Abstract
This project will explore the magnitude and duration of effects from operational forest fertilization on forest biodiversity and productivity. The official report on fertilization effects on forest ecosystems (Nitrogen 2002 – an impact assessment of forest fertilization in Sweden) stated that the current operational practice of adding 150 kg N ha-1 yr-1 for up to three times during a forest generation caused only short-term (< 10 years) effects of moderate magnitude on forest biodiversity and productivity. In sharp contrast, we have found strong evidence for significant long-lasting (> 20 years) effects of fertilization on forest biodiversity. The effects appeared in the forest generation following the one fertilized, and included increased abundance of grasses and N-favored herbs/mosses, and decreased (c. 40 %) abundance of Vaccinium dwarf-shrubs. In the context of forest productivity, the observed changes in plant community composition suggests that forest fertilization had induced a permanent shift of the site index, with a long-lasting fertilizer derived enhancement of tree growth. The planned project will quantify long-lasting fertilization effects on forest biodiversity and productivity, and identify responsible mechanisms. Knowledge provided will be critical for the Swedish forestry sector in its effort to make informed decisions about the optimal forest management strategy to ensure that both production and nature conservation goals are accomplished.
Sweden