From the outset the Cambridge meeting was intended to be a special memorial event to celebrate two of the Society’s most active and long-standing members. Professor Paul Richards and Dr Eustace Jones (Jonah). Between them they had clocked up 127 productive years as members of the Society, as a result of which the bryological world has become the richer.
In recognition of this achievement, all of the papers read on Saturday 22 September had some connection with the bryological interests of either Paul or Jonah. In practice this meant a special emphasis on tropical bryology, a passion they hold in common, and we were pleased to welcome two of our overseas members, Dr Támas Pócs and Dr Rob Gradstein as guest speakers. The Tropical Bryology Group were able to capitalise on this concentration of tropical talent by calling a special workshop meeting in Cambridge on the Friday preceding the AGM.
After short autobiographical talks from Paul and Jonah the meeting heard about the bryological exploration of Africa and the taxonomy and ecology of tropical hepatics. In the afternoon, an ecological investigation of Campylopus introflexus and studies in the changing flora of southern Britain completed the day. Summaries of the papers, written by their authors, are presented below.
The surroundings of Downing College were distinguished and refined, as one would expect of Cambridge, and the weather provided us with a silver mist, for which the city is famed. The meeting was a memorable one, and the arrangements went very smoothly, thanks in no small part to the excellent organisation of the local secretary, Dr Phil Stanley.
Prof P.W. Richards (Cambridge): My first steps in tropical bryology.
My first step in tropical bryology was when I set foot on Barbados, I August, 1929, on my way to British Guiana (now Guyana) as a member of the Oxford Exploration Club’s expedition. In Welshman’s Hall Gully I saw some epiphyllous liverworts, but it was not as good a place for bryophytes as Grenada where the ship called the next day.
The expedition set up camp at Moraballi Creek, a small tributary of the Essequibo about 80 km from the coast, on 11 August. With two other botanists, T.A.W. Davis and N.Y. Sandwith, I remained at Moraballi Creek until the end of November, collecting bryophytes, ferns and other cryptogamic plants, as well as working with Davis on the ecology of the rain forest.
My first impressions of the bryophytes were set out in a short paper which Mr H.N. Dixon invited me to give to a small informal meeting of bryologists in London in January 1930. I identified the mosses as well as I could with some help from Mr R.S. Williams of the New York Botanical Garden and published a list of them in the Kew Bulletin 8, 317-337 (1934). My collection of hepatics was sent to Professor A.W. Evans (Yale University, U.S.A.). He identified about half of it and promised to send a list of the rest. He never did so and the specimens must be presumed lost. In 1953 I published ‘Notes on the bryophyte communities of lowland tropical rain forest, with special reference to Moraballi Creek, British Guiana’ (Vegetatio 5-6,319-328).
Dr E.W. Jones (Kirtlington, Oxfordshire): What am I – Botanist, Forester, Physiologist, Ecology or Taxonomist?
A few personal details which may help to answer the question are recorded in BBS Bulletin 42 (1983). I will add a few more here. I learned to recognise Schistostega pennata in a cave as a very small boy, but made no further progress bryologically until I became a student at Cambridge. Here I became most interested in what grows where and why (i.e. ecology) and as I walked the hills and moors and bogs of the north and west of Britain, where bryophytes are important members of the plant communities, it seemed to me that they had valuable information to give to the student who knew them. With vascular plants help in identification was readily available; with bryophytes one had to be one’s own authority.
I chose for my doctoral studies a physiological subject because I believed (and still believe) that physiology should be the basis of ecology and provides a more rigorous discipline than does e.g. ‘plant sociology’. I look upon bryophytes as members of living plant communities not as twigs or branches of some hypothetical Phylogenetic tree, and the primary job of the taxonomist as the production of classifications that aid identification of taxa and the prediction of behaviour: he should not upset well-tried practical classifications in order to make them conform with his own Phylogenetic theories.
If I have specialised in the taxonomy of African hepatics it is simply because ecological work has taken me to Africa: I found there a gap which was plugged by disordered and often erroneous information which I was in a better position than most bryologists in 1948 to tidy up.
Dr A.J. Harrington (Natural History Museum, London): The bryological exploration of West Africa.
Three discrete periods can be recognised in the bryological exploration of West Africa. The first of these – the heroic – extended from the end of the eighteenth century to the middle of the nineteenth. Plant collecting at this time was closely associated with exploration, the expansion of commerce and the suppression of the slave trade. The early botanists were beset by difficulties and illness, and it is surprising that they managed to collect as many specimens as they did. Of those who included bryophytes amongst their collections, the following deserve special mention: Palisot de Beauvois (southern Nigeria, 1786-8), Adam Afzelius (Sierra Leone, 1792-6), Mungo Park (?Mali, 1795-7), Theodor Vogel (southern Nigeria and Femando Poó, 1841) and Charles Barter (mostly Nigeria and Fernando Poó, 1857-9).
