This is a preliminary study that is the focus
of the graduate student project of Ms. Kimberly Epps. In this
study we are attempting to develop a chemical diversity index
that helps us explain P biogeochemical cycling in the Atlantic
Forest of Brazil. N.B. Comerford is the PI, along with Wendell
Cropper in the Forestry School and James Reeves, III from ARS.
The role of biodiversity in regulating the function of ecosystems
is one of the more contentious environmental debates of our
era. Prompted by concerns over accelerating rates of deforestation,
ecosystem degeneration and unparalleled rates of species losses
during the latter half of the last century, ecologists have
shifted their query from how the environment determines the
quantity and distribution of species to how species and species
diversity affect the environment. This project’ goal is
to discern if soil phosphorus supply mechanisms are influenced
by aboveground plant diversity. A native forest and cacao plantation
in Bahia, Brazil will be the experimental site. Specific objectives
are
(1) to establish an index of chemical diversity based upon
litter qualities,
(2) to examine chemical diversity changes with increasing plant
species richness, and
(3) to determine the influence of litter chemical diversity
on soil processes determining P bioavailability.
Objectives 1 and 2 will be met by an inventory of species and
litter input under the two forest conditions; separating leaf
litter by species; and analyzing leaf litter and roots to determine
their chemical makeup. Analyses will include chemical characterization
as well fingerprinting by FTIR and Pyrolysis GC/MS. The study
will evaluate a chemical diversity index for the litter input
of native forest regions and cacao plantation systems. The premise
of this study is that an index of chemical diversity is more
related to a chemically controlled ecosystem function than is
a typical diversity measure such as species richness. Using
the range of species and their fingerprints, the study will
investigate the relationship between species richness and the
chemical diversity index. The expectation is that a level of
species richness is described by a wide chemical diversity range
that is contingent upon the identity of the species within the
species mix, and that the index reflects the composition of
the plant community. Once defined, the relationship between
species richness and chemical diversity will be employed to
address Objective 3 for which a factorial incubation experiment
will determine the relative influence of chemical diversity
and species richness on litter decomposition, P mineralization
and bioavailable P partitioning in the soil.
The index has been developed and a publication on its development
and characteristics is in review. Kye is again in Brazil working
with Dr. Nairam Barros in Viçosa on the mineralization
component of the study
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