2000-2013年西安市植被覆盖度时空演变

Temporal and Spatial Evolution of Vegetation Coverage in Xi’an City from 2000 to 2013

随着黄土高原地区退耕还林政策的实施,近十几年西安市植被覆盖情况变化发生了显著变化。为了对西安市植被覆盖变化进行深入的研究,利用Mann-Kendall趋势检验法及Hurst指数、Pettitt检验法分析了2000—2013年来西安市植被覆盖度变化特征,并利用重心转移模型和相对发展率分析了西安市植被覆盖度变化的空间变化差异。结果表明:(1)西安市植被覆盖度中等程度变异面积占总面积10.02%;(2)西安市植被覆盖度呈增加趋势的面积占区域总面积86.54%,具有正向持续性的面积占区域总面积72.62%,35.30%面积植被覆盖度呈持续改善;(3)西安市植被覆盖度突变年份均显著发生在2004年、2005年、2006年、2007年、2008年,发生显著突变年份的面积占总面积的17.58%;(4)西安市植被覆盖度相对发展率空间变化范围为-9.07~7.49,相对发展率的负值占区域总面积的20.77%,西安市植被覆盖度空间重心呈现由西南逐渐向东北方向转移的趋势;(5)西安市降雨量与植被覆盖度均值均呈现增加趋势,相关系数为0.47(p<0.09),空间分布重心呈现从东北向西南转移的趋势,与植被变化呈现相反的趋势。研究成果有助于进一步深化对西安市植被恢复状况及其影响因素的认识,为西安市植被恢复等生态建设工程提供一定的科学依据。

With the implementation of the policy of returning farmland to forestland in the Loess Plateau,the changes in vegetation coverage in Xi′an City have changed significantly in the past decade.In order to conduct in-depth research on the changes of vegetation coverage in Xi′an City,the Mann-Kendall trend test and Hurst index,Pettitt test were used to analyze the changes of vegetation coverage in Xi′an City from 2000 to 2013,and the spatial variation of vegetation coverage change in Xi′an City was analyzed by using the gravity transfer model and relative development rate difference.The results showed that:(1)the moderate variation area of vegetation coverage in Xi′an City accounted for 10.02%of the total area;(2)the area of vegetation coverage in Xi′an City increased by 86.54%,and the area of positive persistence accounted for 72.62%of the total area,vegetation coverage of 35.30%of area showed continuous improvement;(3)vegetation coverage mutation years of Xi′an City occurred significantly in 2004,2005,2006,2007,and 2008,respectively,the area of significant mutation years accounted for 17.58%of the total area;(4)the spatial variation range of relative coverage rate of vegetation coverage in Xi′an City ranged from-9.07 to 7.49,and the negative value of relative development rate accounted for 20.77%of the total area;the trend of the center of gravity of vegetation coverage in Xi′an City gradually shifted from southwest to northeast;(5)the average rainfall and regional vegetation coverage in Xi′an City showed the increasing trend,the correlation coefficient was 0.47(p<0.09),and the spatial distribution center of gravity showed a trend of shifting from northeast to southwest,which was opposite to the change of vegetation.These research results will help further deepen the understanding of the vegetation restoration status and its influencing factors in Xi′an City,and provide a scientific basis for the ecological construction projects such as vegetation restoration in Xi′an City.