基于RUE的宝鸡地区生长季退耕还林（草）工程生态效果评价

综合评价第一轮退耕还林（草）工程实施期间（2001~2008）、第一轮退耕还林（草）工程实施后（2009~2013）及第二轮退耕还林（草）工程实施以来（2014~2017）宝鸡地区的生态修复效果，为后续国家生态修复政策的完善和实施提供有针对性的理论参考。研究基于植被降水利用效率（Rainfall Use Efficiency, RUE）模型，综合气候、土地利用/覆盖及光学遥感3个维度，采用经分离后的人为干预（增加/减少）因素探讨了自然和人为驱动因子对植被恢复的影响。结果表明：（1）自2001年以来，宝鸡地区造林面积呈增加趋势的区域遍布全区（83%），第一轮退耕还林（草）工程实施后植被改善面积占比为83.32%，林地（介于0.64~0.67）植被改善最好；（2）夏季人为干预区域降水量最大，RUE值最小。春季RUE增加最显著，夏季RUE减少最显著；（3）累计增强型植被指数（Enhanced Vegetation Index, EVI）与RUE在2001~2008年、2009~2013年和2014~2017年，均呈较好的正相关性。∑EVI分别以0.148、0.029、0.143/a的速度逐年增长；（4）3个时间段上，林地的RUE值最高。其中2001~2008年、2009~2013年人为干预减少的年均RUE值（0.40、0.43）小于人为干预增加（0.48、0.46），2014~2017年人为干预减少的RUE值（0.54）大于增加的RUE值（0.51）。可见，时空尺度上人为干预在短期时间内能够促进植被恢复显著改善，但气候因素对宝鸡地区植被覆盖的影响是长期效应。

Ecological Effect Evaluation of Returning Farmland to Forest (Grass) Project of the Growing Season in Baoji Area Based on RUE

The ecological restoration effect was comprehensively evaluated in Baoji area from three stages, the first two stages during and after the implementation of the first round of returning farmland to forest (grass) project(2001-2008, 2013-2013), and the stage during the implementation of the second round of returning farmland to forest project(2014-2017), which provide a targeted theoretical reference for the improvement and implementation of the subsequent national ecological restoration policy. Based on the Rainfall Use Efficiency (RUE) model and integrated climate, land use/cover and optical remote sensing, this study explores the impact of natural and anthropogenic drivers on vegetation restoration by the use of isolated human intervention (increasing/decreasing). The results show that: (1) Since 2001, the area of afforestation area in Baoji has shown an increasing trend across the region (83%). After the implementation of the first round of returning farmland to forest (grass) project, the area of vegetation improvement was 83.32%, and the improvement of forest vegetation (between 0.64-0.67) was the best; (2) summer artificial intervention area has the largest precipitation and the lowest RUE value. The increase of RUE in spring was the most significant, and the decrease of RUE in summer was the most significant; (3) The Enhanced Vegetation Index (EVI) and RUE showed positive correlations in 2001-2008, 2009-2013 and 2014-2017, respectively. ∑EVI grows at a rate of 0.148/a, 0.029/a, and 0.143/a, respectively; (4) The annual average RUE (0.40, 0.43) of the decrease in human intervention (2001-2008, 2013-2013) was less than the RUR (0.48, 0.46) of the increase in human intervention, and the RUE value of human intervention reduction (0.54) is greater than the value of human intervention (0.51) in 2014-2017. On spatial and temporal scale, it can be seen that human intervention can promote significant improvement of vegetation in a short time, but the climatic factors have long-term effects on the vegetation coverage in Baoji.