考虑气候时间效应的额尔齐斯河流域植被动态变化及其驱动力

Vegetation dynamics and its driving force in the Irtysh River Basin considering climatic temporal effects

气候变化显著影响干旱半干旱区植被的生长状态,认识气候对植被生长的影响至关重要,忽略时间效应可能会导致植被动态归因的偏差。结合Theil⁃Sen Median趋势和Mann⁃Kendall检验方法,查明额尔齐斯河流域2001—2020年间生长季归一化植被指数(NDVI)的变化趋势,采用多元线性回归模型探究植被状况对气候变化响应的时间效应,并进一步改进残差分析量化气候变化和人类活动对NDVI变化的贡献率。结果表明:近二十年来额尔齐斯河流域NDVI整体以0.0017/a的速率呈增加趋势,草地、森林和湿地的增长率分别为0.0019/a、0.0014/a、0.0068/a;降水对植被的影响平均滞后1.92个月,平均累积1.90个月,气温对植被的影响平均滞后1.70个月,平均累积1.57个月;考虑时间效应后,气候变化对NDVI变化的平均解释力提高了7.84%,总体贡献率为29.27%;北部阿尔泰山脉降水增加、气温升高带来的冰川融化促进植被生长,南部荒漠区域降水减少、气温升高导致蒸发增加抑制植被生长。研究考虑时间效应探究了额尔齐斯河流域植被动态对气温和降水的响应关系,为额尔齐斯河流域的生态保护提供更科学的数据基础。

Climate change significantly affects growth status of vegetation in arid and semi⁃arid zones,and it is crucial to recognize temporal effects of climate on vegetation growth.The ignorance of temporal effects could lead to bias in attributing vegetation dynamics.In the study,the Theil⁃Sen Median trend and Mann⁃Kendall test methods were combined to show the trend of NDVI during the growing season between 2001 and 2020 in the Irtysh River Basin.Multiple linear regression model was used to explore the temporal effects of climate change on vegetation.Then,improved residual analysis considering the time effect was applied to quantify the contribution of climate change and human activities to NDVI changes.The results were as follows:1)NDVI in the Irtysh River Basin has been increasing at a rate of 0.0017/a for the last two decades,with growth rates of 0.0019/a,0.0014/a,and 0.0068/a for grasslands,forests,and wetlands,respectively;2)the impact of precipitation on vegetation had an average lag of 1.92 months,with average cumulative of 1.90 months,while the impact of temperature on vegetation had an average lag of 1.70 months,with average cumulative of 1.57 months;3)After considering the time effect,the average explanatory ability of climate change to NDVI changes increased by 7.84%,with an overall contribution of 29.27%;4)increased precipitation and glacial melting due to warmer temperatures in the Altai Mountains promoted vegetation growth,while reduced precipitation and increased evaporation in the south desert regions inhibited vegetation growth.The study can provide data base and scientific support for the ecological conservation of the Irtysh River Basin by exploring the interrelationships between vegetation dynamics and climate change while taking time effect into consideration.