Short-Term Precipitation Exclusion Alters Microbial Responses to Soil Moisture in a Wet Tropical Forest

Bonnie G. Waring, Christine V. Hawkes

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Many wet tropical forests, which contain a quarter of global terrestrial biomass carbon stocks, will experience changes in precipitation regime over the next century. Soil microbial responses to altered rainfall are likely to be an important feedback on ecosystem carbon cycling, but the ecological mechanisms underpinning these responses are poorly understood. We examined how reduced rainfall affected soil microbial abundance, activity, and community composition using a 6-month precipitation exclusion experiment at La Selva Biological Station, Costa Rica. Thereafter, we addressed the persistent effects of field moisture treatments by exposing soils to a controlled soil moisture gradient in the lab for 4 weeks. In the field, compositional and functional responses to reduced rainfall were dependent on initial conditions, consistent with a large degree of spatial heterogeneity in tropical forests. However, the precipitation manipulation significantly altered microbial functional responses to soil moisture. Communities with prior drought exposure exhibited higher respiration rates per unit microbial biomass under all conditions and respired significantly more CO2 than control soils at low soil moisture. These functional patterns suggest that changes in microbial physiology may drive positive feedbacks to rising atmospheric CO2 concentrations if wet tropical forests experience longer or more intense dry seasons in the future.

Original languageEnglish (US)
Pages (from-to)843-854
Number of pages12
JournalMicrobial ecology
Issue number4
StatePublished - May 1 2015

Bibliographical note

Funding Information:
The authors are grateful to the staff of the Organization for Tropical Studies, especially Bernal Matarrita and Danilo Brenes, for their logistical assistance. Many thanks to Jim Dula for help in the field and lab. This material is based upon work supported by a National Science Foundation (NSF) Graduate Research Fellowship to BGW and NSF grant no. DEB-1119169 to CVH.

Publisher Copyright:
© 2014, Springer Science+Business Media New York.


Dive into the research topics of 'Short-Term Precipitation Exclusion Alters Microbial Responses to Soil Moisture in a Wet Tropical Forest'. Together they form a unique fingerprint.

Cite this