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Suffolk Natural History, Vol. 33
IS AD HOC GOOD ENOUGH? TIMOTHY C. G. RICH
Introduction When Martin Sanford asked me to talk he said he wanted something controversial. I will begin by saying that naturalists when they Start are bird watchers, when they grow up they become botanists, and when they go senile they become entomologists! Since 'dot-maps' were first popularised by the Atlas of the British flora in 1962, naturalists in Britain have been avidly recording species and plotting distribution maps on grids at national, county or local scales (e.g. Perring & Walters 1962; Harding & Sutton 1985; Arnold 1993). My thesis today is that the ad hoc sampling methods used for such maps in Britain are not good enough, and I am calling for a major change in the way that recording is carried out by naturalists. Every knows that reliable decision making and the advancement of knowledge depends upon having good quality information. If we want to conserve our national rare and notable species we need to know which they are. If we want to predict the effects of global warming we need to have good data against which to correlate environmental variables. If we want to identify areas of high biodiversity we need to know which really are the rieh areas. Unfortunately in Britain, most of our decisions are based on dot maps created from records which have been collected in a rather ad hoc fashion - on a 'whatcan-we-get' and 'on-the-cheap' basis, largely by semi-skilled naturalists. They are predominately recorded by volunteers who spend varying amounts of time and effort in individually allocated squares. Whilst attempts are usually made to visit every Square, the quality of survey and the time spent recording varies markedly between squares. The resulting records are taxonomically and geographically biased samples and the data for different species or different areas are not directly comparable. I am not for one instant decrying the work of naturalists, but their valuable work must be made more efficient. Little thought is given to the consequences of using ad hoc Atlas data, and there have been few attempts to produced anything more rigorous. Ronald Good's (1948) Flora of Dorset in 1948 was a stunning piece of work years ahead of its time. Similarly the New Atlas ofBreeding Birds (Gibbons, Reid & Chapman 1993) is outstanding. We also have our Flora of Ashdown Forest (Rieh et al. 1996) which is the first true attempt to record systematically. I am pleased to see that the proposals for the National Biodiversity Network aim to give more guidance and set Standards for, amongst other things, the sampling methods. My examples are based on plants but the principles apply to all organisms. I aeeept that for some groups such as critical microspecies of Bramble (Rubus spp.) a different approach may be needed, but for most plants we can do an awful lot better. I am also realistic in what I expect, and have extensive experience working with biological records and naturalists over the last 15 years.
Bias arising from sampling methods The extent to which the distribution maps are representative of the species rather than the recorders is rarely known as information on the sampling effort
Trans. Suffolk Nat. Soc. 33 (1997)