The Winter and Annual General MeetingsSource: Journal of Animal Ecology, Vol. 26, No. 2 (Nov., 1957), pp. 513-515Published by: British Ecological SocietyStable URL: http://www.jstor.org/stable/1776 .

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513

BRITISH ECOLOGICAL SOCIETY

THE WINTER AND ANNUAL GENERAL MEETINGS

7-8 JANUARY 1957

By kind permission of the Zoological Society of London, the Winter Meeting, 1957, was held in their Meeting Room in Regent's Park. A very large number of members was present, the attendance reaching well over 150 on the second day.

Three papers were delivered during the afternoon of 7 January beginning at 2.15 p.m., with Dr. J. Warren Wilson's account of 'Microclimatic control of the distribution of species in late snow areas'. Illustrating his points with coloured slides, Dr. Wilson showed that the winter snow of arctic lands melts especially late each year in certain places; primarily in small hollows in the ground where deep drifts have formed. In these 'late snow areas' special vegetation types occur. At Jan Mayen Island they are arranged in concentric zones: around the edge where snow-lie is brief the vegetation is poor; with later snow'lie the vegetation becomes increasingly rich up to an 'optimum'; and beyond this point towards the centre of the area very late snow-lie brings poorer growth or even bare ground. The enrichment of growth is a result of the reduced wind speeds in these hollows; the central impoverishment arises from restriction of the growing season by excessively late-lying snow.

Local conditions of shelter from wind within late snow areas interact with altitude, so that similar vegetation may occur in the sheltered parts of a late snow area on high ground, and in a more exposed position at low altitude.

Comparing sites at any particular level in the lower ranges of altitude, late snow-lie is associated with the occurrence of low-arctic species since it results from sheltered conditions; but at higher levels where it results more from the lowering of mean temperature, late snow-lie is associated rather with the occurrence of high-arctic species.

Plant growth at Jan Mayen is also limited by nitrogen deficiency. But this effect reinforces the relationships described above, for soil nitrogen levels show the same changes as vegetational richness in relation to duration of snow-lie. This is because the soil micro- organisms which fix nitrogen depend for their activity on the organic substrates provided by dead plants. Counts show that micro-organism numbers are correlated with soil nitrogen content and vegetational richness; and so with shelter from wind. Thus wind speed - determined by microtopography - has ultimate control over the distribution of vegetation types in late snow areas and, indeed, generally at Jan Mayen.

It can be shown that wind speeds are reduced in the shelter of late snow areas, and that plants grow more rapidly here than in exposed positions, given the same soil. This control by wind of plant growth is probably exerted through a cooling effect. Wind disturbs the air, so that the layers near the ground (where arctic plants grow) which become warmed by the insolated soil are cooled by admixture of colder air from higher layers. Also, wind has a direct cooling effect on insolated leaves. As a result of these two effects, leaves exposed to wind may be several degrees cooler than sheltered leaves; and differences of even a fraction of a degree are important to plants in the Arctic, for they are especially sensitive to temperature conditions.

Attention was drawn in the discussion following this paper to the presence of disseminules of various species in the debris on the snow, to the occurrence of small areas exceptionally rich in soil animals, and to the possibility of explaining some of the floristic differences between Jan Mayen and west Greenland in terms of the influence on the latter of a more continental type of climate. Professor G. C. Varley, Mr. A. Macfadyen and Dr. A. S. Watt took part.

In the next talk, on the use of cobalt thiocyanate papers for the estimation of humidity, Mr. M. E. Solomon referred to some of the difficulties in measuring environmental air humidity, and discussed the suitability of the cobalt paper method. A piece of impregnated paper is exposed for an hour or two to the humidity which is to be measured, then immersed

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514 British Ecological Society in oil (liquid paraffin), mounted on white opal glass, and matched against colour standards. The colours are blue at low humidities, pink at high, with violet shades between. Cobalt papers can be used in small spaces, such as burrows or crevices, and are especially useful where there is layering or a gradient of humidity, as in the vicinity of a stem or leaf, or near the soil, or in a humidity-choice or gradient apparatus. They can be inserted into sites which would be inaccessible to most methods. Disadvantages are the rather long exposure period and the fairly low level of accuracy.

Following methods he had described in 1945, a number of ecologists had used either cobalt chloride or cobalt thiocyanate papers in field investigations, and Mr. Solomon referred to some examples.

Ready-made cobalt thiocyanate paper and coloured glass standards were now available from the manufacturers, which made this method much more convenient than before. The speaker presented tables showing the amounts of error to which the method is liable. Estimates could be kept within 5 per cent of the tone value at the higher humidity levels, and within 10 per cent at most of the lower humidities.

Questions about details of the method, its employment and its accuracy as compared with other methods were asked by Professor G. C. Varley, Dr. C. H.- Gimingham, Dr. A. J. Rutter, Mr. A. Macfadyen and Dr. E. W. Jones.

Concluding the session, Mr. T. 0. Pritchard spoke on 'A contribution to the genecology of weeds; work in progress on Euphorbia cyparissias'.

Mr. Pritchard pointed out that establishment and spread of a weed species is largely dependent on efficient methods of reproduction and is often favoured by self-pollination, apomixis and vegetative reproduction. With reference to the evolutionary origin of species and races of a 'weedy' nature, he suggested that selection of already aggressive biotypes may play a part, while favourable characters may also be brought together by introgression from closely related species. Hybridization coupled with polyploidy has played a major role in the origin of some species which have become weeds.

