Suserup Skov (19.2 ha) is an old growth temperate forest dominated by beech Fagus sylvatica, pedunculate oak Quercus robur, ash Fraxinus excelsior, wych elm Ulmus glabra, and black alder Alnus glutinosa, admixed with lime Tilia platyphyllos and sycamore maple Acer pseudoplatanus. KU/IGN-SNB, is a 19,2 ha old-growth beech-dominated mixed deciduous forests on western Zealand owned by Sorø Academy. The forest use dates back to 4200 BC. A conservation act was placed on the forest in 1925 for biological and recreational purposes but allowing a minimum odd felling until the act was updated in 1961 to a non-intervention forest. The forest is unique at European level in terms of nonintervention, and the long-term status as non-intervention forest has led to a unique steady state in biomass and accumulation of dead wood, thus serving as an important reference site for unmanaged temperate deciduous forest development. There are long-term data records of e.g. biomass, dead organic matter, soil, forest structure, flora and fungi starting from 1992. The platform is included in a series of paired managed and non-intervention forests for studies of forest structure, biodiversity and biogeochemistry in mature and old beech-dominated forests. Suserup Forest includes an ICP Forests level II plot (2001-). Upgrades: eLTER master sites: soil moisture content (TDR), remote sensing of growth and forest structure, LAI, NDVI (Lidar, camera), continuous plant phenology (web cam),and insect monitoring (optical sensors) as biodiversity measures, ambient air quality and air pollution.