Sustainable Use and Development of Forests and Forest Soils: A Resume

Abstract

This chapter recaps the outcomes of the National Forest Soil Inventory (NFSI) and the Intensive Forest Monitoring studies, discussing their implications for forestry and forest policies. Clean air policies and forest liming show an effect against soil acidification with sulfur and total acid deposition strongly decreasing over the last decades. Forest liming proved to be suitable to preserve acid-sensitive forest soils. Nitrogen eutrophication remains challenging with nitrogen deposition still being high resulting in an exceedance of critical loads for eutrophying nitrogen on many NFSI sites. Nitrogen oversupply can induce negative effects on forest biodiversity and tree nutrition and can lead to nitrate leaching into the groundwater. Due to this, the reduction of nitrogen emissions should receive high political priority. Nutrient sustainability limits biomass harvest options: many forest sites have a limited natural supply of Ca, Mg, and K, and ecosystem balances of these are often negative. Due to this, increased harvest intensity, in particular of total biomass above ground, must be carefully adjusted to the specific site conditions. Forest soils absorb heavy metals and organic pollutants (POPs) are persistent on the long term. Both heavy metals and POPs are mainly absorbed in the organic humus and soil compounds (SOC). Therefore, critical release from forest soils should be prevented by minimizing all stand and soil treatments leading to SOC decomposition. Heavy metal emissions should be strictly minimized, and pesticides with POPs should only be applied in urgent cases. Carbon sequestration in forest soil supports climate protection. Forests and forest soils provide a significant sink for CO2, complemented by the wood products from forest utilization. Sustainable forestry and highly efficient timber use in long-term products should further be supported by policies. Atmospheric pollution interacts with climate change impacts: air pollutants often predispose forests to extreme weather impacts. A significant lowering of greenhouse gas emissions is urgently needed to limit ongoing climate change (≤2-�-�C aim) to which forests in Germany are able to adapt. Forest transformation affects forest soils positively: forest transformation to broadleaved and mixed forests resulted in decreased soil acidification and increased soil organic matter. Policies should aim at increasing the mixed forest area including also coniferous species