Fig. 2. The maps show the study area in the Stockholm Metropolitan Area, Sweden. The right map is marked with 17 local study sites (small and extended areas), alongside the system of large “green wedges” in-between areas of development and transport infrastructure. Stockholm is situated at the boundary between the northern hemisphere boreal zone and the mid-European nemoral zone, and at the outlet of the freshwater lake Mälaren into the brackish Baltic Sea (59º20′ N, 18º05′ E). The physical landscape is shaped by the last glacial period 10,000 years ago, followed by cultural human practices and it consists of fissured bedrock, clay-covered valleys, and a small-scale rough terrain with a range of habitats conveying a relatively high biodiversity. Stockholm hosts a current population of 1.2 million people; it is the most rapidly growing and most densely populated region in Sweden with 2500 inhabitants/km² (SCB 2007).