The German botanist Gustav Mann, who made extensive collections in Cameroon and the islands of the Gulf of Guinea between 1860 and 1863, acts as a link with the second phase of exploration, the period of the resident collector. This extended from c. 1880 to the First World War, and thus coincides with the major period of colonial expansion. Collecting was concentrated in three areas:
- Guinea and Senegal, where many specimens were gathered, mostly in the early years of the century, by French army officers and colonial administrators, notably Henri Pobéguin.
- Western Cameroon. German and Swedish botanists collected extensively in the area of Cameroons Mountain in the 1890s, prominent amongst them the Swede Per Dusén who, unusually for the time, described several new moss species from his own material.
- The islands of the Gulf of Guinea. The Portuguese botanists Moller, Newton and Quintas were active, especially on Sao Tomé and Príncipe, during the 1880s, while the German bryologist Wilhelm Monkemeyer made a small but significant collection on Fernando Póo in 1885.
Collecting continued in the 30 or so years between the second and third periods of exploration, but the collections are mostly small and incidental; important exceptions are those of Auguste Chevalier from various parts of French West Africa, Paul Richards from south-west Nigeria and A.P.D. Jones from Nigeria.
The third period of exploration – the age of the specialist – commenced with the Cambridge Botanical Expedition of 1947-8 and continues to the present day. It is characterised by two features: the leading role played by trained bryologists in fieldwork, and the wealth of taxonomic studies produced. Many of these studies have benefited greatly from the key specimens collected on the Cambridge Expedition, and, more recently, by Eustace Jones and Paul Richards. The period has also witnessed the participation of indigenous botanists in collecting and research, a development vital for the future of bryology in the region.
In spite of more than 200 years of exploration our knowledge of the bryophyte flora of West Africa is still fragmentary and generally poor; some countries remain virtually unexplored (e.g. The Gambia, Guinea-Bissau), while even in comparatively well-worked states such as Nigeria large areas are scarcely known or have not been investigated. Many more field observations and collections are needed before a clear picture of the distribution and ecology of even the common species can be obtained.
Dr T. Pocs (Hungarian Academy of Sciences): The genus Colura in East Africa.
[Dr Pócs’ paper appears in Bulletin 57: 33-39.]
Dr S.R. Gradstein (Institute of Systematic Botany, Utrecht): A view at the liverwort flora of tropical America.
One of the earliest contributions on neotropical hepatics was by Olof Swartz, a Swedish doctor and pupil of Linnaeus, who collected in the West Indies in the late 18th century. Swartz published a comprehensive Flora of the West Indies in which he described about 30 species of liverworts. They are among the earliest names in tropical hepatics.
The first important collector who penetrated into the vast jungles of the Amazon, around 1820, was the German botanist Karl Friedrich Philipp von Martius, a director of the Botanical Garden of Munich. After his travels, Martius devoted the rest of his life to work up his collections and publish Flora Brasiliensis, probably the largest tropical Flora ever written. His Brazilian liverwort collections were studied by Nees von Esenbeck, who described about 70 species, virtually all of them new to science. No doubt the most important 19th century collector of neotropical hepatics was Richard Spruce. Spruce was a Yorkshire man and an amateur botanist who, at the age of 32, decided to travel to South America. He remained there for about 15 years and brought back a huge collection of plants, most of which were studied by others except for the liverworts which Spruce decided to work up himself. Out of this came his Hepaticae of the Amazon and the Andes, which is the most important work that has ever been written on neotropical liverworts. Spruce treated about 600 species, many of which were new to science.
After Spruce many people worked on the liverworts of Tropical America. Probably the most notable contributions were made be Alexander W. Evans from Yale University, who wrote numerous important taxonomic papers on neotropical liverworts in the beginning of this century, and by his student, Margaret H. Fulford from the University of Cincinnati, who is author of the Manual of the Leafy Hepaticae of Latin America.
The neotropical liverwort flora counts about 180 genera and each year about one new genus is being added. The flora has about twice as many genera as Europe and, more significantly, generic endemism is about 25 times higher in the Neotropics! Schuster (1990) believes that the very high rate of liverwort endemism in the area – the highest in the world – is due to the eventful geological history of the region coupled with an extraordinary ecological complexity. I would like to comment, however, that the tropical flora is still very incompletely known and endemic taxa might in fact be more widespread. Examples of neotropical genera recently shown to be more widespread are Arachniopsis (also in Africa), Gymnocoleopsis (also in Africa) and Cladomastigum (=lwatsukia from Asia).
