作者：ShouJia Sun, Ping Meng*, JinSong Zhang, Xianchong Wan, Ning Zheng, Chunxia He
期刊：Agricultural and Forest Meteorology
发表时间：2014年
卷.期.页码：184:36-47
摘要：
In
terrestrial ecosystems, partitioning ecosystem-scale evapotranspiration (ET)
between plant transpirationand soil evaporation remains a technical challenge.
In this paper, we used a newly-developedlaser-based isotope analyzer (OA-ICOS)
and the Keeling plot approach to partition ET components of a Quercus variabilis plantation in a
lithoid hilly area of north China. The results showed that, on day-ofyear(DOY)
254, 257, and 263, the modeled leaf water 18O composition (δL,b)
and observed leaf water 18O composition (δL,b) were in
substantial agreement and had a significant linear correlation with coef-ficient
of 0.96, indicating that Keeling plot approach and Graig–Gorden model can be
used in portioning ET between plant transpiration and soil evaporation in a
terrestrial forest ecosystem. Isotopic partitionrevealed that the percent
contribution of transpiration to total ET increased from the morning, reachedmaximum
values at noon, with maximum values of 91.19%, 86.30%, and 85.37% for DOY 254,
257, and263, respectively, indicating the transpiration from Q. variabilis
Blum contributed the most to the totalET in this forest ecosystem. On DOY 260,
the stability stratification was unstable, which resulted fromthe foreign vapor
concentration. The increased vapor concentration led to a 80.83% difference
between δsL,b and δL,b. The correlation
coefficients between δsL,b and δL,b decreased
from 0.96 to 0.43 when dataseton DOY 260 was included, indicating foreign vapor
increased the uncertainty in the estimation of δ18O of ET (δET)
and δ18O of transpiration (δT) in the forest ecosystem.
Path analysis results suggested thatwater vapor concentration was the major
factor influencing the partitioning of ET with isotopic approachin the forest
ecosystem. Since the increased water vapor concentration and decreased
atmosphere δ18O disturbed the estimation of δE, δT,
δET, the isotopic approach cannot be used in partitioning ET underthis
condition on DOY 260. Therefore, under most circumstances the isotopic approach
can be used topartition ET for forest ecosystem in a non-steady state (NSS),
while water vapor concentration may causeuncertainties.