Effect of desertification on productivity in a desert steppe

Desertification, one of the most severe types of land degradation in the world, is of great importance because it is occurring, to some degree, on approximately 40% of the global land area and is affecting more than 1 billion people1. Stopping or reversing this process is crucial because desertification not only results in soil degradation and decreased soil productivity2, but it also changes ecosystem function and structure3. Above-ground productivity, which correlates with key aspects of ecosystem function, has been used as an indicator of desertification4, but whether productivity is hampered by a lack of water remains a matter of debate5. Previous studies have reported that ANPP (the aboveground net primary production) is extremely heterogeneous, both temporally and spatially6, so the question of whether productivity decreases in conjunction with desertification remains a central issue in the study of the process4. In arid and semiarid regions, wind erosion7 and over-grazing8 are the principal drivers of land deterioration2,9, and recent evidence suggests that wind erosion results in the heterogeneous distribution of soil nutrients10. Su et al.11 focused on the effects of grazing on soil properties and found that over-grazing changed soil texture and the distribution of soil particle size in a sand grassland. Pei et al.12 observed that over-grazing resulted in decreased productivity, which is valuable for identifying cause–effect relationships to improve our understanding of the changes in soil and vegetation characteristics during land degradation. Recent critical load experiments have focused on individual changes in the soil or vegetation as a consequence of desertification, but these experiments have limitations and are poorly suited for elucidating the mechanisms underlying changes in the productivity of desert steppe undergoing desertification. Understanding the ecological effects of desertification on arid ecosystems is essential, and an understanding of the relationship between grassland productivity and soil properties is necessary for the long-term sustainable management of grassland ecosystems. To maintain the sustainability of desert steppe ecosystems, it is necessary to understand their vegetation degradation dynamics relative to their soil properties. In this study, we used a space-for-time method to study the relationship between vegetation productivity and soil properties and the mechanism underlying the effects of desertification on productivity in the desert steppe ecosystem of Ningxia, China. The objective was to estimate the effects of desertification on soil properties and to analyze the factors affecting vegetation productivity to explain the mechanism underlying variations in the vegetation of the desert steppe ecosystem of northern China.