CONFERENCE 2001 - “FUTURE FLORA”

Bob Stebbings welcomed a full house of 400 delegates to the 12th Annual Suffolk Naturalists’ Society Conference on 20th October. If you were not present, you can get a feel for what you missed from the following precis.
The morning began with a message from David Bellamy; thoughts along the lines of “Wither Botany...”, delivered through the lips of Plantlife’s Martin Harper. He reminded us that there are more field botanists to the square yard in the UK than in any other country, and that we have the opportunity to put teeth into the recent wildlife legislation. The Suffolk Wildlife Trust’s agreement with Railtrack was cited as a good example of the way to move forward.

“Where have all the wildflowers gone?” was the topic for Peter Marren’s opening talk. Introduced as “the twitcher in the swamp”, Peter explained that he lived in a swamp in the Kennet valley in Wiltshire and had watched the colour draining out of the countryside as wildflowers were overtaken by the march of stinging nettles. His past year’s work for Plantlife had been a review of the data to be found in an under-used resource - the County Floras. Analysis of the changing records portrayed in these volumes enabled some interesting comparisons, particularly of rates of local extinctions. Meadow Cranesbill, once known as “the Wiltshire weed”, was still around in plenty in roadside verges, but its colour was no longer a spectacle. It had been overwhelmed by Nettle and Cow Parsley, a plant that some enjoyed, and did indeed look pretty on 3 days each year!
Northants flora was declining at a rate showing that half of its wildflowers were in trouble; 1.4 species had been lost each year over a 60 year period, and the present day rate of loss was probably even higher than this average. Other counties also seemed to be bleeding native species at a rate of round about one per year. It was not easy to find common baselines, but a good start could be made if a county had one flora for 1900, with another very recent edition for comparison. Simpson's Flora of Suffolk (1982) got a fond mention, as the last flora not to appear in A4 format and stuffed with county maps, but instead a "damn good read". It was possible to describe 2 typical patterns of loss: the Cambridgeshire (agricultural) pattern, with a low loss rate from 1890 to 1939 followed by a postwar boom, and the Pastoral (west-country) pattern, with few losses before the 50's, and a whole burst thereafter.
Not all authors defined what they meant by a county native plant, but it was clear that gains over the same period outweighed the losses, provided that nativeness was disregarded. Clearly, losses and gains can not be fairly offset, since many of the non-natives are invasive species, and many gains are of ubiquitous garden plants.
Turning to particular losses, insectivorous plants were seen to be doing very badly, and Peter drew our attention to the Oblong-leaved Sundew, which was typical in retreating to its heartlands. A plant guaranteed to capture the imagination of children, and found on Wimbledon Common in our childhood, the present distribution map led us to ask how many schools are now close to a Sundew? It has been wiped out by competition and nitrogen pollution, as well as the more obvious loss of its peat bog habitat. Other groups doing badly included some weeds, eliminated by herbicides, aquatic plants suffering from loss of water quality, the fern relatives and bog mosses of heathland, as well as the "mud annuals" such as Camomile, lost along with their hoof-trodden wet pasture.
A review by habitat showed that woodland was changing rather less than most, whilst rivers and lakes had almost lost the White Water-Lily, and over-grazed uplands in Cumbria were losing as many species as Suffolk. In many ways, "Pink data book" species were more at risk than the rare red species, many of which occupy very small niches which remain unthreatened.
At the human level, Peter concluded, we were observing change in our own lifetimes, and the loss of Cranesbill hurt. Perhaps it was possible to take a less gloomy view - evolution was happening in our street; future flora was exciting; maybe we should welcome the nettle (taller than ever)!

