Belowground response to drought in a tropical forest soil. II. Change in microbial function impacts carbon composition.

Frontiers in Microbiology

HsiaoChien eLim¹  Nick eBouskill¹  Benjamin P Bowen¹  Zaw eYe¹  Richard eBaran¹  Zhao eHao¹  Peter eNico¹  Hoi-Ying eHolman¹  Trent R Northen¹  Benjamin eGilbert¹  Tana E Wood²  Whendee eSilver³  Eoin L Brodie³ 

[1] Lawrence Berkeley National Laboratory;USDA Forest Service;University of California, Berkeley;

关键词: Carbon Dioxide;    drought;    microbial functions;    soil carbon;    Tropical Forest;   

DOI  :  10.3389/fmicb.2016.00323

来源: DOAJ

【 摘 要 】

Climate model projections for tropical regions show clear perturbation of precipitation patterns leading to increased frequency and severity of drought in some regions. Previous work has shown declining soil moisture to be a strong driver of changes in microbial trait distribution, however the feedback of any shift in functional potential on ecosystem properties related to carbon cycling are poorly understood. Here we show that drought-induced changes in microbial functional diversity and activity shape, and are in turn shaped by, the composition of dissolved and soil-associated carbon. We also demonstrate that a shift in microbial functional traits that favor the production of hygroscopic compounds alter the efflux of carbon dioxide following soil rewetting. Under drought the composition of the dissolved organic carbon pool changed in a manner consistent with a microbial metabolic response. We hypothesize that this microbial ecophysiological response to changing soil moisture elevates the intracellular carbon demand stimulating extracellular enzyme production, that prompts the observed decline in more complex carbon compounds (e.g., cellulose and lignin). Furthermore, a metabolic response to drought appeared to condition (biologically and physically) the soil, notably through the production of polysaccharides, particularly in experimental plots that had been pre-exposed to a short-term drought. This hysteretic response, in addition to an observed drought-related decline in phosphorus concentration, may have been responsible for a comparatively modest CO2 efflux following wet-up in drought plots relative to control plots.

【 授权许可】

Unknown