Integrating indicators, endpoints and value systems in strategic management of the rivers of the Kruger National Park

1. In trying to operationalize the notion of sustainable ecosystem health, ecologists have focused on identifying sets of indicators which can be used to assess river condition relative to some normative, undegraded condition . Recognition and description of this normative state has proved elusive, p articularly in highly variable semiarid ecosystems. Without an operational definition of the desired system condition that reflects both scientific ri gour and broader societal value systems, rivers are unlikely to be managed effectively. 2. Managing river health should not be confused with measuring it. Many mon itoring or assessment programs become ends in themselves instead of being t he means to achieving specific management goals. The absence of a test of t he results of monitoring further introduces the risk of management by obser vation and 'pseudo-fact'. Health 'endpoints' provide a scientific descripti on of management goals, while 'values' provide a societal perspective. Toge ther they complement the use of indicators and provide the basis for a stra tegic rather than reactive approach to management. 3. The integration of value systems, endpoints and indicators of ecosystem health or ecosystem integrity forms the cornerstone of a consultative manag ement process for the rivers of the Kruger National Park. 4. An objectives hierarchy has been developed to service management's insti tutional hierarchy. 'Vision' and objectives serve upper levels of managemen t with value based statements of strategic intent which have been tested ag ainst public opinion. Goals provide managers on the ground with specific ec ological endpoints termed 'thresholds of probable concern' (TPCs). TPCs are described by a range of spatially and temporally bounded indicators of the system's response to the main potential agents of change. 5. TPCs represent statements or hypotheses of the limits of acceptable chan ge in ecosystem structure, function and composition. They thereby provide a n inductive and strategic approach to adaptive management in a data poor si tuation. Integrated monitoring, research and modelling track criteria relat ive to TPCs and question whether management action, or recalibration of the TPC, is needed. TPCs thus provide direction for management but their valid ity and appropriateness are frequently challenged and adaptively modified. 6. The objectives hierarchy gives Kruger Park management a mandate to 'main tain biodiversity in all its natural facets and fluxes'. Alluviation, as a consequence of increased sediment supply and decreased sediment transport c apacity, is a major threat to the biodiversity of the bedrock-controlled ri vers which flow through the park. Thus, for example, TPCs for geomorphic di versity reflect permissible ranges of change in bedrock character of the ph ysical template. They are measured as change in the proportion of different geomorphic units in identified representative reaches. TPCs for riparian v egetation are measured as change in population structure of selected specie s within the representative reaches. They reflect a likely range of biotic responses to change in the physical template. A specific set of indicators, reflecting response to the major agents of change, therefore provides a pa rsimonious program for assessing ecosystem condition relative to explicit g oals and a clearly defined management process.