Most tropical forests have been transformed from large expanses of forest into complex mosaics composed of croplands, pastures, secondary forests, plantations, and forest fragments. This rapid transformation of tropical forests is among the most significant types of land-use/cover change and one of the major causes of habitat loss and species decline. At the same time, hundreds of millions of people in the tropics are dependent on natural tropical forest for their livelihood or as a subsistence 'safety net'. To understand the potential of complex rural landscapes to maintain biodiversity, an understanding of the effects of rural landscape composition and structure (landscape pattern) on key ecological processes (such as dispersion and functional connectivity) is critically needed.
This dissertation research addresses these important issues. The investigators will examine how rural landscapes contribute to the maintenance of regional tree biodiversity in the tropical rainforest of the Selva Lacandona, Mexico. The study will model the effect of different rural land covers on the dispersion of seeds, and how this process can influence the functional connectivity of forest species at the landscape and regional level. The research will have two phases: classification and modeling. The classification of satellite images will focus on revealing the complex land cover classes submerged under the 'non-forest' or 'agricultural use' class. A change analysis will show how landscape structure has changed through time and space. In the modeling phase, the 'permeability' of the landscape to the crossing of dispersers will be quantified by a subpixel classification and field surveys. Then, the dispersion of tree seeds, mediated by different dispersers according to functional groups and through different land covers with differential permeability, will be simulated. Finally, the overall functional connectivity at the level of the landscape and the region will be assessed, together with the effect of the change of scale on the detection of functional connectivity. The outcomes will demonstrate the differential potentials of land uses in rural landscapes to conserve biodiversity and the land use/cover trends at the landscape and regional level.
This study seeks to develop a better understanding of how rural landscape composition and structure can influence ecological processes such as seed dispersion and functional connectivity at the landscape and regional level. The understanding of these dynamics and their potential to maintain key processes for biological diversity would contribute to better management of such landscapes throughout the tropics. Its major contributions are: a) the development of a procedure for continuous "gradient" classification, b) the results produced will incorporate rural landscapes into the study of ecological processes and advance the search for an integrative people-centered conservation in the tropics, and c) the tools provided will inform negotiations among conservation and development interests and will provide an alternative classification and conceptual approach to address conflicts that have proven difficult to resolve in the past.
