Subjects: Geosciences >> Geography submitted time 2024-07-04 Cooperative journals: 《干旱区研究》
Abstract： High-resolution time-series remote sensing plays a vital role in monitoring glacier changes. In this paper, Sentinel-2 multitemporal satellite images from 2016-2022 were used along with the D-UNet semantic segmentation model to extract the glacier change information of Yilian Habirga. These results were compared with the Landsat remote sensing data of the similar temporal phase to ascertain any differences in the accuracies of Sentinel-2 and Landsat for glacier mapping. Based on these findings, 75 typical glaciers were selected to analyze the change- related characteristics of the total glacier area and glacier end in the recent study area. The results show that (1) The overall accuracy of Sentinel-2 glacier mapping was 95.0%,which is 5%-10% higher than Landsat-8 under the same conditions. (2) The average area retreat rate of glaciers in the study area from 2016 to 2022 was 0.75%±0.69%·a-1, in which the region<4600 m above sea level was that of glacier area reduction; the lower the altitude, the greater the area retreat rate. (3) In the last 6 years, the average heights of the 75 typical glacier ends rose by 17.75 m, and the average lengths reduced by 11.39 ± 2.36 m·a-1. Among these, the retreats in the west, northeast, and south were the most significant, which were 15.49 ± 2.36 m·a- 1, 13.95 ± 2.36 m·a- 1 , and 13.14 ± 2.36 m·a-1, respectively; the rate of the glacier end retreated with an increase in the elevation and the decreased.
Subjects: Geosciences >> Geography submitted time 2024-04-29 Cooperative journals: 《干旱区研究》
Abstract： Desert vegetation is an important ecological protection barrier for oasis ecosystems in the Hexi Corridor. Studying the composition of desert vegetation and the spatial distribution of soil nutrients is important to the construction and management of desert-oasis transition zone vegetation. This study is based on several field surveys. Traditional statistical and geostatistical methods were used to investigate the composition of desert vegetation and soil nutrient characteristics in the middle section of the Hexi Corridor and the southern fringe of the Badain Jaran Desert, and their correlation with environmental factors were analyzed. Results indicated that the plant composition in the desert areas of the middle section of the Hexi Corridor and the southwestern fringe of the Badain Jaran Desert was single and had low diversity, with plant species concentrated in a few families. Typical desert plants such as Reaumuria songarica and Nitraria tangutorum were frequently found in the study area. The distribution of herbaceous plants was strongly correlated with the average annual precipitation. In Shandan County, which is located in the southern part of the study area, the biomass of herbaceous plants reached 108.01 g·m−2. Within a certain range of annual precipitation, the biomass of shrubs increased with the increase of precipitation, with the highest value occurring in Suzhou County, near the northern slope of the Qilian Mountains, at 134.03 g·m−2. Increasing precipitation significantly promoted the growth of herbaceous plants. The surface soil had the highest organic carbon, total nitrogen, and total phosphorus contents in the study area, with average values of 2.12, 0.25, and 0.41 g·kg−1, respectively, and higher levels of variability than those in the soil subsurface. In the horizontal direction, the three types of soil nutrients had high variability and weak spatial autocorrelation, with maximum values of 11.22, 1.30, and 0.73 g·kg−1 near Zhangye Oasis. Principal component analysis showed that soil properties and precipitation were the primary factors causing habitat differences in the study area. However, different environmental factors interacted with one another to jointly drive desert vegetation composition and distribution.
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