Tropical forest functional diversity, which is a measure of
the diversity of organismal interactions with the environment, is poorly
understood despite its importance for linking evolutionary biology to
ecosystem biogeochemistry. Functional diversity is reflected in
functional traits such as the concentrations of different compounds in
leaves or the density of leaf mass, which are related to plant
activities such as plant defence, nutrient cycling, or growth. In the
Amazonian lowlands, river movement and microtopography control nutrient
mobility, which may influence functional trait distributions. Here we
use airborne laser-guided imaging spectroscopy to develop maps of 16
forest canopy traits, throughout four large landscapes that harbour
three common forest community types on the Madre de Dios and Tambopata
rivers in southwestern Amazonia. Our maps, which are based on
quantitative chemometric analysis of forest canopies with
visible-to-near infrared (400–2,500 nm) spectroscopy, reveal substantial
variation in canopy traits and their distributions within and among
forested landscapes. Forest canopy trait distributions are arranged in a
nested pattern, with location along rivers controlling trait variation
between different landscapes, and microtopography controlling trait
variation within landscapes. We suggest that processes of nutrient
deposition and depletion drive increasing phosphorus limitation, and a
corresponding increase in plant defence, in an eastward direction from
the base of the Andes into the Amazon Basin.
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and large-scale patterns in Amazon forest structure and function are
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Department of Global Ecology, Carnegie Institution for Science, 260 Panama Street Stanford, California 94305, USA
Gregory P. Asner,
Christopher B. Anderson,
Roberta E. Martin,
Raul Tupayachi,
David E. Knapp &
Felipe Sinca
Contributions
G.P.A. designed and secured funding for the study, and led data
collection and analysis steps. G.P.A., C.B.A., R.E.M., D.E.K., R.T. and
F.S. carried out data collection and analyses. G.P.A. and R.E.M. wrote
the paper.
Competing financial interests
The authors declare no competing financial interests.