1961—2019年黄土高原植被潜在蒸散及影响因子

研究潜在蒸散对于深刻了解区域的生态环境问题及水文循环过程具有重要的理论与现实意义.该研究基于Penman-Monteith模型对1961—2019年黄土高原潜在蒸散的时空变化特征进行了分析，再结合土地利用数据探究了各植被类型潜在蒸散的差异及其影响因素.结果表明:①1961—2019年黄土高原区域呈暖干化趋势，其中平均最高温度、平均最低温度与平均温度均呈显著增加趋势；平均相对湿度、平均风速、日照时数均呈显著降低趋势；降水量非显著减少.②在空间分布格局上，黄土高原区域年均、生长季、春季、夏季和秋季潜在蒸散均呈南北高、东西低的分布特征；1961—2019年春季潜在蒸散以0.41 mm/a的速率显著增加(P < 0.05).③1981—2019年黄土高原区域潜在蒸散平均变化趋势为1.35 mm/a，其中62.98%的区域呈显著增加趋势(P < 0.05)，多分布在东部和西部地区.④1961—2019年黄土高原区域各植被类型潜在蒸散变化均表现为不显著上升趋势，多年平均潜在蒸散大小表现为草原>农田>针叶林>草甸>阔叶林>灌丛，其中，1981—2019年各植被类型潜在蒸散增加趋势大小表现为阔叶林>针叶林>灌丛>农田>草甸>草原.⑤影响黄土高原区域各植被类型潜在蒸散的主要气象因子为平均风速与平均相对湿度，其次为日照时数.潜在蒸散随着平均风速和日照时数的增加而增加，随着平均相对湿度的增加而减小.研究显示，各植被类型潜在蒸散的增加与区域降水的减少可能会加剧水资源短缺态势，建议黄土高原地区在开展植被恢复工作时，应优先考虑耗水较少的树种，优化群落植被结构，充分利用光水热资源，修建蓄水设施，支撑区域生态环境的可持续发展. 

Potential Evapotranspiration and Influence Factors of Vegetation in Loess Plateau from 1961 to 2019

The study of potential evapotranspiration has important theoretical and practical significance for a profound understanding of regional ecological and environmental problems and hydrological cycle processes. Based on the Penman-Monteith model, this study analyzed the temporal and spatial variation characteristics of potential evapotranspiration in the Loess Plateau from 1961 to 2019, and combined with land use data, explored the differences in potential evapotranspiration of different vegetation types and their influence factors. The results showed that: (1) From 1961 to 2019, the Loess Plateau showed warming and drying trends, among which the mean maximum temperature, mean minimum temperature and mean temperature all showed a significant increasing trend. The average relative humidity, wind speed and sunshine duration all showed a significant decreasing trend. The precipitation decreased insignificantly. (2) From the perspective of spatial distribution pattern, the annual average, growing season, spring, summer and autumn potential evapotranspiration was high in the north and south, low in the east and west of the Loess Plateau. The potential evapotranspiration in spring increased significantly at a rate of 0.41 mm/a (P < 0.05) from 1961 to 2019. (3) From 1981 to 2019, the variation trend of average potential evapotranspiration in the Loess Plateau was 1.35 mm/a, of which 62.98% showed a significant increasing trend (P < 0.05), mostly distributed in the eastern and western regions. (4) From 1961 to 2019, the potential evapotranspiration of different vegetation types in the Loess Plateau showed no significant increasing trend, and the average potential evapotranspiration for many years was grassland > farmland > coniferous forest > meadow > broadleaved forest > shrub. From 1981 to 2019, the potential evapotranspiration growth trend of different vegetation types was broadleaved forest > coniferous forest > shrub > farmland > meadow > grassland. (5) Average wind speed and average relative humidity were the most important meteorological factors affecting vegetation types in the Loess Plateau, followed by sunshine duration. The potential evapotranspiration increased with the increase of average wind speed and sunshine hours, and decreased with the increase of average relative humidity. Temperature indicators had little effect on the potential evapotranspiration of different vegetation types. The results showed that the increase potential evapotranspiration of different vegetation types and the decrease in regional precipitation may exacerbate water shortages. Therefore, in the future vegetation restoration work in the Loess Plateau region, priority should be given to the tree species with less water consumption, the structure of vegetation community should be optimized, the light, water and heat resources should be fully utilized, and water storage facilities should be built to support the sustainable development of the regional ecological environment.