Characterization of the Ecological Integrity of Commercially Grazed Rangelands Using Remote-Sensing-Based Ecological Indicators

Document Type

Contribution to Book

Journal/Book Title/Conference

Proceedings from the 6th International Rangeland Congress

Publisher

United States Environmental Protection Agency

Publication Date

1-1-1992

First Page

778

Last Page

780

Abstract

The purpose of this research is to conduct a retrospective assessment of the ecological integrity of a semi-arid landscape subject to commercial livestock grazing. We acquired 27 years of wet and dry season Landsat satellite imagery and combined this with site biological, physical, and administrative characteristics (including historical and current ranch management records) in a Geographic Information System (GIS). A multiple-time by nested multiple-scale experimental design was used to establish causal links between remote-sensing-based ecological indicators, which were diagnostic of rangeland degradation, and management interventions. Rangeland degradation was defined as: (i) a change in plant species composition, contrary to management goals; (ii) a de- crease in plant productivity; (iii) a reduction in soil quality; (iv) accelerated soil erosion; and (v) a change in landscape composition and pattern that affect ecosystem functions. Composition and pattern refer to the spatial organization of ecosystem characteristics when viewed as patches within a mosaic, e.g. a shrub vegetation patch within a bare soil and grassland mosaic (Ludwig & Tongway 1995). Remote- sensing-based measurement indicators de- rived from these five characteristics provide a diagnostic basis for an estimate of the degree of land degradation. In this paper, we present a study which focused on characterization of the ecological resilience of an 88000 ha commercial livestock ranch.

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