ACTA PHYTOGEOGRAPHICA SUECICA 68 EDIDIT SVENSKA V AXTGEOGRAFISKA SALLSKAPET Studies • m Plant Ecology dedicated to Hugo Sjors Edited by Erik Sjiigren Almqvist Wiksell International, Stockholm & UPPSALA 1980 Suggested citation: Studies in plant ecology. Dedicated to Hugo Sjors. Erik Sj ogren. Ed. Acta Phytogeogr. Suec. 68. Uppsala. ISBN 91-7210-068-0 (paperback) ISBN 91-7210-468-6 (cloth) ISSN 0084-5914 © The respective authors 1980 Svenska Vaxtgeografiska Sallskapet Box 559, S-75 1 22 Uppsala Editor: Erik Sjogren Technical editor: Gunnel Sjors Phototypesetting by Textgruppen i Uppsala AB Printed in Sweden 1980 by Borgstroms Tryckeri AB, Motala Preface The Swedish Phytogeographical Society is publishing the present volume in honour of Professor Hugo Sjors, Head of the Institute of Ecological Botany from 1962 to 1980 and holder of the chair of Professor of Ecological Botany during the same period. Hugo Sjors has been and still is the chairman of the Swedish Phytogeographical Society. This combination of activities has b;;en particularly fruitful not only for the Society but also for the Institute and its students. Manuscripts submitted to Acta Phytogeographica Suecica are prepared fo r publication largely as a result of efforts made by members of the Institute. In the world of science Hugo Sjors is fo remost known as an ecologist of mires. His knowledge and results in this respect are not restricted to Scandinavian mires but cover such vegetation within the entire northern hemisphere. Research on mire vegetation at the Institute was earlier firmly anchored in the work of Rutger Sernander and G.E. Du Rietz but for the last two decades it has been led by Hugo Sj ors, with a rich variety of new methods and approaches. During the second half of the 20th century research in ecological botany has been conducted on an increasingly wide base. Research and education at the Institute of Ecological botany has been adapted to this international trend largely as a result of efforts made by Hugo Sjors. Thus, he has initiated and encouraged a large number of research projects within the sector dealing with the reaction of different types of vegetation to cultural influence, and environmental management in connection with this kind of influence. Papers published in this volume are by pupils of Hugo Sjors and by botanists who at one time or another have conducted research at the Institute of Ecological Botany. It has not been possible to collect these contributions under a common title. Instead, they may be considered to illustrate the multi-facetted research programme at the Institute. Nevertheless, it may be observed that many of the contributions contain aspects associated with changes in vegetation. They emphasize to some extent how ecological botany today has a considerably greater interest in vegetation dynamics than earlier, when a large sector concerned plant sociological limitations of plant communities that often came to be regarded as fairly static. The work involved in preparing this volume has been done in a relatively short space of time thanks to the intensive and willing efforts of many of the staffof the Institute of Ecological Botany : Miirta Ekdahl and Stina W rern have typed the manuscripts and all the tables; Agneta Nordgren drew most of the diagrams and maps; Folke Hellstrom did all the photographic work as well as the reductions of diagrams and other illustrations; Nigel Rollison helped the editor with language revision and some translations; Kuno Thomas son checked the lists of references submitted with each contribution; Gunnel Sj ors edited and prepared the material from a technical point of view; Ake Sjodin and Salme Sed man kindly helped with library work; Henrik Mosegaard drew the cover illustration of the bound edition. The Society wishes to warmly thank all people concerned. Uppsala in December, 1980 The Swedish Phytogeographical Society Erik Sjiigren Contents Two Mexican conifers - Cupressus lusitanica and Pinus patula - in a juvenile development observation trial in Tanzania. By Tore Arnborg 7 Vegetation changes after fe rtilization on drained peatlands in Central Sweden. By Ingvar Backeus 17 The history of woodland in Fnjoskadalur. By Agust H. Bja rnason 31 Strandverschiebung und Strandvegetation auf Havero Prastang. Von Wolfgang Cramer 43 The Sibirian fern Athyrium crenatum (Somf.) Rupr. found in Sweden at K vikkjokk, SW Lule Lappmark. By Sten Dahlskog 51 The downward migration of plants on a rising Bothnian sea-shore. By Lars Ericson 61 Ragvaldsmossen. A pollen-analytical study of the Postglacial forest his­ tory at the "limes norrlandicus", South-Central Sweden. By Magnus Fries 73 A comparison between the alpine plant communities of Alaska and Scan- dinavia. By Olav Gj rerevoll 83 Attached algal vegetation in some streams from the Narssaq area, South Greenland. By Catarina Johansson 89 Three new subspecies of the apomictic