in Wiltshire’. 
The North-East Fen [2 & 3] 
The Triple-spotted Pug Eupithecia trisignaria is a 
nationally rare moth. Its food plants Wild Angelica 
Angelica sylvestris and Hogweed Heracleum 
sphondylium grow in many parts of the reserve but 
