Allocation trade-offs dominate the response of tropical forest growth to seasonal and interannual drought

Christopher E. Doughty, Yadvinder Malhi, Alejandro Araujo-Murakami, Daniel B. Metcalfe, Javier E. Silva-Espejo, Luzmila Arroyo, Juan P. Heredia, Erwin Pardo-Toledo, Luz M. Mendizabal, Victor D. Rojas-Landivar, Meison Vega-Martinez, Marcio Flores-Valencia, Rebeca Sibler-Rivero, Luzmarina Moreno-Vare, Laura Jessica Viscarra, Tamara Chuviru-Castro, Marilin Osinaga-Becerra, Roxana Ledezma

Research output: Contribution to journalArticlepeer-review

70 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)2192-2201
Number of pages10
JournalEcology
Volume95
Issue number8
DOIs
StatePublished - Aug 2014
Externally publishedYes

Keywords

  • Bolivia
  • Deep vs. shallow soils
  • Drought
  • Net primary production (NPP)
  • Resource allocation
  • Seasonally dry tropical forest

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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