Colin Hawes
3 Silver Leys, Bentley
Ipswich, Suffolk, IP9 2BS, England
A new milestone has been reached - half a million records are now on computer databases at the Suffolk Biological Records Centre (SBRC). Congratulations to Martin Sanford and his team.
Much of the work of the Suffolk Biodiversity 2000 Project at the SBRC (see progress report p.14) involves computerisation of data and the production of species distribution maps. Such data is essential for monitoring change as well as servicing conservation initiatives such as the recently launched Biodiversity Action Plans.
Unfortunately, however, in spite of its success, the future of the SBRC appears to be under threat as a result of a cost-cutting review being carried out by Ipswich Borough Council. If this is the case, it is to be hoped that the Borough Council is not so shortsighted that it would axe the Records Centre without first giving sufficient notice so that other sources of funding can be found. The SBRC is too valuable a resource to lose.
Congratulations are also due to Elveden Farms Limited which has been recognised for its work with conservationists in caring for the 11 designated Sites of Special Scientific Interest on its land. These heathland sites form part of the Breckland Special Area of Conservation which straddles the Suffolk - Norfolk border. Bill Nickson writes about Lakenheath Warren, part of the Elveden Farms estate, in this issue.
Thanks are due to Bill and all our contributors for providing such a wealth of material for the newsletter. Thanks also go to Brenda Arden, The Robert Stebbings Consultancy Limited, Anne Beaufoy and John Kemmett of Simplith Printing Services for their continued support in producing the newsletter. Copy forWhite Admiral 43 should reach the editor no later than June 7th 1999. Editorial comment in White Admiral 41 concluded with the suggestion that the Biodiversity of your garden could be increased 'by adding log-piles that are allowed to rot down'. 'Pile up for invertebrates' continues this theme.
Gardens often contain an extremely rich and varied fauna. 'Almost half of the British Coleoptera fauna have been taken by careful and persistent collecting over a period of years in one suburban garden' (Hammond, 1974). Many garden invertebrates, especially beetles and Diptera breed in dead wood. The fauna of even a small piece of wood can be large. Log-piles will therefore encourage dead-wood fauna and increase the biodiversity in your garden. They will also provide a significant contribution to the conservation of saproxylic organisms.
Any type of dead wood in any position is valuable, but the richest communities will be supported by logs from broadleaved trees which are placed in partial (dappled) shade. Oak logs, however, tend to provide conditions which produce the greatest biodiversity.
Fresh lengths of timber still with bark attached are most likely to provide habitats for the longest period of time, whilst shattered ends are preferable to sawn surfaces, providing saproxylics with better access to the wood. The presence of bark also provides conditions for organisms, which only live within this habitat. Organisms that only occur directly beneath the bark also benefit.
Other factors being equal, the larger the dimensions of a log the higher its conservation value. Larger pieces of timber last longer and provide more stable conditions than smaller pieces. The interiors of larger logs are buffered from fluctuations in temperature and moisture content, especially when there is a covering of bark.
The micro-climate within dead wood is critical in determining its suitability for saproxylic fungi and invertebrates. Logs lying in full sun may dry out, preventing decay on which the invertebrate succession depends. Logs lying on the soil, and which are partially shaded, will retain more moisture and are of more value.
A diversity of environmental setting for dead wood is recommended if there is room, as is the proximity of flowers. It is usually the larvae of invertebrates that feed on dead wood; the adults have different habitat requirements, needing to take nectar and pollen from blossom. Umbellifers, composites, bramble, ivy and hawthorn are especially important.
The fauna of fallen dead wood tends to be significantly different from that found in dead wood of standing trees. This being the case, it is worthwhile placing some logs vertically in the soil. Vertically placed logs can be seen in this photo taken at High Woods Country Park, Colchester).
These logs have been positioned primarily to create a stag beetle (Lucanus cervus) breeding site but should also provide dead-wood habitat for many other invertebrate species.
The design of the High Woods log-'pyramid' mostly follows that used in Germany by Tochtermann where the structure was built by burying vertically positioned oak logs in a 3m diameter x 0.5m deep pit, the bottom of which had been previously covered with a 10cm depth of partly decayed oak-wood chippings, leaving up to a metre of timber protruding above ground. The gaps between the logs were filled with oak sawdust.
Something similar, albeit on a smaller scale, using two or three logs, should be feasible in most gardens. Even one vertically placed post would be better than nothing.
If log-piles or 'pyramids' are impractical then consider using heaps of bark/wood chippings or even sawdust. These can provide a habitat for some saproxylics, but ensure that they remain undisturbed.
Reference: Hammond, P.M. Changes in the British Coleoptera Fauna. In: Rawkswonh, DL. (1974) The Changing Flora and Fauna of Britain. Academic Press.
Note: Logs of varying size can be obtained from tree-surgeons. It is bad conservation practice to remove fallen timber from the countryside.
Editor
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