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AMMUNITION FOR CONSERVATION: BIODIVERSITY, SPECIES AND HABITATS BRIAN C. E V E R S H A M Background: amateurs, Professionals and data As Peter Marren has demonstrated (Marren, 1997), there was a time, as recently as the 1960s, when most professional conservationists were ecologists, and most professional ecologists were also naturalists; there was thus little conflict between professional and amateur. In recent years, two changes may be discerned. Firstly, the rise of the 'environmentalists': effective campaigners on a ränge of issues, including wildlife habitats and species, such people tend to be motivated by a general concern rather than a specific enthusiasm for a group of plants or animals, in the naturalist's sense. Secondly, the increase in the numbers of life-science graduates, with broader but shallower training: the majority of graduate biologists thus lack the signal attribute which naturalists look for: the ability to identify at least some organisms to species level. Some modern ecologists bemoan the decline in the teaching of taxonomy in our universities. I suspect this is partly based on too rosy an impression of the past.

Graduates now have a poorer understanding of the animal and plant kingdoms than 15 years ago; but even a deeply traditional zoology course went only a short way toward teaching undergraduates to identify species.

The 1980s saw two trends in academic ecology, whose long-term consequences are yet to be determined. The first was the arrival of inexpensive and relatively powerful Computers. The second, not unconnected, was the growth of Statistical numeracy and mathematical modelling abilities among ecologists.

Computers make data analysis much more rapid, and the ability to analyse dozens of environmental variables at once could strengthen the science. Conversely, the attention paid to the design and planning of experiments and sampling programmes may have declined.

The advent of home Computing within the reach of many amateur naturalists, and the continuing development of county and national Biological Records Centres may also have a significant effect. Until recently, books and journals formed a large part of our legacy from previous generations of naturalists and their societies (their collections of specimens, housed in local and national museums, are the other material benefit). Although journals such as Suffolk Natural History remain a vital Channel for communication, and a powerful stimulus to fieldwork, their role as depositories of information may change as more is handed to future generations in databases.

Biodiversity and the naturalist The decline in 'natural history' among ecologists may be checked by a new and politically important term, biodiversity. The Rio conference on biodiversity (UNCED, 1990) defined it rather legalistically: "The variability among living organisms from all sources, including inter alia, terrestrial marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems."

- Article 2 of the Biodiversity Convention.

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A more practical day-to-day definition might be: The fßll natural ränge of habitats, species and the processes and systems which maintain them 'Processes' includes habitat management processes such as grazing, mowing or coppicing; 'systems' would encompass wider influences, such as hydrology (ground-water abstraction is a severe threat to East Anglian wetlands), and pollution (deposition of nutrient nitrogen from the atmosphere may change the character of our grasslands). Suffolk may not spring to mind when one thinks of 'biodiversity'. Tropical rain-forest, African savannah, or coral reefs certainly support more species than the average Suffolk nature reserve. Most of the world's species live in the Tropics; but we know almost nothing about them (Groombridge, 1992; Wilson, 1992). Hence a dilemma: there will be mass extinctions before we have even catalogued the existence of most species.

Britain is a species-poor offshore island, with "the best known and most modified flora and fauna in the world" (Lawton etal., 1994). We may not have much 'biodiversity' compared with Brazil or Australia, but we know where it is, and to a lesser extent, where it was in the past. Britain is thus the ideal place to test ideas and to elucidate the principles underlying 'biodiversity'. The historical dimension allows us to study both the nature and processes of species and communities, and the ways they respond to massive and sustained human impacts.

The origins and development of recording natural history The study of natural history in Britain has its origins in the 17th Century or earlier (Allen, 1976). Co-ordinated gathering of information was well under way during the 19th Century, the era of most first county floras such as Hind (18B9). National overviews, often in the form of county or vice-county maps, were published from early this Century (e.g. Taylor, 1900). In 1951, the Botanical Society of the British Isles embarked on the first national atlas using the 10km squares of the then recently-published Ordnance Survey national grid (Perring, 1992). The resulting Atlas of the British Flora (Perring & Walters, 1962) was a world first in the networking of mainly amateur observers. The idea was quickly taken up by others, and the foundation of the Biological Records Centre at Monks Wood in 1964 provided the beginnings of a national data centre, almost all the data deriving from amateur naturalists, even if some were also professional biologists during their working day. In the succeeding years, over 10,000 species have been mapped, and a further 10,000 are covered by national recording schemes (Harding & Sheail, 1992).

