Oliver
L.
Phillips, University of Leeds, o.phillips@geog.leeds.ac.uk
(Presenting)
Simon
L
Lewis, University of Leeds, s.lewis@geog.leeds.ac.uk
Timothy
R.
Baker, Max Planck Institute for Biogeochemistry, t.baker@geog.leeds.ac.uk
and
31
others, 25 institutions,
We characterise Amazon-scale patterns of stand-level growth, recruitment, and mortality using improved datasets now available that span the last 25 years. Specifically, we assess whether concerted changes are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. We find that: (1) trees >10 cm diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (2) stem turnover rates have increased throughout Amazonia; (3) basal area growth and mortality rates have increased throughout Amazonia; (4) gain rates have consistently exceeded loss rates; (5) absolute increases in rates are greatest in western Amazonian sites; (6) basal area and stem density pools increased by 0.38 ± 0.15 % a-1 and 0.18 ± 0.12 % a-1 respectively; (7) fluxes into and out of these pools increased, in relative terms, by an order of magnitude more than the pools; (8) gain terms consistently exceeded the loss terms throughout, suggesting that whatever process is driving these changes was already acting when the plot network was established The trends cannot be directly driven by a mortality driver (such as increased drought-related death) because the biomass in these forests has simultaneously increased. Large, long-term increases in growth and simultaneous increases in pools imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Our findings therefore indicate that long-acting and widespread environmental changes are accelerating growth and dynamics across the world's largest tract of tropical forest.
Submetido por Oliver L. Phillips em 17-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)