The total NPHK is currently (since 2020) about 12,000 ha, but the eLTER site corresponds to the former perimeter of the NPHK and represents an urbanised protected area of about 60km2 (or 6,000ha) located in the Province of Limburg in the East of Belgium. The NPHK (inaugurated in 2006 and extended from 6000ha to its current 12000ha in 2020), located in a former coal mining area is surrounded by 10 municipalities with more than 200,000 inhabitants, equivalent to a population density of 450/km2 . The park covers a rich variety of habitats, including heathlands, deciduous forest, coniferous forest and fens and evidently the corresponding diversity of fauna and flora. Several research groups from universities and institutes are monitoring and measuring abiotic and biotic parameters throughout the different ecosystems. Research on ecosystem services are also playing a major role, including tourism and mobility.