Tuesday, 7 October 2014

13/09/14 Report of Trip to Chew Valley Lake

Looking More Closely at Chew Valley Lakeside Biodiversity

A select group of seven Bath Nats met at the café site and observed the Lake full
of fishermen and sailing dinghies. Just as well we were not targeting birds. We
visited the nearby woodland and immediately it became clear that the driest
September since 1960 was having its effect. Beech leaves were falling and the
black dry scallops along the edge indicated the effect of drought. Looking at the
crowns of the Beech trees they were obviously thinning. This did not bode well
for a visit aimed at the less popular and obvious elements of biodiversity namely
Lower Plants and Fungi. Nonetheless a walk through the trees around the two
public car parks did produce some fungi namely: Sepia Bolete (Boletus
porosporus), The Deceiver (Laccaria laccata), Lilac Fibrecap (Inocybe geophylla
var. lilacina), lots of Sulphur Tuft (Hypholoma fasciculare) and The Miller
(Clitopilus prunulus). We also found a freshly emerging specimen of Dyer’s
Mazegill (Phaeoleus schweinitzii) which is an uncommon pathogenic bracket
fungus on coniferous trees and checked out its spore-producing surface, without
picking it, using a dental mirror. Meanwhile, the nearby toilets yielded excellent
numbers of Small emerald moths (Hemistola chrysoprasia) attracted by the
permanently on lights (plus a Speckled Bush cricket)!

Alongside the lake we found plenty of Southern Aeshnas hawking for insects of
which there were a lot of Crane flies evident. Few birds were seen or heard but
as we headed towards the ‘Bittern Trail’ we started to get our eye in for the
Lower plants under Alan R’s care and found that some parts of the Bittern Trail
itself looked productive and so would be good use for our intended biodiversity
assessment in the afternoon, which we did during the afternoon, after a lunch
break. Here the crack willows were falling around drunkenly and indeed many of
their trunks were procumbent. They were thus excellent for observing the lower
plants and Fungi. Setting out our first sampling plot, and with Terry in charge of
the dog lead (!), we listed the species seen and counted the number of
individuals of the macrofungi. This turned out to be quite a lengthy business as
there was so much to see and immediate conclusion was that without this sort of
close study we would have missed a lot of the biodiversity. At the end of two
hours we had worked on four plots and decided this was enough for a first
M. pseudocorticolaa Photo by Alan Feest

estimate of the biodiversity.
Index/Taxon
Bryophyt
es Fungi
Liche
ns
Species richness
Simpsons evenness(population)
Simpsons evenness(biomass)
22
17.35
14.06
P. schweinitzii
Gyrodon lividus Photo by Alan Feest
                         


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