Soil multifunctionality is associated with soil water content and fungal richness in Robinia pseudoacacia plantations

Soil multifunctionality (SMF), which was used to mirror the ability of soil to deliver multiple functions simultaneously, is an effective index that reflects ecosystem value. Understanding the response of SMF to stand density is important for developing management strategies to improve the stability of the forest ecosystems.

Robinia pseudoacacia plantations with different stand densities (750, 1125, and 1550 trees ha⁻¹) were selected in Ansai District, Yan’an City, northwest China’s Shaanxi Province. We evaluated the SMF by measuring soil physicochemical properties and soil enzyme activities. We investigated changes in SMF and the composition of bacterial and fungal communities among plantations with different stand densities, and also determined the relationships between SMF and soil microbial community structure and edaphic properties.

Changes in stand density significantly affected SMF and soil fungal community structure. Compared to low-density (750 trees ha⁻¹) and high-density (1550 trees ha⁻¹) plantations, medium-density (1125 trees ha⁻¹) plantations had increased SMF and fungal richness. Mantel tests showed a positive correlation between the SMF and soil water content and fungal richness. The main fungal biomarkers of medium-density plantations were from the class Dothideomycetes.

Medium-density stand improved soil multifunctionality by increasing fungal richness and soil water content in R. pseudoacacia plantations. Further research is required to verify these hypotheses and determine whether there are causations between SMF and fungal richness or soil water content. Our work highlights the need to conserve soil water and biodiversity through stand density management to improve soil multifunctionality in R. pseudoacacia plantations.