Soil base cation availability regulates tropical soil carbon stocks via a negative relationship with fine root biomass.
Scientists at the University of California, Los Angeles (UCLA), and the Smithsonian Institution conducted an extensive study of predictors of tropical soil carbon stocks to 1 m depth at 48 sites in Panama, including measurements of soil characteristics, plant biomass, and climate. The study revealed a nearly three-fold change in soil carbon stocks across five soil orders, with soil characteristics like fine root biomass, clay content, and nutrient base cations the strongest predictors of soil carbon stocks.
Tropical forests are the most carbon rich ecosystems on Earth, containing 25% to 40% of global terrestrial carbon stocks. Quantification of aboveground biomass in tropical forests has improved recently, but soil carbon dynamics remains one of the largest sources of uncertainty in Earth system models. Including soil base cations in carbon cycle models, and thus emphasizing mechanistic links among nutrients, root biomass, and soil carbon stocks, will improve prediction of climate-soil feedbacks in tropical forests.
Overall, soil characteristics were the best predictors of soil carbon stocks, with no relationship to aboveground plant biomass or litterfall. The best fit model for the study's data suggested that available base cations provide an indirect control over tropical soil carbon stocks via a negative relationship with fine-root biomass. Soil clay content and rainfall also emerged as significant predictors of soil carbon. In addition to the nearly three-fold change in soil carbon stocks, the sites used here covered five soil orders, over 25 geological formations, a two-fold range in rainfall, a 20-fold range in base cations, and a 100-fold range in available phosphorus. Thus, although the data come from a relatively restricted geographic region, the diversity of environmental conditions means that the results are likely to be broadly applicable over much larger geographical ranges.
BER Program Manager
Terrestrial Ecosystem Science, SC-23.1
Daniela F Cusack
Assistant Professor, Department of Geography
University of California, Los Angeles
Los Angeles, CA 90095
Funding was provided by the National Science Foundation (NSF) GSS Grant #BCS-1437591 and the U.S. Department of Energy (DOE) Office of Science Early Career Research Program Grant DE-SC0015898 to D. F. Cusack, and UK Research and Innovation's National Environment Research Council (NERC) Grant NE/J011169/1 to O. T. Lewis.
Cusack D.F. et al. “Soil carbon stocks across tropical forests of Panama regulated by base cation effects on fine roots.” Biogeochemistry 137, 253–66 (2018). [DOI:10.1007/s10533-017-0416-8]
Complete data on location, rainfall, geology, soil, litterfall, aboveground and root biomass in 48 plots in central Panama, excel format
SC-33.1 Earth and Environmental Sciences Division, BER
BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER
Mar 23, 2021
Molecular Connections from Plants to Fungi to Ants
Lipids transfer energy and serve as an inter-kingdom communication tool in leaf-cutter ants&rsqu [more...]
Mar 19, 2021
Microbes Use Ancient Metabolism to Cycle Phosphorus
Microbial cycling of phosphorus through reduction-oxidation reactions is older and more widespre [more...]
Feb 22, 2021
Warming Soil Means Stronger Microbe Networks
Soil warming leads to more complex, larger, and more connected networks of microbes in those soi [more...]
Jan 27, 2021
Labeling the Thale Cress Metabolites
New data pipeline identifies metabolites following heavy isotope labeling.
Aug 31, 2020
Novel Bacterial Clade Reveals Origin of Form I Rubisco
List all highlights (possible long download time)