“Understanding the ecology of change in the British Flora”, or why small species go extinct, made a natural follow-on, being the topic of Kevin Walker’s research at Monks Wood. He studied the evidence of change, sought out the shared traits of the declining species, identified the causes of change, and considered their consequences for the future. As well as the county floras, he had looked at the results of a monitoring scheme which studied the decline of 195 species between 1930/60 and 1987/88, and a number of projects on particular species. He presented extinction rates for 16 counties which averaged out at just below 1 per annum, with the variability of estimates due largely to the definition of native species.
The cause of the change could be summarised as the destructive effect of man’s influence on the natural environment. This accelerating destructive process featured habitat loss, fragmentation and degradation as a result of urbanism, with the decline of pastoralism, and the increased use of fertilisers and herbicides. Hardest hit had been habitat-specialist species, poor dispersers, and self-incompatible species unable to find a mate. Over the past century, some 10% of native species had been lost, and the present rate of loss is greater than the long-term average.
Consideration of changing habitat against the Ellenberg Indicator values for light, acidity and nitrogen was instructive. Losses were much greater in full sun habitats than in shade, whilst the results for acidity showed a curve, with high losses at both the extreme acid and chalk ends, and lower losses in the neutral soils. The nitrogen scale also showed higher losses at the extremes of poor fertility and over-fertilisation, compared to the middle ground. Aquatic habitats, acid grassland, and calcareous communities have all lost more species than woodland, scrub and natural grassland. Plant height was another factor, and low-growing species were particularly vulnerable to loss as a result of being shaded out by competition.
A portrait of an unsuccessful plant species was therefore: one that grew in very open habitats, preferred acidic, infertile soils, and was small. It was of interest that the number of plants sharing these attributes, using below 60cms as a definition of small, amounted to precisely 42 - a figure we all recognised as the meaning of life, the universe and everything! A study of 16 such unsuccessful plants showed their decline in Cambs, Beds and Northants to be predictably depressing. Kevin concluded with the notion of slow-growing plants of infertile relatively undisturbed habitats, restricted to fragmented islands, surrounded by a sea of unsuitable habitat.

"Knowing what we have: the ever-changing inventory" was the lucid contribution of Clive Stace, the distinguished botanical author and Professor of Plant Taxonomy at the University of Leicester. He explained that he is always being asked how many species we have in Britain, but that any answer needs a lot of qualification - for example, do you want to count the 400 dandelion semi-species, and how about aliens? In 1908, Druce listed 1765 native species, whereas Kent, 2000 shows a total of 6916, including some 2500 native. Clearly there is an upward trend in the inventory, but this masks deletions (extinctions and misidentifications) on the one hand, and additions (arrivals, discoveries and novelties), as well as changes (taxonomic and nomenclatural).
Early arrivals after the last ice age, such as the Alpine Poppy had gone for ever, as our climate warmed up, and we continue to lose mountain species as a natural process. Only a relatively small number of total extinctions of native species - just 16 on his tablet of stone, had occurred in the last 200 years, as a result of contraction of range. A distinction to note was that the reduction of distribution - as shown by the Sundew, for example, occurred within an unaltered overall geographic range. Extinctions were a natural process, whilst planting was not conservation, but just gardening. Conservation does have a role to play though, in counteracting habitat loss.
Arrivals were simply the reverse of natural losses, for example fine-seeded orchids and broomrapes could be blown across the Channel, but we should not think in terms of a queue of species lined up waiting to cross. In time, these could be thought of as new natives, but in most cases it would not be possible to know the real source. Shots of Oxford Ragwort with Mt Etna in the background, and of Japanese Knotweed under Mt Fuji served to remind us that some aliens, though not all, are successful. Recent discoveries included a presumably native plant growing on a single hill in Wales, and overlooked as it can only be found in January or February. The category of novelties includes some 800 hybrids, many between natives and aliens. The Japanese Knotweed (in UK) is a female clone, and can only set the seed of a hybrid, but crossed with Giant Knotweed, the hybrid Bohemian Knotweed is produced, and such a process opens the possibility of the creation of a new super race in future!
The Professor explained the intertwined causes of taxonomic change without getting the audience out of its depth, and with examples of how reclassification from one genus to another can trigger a change of specific name. The rules of nomenclature are precise, and they are followed to the letter. If a species is moved again, into a genus where the old species name is unused, the plant can have its original name re-instated. If it is re-ranked, say from sub-species to species, the code may demand another name change, and furthermore, this process will have added another species to the inventory.
DNA evidence was now providing better information (not fingerprinting, but sequencing) on the ancestry of plants, and this was often unequivocal in allowing us to correctly allocate species within groups. Using the family tree of the Orchid group as an example, it was shown that past assumptions, based on plant morphology, had often been wrong. If we believed that classification should reflect ancestry, we would have to accept that many more changes were yet to come. The plant inventory, Clive reminded us, was ever-changing, with fresh ideas, and new arrivals, as well as extinctions.

