摘要:基于月尺度气温、降水以及MODIS-GPP、MODIS-ET遥感数据，采用基于像元的时滞偏相关分析，揭示了陕北黄土高原植被生态系统水分利用效率气候时滞效应及其影响因素。结果表明：①2000-2014年，受退耕还林草生态工程和气候变化的双重影响，陕北黄土高原WUE呈波动变化趋势，2001-2003年显著下降，2003-2005年、2010-2013年显著上升。受不同植被类型的影响，年内WUE呈急速双峰、缓速双峰和单峰型3种变化状态。②陕北黄土高原WUE对降水存在明显的时滞效应，滞后时间多为3个月，人为扰动较大的I-1、I-2、Ⅱ-2生态区以及植被覆盖度较高的Ⅲ-3生态区WUE对降水的时滞响应程度明显低于其他生态区；而对气温的时滞效应较弱，仅南部的Ⅲ-2、Ⅲ-3生态区WUE对气温存在1-2个月滞后时间。③不同植被类型WUE对降水的时滞效应较明显，荒漠类植被WUE对降水时滞响应程度最强，滞后时间近3个月，针叶林时滞响应程度最弱，滞后时间为2.1个月；但对气温的时滞效应总体较弱，针叶林WUE对气温滞后时间为15 d，其余大多数植被类型WUE对气温不存在滞后时间。④WUE气候时滞效应对植被覆盖度的敏感性存在一定的阈值效应，植被覆盖度高于阈值62.3%时，对降水的时滞效应开始逐渐减弱，而对气温的时滞效应逐渐显现。



Abstract:Based on the primary data such as temperature, precipitation, MODIS-GPP and MODIS-ET datasets at monthly scale from 2000 to 2014, using pixel-based time-lay patial correlation analysis, the climate time-lag effect of water use efficiency (WUE) and its effective factors on the Loess Plateau of northern Shaanxi were analyzed. The results showed that under the influence of the ecological project of converting farmland to forestry or grassland and the climate change, the interannual WUE in the Loess Plateau of northern Shaanxi showed a fluctuating trend, among which, 2001-2003 decreased significantly, 2003-2005 and 2010-2013 increased significantly, and the change ranged from 1.06 to 1.67 gCmm^-1m^-2 from 2000 to 2014. Influenced by different vegetation types, the intraannual WUE showed three kinds of changes: rapid double peak, slow double peak and single peak. WUE in the Loess Plateau of northern Shaanxi had obvious time-lag effect on precipitation, and the lag time was mostly 3 months. But the response degree and time-lag of WUE to precipitation in I-1, I-2, II-2 and III-3 eco-functional areas were significantly lower than those in other eco-functional areas. However, the time-lag effect of WUE to temperature was weak, and the lag time of WUE to temperature was 1-2 months, which only lied in III-2 and III-3 eco-functional areas. The time-lag effect of WUE to precipitation under different vegetation types was more significant. WUE of desert vegetation had the strongest time-lag effect to precipitation, with the lag time of nearly 3 months, while the lag time was the weakest under coniferous forest, with the lag time of 2.1 months. But the time-lag effect of WUE to temperature was generally weak. The time lag of WUE to temperature under coniferous forest was 15 d, and there was no time-lag under most other vegetation types. The sensitivity of time-lay effect on climate to vegetation coverage had a threshold effect. When the vegetation coverage was higher than 62.3%, the time-lag effect to precipitation gradually weakened, and that to temperature gradually appeared.





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