DERC Newsletter

No. 61 Spring 2009

In this issue:

Dorset Flora Group
Mapping Dorset’s building stones
Orthoptera recording

Preparing the spring newsletter (which is done early, whilst there is still frost on the ground) gives us a chance to look ahead to the coming field season. As always we are hoping for good warm weather that will see the hedgerows budding and the insects buzzing. I hope that the two articles by Bryan and John will encourage you to step out and join in with recording and field trips. And for those of you with broader interests, I have also included a report on two geology projects DERC has recently completed.

Carolyn Steele (Record Centre Manager)

The Dorset Flora Group is looking forward to Spring and a new recording season

Bog Orchid

Photo: Bryan Edwards

The biting cold that has descended on us since late December makes the thought of the sun shining on a wildflower meadow all the more enticing. The Flora Group committee have now finalised most of the programme for next year and the main event will be the first Dorset Wildflower Week, taking place at the end of May. Walks are on offer as far apart as Portland and Bournemouth Gardens, with Fontmell Down featured in the north and several sites in Purbeck in the South. The walks are open to everyone and we hope to attract newcomers and visitors to the area in addition to our regular members.

The Flora Group will also be running field days, beginning in April and May with trips to Shermel Gate and the Ackling Dyke area. In June we will pay our first group visit to Tadnoll meadows, where we plan to search sites of past records from the Dorset Rare Plant Register. July sees us return to the hunt for the elusive Bog Orchid, with hopes of repeating our success of last season. August includes a search for Marsh Fern, a rarity many of us will not have encountered, with the promise of other fascinating plants en-route.

Our first training course – an Introduction to Common Grasses – will take place in June. We expect to have room for 12 participants, with priority being given to Flora Group members. If this succeeds we will offer more courses in the future, so please ask if there is anything that you would like to know more about!

DERC will be adding a Flora Group page to their website which will give us space for more details on all our events. The programme for the year ahead will be circulated to members in early February, with a brief account of our very successful first Christmas party. We look forward to seeing you in 2009.

Jon Crewe

Mapping Dorset’s building stones

Dorset Stone; Jo Thomas
Dorset Stone - Jo Thomas

Aside from our natural history interests, the Records Centre also holds information on many geological sites throughout Dorset. In the past few years we have been involved in two geology projects which will make geological information more accessible.

During 2007 and 2008 DERC produced a series of 32 maps for inclusion in Jo Thomas’ new book ‘Dorset Stone’ about the use of building stones in the county. These maps show the geological outcrop for each building stone, the distribution of quarries that have been used historically to source particular stone, and the parishes where each stone has been used as the primary or secondary stone. The stone bridges in the Stour valley were also included. Jo’s comprehensive book is available from all good book shops (price c. £17.95).

Making data more accessible to local authority officers needs a more interactive approach. Using Jo’s building materials data DERC has produced a set of digitally mapped GIS tables. The user is able to select an individual parish of interest (or other special place within a parish if the stone dominance is different) from a map of Dorset and see what the primary, secondary and tertiary building materials used within that parish are. The user is then able to display a distribution map of quarries to see where that particular type of stone has historically been sourced from. This is a fantastic resource, and has been a very interesting project to work on.

Jon Corkill

Orthoptera recording

Woodland grasshopper (male)

Photo: Bryan Edwards

Speckled Bush-cricket (female)

Photo: Bryan Edwards

The production of the book on the Orthoptera and allies of Dorset is well under way and the forthcoming summer season will be the last chance to fill in some gaps for this group. Hopefully the summer will be better than the last two, when numbers have been rather low. The map shows where the gaps are, and, as usual, the north and west of the county is poorly covered. However, we would welcome all records from any location in the county, particularly of the three native cockroaches, the three earwigs, and for the more elusive species such as Oak and Speckled Bush-crickets. With a good recording season we hope that the book will be published in 2010.

Orthoptera records on the database (all dates)

Bryan Edwards