02323naa a2200349 a 450000100080000000500110000800800410001902400270006010000160008724501040010326000090020752013580021665000120157465000130158665000220159965300220162170000230164370000230166670000200168970000230170970000170173270000170174970000160176670000170178270000180179970000230181770000210184070000200186170000190188170000130190077300600191320914692018-05-22       2018    bl uuuu     u00u1 u    #d7 a10.1111/nph.150242DOI1 aROWLAND, L.  aDrought stress and tree size determine stem CO2 efflux in a tropical forest.h[electronic resource]  c2018  aCO2 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 &gt 20 cm diameter, including large increases in maintenance respiration in the largest droughted trees, &gt 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.  aCarbono  aFloresta  aFloresta Tropical  aEstresse hídrico1 aCOSTA, A. C. L. da1 aOLIVEIRA, A. A. R.1 aOLIVEIRA, R. S.1 aBITTENCOURT, P. L.1 aCOSTA, P. B.1 aGILES, A. L.1 aSOSA, A. I.1 aCOUGHLIN, I.1 aGODLEE, J. L.1 aVASCONCELOS, S. S.1 aS. JUNIOR, J. A.1 aFERREIRA, L. V.1 aMENCUCCINI, M.1 aMEIR, P.  tNew Phytologistgv. 218, n. 4, p. 1393-1405, June 2018.