Abstract: Stable and complex natural environments are favorable to the formation and conservation of biodiversity,while the changing and simplified disturbed environments usually damage biodiversity.A case study in the central Yunnan Province shows that 36 species or 30% of the 119 plant species will go to extinction when the zonal evergreen broad leaved forest is replaced by secondary grasslands.It is required that suitable environments for the species to survive permanently be provided.The concept of biological minimum area,which consists of space minimum,resistance minimum and regeneration minimum,and which deals with relationships between the permanent survival of species and the size of plant community or landscape, is the most fundamental theoretical framework for biodiversity conservation. According to the practices of natural conservation,a concept of minimum landscape is added to the concept of biological minimum area.The author also discusses the applications of the concept of biological minimum area to the management of nature reserves, the investigation of the natural characteristics of the preserved species and their habitats, and the establishments of a more ecologically sound nature reserves network.