Taxonomic Identification of Amazonian Tree Crowns
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TAXONOMIC IDENTIFICATION OF AMAZONIAN TREE CROWNS FROM AERIAL PHOTOGRAPHY AND IMPLICATIONS FOR UNDERSTANDING LANDSCAPE SCALE DISTRIBUTIONS OF KEY TAXA Submitted by CARLOS EDUARDO GONZALEZ OROZCO A THESIS SUBMITTED TO THE UNIVERSITY OF LONDON FOR THE DEGREE OF DOCTOR OF PHILOSOPHY KING’S COLLEGE LONDON DEPARTMENT OF GEOGRAPHY 2008 1 ABSTRACT The aim of the thesis is to use high-resolution aerial photographic imagery for the identification of tree crowns. The study site is Tiputini Biodiversity Station (TBS) located in the Amazon of eastern Ecuador. Visual/manual aerial identification keys have been produced, tested with 100 volunteers and validated. The keys are useful to produce distribution maps across the landscape. A total of 2333 crowns corresponding to ten taxa were mapped. The mapped families and genus are Arecaceae (Iriartea and Astrocaryum), Fabaceae (Inga and Parkia), Moraceae (Cecropia and Pourouma), Bombacaceae (Ceiba), Meliaceae (Guarea), Myristicaceae (Otoba) and Sapotaceae (Pouteria). Eight terrain variables were used as environmental controls in a distribution analysis. These variables are elevation, mean curvature, slope, slope position, eastness, northness, solar radiation and TopModel wetness index. The distribution maps for taxa at TBS are used as indicators for better understanding patterns of tree distribution and diversity as well as the environmental controls upon them. The validation of the key with many and varied users presents identification accuracy over 50% for five of ten taxa. Crown with an intermediate rough texture are less reliable in term of identification accuracy (ID) than crown properties with regular or well-defined surfaces. When spatial patterns are examined, clumped spatial distribution patterns are reported for the majority of the mapped taxa. Two distribution forms are suggested: linear and non-linear. The predominant forms are lines, pits (clusters) and S-shaped distribution patterns. 2 There are interesting correlations between terrain characteristics and tree composition. Analysis of terrain and taxa distribution shows that the more statistically significant terrain variables controlling taxa distributions are elevation, slope, slope position and curvature. When diversity patterns are examined, the northeast part of TBS appears to have the highest diversity of taxa and a local hotspot map is proposed. The aerial identification technique provides encouraging results as a useful methodological tool for understanding biotic/abiotic environmental processes in Amazonian forests. 3 RESUMEN El propósito de la tésis es usar fotografía aérea de alta resolución para la identificación de copas de árboles. El sitio de estudio es la Estación de Biodiversidad Tiputini (TBS) localizada en la parte este del Amazonas Ecuatoriano. Se produjeron claves de identificación aérea de tipo visual y manual. Estas claves fueron probadas y validadas por 100 voluntarios. Las claves resultaron útiles para producir mapas de distribución de árboles através del paisaje. Un total de 2333 copas que correponden a 10 taxa fueron mapeadas. Las familias y generos mapeados fueron: Arecaceae (Iriartea and Astrocaryum), Fabaceae (Inga and Parkia), Moraceae (Cecropia and Pourouma), Bombacaceae (Ceiba), Meliaceae (Guarea), Myristicaceae (Otoba) and Sapotaceae (Pouteria). Ocho variables de terreno fueron usadas como reguladores medioambientales en un análisis de distribución. Las variables de terreno son altitud, curvatura media, inlcinación, posición de la inclinación, aspecto del terreno, radiación solar y humedad del suelo. Los mapas de distribución en TBS son usados como base para un mejor entendimiento de los patrones de distribución y diversidad de los árboles y asi como también entender cuales son las variables de terreno que más influyen en su distribución. Numerosos y variados usuarios de la clave obtuvieron una exactitud de identificación promedio mayor de 50 % en cinco de los diez taxa estudiados. Las copas de los árboles que tienen una textura de tipo rugosa intermedia son menos confiables a la hora de medir la precisión de identificación pero las copas con 4 una superficie regular o bien definida son de mayor confiabilidad de identificación. Con respecto a los patrones de distribución espacial, la mayoria de los taxa mapeados presentaron una distribución espacial agrupada. Dos formas de distribución son propuestas: lineares y no lineares. Dentro de estas, los tipos predominantes de distribución son líneas cortas, grupos de líneas y curvas en forma de S. Se encontraron correlaciones interesantes entre la composición de árboles y las características del terreno. Los análisis estadísticos muestran que las variables de terreno que más influeyen la distribución de los taxa en el pasisaje son altitud, inclinación, posición de la inclinación y curvatura. Examinando los patrones de diversidad se reporta que la parte nor-este de TBS presentó la mayor diversidad y al mismo tiempo se presenta un mapa de zonas claves de diversidad de árboles. La técnica de identificación aérea ha producido resultados alentadores ya que es una herramienta metodológica de gran utilidad para entender los procesos medioambientales (bióticos o abióticos) que se presentan en el bosque Amazónico. 