The Community Ecology, Dynamics and Productivity of Tropical Grasslands in the Andes
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The Pdramo Vegetation of Ecuador: the Community Ecology, Dynamics and Productivity of Tropical Grasslands in the Andes. by Paul Michael Ramsay A thesis submitted for the degree of Philosophiae Doctor of the University of Wales. December 1992 School of Biological Sciences, University of Wales, Bangor, Gwynedd, LL57 2UW. i Dedicated to the memory of Jack Higgins, my grandfather. "... a naturalist's life would be a happy one if he had only to observe and never to write." Charles Darwin ii Table of Contents Preface AcknoWledgements vii Summary ix Resumen Chapter 1. Introduction to the Ecuadorian P6ramos 1 Ecuador 2 The Pâramos of the Andes 2 Geology and Edaphology of the Paramos 6 Climate 8 Flora 11 Fauna 14 The Influence of Man 14 Chapter 2. The Community Ecology of the Ecuadorian P6ramos 17 Introduction 18 Methods 20 Results 36 The Zonal Vegetation of the Ecuadorian Paramos 51 Discussion 64 Chapter 3. Plant Form in the Ecuadorian Paramos 77 Section I. A Growth Form Classification for the Ecuadorian Paramos 78 Section II. The Growth Form Composition of the Ecuadorian Pâramos Introduction 94 Methods 95 Results 97 Discussion 107 Section III. Temperature Characteristics of Major Growth Forms in the Ecuadorian PSramos Introductio n 112 Methods 113 Results 118 Discussion 123 III Table of Contents iv Chapter 4. Aspects of Plant Community Dynamics in the Ecuadorian Pgramos 131 Introduction 132 Methods 133 Results 140 Discussion 158 Chapter 5. An Assessment of Net Aboveground Primary Productivity in the Andean Grasslands of Central Ecuador 165 Introduction 166 Methods 169 Results 177 Discussion 189 Chapter 6. A Greenhouse Study of Competition Between Three Andean Grasses at Two Regimes of Water Availability 196 Introduction 197 Materials and Methods 198 Results 201 Discussion 212 Chapter 7. Overall Discussion 216 References 227 Photographic Plates 244 Appendix 1. Vascular Plant Species 255 Appendix 2. Example Calculation of Chi Square Expectation for Transition Probabilities 272 Preface t the beginning of the nineteenth century, Alexander von Humboldt and Aime ABonpland travelled amongst the Ecuadorian Andes. The 'Avenue of the Volca- noes', as Humboldt described this section of the Andes, proved an excellent outdoor laboratory, generating ideas which have become the foundation for many aspects of plant ecology today. Their plant collection still remains the basis for plant taxonomy in the region (evidenced by the number of species in this work with the authority of "H.B.K.", the abbreviated names of Humboldt, Bonpland and Kuntze). Richard Spruce was collecting in the high pdramo grasslands above the Ecuadorian forests around the time of Humboldt's death. Soon afterwards, the golden age of plant col- lecting in South America had begun to decline. Since then, a number of trips have been made to the Ecuadorian paramos by col- lectors, but their work has tended to be small-scale (by comparison with the efforts of Humboldt et al.) and concentrated in the more accessible regions. More recently, scientific interest in the paramos has increased. A project to produce a Flora of Ecua- dor is now in progress, based on international research coordinated in Scandinavia. Taxonomically, therefore, the paramo flora is relatively well-known, though in the absence of a complete guide to the flora, obtaining identifications still requires lengthy research in herbaria. However, other aspects of paramo vegetation have been neglected. Lately, the Centro de Investigaciones EcolOgicas de los Andes Tropi- cales (CIELAT) based at the Universidad de los Andes in Mêrida has concentrated on Venezuelan paramo vegetation, with particular emphasis on environmental condi- tions, productivity, population and reproductive ecology. A co-operative research programme involving Colombia and the Netherlands (Investigaciones de Ecosiste- mas Tropandinos —ECOANDES) has produced major contributions to our knowl- edge of the community composition and biogeography of the Colombian paramos. Despite this intense effort elsewhere in the Northern Andes, the paramos of Ecua- dor have not been subjected to the same degree of detailed study as those in neigh- bouring countries. The country is well-known as a centre of biological diversity and this has perhaps led research programmes away from the highlands to the species- rich forests. The miserable climate at high altitudes cannot have helped the case for the paramo in this respect (locals have coined the term parameando to mean "It's raining"). During the course of three student expeditions to Ecuador I had the opportunity to make extensive observations in the high altitude grasslands of the Andes. The work was of necessity broad-based: so little is known