Censuses of tropical forest plots reveal large variation in biomass and plant composition. This paper evaluates whether such variation can emerge solely from realistic variation in a set of commonly measured soil chemical and physical properties. Controlled simulations were performed using a mechanistic model that includes forest dynamics, microbe-mediated biogeochemistry, and competition for nitrogen and phosphorus. Observations from 18 forest inventory plots in Guanacaste, Costa Rica were used to determine realistic variation in soil properties. In simulations of secondary succession, the across-plot range in plant biomass reached 30% of the mean and was attributable primarily to nutrient limitation and secondarily to soil texture differences that affected water availability. The contributions of different plant functional types to total biomass varied widely across plots and depended on soil nutrient status. In Central America, soil-induced variation in plant biomass increased with mean annual precipitation because of changes in nutrient limitation. In Central America, large variation in plant biomass and ecosystem composition arises mechanistically from realistic variation in soil properties. The degree of biomass and compositional variation is climate sensitive. In general, model predictions can be improved through better representation of soil nutrient processes, including their spatial variation.
Bibliographical noteFunding Information:
DM, BGW, and JSP were supported by the US Department of Energy, Office of Science, Terrestrial Ecosystem Science Program, Award DE-SC0014363. The field plots were maintained by National Science Foundation CAREER Grant DEB-1053237 to JSP. GW was supported by the Energy Exascale Earth System Model (E3SM) project and the Climate Model Development & Validation (CMDV) project under contract DE-AC05-00OR22725 to Oak Ridge National Laboratory. WJR and QZ were supported by the RUBISCO Scientific Focus Area under contract DE-AC02-05CH11231 to Lawrence Berkeley National Laboratory. The original manuscript was significantly improved by the comments of four anonymous reviewers.
- ecosystem composition
- forest biomass
- soil nutrients
- soil texture
- spatial variation
- terrestrial ecosystem modelling
- tropical forests