International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.6, 277-285 http://ecoevopublisher.com/index.php/ijmec 281 3.3 Soil temperature and permafrost dynamics The adiabatic effect of snow cover is of crucial significance to soil temperature and permafrost stability in cold regions. Thick snow accumulation can significantly reduce the depth of freezing in winter and protect root systems and soil microbial communities from damage caused by extreme low temperatures. On the contrary, thin snow accumulation or premature melting will lead to an increase in the depth of permafrost, causing root damage, restricting microbial activity, and accelerating the frequency of freeze-thaw cycles. In permafrost regions, snow cover changes are closely related to permafrost temperature, ice layer structure and melting rate. Snowmelt replenishment also determines the seasonal variation of soil moisture content. When snowmelt occurs prematurely and rapidly, the soil is prone to a pattern of "moist in early spring - dry in summer", which affects the germination and initial growth of vegetation. Therefore, the regulation of permafrost and soil heat-water state by snow cover is the fundamental mechanism for maintaining the stability of ecosystems in cold regions (Pedron et al., 2023; Lathrop et al., 2024). 4 The Impact of Snow Cover on Biological Communities and Ecological Processes 4.1 Plant ecological roles The ecological effects of snow accumulation on plants are mainly reflected in three aspects: heat preservation, moisture retention and delayed phenology. Firstly, snow cover can significantly reduce the loss of surface heat, creating a relatively stable "greenhouse effect under snow", and protecting buds, root systems and surface vegetation from extreme low temperatures. Tundra plants particularly rely on the insulation function of snow. Thick snow can reduce the damage to the ground cover caused by cold winds and ice, and increase the survival rate of overwintering. Secondly, the melting of snow provides the first wave of water source for plants in spring, which is particularly crucial in dry and cold regions. Meltwater replenishment helps maintain soil moisture and promotes plant germination, early growth and nutrient acquisition (Irannezhad et al., 2022). Snow cover also shapes the phenological rhythms of plants. In areas where snow melts late, the growing season of vegetation is correspondingly shortened, and plants must adjust their growth rhythm to adapt to short-cycle light and heat conditions. Snow cover changes also affect the structure of plant communities. For instance, in alpine meadows, a reduction in snow cover promotes the expansion of drought-tolerant species, while low-growing shrublands with strong adaptability in areas with thick snow cover may face competitive pressure. Due to the high spatial heterogeneity of snow cover, plant communities show obvious micro-topographic differentiation, which is called "snow mosaics", and its formation mechanism is becoming an important content in ecological research. 4.2 Animal survival strategies and adaptation The relationship between animals and snow cover is complex and dependent on the type of ecosystem. For birds and medium-sized mammals, snow is both an obstacle and a protective barrier. For instance, species such as Arctic foxes and reindeer adapt to changes in snow cover by adjusting their activity paths, migration rhythms or food choices. Some animals use snow as hiding places. For example, rodents often build wintering nests in the subnivean space, which has relatively stable temperature and humidity, which is conducive to foraging and avoiding predators (Freppaz et al., 2017). However, a reduction in snow accumulation or a thinning of the snow layer can destroy such microhabitats, significantly increasing the survival risk for rodents and subsequently affecting their predators, such as owls and foxes. Deep snow accumulation can also alter the migration routes and hunting efficiency of large animals. For instance, wolves are more likely to catch deer, which have difficulty moving, in deep snow. As the dynamics of snow cover change, the migration, reproduction and overwintering strategies of animals all need to be actively adjusted (Bokhorst et al., 2016). 4.3 Microhabitats and microbial interactions Snow cover creates unique microhabitat conditions, especially the constant temperature, weak light and high humidity environment beneath the snow, providing suitable habitats for a series of microorganisms. Soil microorganisms are not completely dormant in winter but maintain a low-speed metabolism and continue to
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