1 Disturbance, Nutrient Availability and Plant Growth in Phenol-rich Plant Communities

Disturbances, such as fire, usually result in a higher N and nutrient availability. However, little is known regarding the role of fire-produced charcoal and other disturbance-induced effects on nutrient availability and the consequences for plant growth and ecosystem development. Late-successional boreal forests and subarctic forest-tundra ecotones are dominated by plants with high tissue-levels of phenolic compounds and have large quantities of N locked up in thick humus-layers. Factorial experiments were set up in both field and laboratory, manipulating amount of phenol-rich litter, charcoal and glycine. Nitrogen mineralization, nitrification, soluble P and phenolic compounds were measured by ionic and non-ionic resin capsules. Nitrogen-fixation was measured by acetylene reduction assays. Removal of phenol-rich litter with the charcoal-layer intact in a recently burned stand increased growth and nutrient uptake by tree seedlings, with birch (Betula pendula) being the most responsive species. Litter and charcoal may function synergistically thus influencing seedling establishment after fire, especially in early-successional species like birch. Nitrification-rates increased with addition of activated carbon (AC) (as a surrogat