• 论文与研究报告 •

### 六盘山半干旱区华北落叶松人工林林下日蒸散特征及其影响因子

1. 1. 中国林业科学研究院森林生态环境与保护研究所 国家林业和草原局森林生态环境重点实验室 北京 100091;
2. 宁夏农林科学院荒漠化治理研究所 宁夏防沙治沙与水土保持重点实验室 银川 750002;
3. 新乡学院生命科学技术学院 新乡 453000
• 收稿日期:2018-04-03 修回日期:2019-08-12 发布日期:2019-10-28
• 基金资助:
宁夏回族自治区全产业链创新示范项目（QCYL-2018-12）；国家重点研发计划（2017YFC0504600；2016YFC0501702）；国家自然科学基金重大项目（41390461）、面上项目（41671025）；国家林业和草原局宁夏六盘山森林生态定位站和宁夏回族自治区生态修复与多功能林业综合研究中心资助。

### Daily Forest Floor Evapotranspiration of Larix principis-rupprechtii Plantation and Its Influencing Factors in the Semi-Arid Area of Liupan Mountains

Han Xinsheng1,2, Wang Yanhui1, Li Zhenhua1,3, Wang Yanbing1, Yu Pengtao1, Xiong Wei1

1. 1. Institute of Forest Ecology, Environment and Protection, CAF Key Laboratory of Forestry Ecology and Environment of National Forestry and Grassland Administration Beijing 100091;
2. Institute of Desertification Control, Ningxia Academy of Agriculture and Forestry Sciences Key Laboratory of Desertification Control and Soil and Water Conservation of Ningxia Yinchuan 750002;
3. Xinxiang University, School of Life Science and Technology Xinxiang 453000
• Received:2018-04-03 Revised:2019-08-12 Published:2019-10-28

Abstract: [Objective] The variation of daily forest floor evapotranspiration (DFFET) of a larch (Larix principis-rupprechtii) plantation and its response to environmental factors were studied in the small watershed of Diediegou at the northern part of Liupan Mountains, in the semi-arid northwestern China, for an accurate calculation and prediction of the forest evapotranspiration (ET), and for the fine forest management to solve the forest-water contradiction.[Method] A representative sample plot of larch plantation was selected, and the meteorological conditions both inside and outside the forest plot were monitored in August-October of 2013. The potential evapotranspiration (PET) was selected as a meteorological factor to reflect the integrated effects on DFFET by the various meteorological parameters. Within the plot, 11 micro-lysimeters were set up at representative sites, of which 6 were rain-proof treated to enlarge the soil moisture variation range for a better analysis of the soil moisture effect, while other 5 ones were treated under natural conditions. The DFFET and daily soil moisture in the lysimeter were monitored. Based on the analysis of the responses of DFFET to soil moisture and meteorological factors, a DFFET model was established to reflect the comprehensive effects of environmental factors.[Result] During the study period, the DFFET showed a large fluctuation range, and characterized by a gradual decrease with declining air temperature, solar radiation and rainfall. The DFFET was obviously influenced by many meteorological factors, but the main meteorological factors differed among months and weather types, from the saturation vapor pressure deficit in August to the solar radiation in September and the daily maximum temperature in October; and from the PET and solar radiation in cloudy days to the temperature in sunny days and the PET in rainy days. Besides the weather parameter of PET which can reflect the integrated impact of many meteorological factors, soil moisture is also an important factor influencing DFFET under both rain-proof and natural conditions. With rising PET and soil moisture, the DFFET increased rapidly at first and then slowly, but leveled off after a certain threshold (PET of 4.5 mm·d-1, volumetric soil moisture of 35% or relative soil moisture of 0.56) was reached. The model of DFFET (ETU, mm·d-1) coupling the effects of PET (mm·d-1) and volumetric soil moisture (VSM,%) was established and well fitted using field measured data, as:ETU=(-0.045PET2+1.392PET)(1-EXP(-1.292VSM)), (R2=0.80).[Conclusion] The DFFET of the larch plantation in the semi-arid area of Liupan Mountains increased with rising PET and soil moisture, but with a gradually declining rate and finally stabilized after reaching their thresholds. Using a DFFET model considering the effects of both PET and soil moisture can improve the calculation and prediction accuracy..