A multi-scaled approach to understanding the environmental drivers of Southeast Asian forest-savanna mosaics
department or school: Arts, Faculty of
department or school: Geography, Department of
data provider: DSpace
degree campus: UBCV
creator: Pletcher, Elise
issued: 2021-08-11T16:50:10Z
issued: 2021
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Seasonally dry tropical forest in Southeast Asia is a complex mosaic of dry evergreen forest and deciduous dipterocarp “forest” (which are structurally and functionally savanna). These patchy savannas are threatened by fragmentation and forest-centric management practices. Understanding the ecological processes that govern the boundaries between forest and savanna is essential for their proper conservation. I analyzed patterns of remotely sensed tree cover and identified the key determinants of both tree cover and landscape mosaics across SE Asia. First, I examined distributions of tree cover for bimodality—evidence that forests and savanna exist as alternate stable states. I found no bimodality in tree cover regionally; however, bimodality was present within landscapes. Second, I analyzed the relative importance of environmental factors in shaping patterns of tree cover and landscape mosaics, using regression models. I found that fire was the strongest predictor of tree cover at the regional scale and that the prevalence of landscape mosaics is dependent on climate (rainfall and seasonality). These results reveal that the same environmental factors important in delineating the distribution of savannas globally drive patterns of tree cover and landscape mosaics across SE Asia. More broadly, this work shows a useful approach for parsing out which environmental factors maintain and drive forest-savanna mosaic formation. While global vegetation products (GVPs), such as those I employed in my first analysis, are powerful and easy to use, their applicability in highly heterogeneous landscapes such as savanna-forest mosaics is poorly understood. I therefore explored the limitations of global vegetation structure products, including those used in my primary analysis using Airborne Laser Scanning. I found that no GVP was a clear winner. MODIS VCF significantly underestimates tree cover in SE Asian savannas, relative to forests, and the Global Forest Change (GFC) product’s a…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/79264
note: A MULTI-SCALED APPROACH TO UNDERSTANDING THE ENVIRONMENTAL DRIVERS OF SOUTHEAST ASIAN FOREST-SAVANNA MOSAICS by Elise Pletcher B.Sc., University of Washington, 2017 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Geography) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August 2021 © Elise Pletcher, 2021 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: A multi-scaled approach to understanding the environmental drivers of Southeast Asian forest-savanna mosaics submitted Elise Pletcher in partial fulfillment of the requirements the degree of Master of Science in Geography Examining Committee: Dr. Naomi B. Schwartz, Geography, University of British Columbia Supervisor Dr. Greg Henry, Geography, University of British Columbia Supervisory Committee Member Dr. Carla Staver, Ecology and Evolutionary Biology, Yale University Supervisory Committee Member iii Abstract Seasonally dry tropical forest in Southeast Asia is a complex mosaic of dry evergreen forest and deciduous dipterocarp “forest” (which are structurally and functionally savanna). These patchy savannas are threatened by fragmentation and forest-centric management practices. Understanding the ecological processes that govern the boundaries between forest and savanna is essential for their proper conservation. I analyzed patterns of remotely sensed tree cover and identified the key determinants of both tree cover and landscape mosaics across SE Asia. First, I examined distributions of tree cover for bimodality—evidence that forests and savanna exist as alternate stable states. I found no bimodality in tree cover regionally; however, bimodality was present within landscapes. Second, I analyzed the relative importance of environmental factors in shaping patterns of tree cover and landscape mosaics, using r…
has type: Thesis/Dissertation
date issued: 2021-11
is shown at: 10.14288/1.0401383
language: eng
degree discipline: Geography
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Schwartz, Naomi B.
type: Text
identifier URI: http://hdl.handle.net/2429/79264