The woody plant Haloxylon ammodendron (C. A. Mey.) provides new insights into the self-thinning relationship and size inequality with wind erosion stress

The self-thinning process and size inequality of plants change with age and wind erosion stress conditions. In this study, we used Haloxylon ammodendron shrubs in their juvenile stage (1–6 years) were the study subjects. Their density, height, and survival were investigated. The relationship between the mean and variation in the densities was calculated using Taylor’s power law, and the change laws of the density clustering state were analyzed. Additionally, changes in size inequality and the self-thinning process were examined. The results indicated that under the same wind erosion stress, the self-thinning slope was positive (P < 0.05); the shrub density aggregation of H. ammodendron became denser with increasing wind erosion stress. The size inequality first increased and then decreased as the developing stage progressed. Under the same stress, the competition index increased with increasing age and decreased with increasing stress. We demonstrated that under a harsher microenvironment for plant growth, plants clustering and growth increased facilitation, resulting in a shift in the net effect of the positive and negative interactions between individuals. Furthermore, the results revealed that as age increased, the size inequality was left-skewed.