Inter-annual rainfall variability in Central Asia - A contribution to the discussion on the importance of environmental stochasticity in drylands

Drylands are characterised by pronounced climatic fluctuations, especially in regard to precipitation. We tested the relationship between mean precipitation and variability values using monthly data from climate stations in both arid and semi-arid parts of Central and High Asia. Total annual and growing season precipitation values were also compared in order to produce results relevant to plant biomass productivity and thus land use. Our study confirmed the well known observation that variability increases with lower overall precipitation levels. The observed correlation indicated that growing season precipitation variability increased dramatically where mean precipitation levels fell below ∼100 mm. This sheds new light on the transition between regimes with more regular rainfall patterns and those with episodic rainfall; a focus on the growing season indicates a stronger relation between rainfall sums and rainfall variability compared to annual values. We therefore encourage future analysis for other parts of the world to improve our understanding of the relationship between climatic conditions and productivity in drylands.