Global Change Impacts on Growth Strategies of Deep-Rooted Plants in Hyperarid Deserts

In the context of global change, desert ecosystems within extremely arid regions, such as the Taklamakan Desert, are confronting severe environmental challenges. This desert is particularly characterized by an annual rainfall of merely 35.1 mm and soils deficient in nutrients, making water and nutrient availability primary limiting factors for vegetation growth. Among the flora in this region, Alhagi sparsifolia, a deep-rooted desert plant, is pivotal for sand stabilization and maintaining the ecological security of oases. This research, conducted through long-term controlled field experiments, delves into the impacts of two critical factors associated with global change—groundwater level and nitrogen deposition—on the survival strategies of A. sparsifolia. The findings indicate that inappropriate groundwater levels, whether excessively deep or shallow, considerably restrict the biomass accumulation in A. sparsifolia. This limitation compels the plant to reallocate biomass among its organs to adapt to environmental stress. Notably, fluctuations in groundwater levels predominantly influence the phosphorus and potassium content within the leaves, while the effects on carbon and nitrogen levels are minimal. The study further reveals that juvenile A. sparsifolia (1-2 years old) respond to groundwater level variations by extensively adjusting their nitrogen, phosphorus, and potassium utilization and recycling strategies. In contrast, older, perennial plants primarily modify their phosphorus and potassium recycling approaches to cope with environmental shifts. Additionally, nitrogen deposition has been found to significantly alter the α-diversity of soil bacteria and the nutrient content of desert plants, underscoring the broader implications of global change. In regions with shallow groundwater, surface nutrients emerge as the most significant environmental factor influencing the nutrient content of A. sparsifolia leaves. Conversely, the impacts of groundwater level, groundwater mineralization, and soil salinity are comparatively minor. These insights highlight the profound effects of global environmental changes on the survival strategies and adaptability of deep-rooted desert plants. This research not only enhances our understanding and predictive capacity regarding the responses of desert plants to global changes in extremely arid regions but also provides a scientific foundation for plant restoration and conservation initiatives in these challenging environments.