Drought stress and tree size determine stem CO2 efflux in a tropical forest.

• Autor(a) principal: ROWLAND, L.
• Data de Publicação: 2018
• Outros Autores: COSTA, A. C. L. da, OLIVEIRA, A. A. R., OLIVEIRA, R. S., BITTENCOURT, P. L., COSTA, P. B., GILES, A. L., SOSA, A. I., COUGHLIN, I., GODLEE, J. L., VASCONCELOS, S. S., S. JUNIOR, J. A., FERREIRA, L. V., MENCUCCINI, M., MEIR, P.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1091469
• topic: Estresse hídrico; Carbono; Floresta; Floresta Tropical

CO2 efflux from stems (CO2_stem) accounts for a substantial fraction of tropical forest gross primary productivity, but the climate sensitivity of this flux remains poorly understood. We present a study of tropical forest CO2_stem from 215 trees across wet and dry seasons, at the world?s longest running tropical forest drought experiment site. We show a 27% increase in wet season CO2_stem in the droughted forest relative to a control forest. This was driven by increasing CO2_stem in trees 10?40 cm diameter. Furthermore, we show that drought increases the proportion of maintenance to growth respiration in trees > 20 cm diameter, including large increases in maintenance respiration in the largest droughted trees, > 40 cm diameter. However, we found no clear taxonomic influence on CO2_stem and were unable to accurately predict how drought sensitivity altered ecosystem scale CO2_stem, due to substantial uncertainty introduced by contrasting methods previously employed to scale CO2_stem fluxes. Our findings indicate that under future scenarios of elevated drought, increases in CO2_stem may augment carbon losses, weakening or potentially reversing the tropical forest carbon sink. However, due to substantial uncertainties in scaling CO2_stem fluxes, stand-scale future estimates of changes in stem CO2 emissions remain highly uncertain.