Document Type

Thesis

Degree

Master of Science

Major

Biology

Date of Defense

7-12-2013

Graduate Advisor

P. F. Stevens

Committee

Zanne, Amy

Jimenez, Ivan

Abstract

Amazonian forests comprise almost 10% of stored carbon (C) in the world’s land ecosystems. This C is held both in above-ground biomass (AGB) and in the soil. AGB in an individual plant depends on plant size, often measured in trees as height (H) and diameter (D), and the density of plant tissues, often approximated in trees by wood density (WD). Soil C storage depends on the balance between inputs from AGB due to mortality and senescence and outputs due to decay and erosion. Peatlands, wetlands recently described in northern Peruvian Amazonia, show unusually high rates of soil C accumulation. For these habitats information on C budget contributions from peatland plants is unavailable. In this study I estimated AGB in various peatlands of northern Peruvian Amazonia, and asked why some of these peatlands store more AGB than others. I first set out to estimate the relative contribution of inter- and intra-specific variation to variation in AGB among individual peatland trees. I found that 80% of the variation in AGB among individual trees was due to inter-specific variation. Then I assessed the extent to which the three traits that determine AGB (i.e., D, H and WD) contribute to inter- and intra-specific variation in AGB among peatland trees. I found variation in D and the interaction between D and H contributed most to inter- and intra-specific variation in AGB among trees. Last, I estimated the extent to which variation in AGB among peatland locations was due to variation in species composition, stem density and intra-specific variation in AGB. I found that species composition and intra-specific variation, but not stem density, explained nearly equal amounts of variation in AGB among peatland locations. In summary, detailed knowledge of tree size can provide good estimates of species level biomass estimates in the peatlands of northern Peruvian Amazonia. Additionally, what species are present, as well as how their biomass varies (intra-specifically) from site to site drives AGB variation among peatland locations.

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