Visit to Portbury
Wharf Nature Reserve, 10th September 2013
A select team of four gathered (fully equipped with three
canes, a dog lead and gps ) to assess the biodiversity of some of the site
using either fungi or bryophytes as indicator organisms. It rapidly became
apparent that the dry weather had stopped any possibility of macrofungi
fruiting and indeed we had great trouble getting our canes into the ground.
Whilst waiting at the entrance to start we realised that
this site is a dog-walkers favourite and this did not bode well for high
biodiversity. The pathway to the site was littered with “signs” of dogs and
giant plantain plants (leaves >40cm long and flower stalks >60cm high!)
confirmed this site was subject to eutrophication on a grand scale.
We did three sites and only five plots on each site as it
rapidly became apparent that further plots would add nothing more. No fungi
were found on any plot and bryophytes alone were surveyed.
Site 1. A meadow with
course grasses and plentiful signs of cattle grazing. In the sample five plots
we recorded four specimens of two
species (Kindbergia praelongum and Brachythecium
rutabulum) of bryophyte (sometime just a tiny thread was found). The
species are indicators of eutrophication.
Site 2. A similar
meadow to site 1 but with a trackway running across it. In the five sample
plots we recorded eight specimens of
four species namely the two species as in Site 1 and two species on the
trackway (Pseudocrossidium hornschuchianum
and Barbula unguiculata) indicating
Site 3. Was a dried up pond where we felt we were more
likely to find bryophytes and indeed this was the case and the ground was
carpeted with moss albeit a single species (Kindbergia
praelongum) we had already recorded.
From this survey we could tell that the fields were
eutrophicated and we have set baselines for further visits and hope that the
weather will be kinder to us next time.
Whilst we had our heads down we did see several common
butterflies and a less common one (Small Copper), heard a Cetti’s Warbler and
saw a Wheatear. In a rhyne we saw some interesting plants, including Gypsywort,
Water Parsnip and Everlasting Pea, and perhaps most notably Sweet Galingale (Cyperus longus), which has been
associated with the Gordano Valley since the eighteenth century, but now only
remains at Portbury. We took some pictures of a spectacularly bright chestnut
coloured spider (Araneaus quadratus)
consuming a crane fly, and the leafhopper, Macrosteles
af. sexnotatus (identified by
Rob) was extremely abundant (in thousands!) hopping off the grass as we walked
through. Click photos to enlarge
Macrosteles cf sexnotatus
A party of seven were guided by the reserve warden (Bernie)
around the reserve with a full explanation of why it is there and what the aims
are. The whole site is a Biodiversity
compensation scheme resulting from the housing development (2,700 houses)
adjacent to the site. The main intention is to provide wetland sites and high
tide roosting sites for ducks and wading birds on the estuary and the houses
are subject to a levy to support this.
Several hides have been built with views over the shallow “scrapes”, of
which there are six, and a larger open water area. The scrapes seemed to be
mostly populated with Gadwall. Adjacent to one hide we found a good strong
specimen of Conyza sumatrensis
looking like a strange Canadian Fleabane.
Rob said that this is a recent colonizer from South America (despite its
name!). How did it get there?
We wandered onto the salt marsh and found a good growth of
Sea Spurrey, Sea Aster and Spartina; the latter of which was infected with
ergot producing long sclerotia (the fruit bodies of the fungus Claviceps
purpurea and the source of the poison ergotamine). On the mud close by were
feeding Redshank , Curlew and Black-tailed Godwits (the latter in summer
plumage). On the pathway to the coast
Alan found Coltsfoot infected with two fungi (Puccinia poarumand
Coleosporium tussilaginis) sometimes both on a single leaf and earlier on
in our walk we noticed a fine specimen of the bracket fungus, Inonotus hispidus, growing from the
trunk of a large ash tree.
Finally we visited the non-public access area which was a
series of scrubby areas and clearings.
This was botanically much richer although recent mowing removed most of
the flowers . Particularly strong plants
of Red Bartsia (Odontites verna) were
seen but perhaps the most spectacular site to see was the dozens of Southern
Hawkers flying over our heads (and even landing on someone’s head).
Clearly this is a site in development and it bodes well for
the bird populations being at the entrance of the Gordano Valley and adjacent
to the estuary.