The 1970s and early 1980s saw a proliferation of local recording initiatives, such as that based at Ipswich Museum, but there was also some loss of cohesion (and lack of funding) nationally. The late 1980s and 1990s have been notable for their committees, federations and commissions: careful studies of the Problems of data processing and transfer, in the absence of adequate funding.

Though they failed to provide solutions, these bodies helped direct attention to the problems. In 1996, an application to the Millennium Commission, a joint initiative of research council, statutory conservation agencies, wildlife trusts and the Natural History Museum, London, was turned down, but the good will it engendered may yet be productive. We must hope that such initiatives retain

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the support of amateur naturalists, who want to see their records put to better and more immediate use, rather than making them feel exploited.

Species distribution mapping Atlases resulting from national recording schemes revealed for the first time the detail of individual species distribution patterns which had previously only been suspected. Some were especially striking, such as calcicole species like Pomatias elegans (round-mouthed snail; Kerney, 1976), Helianthemum nummularium (rock-rose; Perring & Walters, 1964) and other calcicoles, whose distributions clearly pick out each of the major chalk and limestone formations.

Some sharply-defined distributions were less easy to explain. The Black Hairstreak Satyrium pruni occupies a coffin-shaped distribution across the Midlands, with strongholds in Cambridgeshire but failing to reach Norfolk and Suffolk; and the Swallowtail butterfly Papilio machaon is a Broads speciality.

Both distributions reflect historical patterns of land use (Heath et al. 1984).

National atlases also drew attention to important regional centres of diversity and rarity. Many characteristic species had once been widespread (and appeared so if one consulted the various county floras or species-lists in the Victoria County Histories of England), but during this Century had been lost from much of lowland Britain. Few such species groupings are better defined than the Breckland flora and fauna. Botanists and entomologists had long realised that many species were easier to find in Breckland, but the Atlas (Perring & Walters, 1962) revealed the extent of decline of species such as Veronica triphyllos in other parts of Britain.

National patterns of species-richness in Britain To define a set of species characteristic of Breckland assumes an important point: there are not as many patterns of distribution as there are species. A simple way to examine trends is to map species-richness: counting the number of species in a particular taxonomic group which have been recorded from a 10km Square. In the early stages of recording, such patterns merely show where recorders have been most active. As recording progresses, real patterns stand out (Eversham & Roy, in press). These new patterns - the mapping of national biodiversity - can derive only from collations of amateurs' data: Britain is one of few countries where such an accurate and fine-scale overview is possible.

Dragonflies and butterflies illustrate a common theme in species-richness: there are more species in south-east England than elsewhere (Lawton et al., 1994). Most groups of insects and flowering plants show this same trend. It is easily explained by several major environmental gradients. The south-east is warmer, drier and sunnier, predominantly lowland, composed of soft, mainly base-rich rocks, large and slow-flowing rivers meander across rieh alluvial floodplains, and it has escaped ice cover during most recent glaciations.

Conversely, north-west Britain is comparatively cold, wet, and upland, with hard, acidic, volcanic rocks, fast-flowing streams, and has been scoured by glaciers in each successive Ice Age. Although conditions in the north-west are inimical to many plants and invertebrates, some groups, such as mosses and liverworts, ferns and sedges, are favoured, so have their peaks of diversity in western Scotland.

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National environmental gradients determine broad patterns of speciesrichness, but there are important departures from the trend, too. This can most clearly be seen by examining a transect across the country, say, from Dorset to East Anglia (Lawton et al. 1994). Butterflies and dragonflies show the same overall trends (most species in Dorset and a gradual decline northward along the transect), but richness fluctuates around the trend lines, and the fluctuations are out of Step. Dorset is rieh in both butterflies and dragonflies; Wiltshire (especially the dry chalk grassland of Salisbury Piain) is rieh in butterflies but very poor for dragonflies; urban areas on the outskirts of London have reduced the richness in both groups; and the ancient wetlands of the Norfolk/Suffolk Broads are peaks of species-richness. Most naturalists will see the causes at once: habitat availability and land-use history. The Broads are a uniquely valuable area of wetlands, characterised by species such as the Swallowtail butterfly and the Norfolk Hawker dragonfly Aeshna isosceles, which have been absent from the rest of Britain since the drainage of the Cambridgeshire Fens in the nineteenth Century (Heath et al., 1984; Merritt et al., 1996).

