Monday, 16 September 2013

Trip Report Portbury Wharf Nature Reserve

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 bare areas.
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
Araneus quadratus
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 poarum and 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. 
Click photos to enlarge

Galingale (Cyperus longus)
Shaggy Bracket (Inonotus hispidus)

Alan Feest

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