Aridity mediates the scale-dependent relationship between plant diversity and soil multifunctionality

Area of Science:

• Ecology
• Environmental Science
• Biodiversity Research

Background:

• Dryland ecosystems face increasing aridity and plant diversity loss, threatening ecosystem multifunctionality.
• Understanding the scale-dependent effects of plant diversity (α and β) on ecosystem functions under changing environmental conditions is limited.
• Ecosystem multifunctionality refers to the capacity of ecosystems to simultaneously sustain multiple functions.

Purpose of the Study:

• To investigate the effects of plant α-diversity and β-diversity on soil multifunctionality across a large aridity gradient in China's drylands.
• To examine how the relationships between plant diversity and soil multifunctionality change with intensifying aridity.
• To assess the combined impacts of plant α- and β-diversity on soil multifunctionality under aridity stress.

Main Methods:

• Measured 12 soil variables related to carbon, nitrogen, and phosphorus cycling and storage to characterize soil functions.
• Quantified soil multifunctionality using both averaging and multiple threshold approaches.
• Analyzed shifts in plant α- and β-diversity effects on soil multifunctionality along a 3200 km aridity gradient.

Main Results:

• Both plant α-diversity and β-diversity promote soil multifunctionality, but the positive effect of α-diversity increases with aridity, while β-diversity's contribution decreases.
• Complementarity and facilitation processes become more important than competition as plant water stress tolerance increases.
• Plant α-diversity can enhance β-diversity, leading to synergistic improvements in soil multifunctionality.

Conclusions:

• Biodiversity conservation across multiple scales is essential for maintaining dryland ecosystem multifunctionality.
• Findings provide insights for developing aridity-specific biodiversity conservation policies.
• Plant diversity, at both local and spatial scales, is critical for soil functions in drylands facing increasing aridity.