Main concerns relate to the impacts of human activities on biodiversity. Pressures can be physical (habitat alteration and fragmentation through changes in land use and cover), chemical (toxic contamination, acidification, oil spills, other pollution) or biological (alteration of population dynamics and species structure through the release of exotic species or the commercial use of wildlife resources). Primaiy drivers are land use changes for conversion from natural state to agriculture and infrastructure, unsustainable use of natural resources, invasive alien species, climate change and pollution.