N limit as a switch node between positive and negative plant-soil feedback: A meta-analysis based on the covariant diagnosis of plant growth and soil factors

Abstract

Mounting evidence has confirmed the existence of plant-soil feedback, a reflection of plant-soil interaction. However, analysis of ecological feedback pathways remains a challenge. In this study, single and mixed plant communities in different soil ecosystems were screened using strict control systems in global ecosystems to identify the positive or negative feedback effects in indicator plants. Furthermore, the plant components and biomass were identified in each pathway. The significantly changed components indicated pathway factors. As negative feedback increased, the InRR (Response Ratio) of soil organic matter, soil total N, microbial alpha diversity and the symbiotic fungi proportion were significantly up-regulated (P < 0.05). In contrast, the stoichiometric ratio (C: N), water content, and the pathogenic bacteria proportion were downregulated (P < 0.05). However, the positive feedback showed the opposite trend. Importantly, N limit as a transform node between positive and negative plant-soil feedback predicted by Akaike information criterion (AIC > 0.8). Therefore, it has become an important evaluation standard for the inter-species relationship and ecological environment changes under the background of global N deposition. Finally, the feedback values of each sampling site were recalculated over the next 20 years, 50 years, and 100 years based on the global temperature rise and changing rainfall patterns. We also found that global warming and extreme rainfall may change the distribution of interspecies relationships on a global scale, with global warming having the greatest recognisable effect and decreasing the negative feedback layout by 21.7% (P < 0.05). Therefore, this work promotes the cognition of relationship of soil environment, microbial abundance and function, plant diversity and plant- soil feedback model. Meanwhile, it is of great significance to protect species diversity and restore environmental degradation.

Keywords: Arbuscular mycorrhizal fungi; Cooperative symbiosis; Meta-analysis; Plant-soil feedback; Soil microbial.