运用Mann-Kendall方法探究地表植被变化趋势及其对地形因子的响应机制——以太湖苕溪流域为例

Dynamics of vegetation and its responses to terrain factors with Mann-Kendall approach:a case study in Tiaoxi watershed,Taihu Lake

利用Mann-Kendall方法对浙江太湖苕溪流域植被随时间、高程、坡度序列变化的特征与机制进行分析.结果表明:在2000—2010年间,植被随时间变化波动大,但该流域植被覆盖和空间变异均呈不显著增长趋势,2004年植被覆盖最低,植被空间异质性在2002年至2004年间达到最高水平;植被覆盖随高程、坡度的增加而增长,植被空间变异随高程、坡度的增加呈下降趋势,在高程200 m和坡度15°区域有一突变点.该研究结果不仅揭示了植被随时间、高程、坡度的变化趋势,还揭示了植被发生突变的时间段、高程带、坡度带,为进一步研究植被时空变异规律及驱动因子奠定了基础.

Mann-Kendall approach was applied for characterizing the features and mechanisms of vegetation changes with time,elevation and slope in the Tiaoxi watershed,Taihu Lake region,Zhejiang Province,east China.The results indicated that the annual vegetation in the area fluctuated dramatically and showed a moderate trend of increase from 2000 to 2010,but in 2004,the coverage dropped to the lowest level;The variability of spatial distribution also showed a moderate trend of increase during the study period,with the spatial heterogeneity reaching the highest between 2002 and 2004;the vegetation coverage kept increasing while the spatial heterogeneity decreased with the increment of elevation and slope.At elevation of about 200 m or slope around 15 degrees,there were signs of catastrophe change.The results above reveal the trend of vegetation changes with time,elevation and slope,and identify when and where the catastrophes occur,which lays a sound basis for further study on the spatiotemporal dynamics of vegetation and its driving factors.