The number of species in the neotropics can be only roughly estimated. Stephani in his Species Hepaticarum listed about 3000 species but my figures from monographs for FLORA NEOTROPICA indicate that there are probably no more than 1200 species. Most parts of Tropical America are still under-explored but some areas are certainly more poorly known than others. Whilst the West Indies have received considerable attention, large parts of the Amazon basin, the table mountains of Guayana and the Pacific coast of northern South America virtually remain terra incognita.
As to habitats, cultivated land, road sides and riverbeds are places of interest for liverworts which have been neglected. For example, the genus Riccia was unknown in the Guianas – one of the relatively better-explored regions in tropical America – until it was recently found to be relatively common in gardens. On bare soil in an oil palm plantation in coastal Ecuador, where vegetation had been removed with herbicides, we found masses of Cyathodium new to the country. Riverbeds contain interesting rheophytic forms such as Myriocolea, Myriocoleopsis, Potamolejeunea and Stenorrhipis which have only rarely been collected.
The habitat most urgently needing more study is the canopy of the tropical lowland rain forest. Dr Schuster has recently repeatedly called attention to the supposed poverty in liverworts of the lowland forest: “students are doomed to terrible disappointment, when first exposed to lowland tropical rainforest. They will miss the innumerable genera…of Hepaticae they have become familiar with in temperate and boreal climate (Schuster, 1988: 241). Over a distance of. about 1000 km along the Amazon he could find no more than 50-60 hepatics and a square kilometre yielded no more than 5-10 species on average.
It should be realised, however, that most collecting in the tropical rain forest has been done at ground level, from tree trunks and fallen branches. Using mountaineering techniques my students have recently inventoried the bryophyte flora of the rain forest canopy in the Guianas, an area where Professor Richards did his classical work on tropical rain forest ecology (Richards, 1952, 1954). The results indicate that a single tree may on average harbour 50 species of bryophytes, the majority of them liverworts (Gradstein et al., 1990). In humid forest almost 100 species of liverworts were found on only 28 trees. The sampling in the tree tops yielded many species new to the region, including taxa that had previously been collected only large distances away. Verdoornianthus griffinii (Lejeuneaceae), for instance, was first described from a tree near Manaus (Brazil) in 1974 and has since been found in forest near Iquitos (Peru) and in French Guiana. The three localities are thousands of miles apart. I would expect that careful sampling of forest canopies in intermediate Amazonian lowland areas will yield many more collections of this and other “rare” species. The liverwort flora of the lowland rain forest certainly cannot be considered poor in species and is in urgent need of study in view of the continuing destruction of the forest.
Gradstein, S.R., D. Montfoort, & J.H.C. Cornelissen (1990). Species richness and phytogeography of the bryophyte flora of the Guianas, with special reference to the lowland forest. Trop. Bryol. 2, 117-126.
Richards, P.W. (1952). The Tropical Rain Forest. Cambridge.
Richards, P.W. (1954). Notes on the bryophyte communities of lowland rain forest with special reference to Moraballi creek, British Guiana, Vegetatio5-6, 319-327.
Schuster, R.M. (1988). Ecology, reproductive biology and dispersal of the Hepaticae in the Tropics. J. Hattori Bot. Lab. 64, 237-269.
Schuster, R.M. (1990). Origins of neotropical Leafy Hepaticae. Trop. Bryol. 2, 239-264.
Dr M. Equihua (University of York): Campylopus introflexus on the North York Moors National Park.
Campylopus introflexus was first reported to be spreading in the British Isles by Professor P.W. Richards in 1963. He indicated that the first time this moss had been found in Britain was 1941. He also pointed out that from 1949 onwards it had been reported with increasing frequency from new localities in the British Isles. Professor Richards and Dr A.J.E. Smith in 1975 reported that by then C. introflexus had been found in 440 localities contrasting with the 120 known in 1963. It is now also known in Europe from France, Belgium, Denmark, Germany, Holland, Norway, Spain and Sweden and is thought to have originated from the temperate regions of the southern hemisphere.
The aim of the present research project on this species in the North York Moors is to explore the effects this moss could have on the moorland vegetation of the National Park. Two main issues were considered: first, how is its distribution related to the vegetation and other environmental factors, and second, what are the effects this moss could have on the recovery of Calluna vulgaris after being burnt or cut.
It was found that C. introflexus is most frequent on loamy stagnopodzols and open Calluna moor where the vegetation is around 18cm tall. It is possible to have a potentially active Calluna seed bank in carpets of C. introflexus; however, the activation of this seed bank can be severely limited by the hydrological balance. The presence of C. introflexus together with a limitation in water supply markedly reduces the germination rate of Calluna seeds. There was no evidence that C.introflexus has an allelopathic effect on the germination of Calluna seeds.
