Botanical Diversity in the Tropical Rain Forest of Guyana The Tropenbos-Guyana Programme operates within the framework of the international programme of the Tropenbos foundation and is executed under the responsability of Utrecht University. The multi-disciplinary Tropenbos-Guyana Programme contributes to conservation and wise utilization of forest resources in Guyana by conducting strategic and applied research and upgrading Guyanese capabilities in the fieldof forest-related sciences. The Tropenbos-Guyana Series publishes results of research projects carried out in the framework of the Tropenbos-Guyana Programme. R.C. Ek Botanical diversity in the tropical rain forest of Guyana Tropenbos-Guyana Series 4 Tropenbos-Guyana Programme - Georgetown, Guyana ISBN: 90-393-1773-9 Keywords: Botanical diversity, species richness and abundance, logging, logging damage. © 1997 Tropenbos-Guyana Programme, Renske C. Ek All rights reserved. No part of this publication, apart from bibliographic data and brief quotations in critical reviews, may be reproduced, re-recorded or published in any form including photography, microfilm, electronic or electromagnetic record, without wrinen permission. Printed by Elinkwijk bv Cover Photos and computer image by Renske Ek. Frontpage and background: Lianas in Greenheart forest, Pibiri, with e.g. Conn,irus perrotteti var. rufi1s, Moutabea guianensis & Lonchocarpus negrensis. Backpagc: Administration of logged Greenheart tree, Pibiri. Computer image: Presentation of exploited one-ha plot, Waraputa. Invitation: Young palm, Mixed rain forest, Saiil. French Guiana. Lay-our Bart Landman. Botanical diversity in the Tropical Rain Forest of Guyana Botanische diversiteit in het tropisch regenwoud van Guyana (Met een samenvatting in her Nederlands) Proefschrift Ter verkrijging van de graad van doctor aan de Universiteit Utrecht, op gezag van de Rector Magnificus, Prof. Dr. H.O. Voorma, ingevolge het besluit van het College van Decanen in het openbaar te verdedigen op donderdag 4 December 1997 des middags re 12.45 uur door Renske Cornelia Ek geboren op 24 December 1960 re Dordrecht Promotoren: Prof. Dr. M.J.A. Werger Hoogleraar in de botanische oecologie en vegetatiekunde, Universiteit Utrecht Prof. Dr. P. Hogeweg Hoogleraar in de theoretische biologie, Universiteit Utrecht TROPENBOS ��'� � � Universiteit Utrecht �A� The investigations reported in this thesis were carried out ar the Mabura Hill fieldwork site of rhe Tropenbos Guyana Programme, l 2E Garnett Street, Campbelville, Georgetown, Guyana and at the Departments of Botanical Ecology and Evolutionary Biology and Theoretical Biology, Utrecht University, P.O. Box 800.84, 3508 TB Utrecht, The Netherlands. e-mail: [email protected] Funding was provided by the Tropenbos foundation and the European Commission. All she wanted was her three wishes granted. Nothing fancy: to be the new Tarzan of the 20th century, to contribute to wise management of tropical forest, to save the world, the usual stuff What she got was something completely different: 'jungle surrounded her. It wasn't nice, interesting, open jungle, such as leopard-skin-clad heroines might swing through, but serious, real jungle, jungle that towered up like solid slabs ofgreenness, thorned and barbed, jungle in which every representative ofthe vegetable kingdom had really rolled up its bark and got down to the strenuous business of outgrowing all competitors. The soil was hardlysoil at all, but dead plants on their way to composthood; water dripped from leafto leaf, insects whined in the humid, spore-laden air, and there could be this terrible breathless silence made by the motors of photosynthesis running flat out. Any yodeling heroine who tried to swing through that lot might just as welltake her chances with a bean-slicer. ' After:--Fttm+-Eric. A discworld novel, by T. Pratchett, 1990 Contents Chapter 1 General introduction 9 Chapter 2 The flora of the Mabura Hill area, Guyana 27 R. C. Ek erH. Fer Stage. Accepted fin publication in Botanishe }tzhrhiicherfzir Sysrenuitik, Pfla nzmgeschi,hte 11ml Pjlanzengeographie. Chapter 3 Vertical distribution and associations of vascular epiphytes in 65 four different forest types in the Guianas R. C. Ek, H. Ter Steege & ]. C. Biesmeijer. Chapter 4 Botanical diversity of Greenheart dominated mixed rain forest 91 near Mabura Hill, Guyana R. C. Ek erP. Vim der Hout Chapter 5 The effects of logging on the liana vegetation in Greenheart 143 dominated tropical rain forest in Guyana R. C. Ek, C.A. Van der Kooij & ].A. C. Vim Dam. Chapter 6 Patterns of species diversity in the neotropical lowland 171 rain forest of Guyana R.C. Ek Chapter 7 Conclusions and recommendations for forest management 193 Chapter 8 Summary 201 Samenvatting 207 References 221 Acknowledgements 