Artículos de revistas
Surface ecophysiological behavior across vegetation and moisture gradients in tropical South America
Fecha
2014-03-25Registro en:
10.1016/j.agrformet.2012.11.015
Autor
Baker, I.T.
Harper, A.B.
Rocha, Humberto Ribeiro da
Denning, A.S.
Araújo, A.C.
Borma, L.S.
Goulden, M.L.
Manzi, A.O.
Miller, S.D.
Nobre, A.D.
Restrepo-Coupe, N.
Saleska, S.R.
Stöckli, R.
Randow, C. von
Wofsy, S.C.
Freitas, H. C.
Institución
Resumen
Surface ecophysiology at five sites in tropical South America across vegetation and moisture gradients is
investigated. From the moist northwest (Manaus) to the relatively dry southeast (Pé de Gigante, state of
São Paulo) simulated seasonal cycles of latent and sensible heat, and carbon flux produced with the Simple
Biosphere Model (SiB3) are confronted with observational data. In the northwest, abundant moisture
is available, suggesting that the ecosystem is light-limited. In these wettest regions, Bowen ratio is consistently
low, with little or no annual cycle. Carbon flux shows little or no annual cycle as well; efflux and
uptake are determined by high-frequency variability in light and moisture availability. Moving downgradient
in annual precipitation amount, dry season length is more clearly defined. In these regions, a dry
season sink of carbon is observed and simulated. This sink is the result of the combination of increased
photosynthetic production due to higher light levels, and decreased respiratory efflux due to soil drying.
The differential response time of photosynthetic and respiratory processes produce observed annual
cycles of net carbon flux. In drier regions, moisture and carbon fluxes are in-phase; there is carbon uptake
during seasonal rains and efflux during the dry season. At the driest site, there is also a large annual cycle
in latent and sensible heat flux.