Abstract:

It is of great significance to study the relationship between the phenological periods of Larix gmelinii and characteristics of seasonal permafrost change to provide scientific guidance for the rational utilization of permafrost resources and the practice of local forestry production. Using statistical methods such as linear tendency estimation and Pearson correlation coefficient, this study focuses on the phenological periods of Larix gmelinii in Erguna and its relationship with the characteristics of seasonal permafrost change based on the permafrost data from Erguna Ground Meteorological Station and the phenological observation data from Erguna Agrometeorological Observation Station from 1991 to 2023. The results showed that: (1) seasonal permafrost in the study area had undergone significant changes, with the first day of freezing delayed by 5 days per 10 years on average, and the last day of melting advanced by 18 days per 10 years. It also indicated that the first day of thaw was relatively stable. The maximum permafrost depth decreased by 29 cm, the number of thaw days and the freeze-thaw cycle were shortened by16 days, and 23 days per 10 years on average, respectively. (2) During the study period, the spring and autumn phenological periods of Larix gmelinii showed a postponement trend, with the flower bud opening stage and the beginning of leaf development delaying by an average of 5 days every 10 years, and the complete leaf discoloration stage and the end defoliation stage delaying by 11 days on average every 10 years. The length of the growing season was extended by 6 days every 10 years on average, and the extension of the number of days from the initial period of leaf exhibition to the complete discoloration period at the middle of the growing season contributed the most. (3) The different phenological periods of Larix gmelinii were closely related to the seasonal permafrost. The postponement of different phenological periods and the extension of the growing season of Larix gmelinii were closely related to the postponement of the first day of permafrost freezing, the advance of the last day of thawing, the number of thawing days and the shortening of the freeze-thaw cycle, and the shallow depth of the maximum permafrost also had a certain impact on the postponement of the phenological period of Larix gmelinii. This study demonstrated the phenological periods of Larix gmelinii in Erguna and their relationship with seasonal permafrost changes, providing a reference for guiding scientific forestry production.

Key words: seasonal permafrost, Larix gmelinii, phenological period, correlation, Erguna