北京林业大学学报2017，Vol.39Issue(12)：61-70,10.DOI:10.13332/j.1000-1522.20170172
北京山区侧柏林生长旺季蒸散组分δ18O日变化及其定量区分
Daily variations of δ18 O and its quantitative distinction in evapotranspiration components of Platycladus orientalis plantation during the rapid growth season in the mountainous area of Beijing
摘要
Abstract
As the dominant coniferous tree species in the mountainous area of Beijing, it is imperative to have an insight into the evapotranspiration of Platycladus orientalis in the rapid growth season and its components for deeper understanding of atmospheric vapor exchange of terrestrial ecosystems and plant water demand. The variations of daily δ18 O in a Platycladus orientalis plantation during the rapid growth season and proportions of plant transpiration and soil evaporation to evapotranspiration were analyzed. The continuous water vapor stable isotope analyzer was used to measure δ18 O values of the atmospheric vapor in August, 2016. Mature and suberized twigs of plant and soil samples were collected and measured simultaneously to analyze δ18 O values of transpiration (δT ) and soil evaporation (δE ) , where δT and δE were determined respectively via the steady state hypothesis of isotope and the Craig-Gordon equation. The oxygen isotopic compositions of total evapotranspiration (δET ) could be estimated by a Keeling plot linear regression function. The results showed that: values of δE ranged from -5. 968% to -2. 689%, which rised firstly and then declined at the daily scale; and δ18 O values peaked between 12:00 and14:00, whereas the atmospheric relative humidity ( h) dropped firstly and then rised. The relationship between δE and h was δE = -0. 03h2 +4. 85h-209. 5 (R2 =0. 55,n=32), which indicated that the isotopic fractionation was intensified with h when its value was above 75%. Although the diurnal variations of δET and δT values were complex and there was inconsistent variation tendency for the two in the four experimental days ( ranged from -1. 210% to -0. 951% and -1. 599% to -1. 004%, respectively) , both of them basically shared identical changing trend at the same observation days, suggesting that the evaluation of δT values was probably affected by non-steady state of stable isotopes in the leaf water. And the variations on δET were dominantly driven by δT rather than δE . The results of evapotranspiration partition showed that the contribution of plant transpiration (FT) ranged from 90. 14%to 92. 63% during the experimental days, indicating that the main component of evapotranspiration was plant transpiration during the rapid growth season. The results may have further implications for future forest construction and management in this area.关键词
侧柏林/生长旺季/蒸散发/同位素稳定态Key words
Platycladus orientalis plantation/rapid growth season/evapotranspiration/steady state of isotope分类
农业科技引用本文复制引用
刘璐,贾国栋,余新晓,张永娥..北京山区侧柏林生长旺季蒸散组分δ18O日变化及其定量区分[J].北京林业大学学报,2017,39(12):61-70,10.基金项目
国家自然科学基金青年项目(41401013)、国家自然科学基金重点项目(41430747)、林果业生态环境功能提升协同创新中心(PXM2017014207000043). （41401013）
