Degradation mechanisms and restoration strategies of Haloxylon ammodendron Forests: Insights from water use and environmental stress

Abstract

Haloxylon ammodendron as a key sand - fixing tree species in the oasis - desert ecotone of arid regions, its degradation seriously threatens regional ecological security. In this study, by integrating heat diffusion technology, isotope tracing, and multi - environmental factor monitoring, the water - use strategies of H. ammodendron forests with different degradation degrees and their response mechanisms to environmental stresses were systematically analyzed. The results showed that net radiation was the core driving factor regulating the transpiration water consumption of H. ammodendron. Under high - temperature and drought stress, H. ammodendron reduced water consumption by decreasing the number of branches and assimilating branches. However, the shrinkage of the canopy aggravated surface wind erosion, resulting in the exposure and damage of shallow roots. Isotope analysis indicated that degraded H. ammodendron relied on water from thick roots to repair fine roots, but the water supply to the above - ground parts was limited, forming a vicious cycle of “root damage - canopy degradation - aggravated wind erosion”. Based on this, a hierarchical restoration strategy was proposed: for mildly degraded forests, pruning the canopy to optimize water distribution; for moderately degraded forests, removing secondary dead branches to reduce ineffective water consumption; for severely degraded forests, cutting the trunk and setting up sand barriers to block the sand - wind flow. The field restoration experiment in 2023 showed that the above - mentioned strategies significantly improved the survival rate and functional restoration of H. ammodendron. This study revealed the multi - scale driving mechanisms of H. ammodendron degradation, providing a scientific paradigm for ecological restoration in global arid regions.