Drought stress and tree size determine stem CO2 efflux in a tropical forest.
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.
Main Authors: | , , , , , , , , , , , , , , |
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Other Authors: | |
Format: | Artigo de periódico biblioteca |
Language: | English eng |
Published: |
2018-05-15
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Subjects: | Estresse hídrico, Carbono, Floresta, Floresta Tropical, |
Online Access: | http://www.alice.cnptia.embrapa.br/alice/handle/doc/1091469 |
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