Monitoring ecological indicators of rangeland functional integrity and their relation to biodiversity at local to regional scales

• Published in: Austral ecology Vol. 29; no. 1; pp. 108 - 120
• Main Authors: Ludwig, J.A, Tongway, D.J, Bastin, G.N, James, C.D
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science, Ltd 01.02.2004
• Subjects: biodiversity; landscape function; landscape integrity; monitoring; rangeland; remote-sensing; Australia
• ISSN: 1442-9985; 1442-9993
• DOI: 10.1111/j.1442-9993.2004.01349.x

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.