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Abstract
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Biodiversity affects the provision of ecosystem services over time and space. This study was done to find how ecological succession regulates the relationship between biodiversity and supporting services in arid ecosystems. So, the effects of biodiversity on ecosystem supporting services, including soil stability, infiltration, and nutrient cycling, were investigated at three successional rangelands (early, mid, and late successional stages) in Iran. Linear and nonlinear modeling and structural equation modeling were used to assess the relationships between species diversity and supportive services at different successional stages. The results showed that the provision of the ecosystem supporting services increased with increasing species diversity along with ecological succession gradients, exponentially at the early and late successional stages and linearly in the mid successional stages. Structural equation modelling showed that succession, the dominance of functional types, species diversity, and vegetation cover were the most critical drivers of supporting services in arid ecosystems. Shrubs were the most critical functional type in providing ecosystem supporting services and should be involved in semi-arid rangeland restoration programs. In general, functional dominance is a good indicator of the health of ecosystems and their potential for providing support services in arid lands. Therefore, preserving plant composition is better than maximizing species richness to maintain semi-arid ecosystem services.
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