There are a number of management considerations. The moss seems to be promoted by the current management practice. Considering its potential effect on delaying recovery of the moor after heather burning, would it not be sensible to consider possible alternative management procedures? Because Calluna management is dependent on a quick recovery of the mature moor, C. introflexus should be considered a potentially important invasive species, with a potential impact on the local economy. What is the potential economic importance of the species?
Dr E.W. Jones (Kirtlington, Oxfordshire): Two hundred years of Oxfordshire bryophytes.
The first bryophyte flora of Oxfordshire, by John Sibthorp, was published in 1794. Subsequent important accounts of the flora appeared in 1886 (Henry Boswell), 1922 (G.C. Druce) and 1952-5 (E.W. Jones). The number of taxa recorded from the county has increased from 108 in 1794 to 362 in 1990 – an increase due chiefly to the increasing discrimination and facility with which species have been recognised, but dependent on the presence of skilled observers.
The records are much less efficient for indicating losses than gains, but suggest that about 20 species may have become extinct; experience suggests that many more species have declined greatly in abundance and comparison of lists made during the period 1940-50 with lists made from 1970 onwards confirm some of these impressions. Drainage, changing agricultural practices (especially the increased use of fertilizers), changing silvicultural practices and a decline in grazing, especially by rabbits, have all contributed. The decline in frequency of many corticolous bryophytes has long been recognised as a widespread phenomenon and attributed to atmospheric pollution. Some terricolous species may also have declined for this reason.
There have, however, also been gains which are due to increasing frequency of the plants, not to increasing facility of recognition. Two or maybe three of these are riverside plants and may have been favoured either by eutrophication of the water or by regulation of water levels. The remaining species, at least 16 in number, for which an increase can be either proved or suspected, are all acidophile; most grow on wood or bark, but a few grow on earth.
Sibthorp’s records suggest that fruit, especially of dioecious species, was produced more freely in the 18th century than it is now. In this, as also in the decline of some corticolous species and the increase of acidophile species, we seem to be seeing the effects of slight but prolonged atmospheric pollution, resulting in the slow but steady acidification of the substrata.
A much more detailed account is being prepared for publication.
Dr J. Bates (Imperial College, Ascot): Studies of Berkshire’s mosses and hepatics.
A progress report was given eight years into a ten-year flora project in Berkshire (v.-c. 22). Major environmental patterns are imposed by geology, rainfall variations and atmospheric pollution and their effects are seen in the distribution patterns of many species. Dot maps plotted using 5 x 5 km recording units showed the distribution of characteristic riparian, calcifuge, calcicole and epiphytic bryophytes. In the latter group a sequence of examples demonstrated putative differential sensitivities to atmospheric pollution and the importance of rainfall variation (Metzgeria temperata only occurs in the highest rainfall district). Some evidence was presented for an increase in the abundance of epiphytes, notably Orthotrichum stramineum and Ulota phyllantha, with falling SO2 levels. Some bryophytes of arable fields, especially Riccia species, are much rarer than formerly while increases have continued, or are becoming app arent, for Campylopus introflexus, Plagiothecium curvifolium, P. latebricola, Dicranum tauricum, D. montanum, Platygyrium repens and Zygodon conoideus. Lastly, the warm dry climate of Berkshire is emphasised by recent discoveries of Cololejeunea minutissima and Scorpiurium circinatum and the persistence of a sizable population of Pallavicinia lyellii at Silwood Park for at least 20 years.
Following the Annual General Meeting (Minutes in Bulletin 58), there was an evening conversazione at which several demonstrations were staged.
After the dry summer of 1990 it was impossible to find suitable sites in Cambridgeshire for an excursion, so members travelled to West Norfolk to visit Ringmere. This is one of the ‘Breckland meres’ and consists of a basin with a fluctuating water level, being full when the water-table of the underlying chalk is high. The water in the mere gradually fell during the summer of 1990 and the mere dried out (for the first time since 1977) shortly before the BBS excursion. Riccia cavernosa proved to be the first species to appear on newly exposed mud, and was locally abundant at higher levels The rare Physcomitrium eurystomum was seen with the commoner P. pyriforme on the dried bed of the mere. The only other bryophyte which grew in quantity at this level was Leptobryum pyriforme.
A reduced party travelled to Grimes Graves for lunch. The grassland was too dry for serious bryologising, but we paid our respects to Rhytidium rugosum. Vegetation stripes reflecting soil patterns of periglacial origin were clearly visible at the fringes of the site.