首页|树木夜间液流组分划分方法对比——以毛白杨为例

树木夜间液流组分划分方法对比——以毛白杨为例

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夜间液流可通过叶片气孔流失，即夜间蒸腾，也可存储在茎干中，即茎干充水。从夜间液流中区分夜间蒸腾与夜间茎干充水是一个亟待解决的难题。预测充水法由于其便捷性被广泛应用，但其准确性备受质疑。为了系统分析现有的不同预测充水法在夜间液流组分划分中的准确性与适用性，该研究以毛白杨(Populus tomentosa)为实验材料，利用热扩散探针在高1。3 m处和7。0 m处进行液流测量，结合高度差法和预测充水法分别在茎干充水和夜间蒸腾上的准确性优势，分析对比4种传统预测充水法的估算效果。就4种预测充水法对不同高度液流进行分析得出的夜间蒸腾量而言，仅基于线性衰减模型的预测充水法(Line法)误差不显著，其他方法均存在较大偏差。采用4种预测充水法估算的茎干充水量与高度差法所得结果相比，仅基于蒸腾反推的预测充水法(Et法)的预测结果与之存在极显著差异，其余预测法差异均不显著，且Line法偏差最小。基于以上结果，该研究提出"液流高度差预测充水法"作为夜间液流组分划分新方法，可将夜间液流划分为3个组分，即茎干充水、冠层充水和夜间蒸腾。新方法通过高度差法提高对冠层以下茎干充水量估算的准确性，通过误差最小的Line法提高冠层充水组分和叶片蒸腾组分划分的准确性。新方法计算的夜间充水约为76。5％，较现有研究提高了 19。8％-26。5％。划分出的夜间液流组分对环境因子的响应结果表明，空气水汽压亏缺(VPD)与浅层土壤含水率为夜间充水的主要影响因子，夜间蒸腾在夜间液流中的占比与VPD呈非线性负相关关系。
Comparison of methods for dividing nighttime sap flow components in Populus tomentosa trees
Aims Nighttime sap flow can be lost through the leave stomata as nocturnal transpiration or stored in the stem as nocturnal refilling.Distinguishing transpiration and refilling from nighttime sap flow has been a challenging and pressing problem that needs to be addressed.Although the water-refilling forecasting method is widely used due to its convenience,its accuracy is highly questionable.Methods To systematically analyze the accuracy and applicability of four water-refilling forecasting methods for the division of nighttime sap flow components,we conducted a study using Populus tomentosa as the test material.The thermal dissipation probe(TDP)were utilized to measure the nighttime sap flow.By combining the accuracy advantage of the height difference method in stem water-refilling with that of the water-refilling forecasting method in nighttime transpiration,we compared and analyzed the estimation effects of the four commonly used water-refilling forecasting methods in this study.Important findings In terms of estimating the amount of the nocturnal transpiration using the four methods based on sap flow atdifferent heights,only the linear decay model method(Line Method)showed no significant difference,while the other methods exhibited large deviations.When comparing the estimated stem water refilling using the four water-refilling forecasting methods with the results calculated by the height difference method,only the prediction method based on transpiration inversion(Et method)showed a significant difference,while the other methods did not.Additionally,among the four water-refilling forecasting methods,the Line method had the smallest deviation.Thereby,we propose using the sap flow height difference method for water-refilling forecasting to divide nighttime sap flow into three components,namely stem water-refilling,canopy water-refilling,and nocturnal transpiration.This method improves the estimation accuracy of stem water-refilling below the canopy by applying the height difference method.Furthermore,it enhances the accuracy in differentiating canopy water-refilling and nocturnal transpiration through the Line method with the smallest error.Using the new method,the calculated amount of nocturnal refilling was approximately 76.5％,which was 19.8％-26.5％higher than the findings of existing studies.The responses of the divided nighttime sap flow components to environmental factors indicated that vapor pressure deficit(VPD)and shallow soil water content were the main factors influencing nocturnal refilling.The proportion of nocturnal transpiration in nighttime sap flow exhibited a negative and nonlinear correlation with VPD.

comparison of methodsnighttime sap flownocturnal transpirationnocturnal refillingcomponent divisionpoplar plantationthermal dissipation probe

杨尚锦、范云翔、章毓文、韩巧玲、赵玥、段劼、邸楠、席本野

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北京林业大学工学院,北京 100083

北京林业大学省部共建森林培育与保护教育部重点实验室,北京 100083

干旱半干旱地区森林培育和生态系统研究国家林业和草原局重点实验室,北京 100083

内蒙古大学生态与环境学院,呼和浩特 010021

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方法对比 夜间液流 夜间蒸腾 茎干充水 组分划分 杨树人工林 热扩散探针

国家自然科学基金国家自然科学基金内蒙古自治区自然科学基金

32001304321717632020BS03002

2024

10.17521/cjpe.2023.0043

植物生态学报
中国科学院植物研究所　中国植物学会

植物生态学报

CSTPCD北大核心
影响因子：2.162
ISSN：1005-264X
年,卷(期)：2024.48(4)
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