Concept and Methodology of the National Forest Soil Inventory

Abstract

The present report is based on the National Forest Soil Inventory (NFSI) as well as on case studies from Intensive Forest Monitoring sites in Germany. The current as well as the temporal development of forest soil conditions and the major threats to forest ecosystems are discussed. Following the discussion on forest decline in 1980s, a national forest monitoring was established, consisting of the Forest Condition Survey, the Intensive Forest Monitoring as well as the NFSI. In 1984, the sites for the Forest Condition Survey were installed on a 16 × 16 km grid which is part of the UN/ECE ICP Forests Level I Monitoring as well as of the European Soil Monitoring Project (BioSoil). The NFSI plots were subsequently established based on the same grid with an 8 × 8 km raster yielding at about 1800 sampling sites. The first NFSI took place between 1987 and 1992. In 2006, the second NFSI was conducted simultaneously with the BioSoil programme. The NFSI focused on specific questions for forest soils in respect to nitrogen levels and sensitivity to inputs of nitrogen; to carbon storage and carbon stock changes; to background loading with heavy metals and organic trace elements; to the interplay of soil characteristics and forest nutrition, crown condition and vegetation; to the risk due to negative changes such as nutrient removal or soil acidification; and to effects in terms of soil chemistry and nutritional status measures to stabilize forest ecosystems. To fulfil these objectives, the NFSI included the sampling of chemical and physical soil parameters, the determination of foliar element concentrations, the assessment of the composition and diversity of understory vegetation as well as an inventory of the tree stands including dead wood. A comprehensive concept of quality control and quality assurance for field assessments, laboratories, data management and evaluations has been established to ensure data harmonization and a high quality of statistical evaluations.