This award will support collaborative research in ecology between Dr. Robert Antibus, Clarkson University and Dr. John Dighton, Merlewood Research Station, Institute of Terrestrial Ecology, Cumbria, England. The objective of the project is to investigate hydrolytic enzyme production by ectomycorrhizae collected in different age forest stands. Mycorrhizae are mutualistic associations formed between roots of higher plants and fungi. Most commercially important temperate zone trees form ectomycorrhizae. Numerous species of fungi are capable of forming ectomycor- rhizae with a particular tree species. However, little is known about factors that affect fungal distribution and how different fungi influence tree growth. The concept of ectomycorrhizal fungal succession has recently been studied by researchers in England. They have shown that as trees age, the species of ectomycorrhizal fungi fruiting in a stand change. The proposed studies will be conducted in different age class stands of Sitka spruce in England. Dr. Dighton at the Merlewood Research Station has collected background data on these stands for several years. During this project, Dr. Antibus will spend two field seasons at Merlewood. The proposed work will bring together Dr. Antibus' expertise in ectomycorrhizal enzyme research with Dr. Dighton's work on fungal succession and phosphorus uptake in relation to tree nutrition. Valuable information will be gained from this study relative to the function of ectomycorrhizae in forest nutrient cycles. The information obtained and methods applied will be important to forest ecologists and managers in many parts of the world.