Euphorbia cyparissias is a native of Europe introduced into North America where it has become a serious weed of pastures, especially in eastern Canada. Two cytological forms have been discovered there - a male-sterile diploid (2n = 20) which is an escaped garden orna- mental with no seed production, and a fertile tetraploid (2n = 40). Both forms can reproduce vegetatively by means of rhizomes. The tetraploid may be distinguished by the significantly larger area of its epidermal cells. A fertile diploid is unknown in Canada. An examination of British material indicated a similar situation here, except that the garden sterile diploid has not escaped and, apparently, all the wild plants in Britain are tetraploid and fertile. No fertile diploid form is known in Britain. Pollen grains were also measured and their contents examined. By this method, the hitherto unknown fertile diploid was located in France. It has, however, a very restricted range compared with the tetraploid, which extends east to Russia, north to Scandinavia and Britain.

Preliminary observations have indicated obvious differences in the field behaviour of the tetraploid and fertile diploid. The tetraploid is very aggressive and it grows successfully in tall-grass communities; it reproduces vegetatively by means of rhizomes and produces a large number of seeds as well; it is shade-tolerant. The fertile diploid which was examined at Fontainebleau does not reproduce vegetatively or only very slightly; it cannot compete with grasses; it is much less shade-tolerant than the tetraploid.

The cytology and breeding behaviour of the three forms of E. cyparissias and the related E. esula were discussed. Meiotic division is regular in the sterile and fertile diploid and the tetraploid E. cyparissias. The chromosome count of 2n = 60 obtained for E. esula and the fact that this species crosses freely with the tetraploid E. cyparissias has presented an interesting complex for analysis.

It was suggested in conclusion that the superior reproductive capacity of the tetraploid, with its seed as well as vegetative methods of reproduction, has aided its spread at the expense of the, presumably, parental diploid. Furthermore, polyploidy may also have been accompanied by physiological changes in the species enabling the tetraploid to tolerate a greater range of ecological conditions.

The position of the sterile diploid is still obscure; it is of less interest in this context, being an ornamental probably originating through selection by man.

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British Ecological Society 515

Professor G. C. Varley, Professor D. H. Valentine and Dr. E. W. Jones referred to the capacity for vegetative reproduction possessed by the tetraploid type and its persistence and aggressiveness. Mr. Pritchard suggested that while aggressive in some of its European stations, more extensive habitats were open to it in Canada where it had become a pernicious weed. Others taking part in the discussion were Dr. G. C. Evans, Dr. J. F. Hope-Simpson and Mr. H. C. Gilson.

The meeting was concluded with tea at 4.30 p.m. A soiree was held in the Fellows' Restaurant of the Zoological Society during the evening, beginning with an informal dinner at 7.30 p.m. This was attended by about 60 members and was greatly enjoyed by all present, who spent the remainder of the evening in profitable conversation.

THE ANNUAL GENERAL MEETING The 38th Annual General Meeting of the Society began at 10 a.m. on the following

morning, 8 January. The following are the (unconfirmed) Minutes of this meeting. MINUTES OF 38TH ANNUAL GENERAL MEETING

The President, Professor G. C. Varley, took the chair in the Meeting Room of the Zoological Society of London, Regent's Park, at 10 a.m.

(1) The Minutes of the 37th Annual General Meeting, having appeared in J. Ecol., 44, 2, 640, and being due to appear in J. Anim. Ecol., 24, 2, were taken as read and were accepted.

(2) The Report of the Honorary Secretaries for the year 1956 was read by Dr. C. H. Gimingham, as follows:

Report of the Honorary Secretaries The 37th Annual General Meeting of the Society was held in the Department of

Botany, Oxford University, at 10 a.m. on 5 January 1956, following a soiree on the previous evening when exhibits were on view and coloured slides of the vegetation of New Zealand and Tasmania were shown by Professor Gordon.

An account of the business meeting, at which the President, Professor Varley, was in the chair, has appeared in J. Ecol., 44, 2, 640, and wil appear in J. Anim. Ecot., 24, 2.

The remainder of the day was devoted to a series of papers concerned with ecological- genetical problems in plant and animal populations, introduced by Dr. W. B. Turrill, who was followed by Professor D. H. Valentine, Professor C. D. Darlington, Dr. E. B. Ford and Captain C. R. P. Diver. The discussions following these papers indicated that this was a subject commanding widespread interest among members. Papers by Mr. I. H. Rorison, Mr. C. H. Fernando and Mr. J. K. Bates were given on the following morning. The Society is grateful to Professor Darlington and members of his Department for their hospitality. Visitors to Oxford were denied the pleasure of sight-seeing by dense fog but were perhaps the better able to appreciate the academic atmosphere within the precincts of Queen's College.

On 27 and 28 March a two-day symposium on the subject of 'Production' was held in the rooms of the Nature Conservancy, London. This meeting was attended by a large number of members, who heard and discussed papers by Dr. J. D. Ovington, Mr. J. A. Gibb, Dr. F. H. Whitehead, Professor W. H. Pearsall and Dr. E. Gorham, Mr. A. Macfadyen, Mr. J. Corlett, Dr. J. H. Mundie, Mr. E. D. Le Cren, Mr. C. W. R. Spedding, Dr. R. E. Hughes and Mr. A. D. Bradshaw. Estimations of 'stock', 'production' and 'crop' in a variety of plant and animal populations ranging from forest stands to freshwater and sea fisheries were presented. This resulted in a fruitful survey which, we understand, has provided members with fertile ideas for applicatibn in related fields. The Society's thanks are extended to the Director-General of the Nature Conservancy for accommodating this meeting.

The Summer Meeting was held in the Lake District, with headquarters at The Ferry House, Far Sawrey, from 13-17 July. Excursions were made to Esthwaite North Fen, habitats in Windermere, Coniston Old Man, the Sunbiggin Tarn area, Roudsea and Witherslack woods and the Merlewood Research Station of the Nature Conservancy. With one notable exception the weather was favourable and a variety of interesting habitats was

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