1982—2012年北半球荒漠草原过渡带植被物候特征及其与气候因子的关系

摘要

The annual vegetation phenology in the desert/grassland biome transition zone of Northern Hemisphere was deduced from the GIMMS NDVI 3g dataset and the spatio-temporal changes of phenology during 1982-2012 were studied. At the same time, the climatic driving factors of phenology change were also analyzed by coupling global meteorological reanalysis data. The results show that the vegetation phenology in each desert/grassland biome transition zone during 1982-1997 had different characteristics. However, the regular phenomenon of vegetation phenology changed after 1998. The end of growth season (EOS) in almost all desert/grassland biome transition zones of Northern Hemisphere became earlier during 1998-2012, which the rate is 0.41 d/a. The length of growth season (LOS) shortened in each region except for the Sahel, which the average shorten rate is 0.88 d/a. The correlation analysis between vegetation phenology and climatic factors show that the phenology of desert/grassland biome transition zone is affected by climate significantly and the main driving factors are different in each region. In the middle and high latitudes, the temperature is the key factor to limit the vegetation activity and the temperature rising can promote the start of growth season earlier. However, the precipitation increasing could weaken the growth of vegetation in these regions. In contrast, the water deficit that caused by the high temperature could shorten the vegetation growing season, and that is the key impact factor in the low latitudes of Northern Hemisphere. Finally, the relationship between phenology and climatic factors in different time-lags were also analyzed. The results show that the phenology change of desert/grassland biome transition zone is responded obviously to temperature change. In addition, there has a time lag effect in the response of phenology change to evapotranspiration. Nevertheless, this rule does not exist between phenology change and precipitation.%基于GIMMS(global inventory modeling and mapping studies)NDVI 3g数据,在提取北半球荒漠草原过渡带每年植被物候期的基础上,研究了1982—2012年物候期的时间演化趋势及空间分异特征,并结合全球气候再分析资料,探讨了物候变化的气候驱动因素.结果表明:在1998年之前,荒漠草原过渡带植被物候期变化地区间差异较大,而在1998年之后,北半球荒漠草原过渡带生长季结束期整体提前,平均提前0.41 d/a;同时,除萨赫勒以外的各地区植被生长季长度普遍缩短,平均缩短0.88 d/a.植被物候期与气候因子的相关分析发现,荒漠草原过渡带植被物候变化受气候变化影响显著,且空间差异明显.在中高纬度地区,气温是限制植被活动的关键因子,温度升高可以促进生长季开始期的提前,而降水增加则会妨碍植被生长;在较低纬度地区,水分是影响植被活动的关键因素,高温造成的水分亏缺会导致植被生长季缩短.从植被物候期对各气候因子响应的时滞性来看,荒漠草原过渡带植被的物候期对气温变化的响应最迅速,对蒸散的响应存在一定的滞后性,而对降水的响应不存在时滞差异.