LANDSCAPE DISTRIBUTION OF ORGANISMS AND THE SCALING OF SOIL RESOURCES

We demonstrate that the competitive ability and landscape distribution of organisms can be affected by the interaction between their size and scaling properties and the scaling properties of the resources they consume. First, we prove that the landscape distribution of plants can be significantly affected by the interaction between their root lateral spread (RLS) and the scaling of soil N. Furthermore, we show that the nature of this interaction is highly dependent on the levels of soil N and plant age (adults or seedlings). We also demonstrate how the optimal RLS depends on the combination of soil N scaling properties at different levels of resolution. We made the ALLOCATE model spatially explicit for RLS and soil N scaling to analyze plant competition in a fractal environment. We show that, on the average, plants with low RLS and high root density (RD) dominate under low N stress, while plants with high RLS and low RD dominate at high N stress and that the scaling of soil N significantly controls the degree of dominance and the performance of seedlings. These results may cast some light regarding present disagreements as to which plant trait may be optimal in the competition for soil nutrients.