The influence of N load and harvest intensity on the risk of P limitation in Swedish forest soils.

Nitrogen (N) is often considered to be the major factor limiting tree growth in northern forest ecosystems. An increased N availability, however, increases the demand for other nutrients such as base cations and phosphorous (P) which in turn may change which nutrient is the limiting factor. If P or base cations become limiting, N will start to leach which means a risk of increased eutrophication of surface waters.

Effects of hardened wood ash on microbial activity, plant growth and nutrient uptake by ectomycorrhizal spruce seedlings.

Abstract Plant growth, nutrient uptake, microbial biomass and activity were studied in pot systems containing spruce seedlings colonised with different ectomycorrhizal fungi from an ash-fertilised forest. The seedling root systems were enclosed in mesh bags inside an outer compartment containing crushed, hardened wood ash. Three different species of mycorrhizal fungi and a non-mycorrhizal control were exposed to factorial combinations of ash and N addition.