| Snow cover and green cover(covered with green vegetation cover)are all land cover types closely related to the ecological environment and phenological changes in Sichuan Province.Therefore,this paper covers the snow cover and green cover in Sichuan Province as the research object.Taking the period of 2006-2015 for nearly 10 years as research period,based on high-temporal MODIS image datas which are once every eight days,a total of 46 issues in a year,and 460 issues in 10 years.Combined with DEM and meteorological data,using the techniques and research of remote sensing and GIS Methods to do the study of snow cover and green pheromone information extraction and coverage changes was conducted to explore the temporal and spatial variations of snow cover and green cover during the study period and provide information for the use and protection of snow and green bedding resources in Sichuan Province.For the purpose of decision support,it is of great significance to the Climate research,drought and flood mitigation,green potential growth,construction of ecological security barriers and ecological civilization in Sichuan Province.The main research results are:(1)The largest area of snow in each year of the study period was around March,and the smallest area of snow appeared in August of each year.(2)During the study period,the correlation coefficient between the average temperature in August in each year of Sichuan Province and the area of snow covered area in the year was 0.01.The correlation coefficient was-0.907,showing a highly significant negative correlation.In the 10 years,the height fluctuation range of the snow line is between 5038-5060 m with a fluctuation range of 22 m;There was no significant correlation between snowline changes in the snow-covered areas throughout the year and the average rainfall in the corresponding areas,but the correlation coefficient with the average temperature in the corresponding area at the level of 0.01 was 0.797,showing a significant positive correlation.(3)The green-covered area of Sichuan Province showed an increasing trend from April to August in one year,until the maximum green area coverage in July and August,and the area of green areas showed a decreasing trend from the beginning of September to the end of the year.From December to the March of next year,the green area remained basically unchanged.In 2015,the area covered by green was 2904 km2 more than in 2006.The area of different green-covered days in each year did not change significantly.(4)During each year of the study period,the correlation coefficients between the green-covered area of each season in Sichuan Province and its corresponding temperature ranged from 0.937 to 0.968,showing a positive correlation.The correlation coefficient with the corresponding rainfall was between 0.842 and 0.907,showing a positive correlation.For the seasons during the study period,the correlation between the green-covered area and the corresponding autumn and winter temperatures and rainfall was not significant.For the spring,the correlation coefficient between the greencovered area and the corresponding temperature at the level of 0.01 is 0.836,showing a highly positive correlation.The coefficient of correlation with the corresponding rainfall at the level of 0.05 is 0.737,showing a moderate positive correlation.For summer,the correlation coefficient between the green-covered area and its corresponding temperature at the level of 0.05 is 0.651,showing a positive correlation with the medium.The correlation with the corresponding rainfall is not significant.Therefore,under the conditions of terrain,light,gas,and soil required for vegetation growth,if the areas are still with low green coverage,then can consider to focus on increasing temperature and moisture in spring and summer to increase the level of green coverage. |
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