TY - JOUR
T1 - Allocation trade-offs dominate the response of tropical forest growth to seasonal and interannual drought
AU - Doughty, Christopher E.
AU - Malhi, Yadvinder
AU - Araujo-Murakami, Alejandro
AU - Metcalfe, Daniel B.
AU - Silva-Espejo, Javier E.
AU - Arroyo, Luzmila
AU - Heredia, Juan P.
AU - Pardo-Toledo, Erwin
AU - Mendizabal, Luz M.
AU - Rojas-Landivar, Victor D.
AU - Vega-Martinez, Meison
AU - Flores-Valencia, Marcio
AU - Sibler-Rivero, Rebeca
AU - Moreno-Vare, Luzmarina
AU - Jessica Viscarra, Laura
AU - Chuviru-Castro, Tamara
AU - Osinaga-Becerra, Marilin
AU - Ledezma, Roxana
PY - 2014/8
Y1 - 2014/8
N2 - What determines the seasonal and interannual variation of growth rates in trees in a tropical forest? We explore this question with a novel four-year high-temporal-resolution data set of carbon allocation from two forest plots in the Bolivian Amazon. The forests show strong seasonal variation in tree wood growth rates, which are largely explained by shifts in carbon allocation, and not by shifts in total productivity. At the deeper soil plot, there was a clear seasonal trade-off between wood and canopy NPP, while the shallower soils plot showed a contrasting seasonal trade-off between wood and fine roots. Although a strong 2010 drought reduced photosynthesis, NPP remained constant and increased in the six-month period following the drought, which indicates usage of significant nonstructural carbohydrate stores. Following the drought, carbon allocation increased initially towards the canopy, and then in the following year, allocation increased towards fine-root production. Had we only measured woody growth at these sites and inferred total NPP, we would have misinterpreted both the seasonal and interannual responses. In many tropical forest ecosystems, we propose that changing tree growth rates are more likely to reflect shifts in allocation rather than changes in overall productivity. Only a whole NPP allocation perspective can correctly interpret the relationship between changes in growth and changes in productivity.
AB - What determines the seasonal and interannual variation of growth rates in trees in a tropical forest? We explore this question with a novel four-year high-temporal-resolution data set of carbon allocation from two forest plots in the Bolivian Amazon. The forests show strong seasonal variation in tree wood growth rates, which are largely explained by shifts in carbon allocation, and not by shifts in total productivity. At the deeper soil plot, there was a clear seasonal trade-off between wood and canopy NPP, while the shallower soils plot showed a contrasting seasonal trade-off between wood and fine roots. Although a strong 2010 drought reduced photosynthesis, NPP remained constant and increased in the six-month period following the drought, which indicates usage of significant nonstructural carbohydrate stores. Following the drought, carbon allocation increased initially towards the canopy, and then in the following year, allocation increased towards fine-root production. Had we only measured woody growth at these sites and inferred total NPP, we would have misinterpreted both the seasonal and interannual responses. In many tropical forest ecosystems, we propose that changing tree growth rates are more likely to reflect shifts in allocation rather than changes in overall productivity. Only a whole NPP allocation perspective can correctly interpret the relationship between changes in growth and changes in productivity.
KW - Bolivia
KW - Deep vs. shallow soils
KW - Drought
KW - Net primary production (NPP)
KW - Resource allocation
KW - Seasonally dry tropical forest
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U2 - 10.1890/13-1507.1
DO - 10.1890/13-1507.1
M3 - Article
C2 - 25230470
AN - SCOPUS:84905661577
SN - 0012-9658
VL - 95
SP - 2192
EP - 2201
JO - Ecology
JF - Ecology
IS - 8
ER -