"Approaches to native and alien species" was the contribution by Chris Preston from the Biological Records Centre at Monks Wood, where he has been reviewing the status of British plants for the forthcoming Atlas 2000. He began with definitions: Native:
arrived without intervention by man, having come from an area in which it is native.
Alien:
either: brought by man intentionally or unintentionally, even if native in the source area.
or: arrived naturally from somewhere it was alien.
These definitions related only to the means of arrival, and not to time; aliens remain alien, no matter how long they have been resident. Furthermore, they are definitions, and not value judgements.
By 1584, Turner made a distinction between wild and garden plants. By the 17th century, translocation from garden to wild had been recognised, and early accusations of botanists planting out in order to "discover" had been made! By 1769 the Royal Society was debating whether the Sweet Chestnut was an exotic tree, and after protracted correspondence, concluded that it was a Roman introduction behaving as a native. This led to Watson's terms: native/denizen/colonist/aliens/casuals. The subsequently-used category "introduced", loses all the subtlety of Watson's definitions.
Fossil records allow 2 further categories: archaeophyte (pre AD1500), and neophyte (post 1500). The dividing date of 1500 does have a relevance, as it fits nicely with the change in human trading patterns, as well as the baseline that Botany started in 1562. Neophytes therefore include most weeds from southern Europe, coniferous trees, and garden plants from Asia and the New World.
Chris then moved from definitions to conservation, and surprised the audience by asking them to subscribe (or not) to current orthodoxy: that conservation effort should be directed towards native species; that natives were more valuable to wildlife; that aliens have caused great damage to ecosystems. Most raised their hands at once; just 4 voted against. Such voters were described as heretics, and Chris went on to outline the challenge to orthodoxy being mounted by the "Glasgow School", who perceive "nativism" as a misguided attitude. He summarised their arguments under 9 threads:

The problems of defining what species is native, particularly from "partial natural history records".
The alien problem is exaggerated.
The utility of aliens is under-rated; they do provide habitats.
The urban perspective; there is no "natural" habitat.
Fondness for natives is a historic association.
Boundaries are man-made.
Ecological theory arguments (the super-organism); hybridisations are evolution are good.
Political Correctness for plants: nativism=Naziism.
What we do does not matter anyway in the long scale.

The future, Chris reminded us, is that aliens are here to stay, so what approach should we take? Predictably, this led to some lively questions on orthodoxy as well as heresy.

"The Common Plants Survey - counting on people and plants" was a crusading contribution from Plantlife's Conservation Director, Martin Harper. Beginning unexpectedly with the RSPB, Martin applauded the achievement of spin, through which that organisation had moved public emotion to persuade the Government to adopt a count of the number of breeding birds as a Quality of Life Indicator. From this stemmed Plantlife's ambition for "Keeping up with the RSPB". Plantlife saw itself as the Nation's champions of wild plants, and presently had 12,000 members and 22 reserves, was lead partner for 77 BAP species, and organiser of the "Back from the Brink" plant conservation programme. They had taken on the role of Secretariat for Planta Europa, engaged volunteers as "Flora Guardians" in conservation work, and had been pleased to campaign for the Countryside and Rights of Way Act, helping to introduce the first wildlife legislation in 20 years.
The Common Plants Survey was a joint initiative for tapping volunteer effort to achieve an annual survey which would complement the BSBI Atlas and the Countryside Survey. The pilot phase had involved 168 surveyors at 178 locations, mainly (153) in England. The survey proper would start in 2002, with surveyors each making 3 visits/year to a 1km square to record 58 (easily-identified) species. It would provide information on the health of our flora, and "Information is Power", Martin intoned. (Shades of 1984?) The squares had been chosen as a random selection of typical sites, and definitely not the botanically best. Some linear locations had also been selected. The data from the pilot study seems to support the belief that vegetation is dominated by a few widely occurring species. The top 4 were: Nettle, Hawthorn, Cleavers, and Ribwort Plantain. Effort would be put into developing the volunteers from single-species surveyors, to indicator species recorders, with experts conducting the plant monitoring tasks.
Anyone wishing to participate in the survey may obtain more details from Plantlife's website at www.plantlife.org.uk or 020 7808 0116. Martin had a receptive audience, and his presentation probably recruited new members.

