PJB-2018-221
Response Relationship between the Seasonal Freezing-Thawing Process of Soil and Spatial Factor Changes in the Dayekou Basin of the Qilian Mountains
yun niu
Abstract
[Objective］In this study, the influence and response relationship between the seasonal freezing-thawing process of soil and the spatial factor changes in the management and utilization of water resource processes were explored. [Methods] The monitoring equipment in this study was arranged at different altitudes, gradients, and slope directions, such as the typical forest sample area in the Dayekou Basin of the Qilian Mountains. The spatial variation characteristics of the seasonal freezing-thawing process of the soil were analyzed, and a regression model was established. [Results] (1) The results of this study determined that the rate of the soil’s freezing increased with the altitude in a trend of volatility. However, the rate of the thawing of the frozen soil was found to have an opposite trend. The variation degree of the freezing-thawing process increased with the altitude in a trend of volatility. The end time of the approximate soil freezing with altitude increased in a volatility trend ahead of schedule. However, the opposite was observed in the thawing rate of the frozen soil; (2) The rate of the soil’s freezing under the mosses of the spruce forest at an altitude of 3,028 m was found to be the lowest. However, in the sub-alpine scrub forest at an altitude of 3,300 m, a maximum in the spatial ordering was observed, with an average of 1.9 cm•d-1. The thawing rate of the frozen soil in scrub-spruce forest at an altitude of 3,300 m was found to be minimal. However, in the sunny slope grassland at an altitude of 2,946 m, a maximum in the spatial ordering was observed, with an average of 1.5 cm•d-1. In the spatial ordering of the variation degree of the process of freezing-thawing with an average of 1.2, the scrub-grassland at an altitude of 2,518 m was found to be the lowest, and the scrub-spruce forest at an altitude of 3,195 m was also low; (3) The soil freezing began on approximately October 20th, and the rate of soil freezing gradually became reduced. The arrival time of the frozen soil of up to 150 cm in depth in sub-alpine scrub forest was first observed at an altitude of 3,028 m. However, the scrub-spruce forest at an altitude of 3,100 m did not become frozen until approximately January 12th on average. Then, the thawing rate of the frozen soil increased gradually. The end time of the thawing was earliest observed in the sunny slope grassland at an altitude of 2,946 m. However, the scrub-spruce forest at an altitude of 3,100 m was found to be the last to thaw, and averaged approximately July 27th. The average durations of the freezing and thawing of the soil were 77 and 121 days, respectively, and the average duration of the entire process of freezing-thawing was 199 days; (4) This study’s established regression models of the duration times of frozen soil’s thaw, and the rate of frozen soil’s thaw, all passed the R test of goodness of fit, F test of variance, and t test. [Conclusions] The characteristics of the seasonal freezing-thawing process of the soil with the spatial changes were seasonal. However, the characteristics under the different spatial factor influences were not the same.
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