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Ecology and Biological Diversity of Andean Rivers
J. David Allan (University of Michigan)
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Alex S. Flecker (Cornell University)
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Headwater of Rio Siniguis ca. 4000m, Venequelan Andes
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J.D. Allan (left) & Alex Flecker (right) &
friend, Rio Siniguis. Cleared and burnt land is evident.
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Research under this proposal will take place along
the southern flank of the Venezuelan Andes, and will examine how the ecology
and biological diversity of tropical rivers are altered by changes in land
use at the catchment (watershed) scale. We will carry out a detailed investigation
along the length of one relatively undisturbed river from its origin at
4,00 0 m on Pico Humboldt, one of the highest mountains in Venezuela, until
it reaches the great lowland savannahs called the llanos at approx. 200
m elevation. Using this river as a benchmark, we will compare a series
of piedmont (foothill) rivers that have experienced differing degrees of
landscape transformation. We will address fundamental issues of structure
and function of tropical river systems via specif ic hypotheses concerning
altitudinal trends in:  1)
species richness and range, 2) size of individuals and biomass of populations,
3) re source availability and guild structure, and 4) habitat structure.
The biodiversity of these rivers will be examined by: 1) assessing local
(alpha) diversity by additional collecting to include adults and seasons
and determining local species richness us ing species accumulation curves;
and 2) examining beta diversity (complementarity) among collection locations.
Long-range goals are to expand scientific knowledge of the fundamental
structure and function of tropical rivers, and to examine how riverine
e cology may be altered in response to human impacts and changing land
use. |