Diversity, rarity and conservation value at the national level The pattern of species richness can be simplified by examining exceptionally rieh areas: 'diversity hotspots', most easily defined as the most species-rich 10km squares of the national grid. The distribution of hotspots has two features which may not surprise naturalists, but which are deeply inconvenient to conservation biologists. Centres of diversity for different organisms are in different places (the overlap of hotspots is little better than by chance (Prendergast et al. 1993)), and many rare species do not occur in hotspots. Thus, the rare annual bryophytes found in arable fields in East Anglia (Hill et al., 1992) are not represented in bryophyte hotspots, which are largely north-western.

Northern butterflies and dragonflies, such as Scotch Argus Erebia aethiops and the Azure Hawker dragonfly Aeshna caerulea are completely absent from butterfly and dragonfly hotspots. Although it is debatable how far these analyses, at 10km scale in a severely human-modified country like Britain, are relevant to other parts of the globe, they serve as a warning to those who assume that a conservation strategy based on one group (for instance, birds) will automatically conserve all other species, too.

The development of nature conservation in Britain has run in parallel with that of natural history. Pioneers in nature conservation, such as Rothschild and Diver, were also first-rate naturalists. As a consequence, Britain has avoided simplistic definitions of conservation value, and the comprehensive set of criteria eventually proposed for selection of National Nature Reserves (Ratcliffe, 1977) has formed the basis of many systems elsewhere. The two most widely used criteria are diversity and rarity (Margules & Usher, 1981). A hope, bordering on a belief, has grown up among conservationists that the two attributes are linked, that places with high species diversity will contain many rare species. When comparing a Single habitat type, this may be partly true: the calcareous grasslands with the most species will support many of the scarcer species. But the relationship breaks down in comparisons between habitats.

Thus, a pristine saltmarsh on the Suffolk coast may well contain far fewer species of plants than a degraded and medioere example of chalk grassland in

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the west of the county; but the saltmarsh flora will comprise species with far more restricted national distributions.

Detailed studies of individual sites and species The discussions so far have been rather academic and abstract, and have also been based on other naturalists' work - the BRC databases. To explore the same pnnciples at a finer scale, I shall draw on my own studies of two areas: Britain's two largest lowland raised bogs, Thorne and Hatfield Moors just north of Doncaster; and the Breckland of Suffolk and Norfolk. The first example illustrates the value of the taxonomic breadth which a team of keen amateurs can bring to site surveys. The second shows how careful observations, regulär Visits and a wide ränge of often labour-intensive sampling methods, such as an amateur may choose, can detect the presence of many species which the more objective or 'cost-effective' methods used by Professionals tend to miss. Patient study of individual species can also reveal important and unexpected features of the biology of species, which may be vital to their successful conservation.

The Humberhead Levels The Humberhead Peatlands developed on the Levels where the Rivers Aire, Don, Trent and Ouse flow together to form the Humber. About 7% of Britain was once peatland, but only 5.3% of this was lowland raised mire: upland blanket mire was far more extensive. Only 6% of that 5.3% now survives (Lindsey, 1989), and about one third of it - 3300 ha - is at the two sites which I have studied, Thorne and Hatfield Moors.

Drainage and peat cutting in the area began in the Middle Ages or earlier (Limbert, 1987, Eversham, 1991), but until recently, peat cutting had a quaint, almost archaic, image. At Thorne & Hatfield, until the mid 1960s, all peat was dug by men with spades, and removed in horse-drawn wooden wagons. The arrival of an international horticultural industry in 1963 was followed by rapid intensification of peat extraction, and the scale of habitat loss and species extinction which it caused, led in the 1980s to a national campaign. This involved a large consortium of voluntary conservation bodies, ranging from the Wildlife Trusts. RSPB and Friends of the Earth, to the British Dragonfly Society and the Greenland White-fronted Goose Study Group. Thorne and Hatfield Moors were key site sin the campaign because the wealth of detailed natural history Observation and species records provided unrivalled evidence to Support the arguments of the conservationists.

