Evapotranspiration from the understory of a tropical dry deciduous forest in Cambodia
Evapotranspiration from the understory of a tropical dry deciduous forest in Cambodia
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DOI：
10.1016/j.agrformet.2020.108170
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发表时间：
2020-12
影响因子：
6.2
通讯作者：
S. Iida;Takanori Shimizu;K. Tamai;N. Kabeya;A. Shimizu;Eriko Ito;Y. Ohnuki;Sophal Chann;D. Levia
中科院分区：
文献类型：
--
作者：
S. Iida;Takanori Shimizu;K. Tamai;N. Kabeya;A. Shimizu;Eriko Ito;Y. Ohnuki;Sophal Chann;D. Levia
与其他一些森林生态系统相比，人们对热带干旱落叶林的水平衡了解较少。为了帮助缩小这一知识差距，我们分别测量了整个生态系统的蒸散量（ETW），蒸腾（TR）和截留损失（IL）从上层树木，和蒸散从林下植被（ETU）在柬埔寨的热带干燥落叶林。结果表明，在年尺度上，ETW相当于降水量（P）的73.7%。在旱季，ETW相当于P的120.1%，这表明土壤水分利用在丰水期补充。除旱季中期外，由于低估了TRG，用原始系数（TRG）、IL和ETU估算的热耗散（TD）法估算的蒸腾量之和小于ETW。虽然最近报道的校准系数可以合理地correctTRG，未来的TD方法的校准，强烈建议在热带干旱森林的单树尺度蒸腾的精确评估。林下植被对ETW的年贡献率（ETU/ETW）为34.6%，说明在全面了解热带干旱森林水文循环过程时，林下植被不可忽视。ETU/ETW的季节变化主要受地上部分叶面积指数（LAI）的控制，在丰水期ETW总体稳定，ETU随LAI的增加而减小，而在枯水期则相反，即ETU随LAI的增加而减小。ETW随LAI的下降而下降，ETU的变化较小。因此，LAI既影响ETU/ETW的季节性，又影响ETU/ETW的年贡献，对该森林的水文循环有显著影响。
The water balance of tropical dry deciduous forests is less well understood than some other forest ecosystems. To help close this knowledge gap, we separately measured the evapotranspiration from the whole ecosystem (ETW), transpiration (TR) and interception loss (IL) from overstory trees, and evapotranspiration from the understory vegetation (ETU) in a tropical dry deciduous forest in Cambodia. It was found thatETWwas equivalent to 73.7% of rainfall (P) at the annual scale. In the dry season,ETWcorresponded to 120.1% ofP, which indicates the utilization of soil water replenished during the wet season. The sum of transpiration estimated by the thermal dissipation (TD) method with the original coefficient (TRG),IL, andETUwas smaller thanETW,except for the middle of the dry season, due to an underestimation ofTRG. Although recently reported calibration coefficients can reasonably correctTRG, future calibrations of the TD method are highly recommended for the precise evaluation of single-tree-scale transpiration in tropical dry forests. The annual contribution of the understory vegetation toETW(ETU/ETW) was 34.6%, leading to the conclusion that the understory vegetation cannot be ignored when trying to gain a comprehensive understanding of the hydrologic cycle in tropical dry forests. The seasonal variations inETU/ETWwere mainly controlled by the leaf area index (LAI) of overstory trees, resulting from the overall stability ofETWand decreasing trend ofETUwith increasingLAIin the wet season, with the opposite holding true in the dry season, i.e., decreasingETWwith the decline ofLAIand less variations ofETU. Thus,LAIinfluenced both the seasonality and the annual contribution inETU/ETW, exerting a notable influence on hydrological cycling in this forest.