石羊河中游生长季植被覆盖对气候的响应

Response of Vegetation Coverage to Climatic Factors in the Middle Reaches of the Shiyang River in Growing Season

利用MODIS-EVI月合成数据,计算2006—2015年石羊河中游生长季植被覆盖度,探究植被覆盖年际变化以及对气候的响应关系。利用像元二分模型计算植被覆盖度,提取研究区不同植被覆盖程度的年际变化。结果表明：10 a间,中游地区以低植被覆盖类型为主,并与同期降水的年际变化关系密切。其次,采用变化趋势分析法,计算监测时段内植被覆盖的动态变化。结果表明：中游地区生长季植被覆盖度总体上处于增加趋势,增加速率为0.041·（10a）^-1;植被覆盖度显著增加区域集中于绿洲-荒漠过渡带。最后,采用相关分析法,分析了植被覆盖度与生长季平均气温和降水的相关程度。生长季植被覆盖度与同期降水的相关程度高于与生长季平均气温相关性,平均偏相关系数分别为0.14和-0.05;荒漠绿洲过渡带成为与气候因子显著相关的活跃地带。

In this paper,the MODIS-EVI monthly data were used to calculate the values of vegetation coverage in the middle reaches of the Shiyang River in growing season during the period from 2006 to 2015. The interannual variation of vegetation coverage and its response to climate factors were investigated. The dimidiate pixel model（ DPM） was used to calculate the values of vegetation coverage,and the interannual variation of vegetation coverage at different levels in the study area was extracted. The results showed that the low vegetation coverage was mainly distributed in the middle reaches in the 10 years,which was closely related to the interannual variation of precipitation in the same period. Secondly,the trend analysis was used to calculate the dynamic changes of vegetation coverage during the monitoring period. The results showed that the vegetation coverage in the middle reaches was increased,and its increase rate was 0. 041·（ 10 a）^-1. Significant increase of vegetation coverage occurred in the oasis-desert ecotone. Finally,the correlations between vegetation coverage and temperature and precipitation in growing season were analyzed by correlation analysis. The results showed that the correlation between vegetation coverage and precipitation in growing season was higher than that between vegetation coverage and temperature,and the average partial correlation coefficients were 0. 14 and-0. 05 respectively. The desert-oasis ecotone was significantly correlated with climatic factors.