LINKING LAND USE – LAND COVER CHANGE AND ECOSYSTEM FUNCTION IN TROPICAL LOWLAND WATERSHEDS OF BELIZE, CENTRAL AMERICA By DAVID GRAY BUCK A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2012 1 © 2012 David Gray Buck 2 This dissertation is dedicated to my wife, Ellie Harrison-Buck for all of her support during this research; and the Q’eqchi’ Maya communities of the Temash River who willing provided me with an opportunity to live and learn in their watershed. 3 ACKNOWLEDGMENTS I am grateful for the support of a number of individuals and organizations during my dissertation research. I would like to thank my advisor and committee chair Dr. Mark Brenner as well as committee members Drs. Michael Binford, Matthew Cohen and Eric Keys. The University of Florida’s Land Use and Environmental Change Institute provided access to its geospatial laboratory and water quality laboratory. The NSF- IGERT Working Forests in the Tropics program at the University of Florida awarded me a 3-year doctoral fellowship (NSF-DGE 0221599) that helped create an ideal academic environment to explore interdisciplinary questions related to human-environment interactions and the conservation of tropical watersheds. In addition, an NSF Doctoral Dissertation Research Improvement Grant (NSF-BSE 0825278) and a Sigma Xi Grants- in-Aid of Research (Grant ID # G2006351230333459) provided additional funding for field and analytical costs. Field work in the Monkey River watershed was done in collaboration with the Toledo Institute for Development and the Environment (TIDE) and Peter Esselman. Peter shared his experience and insights into the development of the ELSI and human impact mapping and was my partner in data collection for the 2007 impact mapping. Peter continues to be a leading advocate for freshwater conservation in Belize. Field work in the Temash River watershed was done in collaboration with the Sarstoon-Temash Institute for Indigenous Management (SATIIM). Juan Pop (Crique Sarco village) was my primary field assistant during my dissertation field work and without him this work would not have been possible. Anasario Cal (Crique Sarco) served as my boat captain (while the boat was operational) and I am grateful for his time and knowledge of 10-horse power boat motors. In addition, Josiah Bo (Crique 4 Sarco) and Mauricio Tush (Sunday Wood) were invaluable assistants during the matambre interview process. Joel Wainwright (Ohio State University) also provided advice on early versions of the interview questionnaire used for the matambre study. Data collection on land use and land cover was conducted in collaboration with Sean Downey (University of Arizona). Sean developed a database used for storing literally thousands of data fields into a manageable and coherent format that made data analysis streamlined. Rain gauges installed in the Temash were purchased by Sean through an NSF Doctoral Dissertation Improvement Grant (NSF Award # 0647832). I appreciate Sean’s time, energy and commitment to many of our shared research interests. Since completing the field work portion of my dissertation, I have worked at the Biodiversity Research Institute (BRI) in Gorham Maine. Dr. David Evers, the executive director of BRI, has provided endless support, including generous paid leave that helped me to see this project to completion. My parents, Steve and Bettie Buck, have been tremendously supportive during my graduate studies. I am forever grateful to my wife, Ellie Harrison-Buck, and our daughter, Eliza, who joined me during much of the 16 months of field work in southern Belize. Since then, our second daughter Natalie has joined the family. Natalie and Eliza have given me countless hours of enjoyment (and plenty of distractions) during the final writing phases of this dissertation. All three, particularly Ellie, have provided endless support and motivation for the completion of the dissertation. Without Ellie, this would not have been possible. 5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 9 LIST OF FIGURES ........................................................................................................ 11 ABSTRACT ................................................................................................................... 12 CHAPTER 1 BACKGROUND ...................................................................................................... 14 Human – Environment Interactions in Tropical Watersheds ................................... 14 Aquatic Resources of Belize ................................................................................... 16 Statement of Objectives .......................................................................................... 18 2 MONITORING LAND USE CHANGES ALONG RIPARIAN CORRIDORS IN LOWLAND TROPICAL WATERSHEDS: APPLICATION OF HUMAN IMPACT MAPPING AND ESTIMATION OF LOCAL STRESS INTENSITY (ELSI) ............... 22 Introduction ............................................................................................................. 22 Study Site ............................................................................................................... 24 Methods .................................................................................................................. 25 Results .................................................................................................................... 27 Discussion .............................................................................................................. 27 Conclusions ............................................................................................................ 31 3 LAND USE PRACTICES, PESTICIDE APPLICATIONS, AND FRESHWATER RESOURCE CONSERVAtiON IN A LOWLAND TROPICAL WATERSHED .......... 39 Introduction ............................................................................................................. 39 Study Area .............................................................................................................. 41 Study Villages and Watershed ......................................................................... 41 Riparian Zone Land Use within the Temash River Watershed ......................... 42 Methods .................................................................................................................. 43 Results .................................................................................................................... 44 Households and Matambre .............................................................................. 44 Water Use and Water Quality ........................................................................... 45 Matambre Field Management ........................................................................... 46 Discussion .............................................................................................................. 46 Matambre and Riparian Conservation .............................................................. 46 Matambre, Pesticides and Public Health .......................................................... 47 Environmental Fate of Agrochemicals in the Temash ...................................... 49 Conclusions ............................................................................................................ 51 6 4 SOIL NUTRIENT DYNAMICS, ORGANIC MATTER TURNOVER AND LAND USE WITHIN AN ANTHROPOGENIC LANDSCAPE DOMINATED BY SHIFTING CULTIVATION ...................................................................................... 56 Introduction ............................................................................................................. 56 Study Area .............................................................................................................. 59 Methods .................................................................................................................. 60 Soil Sampling and Land Use History ................................................................ 60 Laboratory Analysis .......................................................................................... 61 Estimation of SOM Turnover ............................................................................ 62 Statistical Analyses .......................................................................................... 63 Results .................................................................................................................... 63 Soil Physical and Chemical Characteristics ...................................................... 63 Stable Carbon Isotopes in Vegetation and Soils and the MRT of SOM ............ 65 Discussion .............................................................................................................. 65 Soil Nutrient Dynamics in Milpa Versus Forest Soils ........................................ 65 Cacao Agroforestry and Pasture ...................................................................... 69 Stable Isotopes and MRT of SOM in Temash Soils ......................................... 71 Sustainability of Milpa in the Maya Forest ........................................................ 72 5 TEMPORAL AND SPATIAL