生态学报Issue(23)：7821-7831,11.DOI:10.5846/stxb201405030871
基于树干液流及涡动相关技术的葡萄冠层蒸腾及蒸散发特征研究
Research of transpiration and evapotranspiration from a grapevine canopy combining the sap flow and eddy covariance techniques
摘要
Abstract
In agriculture ecosystems, more than 90% of all water input is lost by evapotranspiration ( ET ) . Thus, the accurate measurement of ET and its associated components (i.e., canopy transpiration and soil evaporation) are essential for many agricultural applications, such as irrigation scheduling, drainage, and yield forecasts. In the arid region of northwestern China, water resources are rare and are often the restricting factor for plant production. By comprehensively using the sap flow method and eddy covariance ( EC) technique, the single tree sap flow velocity and evapotranspiration flux from the grapevine in a desert oasis ecosystem located in Nanhu County, China, were measured during a typical growing season from July 13 to September 12, 2013. Canopy transpiration was then obtained by multiplying the average sap flow per leaf area unit by the leaf area index ( LAI ) , and compared with the EC-measured evapotranspiration flux. The results showed that the diurnal dynamics of sap flow velocity of all sample trees exhibited single peak curves. With increasing diameter of the grapevine at breast height ( DBH) , the peak in the diurnal variation of sap flow velocity tended to increase. Thus, the sap flow velocities of different single trees were mainly controlled by DBH. The average daily water consumption of the grapevine was exponentially associated with DBH, while the regression relationships differed significantly in different months. Mean water consumption of each sample trees ranged from 2.76 kg to 10 kg during a typical growing season, which was consistent with previous studies on the water consumption of Tamarix ramosissima in the hinterland of Taklimakan Desert in China. Daytime dynamics of canopy transpiration upscaled by sap flow (Esf) and evapotranspiration measured by EC (ETec) both exhibited the unimodal type, and their variation trends were also relatively identical. From 08:00 to 12:00 and 17:00 to 20:00, there was good agreement between the values of Esf and ETec, which means that evapotranspiration primarily originated from canopy transpiration for this period. However, from 12:00 to 17:00, the values of Esf were lower than those of ETec, due to the contributions of soil evaporation to the evapotranspiration process. During the study period, the daily evapotranspiration varied from 1.74 mm/d to 10.12 mm/d, with a mean value of 7.13 mm/d, while daily canopy transpiration ranged from 1. 88 mm/d to 8. 12 mm/d, with a mean value of 6. 12 mm/d. The ratios of daily canopy transpiration to daily evapotranspiration varied from 60% to 98. 3%, with a mean value of 85. 8%. On cloudy and rainy days, the difference between daily evapotranspiration and daily canopy transpiration was very small, with both being less than 5 mm/d. These results indicate that evapotranspiration was dominated by canopy transpiration during the growth stage of the grapevine. The difference in daily evapotranspiration and daily canopy transpiration was daily soil evaporation with a mean value of 1.01 mm/d. However, this result still needs further experimental verification. Thus, the comprehensive use of the sap flow method and eddy covariance technique may help us to identify the characteristics evapotranspiration and its different components ( canopy transpiration and soil evaporation) in ecosystem efficiently. This information will improve our understanding about how the evapotranspiration process interacts with environmental factors.关键词
树干液流/热平衡原理/涡动相关/冠层蒸腾/蒸散发Key words
sap flow/heat balance method/eddy covariance/canopy transpiration/evapotranspiration引用本文复制引用
白岩,朱高峰,张琨,马婷..基于树干液流及涡动相关技术的葡萄冠层蒸腾及蒸散发特征研究[J].生态学报,2015,(23):7821-7831,11.基金项目
国家自然基金项目(31370467) （31370467）
教育部“新世纪人才”项目(NCET-11-0219) （NCET-11-0219）
中央高校基本科研业务费专项资金(lzujbky-2013-m02) （lzujbky-2013-m02）
