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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

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is not collected or presented (Rieh & Woodruff 1990, 1992, 1996). Botanically, it is well-established that the recording behaviour and ability of individual botanists, the types of plants being recorded and the survey techniques give rise to marked variations in the records of different plants. For example, Figures 1 and 2 show two extreme examples. The map of a hybrid sedge Carex hostiana x viridula is highly correlated with areas recorded by two expert botanists, whilst that of Ribwort Plantain (Plantago lanceolata), one of the most widespread species in Britain, is broadly acceptable as representing the distribution of the plant (but is it really absent from some squares?).

(Redrawn from Rieh & Woodruff 1992).

Figure 2. Distribution map of Ribwort Plantain (Plantago

lanceolata).

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Variation in the number of records with time may also reflect patterns of recording activity. For instance, Cotswold Pennycress (Thlaspi perfoliatum) is a rare plant which was locally frequent until the 1940s but has declined thereafter. The large fluctuations in the numbers of records per decade (Figure 3) are probably explained better in terms of the recording behaviour of botanists rather than changes in frequency of the Pennycress. With the rise in activity of the Botanical Society of London in the 1830s and 1840s there is an increase in the number of records, followed by a trough in the 1850s when the Society collapsed. Collecting by its successor, the Botanical Exchange Club, in the 1860s and 1870s again results in many records with a peak in 1880. The trough in the 1890s is due to its collapse but it was resurrected from the 1900s onwards. Are the troughs in the 1920s and 1940s due to the depression and Second World War respectively? A further rise in the 1950s and 1960s can be attributed to recording enthusiasm resulting from the Atlas ofthe British flora.

Figure 3. Total number of Cotswold pennycress records per decade.

40 35 N u m b • r

30 r e 26 c o 20 r d 15

os f

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Sources of Variation To investigate sources of Variation in botanical records we carried out a standardised recording exercise in Midhurst, West Sussex in 1992 (Rieh & Smith 1996). Pairs of botanists, representing a typical mixture of abilities, were asked to record species present in comparable tetrads (2 km x 2 km squares) for 2.5 hours. They selected their own areas and habitats to survey within each tetrad, and marked the routes taken on a map. For each subsequent session, individuals were rotated to a different tetrad and paired with a different botanist to minimise bias. Botanists were ranked according to ability on a scale of 1 (inexperienced) to 5 (expert); these ranks were summed to give a 'recording quality' score for each pair. Numbers of species recorded were correlated against various recording factors for the 41 cards completed.

The results were shocking. Despite attempts to minimise the effects of individual botanists on the number of species, the expertise of the recorders Trans. Suffolk Nat. Soc. 33 (1997)

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explained by far the most Variation (Figure 4a). The length of route recorded (Figure 4b) and the number of habitats visited (Figure 4c) explained less Variation in the data. This showed that the major source of Variation was the recorders.

The number of species recorded ranged from 69 to 257 species. 1s it any coincidence that this largest number of species was recorded by myself in my 'hörne' tetrad with Mary Briggs, the BSBI Vice-county recorder?

Figure 4. Relationships between the number of species and various measures of recording during 41 visits to tetrads at Midhurst, West Sussex (after Rieh & Smith 1996).

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: $

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4a. Recording quality (each botanist was ranked between 1 (inexperienced) and 5 (experienced), and the ranks added together to give the recording quality score - a high score indicates more experienced botanists) (r2 = 0.506, pcO.OOl).

N u m b e r

> 200 p e c ISO i e o i 100 f

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4b. Length of route recorded (km) (r2 = 0.148, p = 0.005).

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260 • •

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Number of habitats 4c. N u m b e r of habitats recorded (r 2 = 0.220, p = 0.017).

Recommendations for improving recording In light of these results, the methods used to record dot maps require significant revision. A series of broadly-applicable recommendations were drawn up within the constraints imposed by using volunteers to improve the quality of the basic data (Rieh & Smith 1996);1. Improve the recorders ability by training in identification skills and field craft, and through contact with other recorders; 2. Encourage recorders to visit many different areas rather than concentrate on one area; 3. Try to achieve even, systematic coverage by recording for the same time or having the same number of Visits in each tetrad; 4. Visit as many habitats as possible in each Square, note which habitats have been recorded and try to ensure that all are visited during the course of the work: Ensure adequate seasonal coverage.

Demonstration project - Flora of Ashdown Forest These recommendations were put into practice in a three year demonstration project, the Flora of Ashdown Forest (Rieh et al. 1996). We aimed for a target of ten hours recording by a mixture of different botanists in each of the 71 squares, which was broadly achieved. Good comparable coverage was obtained with botanists of varying abilities, and the defined recording target was a useful incentive to completing the work.

Analysis of the records shows that our survey is representative of the flora and our maps are largely independent of the recording. The n u m b e r of species was not correlated with time spent recording (Figure 5a), the number of botanists who had visited each Square (Figure 5b), or the percentage of the Square recorded (Figure 5c). In contrast, the number of species was highly correlated with the number of different habitats recorded (Figure 5d). Note that these results are completely different to those obtained during the Midhurst meeting described above.

