The Ellis paradigm — humans, herbivores and rangeland systems

The scientific and conceptual contributions Jim Ellis made throughout the course of his career reveal a logical progression towards increased understanding of pastoral ecosystems worldwide. Research in wildlife, large herbivores, systems ecology and energy flows through grazing ecosystems formed the basis of his approach. A leader of the South Turkana Ecosystem Project (STEP), he showed the adaptive basis for opportunistic and spatially extensive resource use in temporally and spatially variable environments. After the STEP, he examined pastoral ecosystems in northern and central Asia and elsewhere in Africa. Spatial extensivity, or scale, emerged as being critically important to pastoral ecosystem function. Livestock development schemes based upon inappropriate ecological and economic assumptions are all too often ecologically and economically unsustainable. However, a new paradigm of pastoral ecology and development is emerging. The paradigm is derived from basic, but comprehensive, understanding of the ecologically adaptive features of pastoral resource utilisation strategies, and the ecological processes and constraints that determine energy flows from plants to livestock and humans in spatially and temporally variable environments. Jim Ellis contributed greatly to improved understanding of the importance of mobility and opportunism in these ecosystems. This understanding could benefit humans, ecosystems and wildlife over a vast portion of the earth’s surface.