Roots and associated mycorrhizae are unevenly distributed in the soil. Some three-dimensional spaces in the soil can be envisioned as "hot spots" or "islands" of root and mycorrhizal activity. These islands affect soil structure, soil micro- organisms, and soil processes - forming an interconnected matrix. The central thesis of this project is that rhizosphere islands are formed in soils, that islands are dependent upon above-ground energy supply for their continuation, that mycorrhizae affect islands size and stability, and that islands change when vegetation changes. Primary research objectives are: to develop methods to measure patterns of rhizosphere islands in a forest soil over a range of scales and to develop spatial statistical methods to detect patterns of islands in soils against a background of pattern created by above-ground (allogenic) inputs. The below- ground (autogenic) inputs will be characterized using both conventional measures (e.g., soil pH) and newer, non-invasive methods of nuclear magnetic resonance. NMR will be used characterize soil organic carbon (c-13 NMR) and soil organic and inorganic phosphorus (p-31 NMR). Proton NMR imaging (MRI) will be used characterize spatial 2-dimensional patterns in soils nondestructively. The significance of this research lies in the quantification of spatial patterns of physiological activity in soils. By measuring this essential property one can understand how interacting processes in soils function to support plant growth. The scientists involved in this collaboration are excellent. Institutional support is quite good. The introduction of these new methodologies into ecological research could have a major positive effect. The Ecosystems Studies Program recommends that this award be made.
