Managing low-output agroecosystems sustainably: the importance of ecological thresholds

Managing vegetation to achieve ecological, economic, and social goals is difficult. Inherent complexity among ecosystem components and unpredictable climate often limit opportunities for converting cultural inputs to harvestable products. In addition, the long lag time between treatment and financial return makes capital investment in vegetation management economically risky. One tool that can assist land managers in dealing with these constraints is the identification of ecological thresholds and elucidation of processes that signal undesirable change before it is entrained. This approach places a premium on early detection of degrading processes and implementation of management responses in the initial stages of land degradation. Managerial expertise and manipulation of naturally occurring processes, rather than cultural inputs, are key management decisions. In this paper we review current applications of the threshold concept as a management decision point and propose modifications for use in managing plant communities with low potential for annual economic return. We also propose that research and institutional programs for sustainable land management shift direction toward identifying ecological thresholds and focus on developing low-input responses to avoid, rather than restore, land degradation.