Framework of the Gorongosa ecosystem

Abstract

A holistic evolutionary approach is used in the Gorongosa thesis in which emphasis is on the salient reciprocal relations and kinetic succession of land surfaces and biotic communities, influenced by landscape processes and prime mover components. As correlations of these relations and processes require both a total interacting framework and the details of its prime components, the thesis is divided into three main parts: (1) synopsis of the essence of the Gorongosa ecosystem and the approach used in field ecology (Perspective); (2) correlation of the physical and living components of the ecosystem; and (3) synthesis. The study attempts to relate the salient features of processes and correlations into a co-evolutionary whole, caught at that particular stage in space and time by the study. The chapter titled Process and Response is the central pivot of the thesis combining the kinetic aspects of geomorphological landscape changes with co-evolutionary sequences of biotic communities which change (expand, contract, and recombine) kaleidoscopically in space and time, in appearance and content. The prime movers in ecosystem change are on the physical side, nickpoint headward eroding sequences and edaphic change in soil moisture balance, and on the biotic side, the frugivores and large ungulate components which affect geomorphic and habitat modification are central. Of these, soil moisture appears to be the master factor. All climatic influences too, appear to be expressed through the edaphic controls which change in-situ, or with each geomorphic surface replacement sequence. This factor seems to orchestrate the opportunities and constraints from below on the possible community evolution possible in a particular time and place. From this, a template of salient factors of the Gorongosa ecosystem is provided for management, based on causes and trends in the kinetic evolution of the various ecosystems. To maintain a diversity of ecosystems in Gorongosa, the fundamental management action is to reinforce or reinstate the natural local base level sills which cause ponding of floodwaters responsible for the mosaic of grasslands and slack marshes of high primary productivity and ungulate carrying capacity. Concomittantly reductions of certain overpopulated ungulate species, chiefly hippo, are required so that management is effective. As natural processes are dynamic, it is necessary to identify and evaluate those salient factors operating at a particular time, as these key controls are altered and replaced by others through natural kinetic succession of landscapes and biotic communities. The salient factors governing the dynamics of an ecosystem or community thus require to be mapped at intervals, to provide templates of the trends and changing importance of key and master factors, in order to anticipate or predict what will result from their influences. With these data valid evaluation can be made with the other correlated information for meaningful management action.