Soil Fungal Community Assembly in Restored Cut Slopes Versus Natural Forests Along an Altitudinal Gradient

Abstract

During the highway construction, forest ecosystems are usually fragmented, leaving numerous bare cut slopes. External-soil spray seeding (ESSS), which is often used for slope restoration, is a technique for re-establishing vegetation on degraded slopes. However, our current comprehension of soil fungal communities during such a process remains limited, especially when considering variations across an altitude gradient. Using high-throughput sequencing technology, we investigated the spatial shifts in the composition, diversity, network properties, and assembly processes of fungal communities in both natural forest (NS) and cut slope (CS) along the altitude gradient. The findings revealed notable differences in β-diversity between NS and CS across various altitudes, linked to soil physicochemical changes. Subsequent research highlighted distinct shifts in fungal community composition along the elevation gradient between NS and CS. Notably, there is a massive accumulation of plant pathogens in CS treatments, such as an increased relative abundance of Gibberella. This change in fungal community composition may inhibit seedling regeneration. Network analysis indicated a lower stability of fungal networks in CS than NS. We also found that deterministic and stochastic processes jointly drove fungal community construction, with stochastic processes playing a major role. The assembly of the fungal community is significantly correlated with soil pH and NH₄⁺-N. This study improves our understanding of how soil fungal communities are restored in cut slopes in subalpine forests across altitude gradients. It also provides critical scientific guidance for restoring ecological functions on cut slopes formed during infrastructure development in forests.