干旱区生态环境知识资源中心

Abundance-occupancy relationships were determined for desert plants in the northwestern Red Sea region, at both the whole landscape, and individual habitat levels. Some 58 stands (having a total of 66 species) were studied, using ten quadrats (10 x 10 m(2)) per stand. The relation was positive and highly significant at both scales, but stronger at habitat level than across the regional landscape. Niche-breadth was estimated as the number of habitats occupied regionally by a species, and was significantly related to both abundance and occupancy. Niche breadth explained just 10.1% of variation in abundance but some 56.2% of variation in occupancy. Using empirical data, we tested whether those abundance-occupancy relationships diverged significantly from a theoretical null model. Relationships diverged significantly from the null model at both regional landscape and habitat levels. Applications of abundance-occupancy relationships for plant conservation showed that 36% of the species in the study region is at risk of extinction.