about paramo vegetation that it was difficult to plan the research programme with any confidence. Access to remote areas of paramo was difficult to assess from the reference sources available. A low budget, coupled with these access difficulties and the terrible weather conditions, limited the technical equipment it was possible to use (warm, rainproof clothing, camping equipment, food and plant presses constituted a heavy pack without addi- tional scientific equipment). Preface vi However, a number of projects were carried out and will hopefully act as a catalyst in encouraging further research in this unique ecosystem. The paramo is an ideal place to study plant responses to environmental gradients and a set of interesting cli- matic conditions with pronounced daily rather than seasonal cycles. It is also an envi- ronment where, in the future, biological monitoring of the greenhouse effect might be possible via the response of plant communities to the changing climate. Paul M. Ramsay, December 1992. Acknowled ements First and foremost, I would like to thank Mr. Ralph Oxley for proposing me for a studentship at the University of Wales, Bangor, and for his supervision. The pro- gramme owed much to his advice and encouragement, not only academically but also in the planning and execution of the three expeditions which formed the basis for this thesis. I was fortunate to have him for company (albeit briefly) on one of these expeditions. My involvement in the field of Ecuadorian botany was the result of a chance liai- son with Adrian Barnett — at the time, a fellow student at the University of Wales, Bangor. His work on the small mammal populations of the Ecuadorian Andes led me to consider a botanical excursion to Ecuador. Adrian's help in the crucial, early stages of my exposure to expedition organisation and logistics was invaluable. The U.C.N.W. El "CAJAS" Expedition to Ecuador in 1985 was the result. The work was supported by a College Studentship maintenance grant from the University of Wales, Bangor. The fieldwork for the research presented in this thesis was funded by many organisations, from trust funds to academic institutions, from large multinationals to local commercial companies. The donations ranged from 125 to /1,124. I would like to express my gratitude to the following organisations for their support: • Overseas Development Administration • Royal Botanic Gardens, Kew • University of Wales, Bangor • Godman Exploration Trust • School of Plant Biology, Bangor • Scarfe Charitable Trust • Royal Geographical Society • ICI Fertilisers • Augustine Courtauld Trust • Minster Agriculture Ltd. • Rio Tinto Zinc • Grafton Ltd. • Busk Charitable Trust • Thomas Kean Advertising Ltd. • British Ecological Society • Anglesey Aluminium • Whitley Animal Protection Trust • Penrhyn Industrial Estate • HRH The Duke of Edinburgh • Pillsbury UK Ltd. • The Rev. Streeter Trust VII Acknowledgements viii I must also thank all the expedition members that accompanied me on my trips to the Andes. Particular mention must go to Pete Merrow-Smith for his company, dedi- cation and hard-work on the two-man Paramos '87 expedition on which the core of the data for this thesis was collected. In addition, he was a member of the earlier Cajas expedition of 1985 which also included James Bury, Trevor Iszatt, Ralph Oxley and Paul Thomas. The Sangay '89 team consisted of Lynn Evans, Ian Whitehead, Joe Creed, Sarah Buckland, Nicky Legg and Michael Bassett. During my sixteen months in Ecuador, Peter Jorgensen, Patricio Mena, Jaime Jara- millo, Henrik Pedersen, Ximena Rodriguez, Katia Romoleroux, Carmen Ulloa and all the others at the botany department of the Pontificia Universidad Cat(Mica, Quito, deserve a very special mention for the help and encouragement they gave — and their friendship. Others in Quito merit special thanks: Fausto Sarmiento and Miguel Moreno at the Museo Ecuatoriano de Ciencias Naturales for their co-operation; Dr. Figueroa, Ministerio de Agricultura y Ganaderia, for the issue of permits for our fieldwork and exportation of specimens; and Yolanda Kakabadse, Director of Funda- ciOn Natura for friendly advice. I must also thank Enrique Aguilar in Quito for his re- peated help and advice in obtaining permits and information. The Instituto Geografico Militar were very co-operative and provided maps and aerial photo- graphs. At the Parque Nacional Sangay headquarters in Riobamba, I received help from Lcdo. Miguel Mejia, head of the park, and many others including Vicente Alvarez and the guardeparques Cesar Urefia, Miguel Jaya, Bernado, Mario, Bolivar Coronel and Jose Vallejo. These latter two also placed their cattle pastures at my disposal for experimental plots, an offer which I gratefully accepted. My thanks also go to Boli- var's family and all the generous people at the village of Daldal.