新疆NDVI时空特征及气候变化影响研究

Spatio-temporal Patterns of NDVI Variations and Possible Relations with Climate Changes in Xinjiang Province

基于新疆50个气象测站2003-2010年逐日降水、气温资料,结合逐月归一化植被覆盖影像资料,利用趋势分析、R/S分析、模糊C均值聚类、图像处理等方法,系统分析了全疆NDVI时空变化特征及其可持续性,并探究NDVI与气候因子(气温、降水)之间的相关性。研究表明:植被覆盖及气象因子年际间差异不大,呈现出整体稳定的态势,但年内变化明显。北疆/天山北坡水热条件优良、植被长势最好,且植被长势对气候因子的滞后效应并不明显且滞后时间短。天山南坡/天山东段次之,而南疆植被覆盖程度最差,南疆/天山南坡植被长势对气候因子(降水、气温)存在明显的滞后效应,植被生长受气温、降水限制性更大,且气温作为主要因子,对天山南坡植被生长的限制作用表现得更为突出。总体上,新疆植被覆盖呈持续性变化,现有植被覆盖情况基本保持不变,但呈退化趋势的面积大于得到改善的面积,在一定程度上与人类活动有很大关系,探查植被长势的变化趋势并及时做出相应调整,不仅能为新疆地区的植被保护以及植被恢复工作提供一定的科学依据,更能够为合理有效地安排农作物生产提供重要的理论指导。

Spatio-temporal patterns of NDVI and possible relations between NDVI and climate factors in Xinjiang Province have been analyzed based on daily precipitation and temperature data covering the period of 2003-2010 from 50 meteorological stations. Results show that inter-annual variations of NDVI and climate factors are not evident and apparent annual changes are well identified. Abundant precipitation and high temperature was observed in summer and autumn with good coverage of vegetation. However, the adverse conditions can be found in winter and spring. The northern Xinjiang as well as the north slope of the Tianshan Mountains are dominated by abundant precipitation and flourishing vegetation. The south slope of Tianshan Mountains and the eastern Xinjiang take second place. The southern Xinjiang, however, is characterized by scarce precipitation, high temperature and poor vegetation coverage. The vegetation condition in northern Xinjiang and the north slope of Tianshan Mountains has no obvious time-lag response to climate factors. Nevertheless, it has obvious time-lag response to climate factors and the growth of vegetation is restricted by climate factors in southern Xinjiang and the south slope of Tianshan Mountains. As the main factor, restriction of temperature is more prominent. Overall, the vegetation varied continuously in Xinjiang and the area of improvement tendency is less than those of degradation tendency. To some extent, human activity has a great influence on the vegetation condition. Exploration of vegetation changes and carrying out of timely adjustments, not only can offer a scientific basis for vegetation protection and restoration, but also can provide important theoretical guidance for crop production effectively.