摘要
利用2000—2014年MODIS/NDVI时间序列数据,采用栅格像元趋势分析、稳定性评价的方法,研究了陕西省近15 a植被的时空变化特征和规律;利用Hurst指数对陕西省植被未来变化趋势进行了预测;并利用相关性分析法分析了NDVI与年均温度和降雨量的关系。结果表明:2000年、2015年陕西省NDVI均值分别为0.427 3、0.494 2, 15 a来增加了0.067,增长了16.0%,其中陕北地区NDVI增加明显,关中部分地区出现负增长,陕南地区NDVI总体维持在较高水平。陕西省植被变化趋势具有明显的空间差异性,全省植被未变化的占52%,改善部分占44.27%,退化部分占3.73%,说明15 a间陕西省植被状况有所改善,植被覆盖改善面积大于退化面积,其中陕北地区植被改善区域面积较大,关中地区植被覆盖面积有所减少,陕南地区植被变化幅度较小。陕西省植被稳定区域占50%以上(0<Cv<0.1),中等程度区域占28%(0.1<Cv<0.2),不稳定区域不足2%(Cv>0.2),说明15 a间陕西省植被较为稳定,变化程度不大;其中陕西省植被最稳定地区主要集中在陕南、延安南部,榆林部分、西安、渭南少部地区变化幅度较大。Hurst指数分析表明陕西省44.54%面积的植被未来有可能面临退化,主要分布在陕北和关中地区的北部,植被未来有可能退化也有可能改善的面积占49.78%,主要分布在延安和陕南地区。陕西省近15 a气温和降水量总体呈增加趋势,增加速率分别为0.48℃·(10 a)^(-1)和69.5 mm·a^(-1);相关性分析结果表明,年均降雨量是影响NDVI的主要气象因子,同时陕西省植被变化也受到了退耕还林还草、防沙治沙、生态政治等人为因素的影响。
Based on NDVI from MODIS during the time period from 2000 to 2014,the spatial and temporal variation of vegetation in Shaanxi Province,China was analyzed using the methods of raster pixel trend analysis and stability evaluation.The vegetation change trends in the future were forecasted by R/S(Rescaled range analysis) method in Shaanxi Province.The correlation analysis was applied between annual temperature,precipitation and NDVI in Shaanxi Province.The results showed that the mean values of NDVI in 2000 and 2014 were 0.427 3 and 0.494 2,respectively,which indicated an NDVI increase of 0.067,or 16% equivalently.The NDVI was increased significantly in northern region of Shaanxi and there was a negative growth in some parts of Guanzhong area,while the NDVI in southern region of Shaanxi was still maintained at a higher level and changed a little.The vegetation variation in Shaanxi Province has obvious spatial regularity.The areas with vegetation of little change accounted for 52.0% in the whole province,while the areas with improved vegetation coverage accounted for 44.27%,and the areas where the vegetation was degraded accounted for 3.73%.It explained that the overall vegetation coverage in Shaanxi Province was improved in the past 15 years.The stability region of vegetation in Shaanxi Province accounted for more than 50% and the Cv value was between 0 and 0.1.The moderate area of vegetation accounted for 28% and the Cv value was between 0.1 and 0.2.The unstable area of vegetation in Shaanxi Province was less than 2% and the Cv value was greater than 0.2.It shows that vegetation condition was relatively stable in Shanxi Province in the past 15 years.The vegetation status was most stable in southern area of Shaanxi Province,southern area of Yan’an City while vegetation status varied greatly in some part of Yulin City,Xi’an City and the southern part of Weinan City.The analysis of Hurst index showed that 44.54% area of vegetation in Shaanxi Province may face degradation of vegetation in the future.It is possibly distributed mainly in the northern area and the Guanzhong area.49.78% area of vegetation in Shaanxi Province may face improving or degrading in the future which is mainly distributed in Yan’an City and southern area of Shaanxi Province.The annual temperature and precipitation showed an increasing trend in Shaanxi Province in the past 15 years and the increasing rates were 0.48 ℃·(10 a)-1 and 69.5 mm·a-1 respectively.The correlation analysis results showed that the annual precipitation was the main meteorological factors affecting the NDVI.The changes of vegetation in Shanxi Province had also been influenced by artificial factors such as the project of returning farmland to forest and grass,sand prevention and ecological politics.
作者
岳辉
刘英
YUE Hui;Liu Ying(College of Geomatics, Xi'an University of Science and Technology, Xi'an 710054, Shaanxi, China)
出处
《干旱区地理》
CSCD
北大核心
2019年第2期314-323,共10页
Arid Land Geography
基金
国家自然科学基金项目(41401496)