233 Curriculum Vitae 237 C H A P T E R General introduction '.A proper understanding of the most relevant aspects of biodiversity in tropical rain forests, as well as the ability to predict the impacts of human intervention on biodiversity, are imperative to conservation efforts of the biological richness of these forests' (Tropenbos 1996) This statement is found in the policy paper concerning priorities in biodiversity research by the Durch Tropenbos Foundation, and encompasses the core of the srudy on 'Botanical Diversity in the tropical rain forest of Guyana', presented in this thesis. It introduces a large part of the terminologies used in relation with biodiversity in tropical rain forests: Tropical rain forests: Tropical rain forests are the evergreen forests of the humid lowlands and hills occurring roughly between the tropics of Cancer and Capricorn, in areas where the annual amount of rain exceeds 1500 - 2000 mm per year (Huston 1994). These forestscover only 7 % of the earth's surface and are estimated to contain more than half of all the species of living organisms on earth (Wilson 1992). Tropical rain forests were initially regarded as stable and unchanging environments where the tropical plant community was at equilibrium. Lately, however, they are considered to be much more dynamic. They are subject to a variety of disturbances and environmental fluctuations, both with small-scale, short-term effects and with large-scale, long-term effects (Huston 1994). 9 CHAPTE R Impacts of human intervention: At this moment, considerable parts of the world's tropical forests are altered by commercial logging activities. Along with the cutting of tropical rain forests for agricultural lands, these logging activities are considered to be the main cause of the rapid reduction of tropical forests (Myers 1988, 1989; Werger 1992; Bruenig 1996).With the disappearance of these forests, animal and plant populations may disappear, in extreme cases leading to extinction. The attention that this issue received resulted in the introduction of a new term: biodiversity. Biodiversity: The term 'biodiversity' is used in several disciplines and many different definitions exist. In general, these definitions can be grouped under three headings: biodiversity as a concept, as a measurable entity and as a social or political construct (Gaston 1996). As a concept, biodiversity encompasses the total variety within the living world, ranging from variation at the molecular and genetic level, through variation at the species level, to variation in functionally related groups of species and their habitats at the landscape level. As a measurable entity, the number of species is the most widely applied measure, implicating that variation at the species level and at the landscape level are the most widely evaluated levels of biodiversity. This explains why, in many discussions concerning biodiversity, species richness is often considered a synonym of biodiversity. Species diversity is described by two parameters: species richness, which is number of species per unit area and species abundance, which is number of individuals of a species per unit area. Lastly, as a social or political construct, the term biodiversity focusses on the effects of changes in land use, associated with changes in species numbers, and in particular on the impacts that these changes in biodiversity will have on the quality of the human environment, both physically and spiritually. The global social and political concern over the decrease in biodiversity, degradation of forests and social inequality initiated the Convention on Biological Diversity of the United Nations Conference on Environment and Development (UNCED) held in Rio de Janeiro in 1992 Qohnson 1993). That conference resulted in a treaty in which a series of recommendations was formulated to stop the destruction of species, habitats, and ecosystems, called 'Agenda 21 '. The overall objectives of the treaty were 'the conservation of biological diversity, the sustainable use of its components and the fairand equitable sharing of the benefits arising out of the use of genetic resources' (EEI 1997). During the preparation phase of the treaty, and afterwards, many new policy initiatives concerning tropical rain forest biodiversity were generated. In relation to forest management, e.g., the International Tropical Timber Organization (ITTO) and the Centre for International Forestry Research (CIFOR) have initiated activities to incorporate the conservation of biodiversity as an additional objective in the management of timber production forest. Biological richness: Biological richness is often used as a synonym for biodiversity. In general, biological richness in natural habitats is high in tropical lowland