Results/Conclusions
The enzymatic profiles differed with treatment and with ectomycorrhizal morphotype.  In winter, soil C degradation activity (glucoronidase) was greater in oak roots than in pine, when the deciduous Q. douglasii was leaf-less in contrast to evergreen pines.  The C demand may have been greater in oak than in pine, resulting in increased C degrading enzyme activity. Phosphatase activity was higher in ECM-pine roots than in oak, but with little seasonal effect.  Higher P demand by pines may be a function of their year-round activity, in contrast to oaks.  Ectomycorrhizal morphotypes differed in their enzymatic profiles. Phosphatase activity was uniform with depth whereas glucoronidase and leucine-aminopeptidase activities were greater in the top 15 cm of soil.   Together, these results indicate that pine and oak ECM produce extracellular enzymes targeting a broad range of resources in soils, including C, N and P resources. However, controls on these enzymes are not clear, particularly as they relate to changes in resource supplies, demands, and organism C:N:P ratios. Our research indicates that ECM have the potential to act as saprotrophs and degrade soil organic C, thus behaving facultatively as mutualists under certain conditions.  ECM enzymatic activities can enhance our understanding of coupled C, N and P interactions and the nature and occurrence of nutrient limitation in ecosystems.