The set of plots is based on 40 preselected forest stands (called regular measurement plot, RMPs) across the federal state of Lower Saxony that contain series of mixed species plots (Douglas-fir and European beech, Norway spruce and European beech, respectively) and pure species plots. The RMP stands are older than 60 years and comprise 8 ‘quintets’ each with three pure plots (European beech, Douglas-fir, Norway spruce) and two beech-conifer mixtures (beech-Douglas-fir and beech-Norway spruce). The quintets will be used to avoid bias due to regional clustering of stand types. The RMPs will cover a range of nutrient and water conditions. The stands have been managed according to the currently best practice guidelines of the lower Saxony state forest enterprise. Species in a mixed RMP stand contribute > 20 % to the basal area. Each plot is 50 m x 50 m in size. Depending on the ecosystem level under investigation, additional measurements of different intensity will take place on the plots. Very laborious measurements will be conducted on a sub-set of 20 plots out of the total number of 40 plots. On these 20 intensive measurement plots (IMPs, 4 quintets along the range of nutrient and water conditions of the RMPs), intensive measurements will be carried out beside the regular measurements of all subprojects. Permanent, highly intensive measurements will be done on special measurement plots (SMPs) which are a subset of 10 out of the 20 IMPs. Thus, the experimental layout is a nested design.