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Figure 5. Relationship between number of species and various measures of recording in Ashdown Forest (Rieh et al. 1996).

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5a. Hours spent recording ( r = 0.04, p>0.05).

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5b. Number of different botanists (r2 = 0.003, p>0.1).

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5c. Percentage of Square recorded (r2 = 0.03, p>0.1).

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350 300 N

u s

250

m p b . 200 • c

' ' 160

0 i 100 1 60

Numbsf of Afferent habitats

5d. Number of different habitats recorded (r 2 = 0.43, pcO.OOl).

The systematic nature of the Ashdown Forest recording means that the relative frequencies of our species are representative and indicate which are common or rare, the distribution patterns can be directly correlated with environment factors, and the survey can be repeated in the future at the same sampling intensity allowing direct comparison of frequencies.

Conclusions The problems of bias indicate that ad hoc distribution maps are no longer acceptable. We need recording schemes to be better planned from the Start, and with professional advice on sampling. The Flora of Ashdown Forest sets new Standards for recording in Britain and it is recommended that all future mapping projects should follow a similar approach. The methods are practical and can be applied to areas of any size or to any group.

The millennium will mark the end of many recording projects, so a fresh start can be made in the year 2000. Naturalists have a very important part to play in providing information for conservation; start planning to do it properly now.

References Arnold, H. R. (1995). Atlas of mammals in Britain. ITE Research publication no. 6. HMSO, London.

Gibbons, D. W„ Reid, J. B. & Chapman, R. A. (1993). The new atlas ofbreeding birds in Britain and Ireland: 1988-1991. T. & A. D. Poyser, London.

Harding, P. T. & Sutton, S. L. (1985). Woodlice in Britain and Ireland: distribution and habitat. NERC/ITE, Huntingdon.

Perring, F. H. & Walters, S. M. (1962). Atlas of the British flora. T. Nelson & Co., London.

Rieh, T. C. G. & Smith, P. A. (1996). Botanical recording, distribution maps and species frequency. Watsonia 21: 161-173.

Rieh, T. C. G., Donovan, P , Harmes, P , Knapp, A., McFarlane, M., Marrable, C„ Muggeridge, N „ Nicholson, R., Reader, M„ Reader, P , Rieh, E. & White, P. (1996). Flora of Ashdown Forest. Sussex Botanical Recording Society, East Grinstead.

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Rieh, T. C. G. & Woodruff, E. R. (1990). BSBI Monitoring Scheme 1987-1988.

Chief Scientist's Directorate Report no. 1265. Nature Conservancy Council, Peterborough.

Rieh, T. C. G. & Woodruff, E. R. (1992). The influence of recording bias in botanical surveys: Examples from the BSBI Monitoring Scheme 1987-1988.

Watsonia 19: 73-95.

Rieh, T. C. G. & Woodruff, E. R. (1996). Changes in the floras of England and Scotland between 1930-1960 and 1987-1988: The BSBI Monitoring Scheme. Biological Conservation 75: 217-229.

T. C. G. Rieh, Department of Biodiversity and Systematic Biology, National Museum and Gallery of Wales, Cardiff CF13NP

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Some beetle pests in old cottages Forge Cottage near the Rushbrooke Arms at Sicklesmere is a timber-frame building of considerable historic interest. Most of the rooms show exposed timbers with wattle and daub. In July 1996 a moderately severe attack of the furniture beetle, Anobium punctatum (DeGeer) was discovered in some of the structure and, more worrying, a slight attack of the death watch beetle Xestobium rufovillosum (DeGeer). The owner was particularly concerned that some furniture of great sentimental value might be attacked. I began some treatment with insecticide.

She showed me a carpet in one of the bedrooms from which I was quickly able to collect a dozen very active beetles. Although they superficially resembled furniture beetles they proved to be bread beetles, Stegobium paniceum (L.).

All three species mentioned belong to the Anobiidae and are similar, slightly elongate and with heads hidden beneath a heavy thorax, but they differ considerably in size. Death watch beetles are dark brown and reach about 7 mm in length. Furniture beetles are dull. reddish brown, and only reach about 4.5 mm. Flour beetles are generally more rounded than the other two species and are bright reddish brown. They only reach 3 mm.

Harde's Field Guide in Colour to Beetles states that S. paniceum 'can occur in very large numbers'. They infest a wide ränge of plant and animal products in warehouses, etc. but are particularly associated with bread and flour products. The question was, why were the beetles in this bedroom?

A possible explanation was given by an elderly Suffolk man who mentioned that cottage walls were often painted with a suspension of flour in water. Could they have been attracted to the treated plaster of the bedroom? The carpet was clean and apparently undamaged.

Incidentally, my old house in Bury is also lightly infested with furniture beetles and we have on two occasions heard death watch beetles tapping late at night. My wife kept up a 'conversation' with the beetles by tapping 3 or 4 times lightly with a pencil to echo the sound made by the beetles. On both occasions we were able to locate the beetles and destroy them.

Treatment of woodworm-infested timber using boron and a special fogging technique has been developed by Rentokil's laboratories which should prove more 'environmentally friendly' than current insecticide treatments, but I have no personal experience of this.

G. D. Heathcote

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