Combining trait- and individual-based modelling to understand desert plant community dynamics

Understanding the mechanisms driving community dynamics helps us to make reliable predictions about communities’ response to environmental change. Studying desert plant communities is particularly challenging because of strong intra- and interannual fluctuations in precipitation. Models rise to this challenge by providing an arena for systematic evaluation of the parameter space in virtual experiments. We applied a trait- and individual-based model to explore how community dynamics arise from the plant traits and interactions of plants with other plants and with their environment. The model is based on data from annual plant communities in the Negev Desert dominated by the True Rose of Jericho (Anastatica hierochuntica). We showed that functional traits that are involved in plant-plant interactions are equally important for community dynamics as traits promoting tolerance to abiotic stress. The sensitivity analysis of the model highlights relative growth rate, maximum biomass, the amount of time in dormancy and germination probability as the most important traits for community dynamics. The model reflects the particular importance of environmental factors such as precipitation and soil water availability based on topography for community dynamics. Our model benefits from the ability of individual-based models to capture plant-plant interactions and derive community properties from individual characteristics and from the feature of trait-based approaches to link traits to organismal functions. Our study demonstrates the advantages of the combined use of trait- and individual-based models for investigating community drivers in changing extreme environments.