2024 Abstracts

Canopy to Root Zone Soil, Water, and Nutrient Dynamics from Field Observations Across Different Environmental Gradients in the Neotropics


Kurt Solander1* (ksolander@lanl.gov), Adam Collins1, Iana Grúllon2, Tana Wood2, Regison Oliveira3, Alicia Monteiro3, Bruno Gimenez4,6, Robinson Negron-Juarez5, Alfonso Zambrano6, Jeff Warren7, Cynthia Wright8, Brent Newman1, Jeffrey Chambers4,5


1Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM; 2International Institute of Tropical Forestry, USDA Forest Service, Luquillo, PR; 3Forest Management Laboratory, National Institute of Amazonian Research, Manaus, Amazonas, Brazil; 4Department of Geography, University of California–Berkeley, CA; 5Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA; 6Smithsonian Tropical Research Institute, Panama City, Panama; 7Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN; 8Southern Research Station, Forest Inventory and Analysis, USDA Forest Service, Knoxville, TN



The ability to measure water and nutrient fluxes from the canopy to the root zone is key to understanding vegetation dynamics in tropical rainforests. Simultaneous measurements of these variables through time can provide powerful insights on the various processes responsible for changes in plant growth and function. The project pairs water volume and nutrient measurements from precipitation, throughfall, and subsurface soil water infiltration to investigate the dynamics of these fluxes across space and time. Sites were selected within tropical rainforests of Brazil, Panama, and Puerto Rico to investigate changes across different soil texture, seasonality, topography, and rainfall gradients. Each field site was conveniently co-located with additional observations that included temperature (air, plant, and soil), evapotranspiration, sap flow, soil moisture, soil matric potential, and leaf area index, which collectively aid in better constraining the impacts of these fluxes on plant function and growth as well as providing estimates of local water balance closure. Researchers compare the impacts of El Niño on these fluxes across sites given the difference in proximity to the El Niño source region. In addition, subdaily infiltration observations were used to run an inverse model simulation within the HYDRUS-1D model to estimate the pedotransfer functions and the soil water retention curve (SWRC). Results reveal the importance of wet and dry season dynamics and soil texture on the water and nutrient fluxes as well as the importance of soil texture and topography in pedotransfer functions and the SWRC. This research will provide useful benchmarks of water and nutrient fluxes as well as soil properties within tropical rainforests that will be used in the development of the Functionally Assembled Terrestrial Ecosystem Simulator model.