| This thesis is composed of five chapters assessing the following specific goals: (1) To estimate the extent and geographic distribution of the neotropical dry forest. (2) To evaluate the potential use of satellite-detected fires as deforestation predictors in tropical dry forest and (3) To evaluate the potential of remote sensing techniques to detect edge effects in tropical dry forest. Preliminarily, in chapter two, I present a literature review of the techniques and concepts behind remote sensing of biodiversity. Here, I stress out the necessity of integrated assessments using multiple spatial and spectral resolution sensors over a wide array of ecosystems in order to find relevant ecosystem properties that would be sensitive to taxonomic and functional biodiversity. Chapter three describes a regional scale mapping effort of the extent and geographical distribution of tropical dry forests. Our results indicate that the total extent of tropical dry forest in the Americas is 519,597 Km2 with only 4.5 % being under protected areas. Results are also presented by subregions and countries. In Chapter four, we show correlations patterns between the number of MODIS Active Fires and forest cover change in four tropical dry forest landscapes in Latin America. At the Santa Cruz site (Bolivia), correlations were strong and significant while at Chamela Site (Mexico) and the Mata Seca site (Brazil) correlations were moderate but significant as well. Chapter five addresses the magnitude of disturbances near the edges of dry forest fragments (edge effects). Results in gap fraction and Fraction of Intercepted Photosynthetically Active Radiation (FiPAR) show that edge influence at tropical dry forests can extend to at least 300-m. Finally, Chapter Six shows the correlation between FiPAR changes at the forest edge and spectral vegetation indices (SVIs) computed from the hyperspectral and multiangular satellite imagery. The work contained in these five chapters address issues that are critical to the advancement of tropical dry forest monitoring. These studies contribute to the current scientific literature on the use and application of optical remote sensing tools, not only applicable in tropical dry forests, but for tropical forest conservation at the continental, regional and local level. |
