Changes in carbon cycling by Brazilian rain forest: effects of soil moisture reduction on soil, leaves and canopy
Patrick
Meir, University of Edinburgh, UK, pmeir@ed.ac.uk
(Presenting)
Ant�nio
Carlos L�la da
Costa, Universidade Federal de Para, Brasil, lola@ufpa.br
Samuel
Almeida, Museu Paraense Emilio Goeldi, Brasil, samuel@museu-goeldi.br
Fisher
Alice
Rosie, University of Edinburgh, UK, rosie.fisher@ed.ac.uk
Raquel
Lobo do
Vale, Instituto Superior de Agronomia, Portugal, raquelvale@isa.utl.pt
Raquel
Medeiros, Museu Paraense Emilio Goeldi, Brasil, raquel-medeiros@bol.com.br
Sotta
Doff
Eleneide, Museu Paraense Emilio Goeldi, Brasil, esotta@gwdg.de
Rafael
Ferreira
Costa, Museu Paraense Emilio Goeldi, Brasil, rfcosta@museu-goeldi.br
Jose Maria
Nogueira da
Costa, Universidade Federal de Vicosa, Brazil, jmncosta@ufv.br
Cl�udio Jos�
Reis de Carvalho, Embrapa-Oriental, Brasil, carvalho.bel@terra.com.br
Lou
Ruivo, Museu Paraense Emilio Goeldi, Brasil, ruivo@museu-goeldi.br
Edso
Veldkamp, Universitat Goettingen, Germany, eveldka@gwdg.de
Manuela
Chaves, Instituto Superior de Agronomia, Portugal, mchaves@isa.utl.pt
Mathew
Williams, University of Edinburgh, UK, mat.williams@ed.ac.uk
Yadvinder
Singh
Malhi, University of Edinburgh, UK, ymalhi@ed.ac.uk
John
Grace, University of Edinburgh, UK, jgrace@ed.ac.uk
Rainfall was experimentally excluded from 1 ha of E. Amazonian forest, at Caxiuana National Forest, Para with the aim of advancing understanding of the response in the forest carbon cycle to low soil moisture. Measurements were made of sap flow, leaf gas exchange, soil respiration, growth, litterfall and canopy structure in both experimentally treated and control (untreated) 1 ha plots. Comparisons were made between the two treatments and also with reference to eddy covariance measurements made 1-2 km distant. The exclusion of rainfall resulted in a reduction in soil water volume content by approximately 30% in comparison to the control and this resulted in clear effects at stand and species level on carbon cycling in leaves and soil. Strong hydraulic constraints appear to underlie the leaf level response to soil drought, rather than changes in leaf biochemistry; changes in soil respiration are also strong, resulting in reduced and lagged rates of efflux. Strong reductions in evapotranspiration were observed at tree and stand levels in response to moisture stress. By using our data to improve modelling of the response in carbon cycling to drought we identify significant reductions in productivity, a result that is supported through measurements of, for example, reduced plant reproductive capacity.
Submetido por Patrick Meir em 18-MAR-2004
Tema Cient�fico do LBA: CD (Armazenamento e Trocas de Carbono)