关键词: 植被指数, 生长状况, 时空特征, 新疆生产建设兵团

Abstract: The reclamation by Xinjiang Production and Construction Corps(XPCC) has made great contribution to the economic development and social stability in Xinjiang, China. Especially since XPCC reorganization in 1981, agriculture, industry and mining in the areas of XPCC have been developed more rapidly. Along with this development, the land use and land cover change have also reached a significant level. Studying the spatialtemporal characteristics of vegetation growth is of great significance for evaluating the local reclamation development and ecological environment. In this paper, temporal series of GIMMS-NDVI and MODIS-NDVI data in the period from 1981 to 2015 were used as data source, and the methods including the linear fitting slope, standard deviation and coefficient of variation were used to analyze the characteristics of vegetation growth status in the areas of XPCC. The results showed as follows:(1)the variation of vegetation growth and the variation of annual mean temperature were relatively consistent within a year. The NDVI value was the lowest in winter, got increased from spring, and reached the peak in summer and then got decreased in autumn. During winter, the NDVI in December, January and February were 0.088, 0.054 and 0.066, respectively. And during summer, the NDVI in June, July and August were 0.326, 0.350 and 0.334, respectively.(2) The NDVI showed an increasing trend by an average of 0.003·a^-1 in the period from 1981 to 2015 and the vegetation coverage and growth were kept improving. The number of years with positive anomaly of NDVI was 19, of which the values in 2007, 2008, 2010, 2012 and 2013 were relatively higher. While the number of years with negative anomaly of NDVI was 16, of which the values in 1982 to1986 and 1989 were relatively lower. In terms of interdecadal variations, the NDVI value was the lowest in 1980s, lower in 1990s, higher in the period from 2000 to 2009 and the highest from 2010 to 2015.(3) The spatial patterns of vegetation growth were different in the whole region of XPCC. The areas with a decreasing trend of vegetation growth status accounted for 37.69%, which were mainly the towns and cities. The areas with an increasing trend were mainly located in farmland and forest, accounting for 62.31%. From the improving perspective, three categories were defined as having mild, moderate and severe improving fluctuation which accounted for 17.29%, 15.55% and 12.35% of the total area, respectively. On the decreasing trend, the areas with severe and extreme severe fluctuations accounted for 5.12% and 2.11% respectively of the whole region of XPCC.(4)Temperature and precipitation were important factors affecting the vegetation growth of in the areas of XPCC. Annual average temperature showed a gradually increasing trend with an average speed of 0.037℃·a^-1. The correlation coefficient between NDVI and temperature in the period from 1981 to 2015 was 0.548. Annual precipitation showed a gradually increasing trend with an average speed of 0.947 mm·a^-1. The correlation coefficient between NDVI and the accumulative precipitation for two consecutive years in the period from 1981 to 2015 was 0.503.(5)Besides the air temperature and precipitation, some human factors such as crop sown area, effective irrigation area, the increase of fertilization rate, effective agroforestry infrastructures and positive ecological policies e.g. "Three-North Shelterbelt" project and The Grain-to-Green Program were also the main driving forces for the improvement of vegetation growth after the reform and opening-up in XPCC.

Key words: NDVI, growth status, spatial-temporal characteristics, XPCC