EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Responses of Soil Microbes to Hydrological Perturbations in Tropical Forest Soils

Stephany S Chacon1, Aizah Khurram1, Markus Bill1, Hans Bechtel2, Jana Voriskova1, Liang Chen1, Lee H. Dietterich3, Ulas Karaoz1, Hoi-Ying Holman1,4, Daniela F. Cusack3,5, and Nicholas Bouskill1
Stephany S Chacon et al.
  • 1Lawrence Berkeley National Laboratory, Ecology, Berkeley, United States of America
  • 2Advance Light Source Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
  • 3Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO, 80523, USA
  • 4Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
  • 5Smithsonian Tropical Research Institute, Balboa, Ancon, Republic of Panama

Model projections predict that climate change impacts on the tropics will include an increased frequency of drought and precipitation cycles. Such environmental fluctuations at the soil pore-scale play an important role in shaping microbial adaptive capacity, and trait composition of a community, which feeds back on to the breakdown and formation of soil organic matter (SOM). Understanding the factors controlling the carbon balance of humid tropical forest soils remains a social imperative. Microbial feedback to SOM pools is critical. Herein, we examine the microbial response to drought perturbations across  3 different, but complementary scales. At the largest scale, we explored the impacts of drought across a 1 m precipitation gradient spanning four sites from the Caribbean coast to the interior of Panama. At each site 4, throughfall exclusion plots (10 x 10 m) were established to reduce precipitation by 50 %. In addition, 4 corresponding control plots were also constructed. At the meso-scale, we incubated intact soil cores from one of these sites (P12) under 3 different hydrological treatments (control, drought, rewetting-drying cycles) for over a 5-month period. For the field and meso-scale experiments, we evaluated changes imparted by hydrological perturbations using multi-omic approaches, and physico-chemical measurements.   In order to identify the traits involved in response to drought at the field and meso-scale, we isolated a range of bacteria to subject to stress at the scale of the single-cell and simple communities.  Cell extracts were subjected to osmotic or matric stress and the short-term physiological responses determined using non-destructive synchrotron radiation-based Fourier Transform-Infrared spectromicroscopy. Through this approach, we identified changes in metabolic allocation within different cells, in particular to the secondary metabolome of the different bacteria. Our contribution will discuss the outcomes of these multi-scale experiments.  Specifically focusing on how shifts in the microbial community and physiological changes may influence tropical soil carbon stability under future scenarios of altered drought and precipitation cycles.

How to cite: Chacon, S. S., Khurram, A., Bill, M., Bechtel, H., Voriskova, J., Chen, L., Dietterich, L. H., Karaoz, U., Holman, H.-Y., Cusack, D. F., and Bouskill, N.: Responses of Soil Microbes to Hydrological Perturbations in Tropical Forest Soils, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3786,, 2021.

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