Drought Resistance of Desert Riparian Forests: Vegetation Growth Index and Leaf Physiological Index Approach

The Hotan River, the sole river traversing the Taklimakan Desert in northwest China, sustains a critical desert riparian ecosystem dominated by Populus euphratica. This riparian habitat is integral to biodiversity maintenance. However, global climate change and anthropogenic disturbances have profoundly impacted the Taklimakan desert landscape, leading to fragmentation and reduced environmental heterogeneity. Consequently, there has been a notable decline in P. euphratica populations. This study aimed to assess the physiological resilience of P. euphratica under harsh conditions and analyze the vegetation distribution patterns along the desert riparian zone. Laboratory tests were employed to determine the physiological indexes including Relative Water Content (RWC), Chlorophyll (Chl), Soluble Sugar (SS), Free Proline (Pro), and Peroxidase Activity (POD) of P. euphratica, providing insights into its capacity to endure challenging environmental conditions. Quadrat surveys were conducted at varying distances from the riverbed to examine vegetation distribution patterns. Plant growth indexes were analyzed to unveil the resistance of the desert riparian forest to drought. The study identified 45 shrubs and herbs belonging to 17 families in the Hotan River understory, with P. euphratica exhibiting the highest abundance. In river flats, annual herbs dominated due to favorable water conditions, while shrub grasslands displayed a relatively complete community structure with trees, crowns, and grasses. As the distance increased from the river channel, more perennial herb and shrub species prevailed, leading to a decline in overall species richness as annual herbs diminished. Physiological assessments revealed that P. euphratica in a medium growth grade (VS3) exhibited the highest physiological indexes, indicating its adaptability to environmental changes. The findings underscore the significance of water conditions in the growth and development of vegetation in desert riparian forests, particularly highlighted by the physiological indexes of P. euphratica. This research contributes valuable insights that can inform the preservation and restoration of desert riparian forests, providing a scientific basis and technical guidance for conservation efforts.