About 70% of the Swedish productive forest land is certified according to either FSC or PEFC, or both systems. The average proportion retained area per clearcut is 3% (Swedish Forest Agency, 2012). In January 2005 a storm, “Gudrun”, hit southern Sweden and 70 million m3 trees fell, equivalent INCB018424 clinical trial to twice the amount of the normal annual cut in the storm area (Swedish Forest Agency, 2006),

and also strongly affecting retention amounts and patterns. Based on data from the long-term Swedish National Forest Inventory (NFI), we here assess what can be achieved by the retention approach. The aim is to quantify the development over time of retained living trees (solitary and small tree groups) and dead trees after final harvest, with a focus on young forests (0–10 years old). We want to describe such changes in relation to regions, stand age classes, ownership categories, tree diameter, tree species (living trees), tree position (dead trees; standing or lying) and decay class (dead trees). Since Sweden was so early in application of the retention approach, results PLX3397 ic50 can demonstrate more general trends and help assess and predict development in countries and regions in which the retention approach has been introduced more recently. Forests cover about 55%

of Sweden’s land area of 41 million ha (Swedish Forest Agency, 2012) and more than 90% of the productive forest land is managed more or less intensely with the clearcutting method, introduced large-scale in the 1950s. Practices have since then been largely similar for small private forest owners, large forestry companies and other forest owners. After clearcutting and soil preparation, regeneration is secured through planting (or sometimes with natural regeneration) of the conifers Picea abies (L.) Karst. and Pinus sylvestris L., later followed by pre-commercial thinning and thinning. Also Dichloromethane dehalogenase birch, Betula pendula Roth.,Betulapubescens Ehrh. is favoured to some extent.

Rotation times vary between 60 and 100 years. NFI started 1923 and performs annual inventories of all land in Sweden, providing data at national and regional levels, with focus on forest and other wooded land. The present design was introduced in 1983 (Ranneby et al., 1987). Data on trees, forests and management history are recorded by field teams in a stratified random systematic cluster design with partial replacement, and in plots with radius of 7 m, 10 m or 20 m, depending on variable. Permanent plots are surveyed every 5–10 years, and at least 5 years of data are usually needed for reliable estimates (Axelsson et al., 2010). The list of recorded variables in the NFI is extensive, covering both forestry and environmental aspects. Living and dead tree volumes and numbers can be compiled for regions, ownership categories and age classes.