| Fractional vegetation cover(FVC) is a multi-discipline and multi-purpose index. It is an indispensable key parameter in the evaluation of ecological environment, soil erosion quantity and qualitative assessment. FVC change research has become an important content of regional ecological environment change research and ecological restoration evaluation. In 2013, the Ministry of Water Resources launched the "national soil erosion dynamic monitoring project", to carry out the dynamic monitoring of soil erosion in the national key control area. The ecological environment is a n important part of the monitoring of soil and water loss. Jinzhai County is one of the typical counties in the monitoring of soil erosion. The change of FVC in the year and the interannual year is still not clear.In order to study the vegetation coverage and its driving factors in Jinzhai County,the Dimidiate Pixel Model Based on, to small satellite Landsat series data and environmental data as the data source, select 1975-2014 during 9 Landsat images for FVC of interannual variability, to 2013 environmental satellite every half a month of remote sensing data for vegetation cover degree in a year of, and combined with the meteorological data analysis of the vegetation cover and the relationship between the degree of change and meteorological factors.The main results are as follows:1.Status of vegetation coverage(1) FVC mean 76.14% of Jinzhai County in 2014, belongs to the high coverage, showing an overall by the Meishan reservoir in Jinzhai County in the central, Eastern ring Hong Dian reservoir, northeast of Meishan Town and Baitafan Town altitude lower region to the surrounding high altitude increasing trend. High coverage accounted for the largest proportion, accounting for 67.73% of the total area of the county; followed by the middle-high coverage, accounting for 17.43%. The vegetation coverage and the grade distribution is basically the same.(2) Distribution of high and middle-high FVC in forest land in the area is the largest, middle and middle- low FVC in the main distribution in land use for paddy field area, bare land in the water conservancy facilities and land distribution in the area is the largest. FVC and terrain factors have a certain relationship. With the increase of elevation, the levels of vegetation coverage area percentage showed a decreasing trend. With the increase of slope in middle- high and high coverage in the county accounted for the proportion was decreased after increasing trend. The slope direction had no significant effect on FVC.2. The characteristics of temporal and spatial variation of FVC during the year.(1) The annual variation curve of FVC of Jinzhai County is a "?" font. The overall FVC increased, basically stable, finally decreased. Early January to early March, FVC basically unchanged; from early March to late April, increased rapidly; end of April to the end of July, slowly rose to the annual maximum, increased to 81.12%; at the end of July to the end of October, a slow decrease trend; at the end of October to late December, rapid reduced.(2) Variation trend of forest land, orchard and tea are basically the same, but the vegetation coverage has obvious differences, the overall performance of protective forest > tea > orchard. In the growth period, tea forest vegetation coverage in stable period was longer than the shelter for half a month, the orchard economic forest with no apparent stable phase.(3) The temperature is the main factor affecting the change of FVC within a year, and has a certain lag. The vegetation coverage and the corresponding half and half temperature were strong correlation, the correlation coefficients were 0.49 and 0.58. The vegetation coverage and the first half was significantly correlated with the significant correlation area accounted for 52.61% and 13.55% of the total area of the county. The precipitation on the vegetation cover affected the degree of change, and has a certain lag effect.3.FVC interannual temporal variation characteristics(1) FVC was generally not significantly increased volatility. In spatial distribution, FVC was with no significant change from 1975 to 2014.(2) 1975-2014 years, Jinzhai County, adjacent typical years between FVC of changes in the area were large, and in more tha n 30%, the mutual transformation mainly between high and middle-high FVC, middle- high and middle FVC, changes in the region mainly distributed in low mountains and hilly areas.(3) Human activities( "forestry two undertaking", major project construction in forestry.) are the main factors affecting the degree of interannual variability of vegetation coverage in Jinzhai County. |
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