Altitude-induced shifts in bacterial communities involved in soil organic phosphorus cycling on Taibai mountain

Abstract

Soil phosphorus cycle is crucial for maintaining ecological balance and promoting ecosystem development, with microorganisms serving as key drivers of this process. Soil phoD-encoding bacteria are vital for enhancing plant nutrient uptake and sustaining the functions of montane forest ecosystems. However, the patterns and potential mechanisms underlying phoD-encoding bacterial communities across altitudinal gradients in alpine forest soils remain unclear. Utilizing high-throughput sequencing, this study examined the impact of altitude, vegetation, and soil factors on phoD-encoding bacteria in alpine forest soils. The results showed that altitude significantly affected the diversity and composition of phoD-encoding bacterial communities in alpine forest soils. The alpha diversity of phoD-encoding bacteria in low-altitude soils (2210 m) was significantly higher than that in other altitude ranges (P < 0.05). As altitudinal gradient increased, the number of nodes and edges within the bacterial networks encoding phoD consistently decreased, leading to reduced network complexity and weakened inter-community interactions. Simultaneously, phoD-encoding bacterial community structure exhibited comparable structural features at similar altitudes. Notably, Pseudomonas and Actinobacteria were dominant groups carrying the phoD gene in high-altitude forest ecosystems, playing key roles in the soil phosphorus cycle. Altitude, soil pH, and plant diversity were identified as the main factors driving the structure of soil phoD-encoding bacterial communities. The altitude differentiation of phoD-encoding bacteria revealed the spatial heterogeneity of phosphate mineralization ability, and the effect of plant diversity on phoD-encoding bacteria indicated that plant species selection and soil microbial function should be considered in future vegetation restoration and management. This study offered new insights into phosphorus cycling mechanisms in mountainous ecosystems and provided scientific guidance for climate change adaptation and alpine forest management.