"The Countryside Survey of Great Britain" has provided sample-based evidence for vegetation change between 1978 and 1998, and was presented by Simon Smart, a Higher Scientific Officer based at the Centre for Ecology and Hydrology at Merlewood. The extensive survey had begun as a woodland survey in 1971, and under the NC, NCC, ITE and finally CEH, the methodology had been refined. The present study compared results from 1978 with those of 1998, analysed 20 years of change, and had been published last November, under the title Countryside 2000. Vegetation in 256 one kilometer squares had been split into ITE's "Land Classes", and field surveys had been conducted at fixed points (an average of 27 in each 1km square), and a heirachical method of analysing change had been devised. Habitat fragments omitted from the broad categories were added at a late stage, and had proved valuable, as had the "linear plots" from hedges, streams, roads and boundaries. Soil samples were also taken, and a "Wally plot" used to show a matrix of component results. Apparently this is no job for a fool, but was named for its inventor - Wally Shaw.
The Countryside Survey results can quantify changes in common plant species across Britain, and those changes can be precisely located. However, it is important to understand that it can not quantify stock or change in rare plants, and is not suitable for making estimates at a small scale. The process of fine grain tracking of large scale changes in common plants can convey information on environmental conditions, indicate reduced opportunities for rarities, and identify the shape and colour of the countryside. It was a complement to BSBI recording, and gave matches for large scale/common species changes, but not for rarities.
The changes identified from 1978-98 satisfied statistical tests, and for 8 plant community classifications, the decreases outweighed the increases. Infertile grassland had shown a big decrease in diversity, and crop weed communities had also decreased substantially, but a small increase had been noted for Heath bog/moorland grass. Tables expressing the loss rate per plot were shown for each plant community. The results for alien plants showed increases for just 3 species, though no aliens had decreased. Amongst the decreases were 5 species of plant important to lowland birds. Agrostis grass species were increasing. An analysis of the Ellenberg scores along the fertility gradient showed reductions in diversity for the less competitive species, and lowland vegetation was seen to be more dynamic than upland. Comparison of 2 photos of the same river bank in 1990 and 1998 left no doubt that nettle was overwhelming everything, and explained why 17 species had reduced to just 7. The big losers were short plants in infertile grassland; the winners were those with high scores on the fertility scale. It was interesting that the small relict biotope patches had not suffered badly; like the linear features, they were valuable refugia. The effect of eutrophication was shown to be greater in the lowlands than in the uplands, with a greater increase in implied substrate fertility over time.
A separate project had studied the causes of change, and Simon concluded by identifying the following as drivers of change:

Lack of cutting of roadside verges.
Conifer plantations.
Atmospheric pollution.
Nitrogen deposition.
A fuller description of the results of the Countryside Survey may be found at: www.cs2000.org.uk

Question Time followed, with a selection of prepared questions chosen to elaborate on the presentation themes. The panel covered the reintroduction of wildflowers to former sites, the use of commercial or "wild" grass mixes, the oxymoron "creative conservation", the planting of obvious exotics in preference to near-natives which can hybridize, agri-environmental schemes, the value of the National Vegetation Classification Scheme, the retention of wasteland as a habitat, and natural history education for the next generation. There was sufficient disagreement on most of these topics to keep the debate lively, and we ran easily into overtime before Paul Lee delivered his thanks to all contributors, and Clive Stace was able to sum up at the end of another thoroughly absorbing conference.
The full proceedings of the conference will be published in Suffolk Natural History Vol 38 (2002).

Rob Parker

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