DERC Newsletter

No. 46 Spring / Summer 2001

In this issue:

Another recording season is now underway and, although Dorset remains free of Foot and Mouth, access to the countryside has been very restricted. This could curtail the usual flurry of recorder activity but David has a few suggestions for botanists and we have tried to retain a varied workshop programme. We look forward to seeing you there.

Despite a lull in fieldwork, the Record Centre remains busy with a number of projects underway. One of the most exciting developments is the Marine Database which will move to DERC on 1st June. This ties in with an English Nature / National Biodiversity Network initiative to map priority habitats in the south-west, including marine. We shall report more fully on these later in the year.

Carolyn Steele (Record Centre Manager)

Invertebrates on Mudeford Spit

Mudeford Spit at the entrance to Christchurch Harbour has suffered considerable disturbance over the last 3 years. Dorset Ecological Consultancy was appointed to advise on the conservation interest and monitoring work. With assistance from Craig House, Mike Jeffs, Mark Holloway and John Hunnisett, 53 species were identified, including several rarities.

In September and October, John conducted a more thorough search. Of the 142 species recorded, 39 were local, two notable and one naturalized. Of particular interest was a thriving population of the harvestman Paroligolophus meadi in a small area of the Distal Dunes (1 other known location in Dorset).

From these first results the Distal Dunes are clearly the richest habitat. The Central and Promenade Dunes are impoverished due to sparse vegetation. Other areas have moderate diversity with mostly common species.
Last year's DERC workshop, and ongoing monitoring work, are building up a respectable list for this overused holiday resort.

Robin Walls

Picture Wing Flies

Picture Wing Flies

Drawings: Robin Walls

One of the ongoing tasks carried out by DERC is to collate the Dorset records of various groups and send them to the appropriate recording schemes so that a better understanding of species distribution can be derived. This exercise has recently been completed for the small group of Tephritidae flies commonly called picture wing or gall-flies. There are about eighty species occurring in the British Isles and many of them can be identified at least to genus by their intricate wing patterns. Most tephritid larvae form galls in fruit, leaf-mines or within flower heads of Compositae, one of the most noticeable being the large gall in the stem of Cirsium arvense which is caused by the larvae of Urophora cardui. The adult forms of both Tephritis bardanae and Cerajocera tussilaginis are very noticeable flying around Arctium in July whilst depositing their eggs in the capitulum.

Composite feeding tephritids often reduce the seed production of their host plant and many of their hosts grow amongst crops or in pasture where tephritids sometimes help in the natural control of these weeds. Therefore it is not surprising to find that some species have been introduced into countries such as Canada where Cirsium vulgare has become a problem.

The most up to date book for identification of Tephritidae is the Handbook for the Identification of British Insects Vol. 10, Part 5a. Tephritid Flies, by Mr. I.M.White.

DERC records show that 41 species have been recorded in Dorset which now ranks 10th in terms of species per vice-county. A full list of species found in Dorset will soon be available on this website.

John Hunnisett

Some ideas for Botanical Recording this season

Hedgerows, road verges and churchyards may be the easiest for access this summer. In late May and early June the Western hedges (c.SY680778) round to beyond the pill-box in the Fleet (c.SY662764) are well worth a visit with populations of Little Robin (Geranium purpureum), Stiff Saltmarsh-grass (Puccinellia rupestris) and Borrer's Saltmarsh-grass (P. fasciculata) amongst more uncommon plants.

Also the shores of Wyke Regis, from Castle Cove round to the Fleet, have been known as a site for rare legumes for 250 years. We would like rare plant forms (available from DERC) completed for Yellow Vetch (Vicia lutea) and Bithynian Vetch (Vicia bithynica) particularly.

David Pearman

Professor Good's Botanical Survey of Dorset Hedgerows

In 1999 DERC secured a grant from the Heritage Lottery Fund to computerise Prof. Good's archive material including many species records and site descriptions. This work will be completed by the end of the year, but we have already begun to discuss further uses for the data.

The data set includes records from 1500 hedgebanks - a habitat that has suffered from a variety of practices including flailing, trampling, neglect and removal. DERC would like to re-survey these sites, looking at the changes in species composition and hedgerow structure.

We would also like more general information about hedgerows in Dorset including their history and management.

If you are able to help, I would be pleased to hear from you.

Nick Button

Thanks

Our continued thanks to all our recorders and volunteers. And a special note of thanks to the Colin Reed Countryside Trust for funding a new laptop computer for DERC.