To a natural ist, Thorne Moors can be pinpointed as where large heath butterfly Coenonympha tullia (Heath et al., 1984) meets the nightingale Luscinia megarhynchos (Gibbons et al., 1993). Any site in Britain might be expected to contain a mix of northern and southern species (a consequence of the environmental gradients described above), but Thorne and Hatfield lie close to the Tees-Exe line, which marks the division of 'Upland Britain" from 'Lowland Britain - (Mackinder, 1902; Stamp, 1946).

Plants, animals and naturalists Despite their reputation for being barren, species-poor habitats, bogs contain a wealth of wildlife, and a higher proportion of rare and threatened species than

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almost any habitat. At Thorne and Hatfield Moors, there are at least six insect species found no-where eise in Britain, most of which are also very rare over the rest of Europe (Eversham et al., 1995), such as the mire pill-beetle or 'boghog' Curimopsis nigrita (Coleoptera: Byrrhidae), which was added to Schedule 5 of the Wildlife & Countryside Act in 1991, and the small ground-beetle Bembidion humerale (Carabidae) which is listed as a priority species in Biodiversity Challenge (Wynne et al., 1995). Each part of the Moors supports specialised flora and fauna. In wettest areas are found plants such as bog rosemary Andromeda polifolia, many species of Sphagnum bogmoss, and breeding birds such as teal Anas crecca and snipe Gallinago gallinago. Drier areas support nightjar Caprimulgus europaeus, over 40 pairs breeding in recent years, monitored annually by a team of local birdwatchers. Heather of the drier parts supports a rieh variety of insects, including scarce moths such as the purple-bordered gold Idaea muricata. Even the invasive birch trees are of conservation interest, as one of the last British strongholds of the scarce vapourer moth Orgyia recens.

An accumulation of data on plants and animals rarely saves a site; Thorne Moors have been well-known since the days of J.C. Dale and F.O. Morris in the 1820s and 1830s; yet much of the most severe drainage occurred in the subsequent half Century (Limbert, 1990). Until recently, there was no mechanism to turn naturalists' knowledge and concern into practical conservation.

In 1990, a particular need for information caused naturalists and conservationists to join together. The peat extractors demanded hard evidence of the conservation value of each surviving fragment of peatland Vegetation, especially for its invertebrate fauna. An intensive survey was mounted: 400 pitfalls and 200 water traps were set; a full-time graduate entomologist was employed for a year to set the traps and sort the catch. But amateur naturalists (and a few Professionals in their spare time) were essential to identify the species, and field Visits by volunteers augmented the lists enormously. By the end of the 1990 survey, over 5000 species of insect had been recorded from the two moors. This diversity, and its quality in terms of Red Data Book and nationally scarce species, illustrates the disparity between taxonomic groups.

The most species-poor Vegetation, comprising 5 or 6 common flowering plant species, 4 or 5 common mosses and perhaps 3 common liehen species, could support a unique assemblage of nationally rare insects: one typical pair of pitfall and water traps on Hatfield Moors caught 345 species of insect in the year, including 1 species new to Britain, 3 Red Data species, 15 Nationally Scarce species and a further 30 which were rare in the county. It seems that water levels and Vegetation strueture are more significant than speciescomposition of Vegetation for all except the direct plant-feeding insects: in such assemblages, over 70% may be predators and detritivores (Heaver & Eversham, 1991).

In February 1992, an agreement between Fisons and English Nature was announced. Although peat cutting continues over large parts of both moors, the agreement does prevent the physical destruetion of Vegetation from half of Thorne and 10% of Hatfield Moors, which removes the imminent threat which has hung over campaigners for the past 20 years. It would not have come about without the support and hard work of local naturalists.

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Breckland beetles: sampling and behaviour The ground-beetles, Carabidae, are among the best known invertebrates, and are usually considered among the most easily sampled (Stork, 1990). They are also well represented in Breckland, which has long been famed for its rare species, and these occur in most of the major habitats for which Breckland is renowned. Since 1992, I and a colleague, Mark Telfer, have been recording Breckland carabids in our spare time, at a wide ränge of sites. Due to a succession of keen amateur coleopterists, the fauna was already well known, but we have added several species to the list (e.g. Telfer & Eversham 1994a 1994b).

The Breckland fauna has also been sampled by professional ecologists, including doctoral and other university students, and ecologists from agricultural research institutes. In common with much ecological research on carabids (Stork, 1990. Desender et al. 1994, and Niemelä (1996)), most Breck research has been based on the catch from pitfall traps (open-topped glass or plastic jars, planted with their mouths flush with ground level, into which passing invertebrates stumble). Pitfall traps are biased toward the larger, more mobile invertebrates (Luff, 1975) and the liquid used to preserve the catch can affect the trap's efficiency, too (Luff, 1968).

