A landscape connectivity index for assessing desertification: a case study of Minqin County, China

As a global and regional environmental problem, desertification assessment is an instrumental component in developing global/regional actions plans aimed at preventing and/or eradicating desertification issues. Using a landscape assessment approach allows for relatively quick assessments of desertification that can then be used in developing practicable application plans at the regional level in desertification prevention planning and decision-making. This study was conducted to determine whether a cost-distance connectivity index could both reveal evidence of, and act as an indicator for, desertification. Cost-distance, a simple GIS-calculated connectivity measure, was applied to a 1997 land use map to indicate desertification in Minqin County, China. The results showed that connectivity based on cost-distance follows basic landscape ecological principles including species-area relations and edge effects, and indicates desertification. Although grain size had a significant effect on the cost-distance index, especially at patch boundaries, log cost-distance closely corresponded with degree of desertification within grain size. Changing the extent of analysis had no significant effect on the cost-distance index and its relevance to degree of desertification. The Minqin County landscape had a high level of connectivity, although the area's grasslands, oasis irrigated cultivated lands, alkali-saline lands and forestlands played important roles in resisting desertification. Three areas require restoration of native vegetation or afforestion to cut the connectivity of desertified patches. The application of connectivity based on cost-distance provides a straightforward, easily visualized description of desertification. In addition, land use data is readily available in China, allowing for relatively easy and quick assessments of regional level desertification for planning and decision-making.