University - Biology
Floristic Patterns in Upper Amazonian Swamp Forests
Wetlands are among the least understood of the world's ecosystems. Recently, wetlands have become a focus of conservation efforts because of their diversity of habitats and importance in water management and wildlife conservation. This study seeks to understand the factors influencing species richness, composition, and primary productivity in a novel wetland study system: the seasonally inundated floodplains of the upper Amazon drainage.
Forested wetlands occur throughout much of the Amazon landscape due to seasonal fluctuations in river level. In southwestern Peru, the proximity of the Manu and Madre de Dios river drainages to the headwaters causes fluctuations in the hydrologic regime to be of much higher frequency and lower amplitude when compared with those down stream; habitats will flood to varying degrees with each strong rain event, leaving a smaller fraction of the floodplain permanently inundated. I have used remote sensing to identify seven distinct floodplain habitats (NASA-JPL Synthetic Aperture Radar [AIRSAR] and LANDSAT images). It is thought that the composition of these habitats is strongly correlated with flooding regime (Richards 1996).
The specific questions that will be addressed in this study are (1) what is the relationship between the flooding regime (micro-topography) and swamp type (floristic composition), and (2) how is net primary productivity coupled to flooding?
Research will encompass the distinct swamp types associated with floodplains of the Madre de Dios River and the Manu River by comparing measurements on habitat distribution, tree species composition, diversity, and density. Also, measurements of flooding frequency, duration, depth and relative soil moisture will be recorded from each swamp type throughout the wet and dry season. Remote sensing images will be used as an aid in determining current and historical floristic composition, micro-topography, and specific site locations and abundance. Finally, annual net primary productivity will be measured using litter traps and tree growth increments. The combination of these measurements will then be applied to determine the existence of a pattern related to the specific flooding regime of each swamp type.
Though little studied, upper-Amazonian forested wetlands are invaluable in controlling floodwater and water quality throughout the Amazon basin and provide keystone habitats for large ungulates such as white-lipped peccaries and tapirs in the form of palm swamps. In terms of productivity, tropical rainforests are zones of high carbon fixation and photosynthetic capacity, extremely important in aspects of conservation of global change. The above results will expand our knowledge of forested wetlands, a particularly important component of the Amazonian ecosystem.