# Differential Responses of Fungal Community Diversity and Soil Environmental Variables to Freeze–Thaw Disturbance in Seasonally Frozen Soil

## TL;DR

This study examines how fungal communities in seasonally frozen soil respond to freeze–thaw cycles, finding that temperature is the main driver of community changes.

## Contribution

The study identifies specific fungal genera affected by freeze–thaw disturbance and highlights temperature as the primary driver of fungal community shifts.

## Key findings

- Fungal diversity increases with temperature and freeze–thaw frequency, with thawed soil showing higher richness and evenness.
- Genera Inocybe and Sebacina are significantly suppressed during freeze–thaw transitions.
- Temperature, rather than nutrients, is the primary driver of fungal community structure during freeze–thaw dynamics.

## Abstract

Permafrost regions serve as sensitive indicators of global warming due to their ecological sensitivity and role as climate archives. To study how soil microbial communities in seasonal permafrost respond to freeze–thaw alternations, we analyzed composition and diversity during freezing, freeze–thaw, and thawing stages, identifying key taxa and environmental drivers. Our results identified 11 known fungal phyla and 13 dominant genera in permafrost regions. Most dominant fungi showed stable abundance during soil warming. However, the genera Inocybe and Sebacina were significantly suppressed when transitioning from frozen to freeze–thaw conditions. Fungal species diversity gradually increased with rising temperature and freeze–thaw frequency, with thawed soil showing higher richness and evenness. Frozen, freeze–thaw, and thawed soil were respectively associated with 90.48%, 71.43%, and 66.67% of node species. Adjacent stages shared 57.14% of coexisting species. Keystone node species declined progressively from frozen to thawed stages, indicating substantial yet continuous community reorganization. Furthermore, total carbon, organic carbon, available nitrogen, and phospholipid fatty acids peaked in freeze–thaw alternating soil. Active fungal biomass and species richness were most strongly correlated with soil carbon, temperature, and moisture. Overall, the influence of nutrients on soil fungi was limited across different freeze–thaw stages, while temperature emerged as the primary driver reshaping fungal community structure during freeze–thaw dynamics.