Modeling belowground competition between grass and shrubs with variable rooting depths and profiles in a semiarid shrub community

Background/Question/Methods: Grass-to-shrub transition has been recognized as an important process of desertification in the world. Previous models often use fixed rooting depths and rooting profiles for functional types. In this paper, we used a modified pipe model to release the restriction of the fixed rooting profile, so that both functional types can grow into depths allowed by the soil water conditions and the dependence of the root density is also determined by the soil water condition.

Results/Conclusions : 

The integrated ecosystem model was then used to simulate the effect of the interannual variability of rainfall on the pattern of biomass and soil moisture in temperate shrub community in northern China. We found that rainfall interannual variability was in favor of the shrubs in the competition with the grasses, and helped to maintain their dominance over a longer time. The interannual variability of rainfall was also a major causual factor of the complex soil moisture dynamics.