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

Rowland, Lucy, da Costa, Antonio C. L., Oliveira, Alex A. R., Oliveira, Rafael S., Bittencourt, Paulo L. ORCID: https://orcid.org/0000-0002-1618-9077, Costa, Patricia B., Giles, Andre L., Sosa, Azul I., Coughlin, Ingrid, Godlee, John L., Vasconcelos, Steel S., Junior, João A. S., Ferreira, Leandro V., Mencuccini, Maurizio and Meir, Patrick 2018. Drought stress and tree size determine stem CO2 efflux in a tropical forest. New Phytologist 218 (4) , pp. 1393-1405. 10.1111/nph.15024

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Abstract

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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Publisher:	Wiley
ISSN:	0028-646X
Date of Acceptance:	22 December 2017
Last Modified:	29 Oct 2024 10:05
URI:	https://orca.cardiff.ac.uk/id/eprint/172724

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