Advancing the dominance of winter annuals under changing rainfall patterns in a temperate desert of Central Asia

Abstract

Understanding how climate change-induced alterations in rainfall patterns impact the composition and structure of plant diversity is crucial. Examining variations in plant life forms is vital for comprehending ecosystem dynamics. This study analyzes plant life form diversity, rainfall variability, and the impact of different rainfall patterns on plant diversity over 15 years in the Gurbantünggüt Desert, a temperate desert in Central Asia. The study identified 96 plant species in the area, comprising 27 winter annuals and 33 perennial herbs. Over the past 15 years, species diversity has remained stable, while diversity among plant life forms has varied significantly. Winter annuals consistently dominated, showing a significant linear increase in importance values (slope=1.135). Conversely, perennial shrubs like Haloxylon ammodendron and Haloxylon persicum exhibited a marked declining trend. Over the past 15 years, the occurrence of minor (<1 mm) and moderate (1–5 mm) rainfall during the spring and autumn seasons initially rose and subsequently fell. Concurrently, heavy rainfall events (≥5 mm) in spring have waned, showing notable yearly fluctuations. The frequency of heavy autumnal downpours has remained steady, with consistent interannual variations. Minor rainfall events primarily influenced winter annuals and perennial herbs during the spring and autumn, whereas heavy rainfall mainly affected perennial shrubs during these seasons. Our investigations suggest that winter annuals, despite their expanding presence, are ineffective in their ecological functions such as dune stabilization and reducing aeolian erosion in the peak summer months. In contrast, perennial shrubs like H. ammodendron and H. persicum, crucial for these roles, are markedly declining. The variable plant life forms might lead to modifications in the ecological roles of the region, thereby rendering it imperative to persistently observe this desert and proactively formulate conservation strategies for the vegetation.