DHILLION, SHIVCHARN.
Dept of Biology and Nature Conservation, pb5014, NLH, N-1432, Aas, NORWAY.
In a old field community local patches of plant assemblages of varying diversity were established. The use of nutrients by targeted species in localized nutrient enrichment patches was evaluated by sampling roots, mycorrhizal formation, and P and N in soil and plants. Patches dominated by a single species (>80%) had more free N and P ions in the soil than patches with 3-6 species. Plants had locally reduced AM development in enriched patches, as arbuscular development was reduced even though overall infection was rarely altered. The response of plants to enriched patches was detected earlier in patches with more than 3 species than those with lower number of species. A target species present at all levels of diversity experienced greater competition for nutrients in higher diversity patches than in lower ones. Highly mycotropic species may benefit most from AM infection in species rich patches. Implications to plant community dynamics will be discussed.