近10年湖北省植被指数时空变化特征及其驱动力

为了明确湖北省植被长势变化特征及其影响因子，研究利用Landsat影像提取2005年、2010年以及2015年湖北省景观类型信息，分析近10年来景观时空变化特征；基于2005-2015年夏季MODIS/NDVI数据，采用一元线性回归、Theil-Sen median趋势、Mann-Kendall检验等分析方法对NDVI时空变化特征及其显著性进行探讨；采用最小二乘法对NDVI与气候之间的相关关系进行分析。使用DMSP/OLS和NPP/VIIRS夜间灯光数据探讨NDVI与人类经济活动之间的关系。结果表明：研究区景观类型变化以建设用地和耕地为主。耕地面积呈现逐年减少的趋势，主要转变为建设用地。建设用地面积不断增多，主要由耕地和林地转变而来，集中在武汉、荆州、襄阳城市圈；研究区NDVI值整体上表现为西高东低，以林地为主的十堰、恩施等地区NDVI值较高，以建设用地为主的武汉、襄阳、荆州等地区NDVI值较低；整体上NDVI变化呈轻微改善趋势，局部地区下降明显，鄂西北、鄂西南等地区NDVI稍有上升，武汉城市圈植被呈退化趋势；NDVI与降水量、气温的相关性均较弱，气候因子不是该区NDVI变化的主导因子；NDVI与夜间灯光亮度值呈显著负相关，相关系数达-0.8030，整体上人类经济活动与NDVI呈负相关关系，且有着分区性的特点，在武汉、襄阳等以建设用地为主的地区人类经济活动对NDVI起抑制作用，而在恩施、十堰等林地为主的地区人类活动对NDVI起促进作用。人类社会经济活动是影响研究区景观格局和植被变化的重要驱动力，城镇化扩张是湖北省植被变化的主要原因。

Analysis of spatial and temporal variations in vegetation index and its driving force in Hubei Province in the last 10 years

To analyze the variation of vegetation growth and further explore the reasons for these changes in Hubei Province, we extracted landscape type information of Hubei Province in 2005, 2010, and 2015 using Landsat data, and analyzed the spatial and temporal evolution characteristic of landscape patterns. Based on the MODIS NDVI data in the summers of 2005 to 2015, the characteristics of spatial and temporal variation in NDVI and its significance were explored by using unitary linear regression analysis, Theil-Sen median trend analysis, and Mann-Kendall test. The relationship between NDVI and climatic factors (temperature and precipitation) was explored using the least squares method. The relationship between NDVI and human economic activities was also examined based on DMSP/OLS and NPP-VIIRS night-time light data. The results concluded that cultivated land and construction land were the landscape types that varied most in the study area between 2005 and 2015. The area of cultivated land continued to decline, and most of the area lost was transferred into construction land. The area of construction land continued to increase, and most of this increase was transferred from cultivated land and woodland, which were distributed in Wuhan City, Jingzhou City, and Xiangyang City. The NDVI value of the study area was generally high in the west and low in the east. The areas with higher NDVI values such as Shiyan and Enshi had woodland as the major landscape type. The areas with lower NDVI values such as Wuhan, Xiangyang, and Jingzhou, had construction land as the major landscape type. The overall variation of NDVI showed a slight improvement trend in Hubei Province. There was also an obvious declining trend for NDVI variation in some areas. The NDVI in the northwestern and western parts of Hubei Province increased slightly, and the vegetation in the Wuhan city showed a degrading trend. The correlation between NDVI and climatic factors (temperature and precipitation) was weak, which indicated that climatic factors are not the dominant factor causing NDVI variation. There was a significant negative correlation between NDVI and night-time light value, with a correlation coefficient of r=-0.8030. Overall, human economic activities were negatively correlated with NDVI, which also showed partitioning characteristics. Human economic activities have inhibited NDVI in areas where construction land is dominant such as Wuhan and Xiangyang, while NDVI is promoted in areas where woodland is dominant such as Enshi and Shiyan. Human economic activities were the key driving force for landscape pattern and vegetation variation in the study area. Urban expansion was the main reason for the spatial and temporal variations of vegetation in Hubei Province.