| Vegetation is the general covering of plant communities on the earth, and it is an important basic data to describe the ecological system. The vegetation index is the best indicator of vegetation growth, it also can be the main factor to monitor the soil erosion, water losses, drought and other disasters. Both Inner Mongolia Autonomous Region and Mongolia belong to the Mongolian Plateau, and they have the same social production and life style, they have rich natural resources on the border, which make it to be the important agriculture and husbandry production zone between the China and Mongolia. However, because of the fragile environment and frequent natural disasters on the China-Mongolia border zone, it caused the serious effects on ecological environment of the border. In this paper, the vegetation changes and its influencing factors on the border zone were researched, which would provide a theoretical basis to the mitigation and management of the disasters on border zone.In this paper,2000-2013 MODIS NDVI data, meteorological data and socio-economic data were used, using trend calculation, comparative analysis and correlation analysis, combined with RS and GIS technology to analyze the temporal and spatial variation characteristics of NDVI China-Mongolia border region nearly 14 years and discuss climate change and human activities on vegetation change. The following conclusions can be drawed:1.The growing season (April-October) NDVI had an increasing trend during 2000-2013 years. In Inner Mongolia and Mongolia within the growing season NDVI increased to 0.0018/a and 0.0021/a rates. In the study period, the mean NDVI of growing season of the two areas was 0.23 for Inner Mongolia side and 0.19 in Mongolia. From the seasonal variation, in the spring (April-May), summer (June-August) and autumn (September-October) the border region of China-Mongolia NDVI showed an increasing trend. Among them, the rate of increasing in summer vegetation NDVI was fastest, the rate of increasing was 0.0032/a for Inner Mongolia sites and 0.0042/a in Mongolia.2.From vegetation NDVI spatial variation of China-Mongolia border areas, the years of 2000-2013 in Inner Mongolia NDVI had an increasing trend of pixel representing 86.88% of the region, significant and extremely significant increase pixel distribution in the north and east of the central Gobi parts areas, Langshan Mountain east region, Abaga banner and Xilinhot in northern, central and northern region in Dongwuzhumuqin banner. In Mongolia the increasing trend of the growing season NDVI pixel accounted for 91.15% of the region area, which significantly increased and its pixel concentrated distribution in the western region of Halha County and the junction of province and Inner Mongolia Xin Barag Right Banner. Seasonal changes in spatial variation scale, both sides showed an increasing trend of summer NDVI pixel maximum, and the Mongolian side of the increasing trend in three seasons had more pixel in Inner Mongolia side.3.Changes of NDVI from China-Mongolia border region on both sides of the comparison, from Buffer 1 (40km from the border) to Buffer 3(120km from the border) NDVI value was increasing in Inner Mongolia side, while Mongolia side was decreased. This showed that, in the Inner Mongolia side farther away from the border line had the increasing trend of vegetation, and the Mongolian side was decreased. From the cross-sectional analysis, the both border sides of the Gobi desert in the southwest region were difficult to distinguish the difference of NDVI. In the middle of the desert steppe region of Inner Mongolia and Mongolia, the difference of NDVI in cross-section 1 (40km from the border) was minimum, the difference in cross-section3(120km from the border) was maximum.In the northeast area of steppe and meadow, the average value of NDVI in Inner Mongolia was usually higher than in Mogolia and NDVI differences between sections in two sides increasesd with distance from the border, particularly in the central and northeastern regions.4.From NDVI change of China-Mongolian border typical region, in recent 14 years, China-Mongolia border typical region growing season and each season NDVI showed an increasing trend. Summer NDVI had the fastest rate of increase. From growing season changes, NDVI of eastern Dongwuzhumuqin showed a trend of increase the area of accounting for 90.29% of the total area, which significantly and limit the increasing number of areas were mainly distributed in the central of Dongwuzhumuqin and northern of Halha county; Mongolia region showed a trend of increase in the area of 91.47% of the total area of the region, mainly distributed in the central of Halha county and northeast of Erdene Chagan county. From seasonal NDVI space changes, each the NDVI of season the increased area of the typical area were greater than the area of a downward trend, which the increased area of NDVI was the largest in summer.5.From the analysis of influence factors, most of the typical area in the growing season was positive correlation between NDVI and precipitation, respectively Dongwuzhumuqinqi and Mongolia region with a total area of 98.97% and 98.85%. It showed the negative correlation between temperature was greater than the area of the area positively correlated. In spring, summer, autumn three seasons, the typical area of positive correlation between NDVI and precipitation were greater than the positive correlation between temperature and the area, and was very significant negative correlation between precipitation area was very little. This showed that precipitation were the main factors of NDVI in many parts of the typical regional growth, the influence of precipitation was greater than the temperature influence. Livestock pressure was less than the carrying capacity of the pastures, with no adverse impact on grassland vegetation, at the same time, the ecological protection project of grassland vegetation recovery played a certain role in promoting. Mongolia area is located in the eastern Mongolia grassland nature reserve, due to the vast and sparsely populated, untouched by human activities, maintain the natural appearance has rich pasture resources. Vegetation changes affected by climate. |
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