Large carnivores are declining globally, with strong direct and indirect ecological impacts on protected area networks (PANs). Human encroachment on ecosystems is a global threat for large carnivores, particularly in savanna Africa, where increasing human resource demands continue to degrade the connectivity and viability PANs. Zambia has a regionally significant role in large carnivore conservation, given that it borders eight countries, includes three transfrontier conservation areas (TFCAs), and manages nearly 40 % of its land for wildlife. Deforestation in general and encroachment in particular are recognized problems in Zambian natural resource management. However, specific impacts on PANs are poorly understood owing to a lack of adequate mapping of encroachment, deriving from widespread difficulty in mapping cultivation and clearing in fire-prone savannas, and severe inaccuracy in several previous land cover data sets. Using simple manual interpretation of diverse and carefully chosen remote sensing imagery, we evaluated land use change from 1965 to 2011 in Zambia, primarily in the Luangwa Valley. We found widespread encroachment extending toward national parks from major roads as fast as 2 km/year and averaging 18 hectares per hour of daylight throughout a 159,805 km2 study area, eliminating designated buffer zones in some areas, decreasing connectivity, and potentially eliminating viable TFCAs. At current rates, Zambia’s PANs would be expected to be reduced into small isolated pockets primarily centered on national parks, with substantial human edge effects threatening the viability of wildlife populations in the region, particularly wide-ranging, low density, and threatened large carnivores such as African wild dogs, cheetah, and lion. It is thus critical that encroachment is accurately mapped across the entire region and that land use plans are developed, implemented, revised where necessary, and enforced with strong governmental support, enabling protection of these areas and the communities that depend upon them.
