Insights into the impacts of freeze-thaw processes on soil microorganisms and their related functions in permafrost regions are crucial for assessing ecological consequences imposed by the shifts in freeze-thaw patterns. Through in-situ investigations on seasonal freeze-thaw processes in the active layer of permafrost in the Qinghai-Tibet Plateau, we found that microbial richness was higher and positively correlated with soil multifunctionality during the freeze-thaw stage (freezing and thawing periods) compared to the non-freeze-thaw stage (completely frozen and thawed periods). This relationship resulted from the higher microbial stability, which was highly consistent with the lower complexity, more keystone taxa, and greater robustness of networks. Although freeze-thaw strength exacerbated the greenhouse effect on climate, it was alleviated by the enhancement of diversity-soil multifunctionality relationship. These findings have substantial implications for exploring the responses of microbial-mediated soil multifunctionality and greenhouse effect in alpine permafrost to more drastic variations of freeze-thaw processes under future warming.

Initially, cryohydrology was referred to as hydrology involving low temperatures, for example, the hydrological study of snow, ice, frozen ground, and cold water. This discipline broadened with the development of cryospheric science and now involves hydrological processes of various cryosphere elements systematically coupled with river basin hydrological processes. However, limited studies have introduced the characteristics and discipline connotations of cryohydrology from a perspective of cryospheric science. Here, we reviewed the evolution of the connotations of cryohydrology and analyzed its hydrological basis and discipline system. Three major conclusions were drawn. (1) Cryohydrology was developed based on traditional hydrology for a single element of the cryosphere and focuses on the hydrological functions of the cryosphere and its impact on the water cycle and water supply to other spheres. (2) The hydrological basis of cryohydrology can be summarized as water conservation, runoff recharge, and hydrological regulation. In detail, the water conservation function is primarily expressed as source of freshwater and cold and wet islands, the runoff recharge function is concerned with water supply, and the regulation function is effective at intra- and inter-annual scales. (3) The core research issues of cryohydrology are research methods, hydrological processes, watershed functions, and regional impact. The important characteristics of cryohydrology are frequent water phase transitions and high variability across spatial and temporal scales. Cryohydrology aims to deepen the understanding of the theoretical and cognitive levels of its mechanisms and processes, accurately quantify the hydrological functions of the basin, and promote understanding of the ecological and environmental impacts of the cryosphere.