Shrub patch configuration in relation to precipitation and soil properties in Northwest China

Shrubland that is patterned by shrubby and herbaceous patches differs in scale and shape across semiarid and arid regions. The configuration of shrub patches and herbaceous vegetation determines ecosystem structure and affects a range of ecosystem functions. Understanding what controls patch configurations can provide fundamental insights into the structure and function of ecosystems. The object of this study was to examine the difference in shrub patch configuration along precipitation gradient and to what extent climate, soil and vegetation affect the shrub patterns based on a data set of 18 plots sampled at 6 sites in Northwest China. We acquired shrub patch configuration and corresponding soil, vegetation properties within a precipitation gradient transect through field investigation. Shrub cover (SC) significantly increased with increasing precipitation. While patch size, height and density showed parabola fitting. Landscape indexes reflected that JQ and TP already formed a good connectivity, but other sites had dense patterns with multiple patches. And in other sites, there was no obvious dominant patch type and all types of patches distributed uniformly in landscape. Overall, the configurations of shrub patch can be divided into two groups. JQ and TP showed many similarities and were different from all other sites. PCA ordination diagrams showed that three replicates of each study sites usually distributed closely, suggesting its internal similarity in shrub patch configuration. Vegetation, weather and soil all impacted the formation of shrub patch configurations with a total interpretation of 76.8% (64.3% after adjusted) with RDA and variation partitioning analysis. Vegetation itself had the highest explanation as 30.9% (p = 0.026), while weather (2.3%) and soil (0.2%) were small. But the combined effects of weather & vegetation and weather & soil was relatively high as 15.6% and 15.3%. These results in Northwest China could provide fundamental insights into the variations of shrub patch configurations along with precipitation gradient and possible factors that affect shrub patterns configuration in arid and semiarid areas.