Austral Ecology (2004) 29, 108–120 Monitoring ecological indicators of rangeland functional integrity and their relation to biodiversity at local to regional scales JOHN A. LUDWIG, 1* DAVID J. TONGWAY, 2 GARY N. BASTIN, 3 AND CRAIG D. JAMES 3 1 Tropical Savannas CRC and CSIRO, PO Box 780, Atherton, Queensland 4883, Australia (Email: john.ludwig@csiro.au), 2 CSIRO, Canberra, Australian Capital Territory 2601, Australia and 3 CSIRO, Alice Springs, Northern Territory 0871, Australia Abstract Functional integrity is the intactness of soil and native vegetation patterns and the processes that maintain these patterns. In Australia’s rangelands, the integrity of these patterns and processes have been modified by clearing, grazing and fire. Intuitively, biodiversity should be strongly related to functional integrity; that is, landscapes with high functional integrity should maintain biodiversity, and altered, less functional landscapes may lose some biodiversity, defined here as the variety and abundance of the plants, animals and microorganisms of concern. Simple indicators of biodiversity and functional integrity are needed that can be monitored at a range of scales, from fine to coarse. In the present paper, we use examples, primarily from published work on Australia’s rangeland, to document that at finer patch and hillslope scales several indicators of landscape functional integrity have been identified. These indicators, based on the quantity and quality of vegetation patches and interpatch zones, are related to biodiversity. For example, a decrease in the cover and width (quantity) and condition (quality) of vegetation patches, and an increase in bare soil (quantity of interpatch) near cattle watering points in a paddock are significantly related to declines in plant and grasshopper diversity. These vegetation patch-cover and bare-soil indicators have been monitored traditionally by field-based methods, but new high-resolution, remote-sensing imagery can be used in specific rangeland areas for this fine-scale monitoring. At intermediate paddock and small watershed scales, indicators that can be derived from medium-resolution remote-sensing are also needed for efficient monitoring of rangeland condition (i.e. functional integrity) and biodiversity. For example, 30–100-m-pixel Landsat imagery has been used to assess the condition of rangelands along grazing gradients extending from watering-points. The variety and abundance of key taxa have been related to these gradients (the Biograze project). At still larger region and catchment scales, indicators of rangeland functional integrity can also be monitored by coarse-resolution remote-sensing and related to biodiversity. For example, the extent and greenness (condition) of different regional landscapes have been monitored with 1-km-pixel satellite imagery. This regional information becomes more valuable when it indicates differences as a result of land management. Finally, we discuss potential future developments that could improve proposed indicators of landscape functional integrity and biodiversity, thereby improving our ability to monitor rangelands effectively. Key words: biodiversity, landscape function, landscape integrity, monitoring, rangeland, remote-sensing. INTRODUCTION The rangelands of Australia are vast, covering 6 million km 2 , and are highly complex, with climate, vegetation, soil and biota varying greatly across the continent (Harrington et al. 1984). These rangelands, defined as those landscapes where the primary use is pastoral, have been classified into bioregions that vary in their likely value for pastoral use and their likely susceptibility to damage by this use (Stafford Smith et al. 2000; Smyth et al. 2003). This pastoral damage takes many forms, but one impact is the loss of land- scape functional integrity, which is the intactness of natural vegetation and soil structural patterns and the processes that maintain these patterns. This loss of landscape functional integrity, including the shelter and food provided by vegetation, is a likely cause of known extinctions and reported declines in native herbaceous plants, small mammals and granivorous birds in rangeland bioregions (Woinarski 1999). However, these losses in functional integrity, and hence in bio- diversity, have occurred at different spatial scales, from local hillslopes to regional catchments. We need to understand better these scale-dependent relationships between losses in functional integrity and losses in biodiversity, defined here as the variety and abundance of the plants, animals and microorganisms of concern. *Corresponding author. Accepted for publication September 2003.