5 ACKNOWLEDGEMENTS The author thankfully acknowledges funding provided by Programme Alban (European Union Programme of High level Scholarships for Latin America, Award nº E03D26669CO), WWF (Russell E. Train fellowship, Education for Nature Program), Royal Geographical Society fieldwork grant, Rufford Small Grant and Herb project fieldwork support (King’s College London). I am profoundly grateful to Dr. Mark Mulligan, my supervisor, for his unconditional advice and wise academic support. He stood up to me during the past 4 years, thank you... it was a great experience for me also! Mark’s cleverness and unique personal and technical capabilities helped me to mature. I nearly understood many of his tastes, but I never quite fancied his brave beer preferences, particularly with the Nut Brown Ale Bottles at the Lyceum pub on the Strand. Before following the tradition of expressing gratitude to my parents, I want to thank to Caroline Anne Hay “la chinita” for all her help (English Editor), support and patience during the first two years of my thesis. To my parents, with all my love, this thesis is dedicated to Maria Cristina Orozco and of course to my dad as well. Thank you to my UK parents, I say, Mr and Mrs Hay in Eildon St. in Edinburgh, they welcomed me into their lovely home and fed me very well by the way. Unfortunately I was not able to beat Richard in golf, but perhaps I performed better in the kitchen. 6 I would like to thank to Camilla Smith for her English spe!!ing correction at Borough market in London. I would like to express my sincere gratitude to Dr. Andrew James Jarvis for his constant personal support and also to his wife Ingrid for her patience during my visits. I always considered him a great scientist and also as “mi segundo supervisor.” I am extremely grateful to Mr. Robert Giles, my London housemate. I will never forget his immense generosity. I must also thank my housemates in Cr. 10 in Cali, Colombia, San Antonio (Felipe, Norbert and the others). I am also deeply grateful to Fabian Nenquimo for his fieldwork support during the long and humid days looking for trees in the Amazonian rain forest in Ecuador. In Cali, I would also like to thank to Dr. Jorge Rubiano and Dr. Mauricio Rincon for their support in providing me access to the GIS laboratories for conducting the online identification exercise in Universidad Nacional de Colombia in Palmira and Universidad del Valle in Cali. Thanks to Edith Hesse for providing logistical support at the beginning of my thesis. It was a pleasure to regularly share experiences with all the wonderful Land Use project team at Ciat. Special thanks to the Universidad San Francisco de Quito and particularly to the TBS staff that logistically helped a great deal, including Constanza, Jaime, David, Kelly, and all the fieldworkers, “the tigers” working there deep in the 7 jungle. I thank the following institutions: Tiputini Biodiversity Station TBS, Universidad Catolica-Quito-, Universidad San Francisco de Quito, Centro Internacional de Agricultura Tropical-CIAT, Museo de Historia Natural (Santiago Ayerbe), Universidad del Cauca. 8 TABLE OF CONTENTS ABSTRACT ..............................................................................................2 RESUMEN................................................................................................4 ACKNOWLEDGEMENTS ........................................................................6 CHAPTER 1: INTRODUCTION AND RESEARCH GOALS...................22 1.1 Introduction..................................................................................................22 1.2 The research problem..................................................................................24 1.3 Hypotheses ....................................................................................................26 1.4 Aim ................................................................................................................26 1.5 Objectives......................................................................................................27 1.6 Rationale .......................................................................................................29 1.6.1 The challenge of landscape inventory.....................................................29 1.6.2 The