SUSTAINABILITY

AROUND THE REGIONS
16
Northamptonshire
Yardley Chase Training Area
Purple Emperor (male) © J A Richardson
The Yardley Chase site of some 200
hectares was purchased in 1940 so
that rail connected storage bunkers
could be built. The site was mainly
woodland, surrounded by meadow
and parkland. For t y-four bunkers
were built with blast walls excavated
from the surrounding clay soil, but it
was not long before these borrow
pits filled with water creating a ring of
ponds around each walled bunker,
124 in total. This unique site is now
suppor ting a diverse flora and fauna,
all three species of newt, frogs and
toads, slow worms and grass snakes
and 22 dragonflies; there is a
creditable list of flora including
vascular plants, mosses, liver wor ts,
algae (including stonewor ts) and
lichens. The whole site was declared
an SSSI in 1981. Many of the ponds
are now becoming overshadowed by
tree and shrub grow th: there is some
clearance in progress but effor ts are
also needed to return the
surrounding meadowland to its
original richness by managing
mowing and grazing.
Focus on lepidoptera in 2014
But ter f lies are in good numbers and
include the black hairstreak and
wood white; the black hairstreak has
not been recorded over the last
three years but could still be on site.
O ver the past three years our
but ter f ly numbers have increased to
include the purple emperor, dark
green and silver-washed fritillar y,
none of these three have been
recorded since the late seventies.
Our total number of lepidoptera
sp ecies has now reached 470.
Focus on desmids in 2014
The desmids have been studied since
Victorian times (John Ralfs) and the
literature is more extensive than with
many freshwater algal groups. There
are more than 900 known species in
the British Isles: so they are
comparable in biodiversity with
bryophytes or birds. These are highly
evolved single celled members of the
Chlorophyta or green algae, they are
among the most beautiful objects
that can be seen under the
microscope and are indicators of
wetland quality. Desmids are more
often found in areas with unpolluted
acid water and have thus been much
less studied in southern lowland areas
of the UK. A study of desmids in the
Yardley Chase ponds is thus of
scientific value and the diversity found
already is greater than originally
expected and it is of interest to
speculate why this should be: perhaps
because of the raised boulder clay
deposits within ancient woodland?
Within the bunker ponds 16 species
from the genus Closterium have been
listed, 9 from Cosmarium, 2 from
Staurastrum and there are
representatives of the genera
Pleurotaenium, Hyalotheca,
Gonatoz ygon, Mesotaenium and
Cylindrocystis. There have been a few
surprises: David Williamson, the UK
expert on this group noticed an
unfamiliar Closterium in 2009 and
established that it was Closterium
regulare, which had not been recorded
for certain in the UK. The bunker
ponds on Yardley Chase remain the
only known location for this species.
C F Carter
Team Member for Algae
J A Richardson
Compton Estate Conservation Advisor
Cosmarium reniforme (Ralfs W. Archer), showing
face view and side view (the cell is about 0.05mm
wide) © C F Carter
Sanctuary 44 • 2015 89