Ranunculus auricomus L. (s. str.) from the Flora Upsaliensis area in Uppland, Sweden. By Erik Julin & John Axe/ Nannfeldt 97 Fine-root dynamics in a Scots pine stand with and without near-optimum nutrient and water regimes. By Hans Persson 101 Vegetationsentwicklung in einem Weidegebiet auf Siid-Oland, Schweden. Von Lars Rodenborg 111 Plant cover regeneration in a mechanically disturbed limestone heath on Oland, Sweden. By Ej vind Rosen 123 Observations on two bushfires in the Western Kalahari, Botswana. By Christina Skarpe 131 Continued investigations of epiphytic lichen flora around K varntorp in Narke. By Erik Skye 141 Dynamics and production of semi-natural grassland vegetation in Fenno- scandia in relation to grazing management. By Eliel Steen 153 Plankton of Lake Kariba re-examined. By Kuno Thomasson 157 Rhodomonas minuta and Rhodomonas lens (Cryptophyceae). Aspects on fo rm-variation and ecology in Lakes Malaren and Vattern, Central Sweden. By Eva Willen, Mats Oke & Frank Gonzcilez 163 Phytoplankton from lakes and ponds on Vestspitsbergen. By Torbjiirn Willen 173 Acta Phytogeogr. Suec. 68 Two Mexican conifers Cupressus lusitanica and Pinus patula 1n a juvenile development observation trial in Tanzania Tore Arnborg Aim of the experiment traduced to Tanzania in about 1905 and proved out­ The experiment was planned as an observation trial standingly successful at high altitudes on mountain to get some information about individual differences sites with deep volcanic soils and annual rainfalls ex­ in plant populations of two exotic conifers, Cupressus ceeding 800 mm. It also did well on poorer soil and lusitanica and Pinus patula, during the ftrst year after since 1930 it has been planted for timber production planting. The experiment started with plantation of in East Africa. seedlings on 22 April, 1977 and ended on 15 June, 1978 but some specific notes were taken until Pinus patula Schiede and Deppe. This pine has a fair­ December of the same year. The main fe atures ly narrow distribution range within Mexico, around observed and measured were the development of the Lat. 20°N and only at high altitude, the highest shoot (the crown with top and branches) and the recorded being about 3000 m above m.s.l. There is root-system. no specific provenance in the home country that is The overall intention with the trial was to compare known to be remarkably better than others. Some a few planting methods in common use or easy to characters, however, show marked clinal variation. apply, and to study the variation in development The monography by \Vormald(1 975) gives all kinds within each species and between the two. In spite of of information about this pine, in its home country the limited number of seedlings, only 180 of each and as introduced fo r man-made fo rests in tropical species, some fm dings give distinct proof of and subtropical regions in Africa and Asia. differences which obviously are of interest to The species belongs to subsection Oocarpae, like silvicultural management practice. It must, however, P. oocarpa and P. radiata. The Spanish name is be stressed that this is an observation trial and that "pino patula" or "pino shino", and in English it is the purpose of this paper is to provide some ideas called the "Mexican weeping pine" or "patula pine", about ways and means to plan fo r fu rther, more the latter being the most accepted name and the only sophisticated, experiments. In addition to the main used here. trial, some notes and photographs from other ex­ The patula pine was introduced to South Africa in periments have been included, even one from Kenya. the earliest years of this century and was very soon used fo r commercial plantations. In East Africa it was only occasionally planted as a single ornamental The species tree and not until around 1930 was it given attention Cupressus lusitanica Miller. This cypress is widely as a very fast growing exotic. Then the patula pine distributed in Mexico, from Lat. 26°N southwards. It was planted in stands, and so was P. radiata, which was introduced to Portugal around the year 1600 and on some sites was even more rapid growing. (The when first named and described, in 1778, it was latter, however, was attacked by Dothistroma blight called "lusitanica" which means "from Portugal". and in 1956 banned for industrial plantations.) Later it was introduced to India, where it was often In Tanzania, as well as in Kenya and Uganda, the called "the cedar of Goa", and to Africa. The most patula pine grows on a wide range of soils. It does common name now is "Mexican cypress". For very well on young volcanic ash but also on mature, further information, reference may be made to Wolf fairly infertile laterite. The rainfall is 900 mm or Wagener (1948) and Dyson & Raunio (1977). more. The pine has a strong root-system and general­ & The Mexican cypress was, as far as is known, in- ly a pronounced tap root.