Abstract:

To rationally utilize frozen soil resources and promote regional sustainable development, based on long-term (1991-2024) frozen soil data and synchronous meteorological observation data from surface meteorological stations in the Daxing’anling forest area, statistical analysis methods such as linear trend estimation and Pearson correlation coefficient were employed to systematically analyze the spatiotemporal variation characteristics of key freeze-thaw parameters of frozen soil and their correlations with meteorological and geographical factors. The results indicated that: (1) during the study period, the seasonal frozen soil showed a significant degradation trend, characterized by “delayed freezing, advanced thawing, and reduced freezing depth”. The initial freezing date was delayed by 2.6 days per decade; the initial thawing date and final thawing date were advanced by 1.6 days and 5.5 days per decade, respectively; the maximum frozen soil depth decreased by 4.3 cm per decade, and the freeze-thaw cycle continued to be shortened. (2) The freeze-thaw process exhibited obvious spatiotemporal differentiation: the initial freezing date was earlier in the north and later in the south, the initial thawing date was earlier in the southeast than in the northwest, the final thawing date spanned nearly 4 months, and the maximum frozen soil depth presented a distribution feature of “shallow in the southeast and deep in the northwest”. (3) Meteorological and geographical factors synergistically drove the changes of frozen soil. The key meteorological factors were autumn average temperature and autumn precipitation (affecting the initial freezing date), annual average temperature (affecting the initial thawing date), and annual/summer precipitation (affecting the maximum frozen soil depth). The core geographical factors were altitude (regulating freeze-thaw timing), longitude (influencing the initial thawing date and frozen soil depth), and latitude (acting on key freeze-thaw timing and frozen soil depth). This study clarifies the freeze-thaw patterns and main driving factors of seasonal frozen soil in the Daxing’anling forest area, providing a scientific basis for frozen soil resource management, ecological protection, and climate change adaptation in the forest area.

Key words: seasonal frozen soil, freeze-thaw patterns, spatiotemporal evolution, driving mechanism, climate change, frozen soil degradation, Daxing’anling