The structure and spatial patterns of three desert shrub communities in the western Ordos Plateau: Implications for biodiversity conservation

The western Ordos Plateau, China, is characterized by shrub species richness. Serious desertification in the western Ordos is threatening some shrub species with high conservation value. We used spatial indices and spatial point pattern analysis methods to investigate several aspects of three western Ordos desert shrub communities. We examined the general spatial patterns of the whole community and of each pair of individual shrub species, and we investigated the interactions of each pair of individual shrub species and of each pair of physiological groups. In the three communities studied, general aggregated patterns were found for the whole community and for each shrub species. These patterns can be explained by the patchy desert environment and by low seed production and dispersal. In this harsh desert environment, the positive interaction between gravel-tolerant and salt-tolerant shrub species in the three communities results in a relatively stable community with a positive successional process. Sand-tolerant shrub species, encroaching on this region from the peripheral desert, are in competition with gravel-tolerant or salt-tolerant shrub species. The formation and development of Nitraria tangutorum sand mounds poses a major threat to gravel-tolerant and salt-tolerant shrub species and to the communities they form. This study offers insights into the aggregated patterns of individual species, into the interactions among pairs of shrub species and among pairs of physiological groups, and into the degradation of endangered ecosystems. This degradation is associated with the loss of key shrub species in the three desert shrub ecosystems. These insights will be useful for implementing protective strategies for endangered shrub species in this region.