Comments on historical variation & desired condition as tools for terrestrial landscape analysis

Abstract

Historic (natural or reference) variability and desired condition are key ecosystem-management concepts advocated in many approaches to terrestrial landscape analysis. Historical variation is considered to be a conservative indicator of sustainability. If current conditions are outside the range of historic values, management actions are described to realign the system within historic ranges. Based on historic variability and social preferences, a management goal called the desired condition is developed This paper examines some of the arguments for and against the use of historic analysis as a direct guide to setting management goals. Among the concerns are inadequate time depth used persistence in inferring historic conditions even where data are unavailable or unknowable, emphasis on using historic values of individual elements rather than composite ranges for multiple indicators, lack of understanding of the hierarchic nature of ecosystem change and higher order environmental influences on ecosystems and their implications for management. Despite criticisms of direct prescriptive applications, however, historic data provide some of the best sources of information about ecosystem behavior, and should remain central to both ecosystem management research and application. With suggested mod$cations in approach, historic data should be included wherever possible in landscape analysis.

Citation

Millar, Constance I. 1997. Comments on historical variation & desired condition as tools for terrestrial landscape analysis. Proceedings of the Sixth Biennial Watershed Management Conference. S. Sommarstrom, editor. Water Resources Center Report No. 92. University of California, Davis (1997): p. 105-131