Salinization Decreases Soil Phosphorus Availability and Plant Productivity in Terrestrial Ecosystems

Soil phosphorus (P) availability is crucial for plant productivity, and salinization is generally expected to reduce plant productivity in global terrestrial ecosystems. However, the response of soil P availability to salinization remains unclear, making it difficult to assess its role in shaping plant responses to salinization. Here, we conducted a meta-analysis of 823 observations from 87 published articles to investigate the effects of salinization on soil P availability and plant productivity across global terrestrial ecosystems. Across these studies, salinization decreased soil total P by an average of 4.6%, available P by 11.2%, and phosphatase activity by 25.4%. The effect of salinization on soil P availability was primarily modulated by salinization magnitude and exposure duration, vegetation types, ecosystem types, and climate conditions. Specifically, the negative effects of salinization on soil P availability were exacerbated with increasing salinization magnitude and duration, and were stronger in ecosystems dominated by herbaceous vegetation and in regions with lower precipitation. Across global ecosystems, the negative effects of salinization on soil P availability were associated with the declines in plant productivity. Our meta-analysis provides a comprehensive understanding of how salinization impacts soil P availability across diverse vegetation and ecosystem types worldwide, and highlights that optimizing fertilization strategies and plant community composition are crucial for enhancing plant productivity and ecosystem functioning in salt-affected areas.