There is intense competition for nutrients between understory vegetation and trees in forest ecosystems. Yet, there has been a notable lack of mechanistic analyses of belowground resource competition and the development of competition-induced resource partitioning in plant communities. This research will quantitatively evaluate belowground competition for nutrients. Mycorrhizal fungi will affect the competitive exploitation of soil resources by plants, Despite the importance of external hyphae to the function of mycorrhizae, few researchers have attempted to quantify their distribution. The objectives of this research are (i) to determine the small-scale spatial patterns of roots and hyphae of mycorrhizal fungi and assess their significance in regards to overlapping depletion zones and nutrient uptake and (ii) to examine the effects of understory roots and mycorrhizae on the seasonal and annual pattern of pine-root growth and nutrient uptake. The research will evaluate the field distribution of roots in species mixtures and monocultures. Under controlled environmental conditions, competition between external hyphae of ectomycorrhizal pine roots and external hyphae of vesicular- arbuscular mycorrhizal grass roots will be examined. Mass flow/diffusion supply models will be used to elucidate how patterns of root and mycorrhiza growth affect nutrient competition. The project will contribute basic ecological concepts which maybe infertile soils.