Using the direct searching techniques favoured by 'amateur' coleopterists, alongside pitfall trapping, illustrates the relative effectiveness of the methods!

The study site was a road-side in Breckland, not far from Brandon, which supported a rieh assemblage of specialised ground-beetles (Eversham & Telfer, 1994). The road-side has been sampled since March 1993, by direct-searching for approximately 2 hours per visit, at approximately two-week intervals during the main season of beetle activity. This rapid-search method, involving hand sifting of the top 4-5cm of sand in random areas of lm2, is well suited to the fauna of sparse Vegetation on light soils, and is similar to the methods advocated by amateur coleopterists since Fowler (1887) and Joy (1932). Direct searching at the roadside was supplemented by two periods of pitfall trapping, in May and August 1993. The traps caught 1172 carabids, of 34 species.

The pitfalls included only four additional species not found by direct searching in the same time period. The traps caught 52% (34 out of 65) of the species found by direct searching. Direct searching thus provides an adequate qualitative sample of the fauna, in this case, more reliable than the widely-used technique of pitfall trapping. The pitfalls had very particular biases. The two most diverse genera of carabids in dry habitats in Breckland are Amara and Harpalus, with 31 and 35 British species respectively; both genera are predominantly seed-eaters. The roadside supports 19 species of Amara and 13 of Harpalus, making it probably the richest known site for seed-eating groundbeetles in Britain. Most Amara appeared in the pitfalls, but very few Harpalus were represented. This seems to be because Harpalus hold on to the edge of the pitfall with their hind tarsi, and haul themselves out of the trap having noticed the preservative chemicals (or perhaps the alarm pheromones of dying carabids). So, the diversity and conservation value of Breckland habitats may be greatly under-estimated by ecologists relying entirely on pitfall trapping.

'Amateur' techniques such as direct Observation can also contribute greatly to our understanding of the behaviour of species. An inspiring feature of

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Victorian naturalists' journals is their patience in spending time 'just watching' the organisms of their choice. Among the commoner ground-beetles in Breckland are seven species of Calathus. Some have been studied in depth by continental entomologists (Aukema, 1986, 1990; Desender 1989). In discussion with a Belgian carabid expert, whose PhD had concentrated on Calathus melanocephalus, I was alarmed to find he regarded the species as exclusively a predator. If you search almost any Breck roadside or field margin, at dusk from April to October, you will find large numbers of this and related species, climbing the Vegetation and feeding on the unripe seeds of crucifers, umbellifers and sand-sedge Carex arenaria. Sadly, few professional ecologists have the time to watch their subject out of doors in the evening.

Watching beetles is probably the best way to develop an understanding of how they live together, and why there are so many species. Based on five years of amateur Observation in Breckland, I am convinced that the many seed-eating carabids share out the habitat and food supply (resource partitioning, in ecological jargon), according to seed size, ripeness, seasonal availability, and location (on the plant, on the ground, or in the soil). The richest fauna is at sites with the greatest diversity of seeds throughout the year.

Conclusions A few practical points arise from the peat campaign. and from Breckland beetle studies, which reflect on the relationship between naturalists and conservationists: facts - precise, accurate, up-to-date information - are essential to a sound conservation case; historical data should also be collated; it may be the only way to convince the sceptic about the scale of losses; broad coalitions help - the opponents of conservation will seek to divide the conservation lobby; conservation can seldom succeed without publicity, and the media are generally sympathetic, and looking for 'a good story', especially during the parliamentary recesses; careful studies of individual species or groups can provide guidance for habitat management and long-term conservation; elaborate equipment is not needed.

There are also a few key points about 'biodiversity' which arise from recent research in Britain, all of it relying on amateur naturalists to provide the original data: high diversity is intrinsically neither good nor bad: some habitats are naturally species-poor but may still be extremely important; rarity and diversity are not closely correlated: species-poor habitats may contain a high proportion of rarities; professional ecologists have neither time nor, in many cases, the taxonomic skills to study the wide ränge of plant and animal species which constitute biodiversity; only the concerted and co-ordinated efforts of amateur naturalists make such studies possible.

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