Granier原始公式测算107速生杨树干液流通量密度的误差及校正公式

以 107 速生杨为对象,基于热扩散树干液流测定技术,采用离体茎段式称重法和整树容器称 重法实测液流通量密度,以验证 Granier 原始公式的适用性,并通过建立实测液流通量密度与热扩散法测定的树干 液流温差系数(K 值)的统计关系,形成校正公式。 和整树容器称重法和室内茎段称重法的实测值相比, Granier 原始公式计算的液流通量密度存在严重低估,误差率分别达-71. 5%和-74. 3%。 基于整树容器称重法和室 内茎段称重法的实测值而建立的校正公式分别为 Fd(液流通量密度,cm3·cm- 2 s - 1 ) = 0. 010 8K0. 566 6 ( R2 = 0. 812 6) 和 Fd = 0. 019 17K0. 952 8(R2 = 0. 940 3) 。经 6月23日、24日数据验证,在以林木自然生长条件下的野外整树容器称重法实测值为基准时,Granier 原始公式的计算值低估 68.90%,而整树容器称重法拟合的校正公式计算值仅低估 2.95%,离体茎段称重法拟合的校正公式计算值低估 15. 75%。 Granier 原始公式在计算 107 速生杨树干液 流通量密度值时存在严重低估,会造成很大误差,但校正公式可反映液流通量密度与K值的关系,能准确表达出真实的液流量。因此,采用基于整树容器称重法校正的 Granier 公式所计算的107速生杨树干液流通量密度具有较高精度。

Taking 107 fast-growing poplar as the research object, this study adopted the excised stem segment weighing method and whole-tree container weighing method to measure sap flux density based on the thermal dissipation sap flow measurement technique, so as to verify the applicability of Granier's original formula. Calibration formulas were then developed by establishing the statistical relationship between the measured sap flux density and the stem sap flow temperature difference coefficient (K value) determined by the thermal dissipation method.

Compared with the measured values from the whole-tree container weighing method and laboratory excised stem segment weighing method, the sap flux density calculated by Granier's original formula showed severe underestimation, with error rates of -71.5% and -74.3% respectively.

The calibration formulas established based on the measured values from the whole-tree container weighing method and laboratory excised stem segment weighing method are as follows: Fd (sap flux density, cm³·cm⁻²·s⁻¹) = 0.0108K^0.5666 (R²=0.8126) and Fd = 0.01917K^0.9528 (R²=0.9403), respectively. Validated using data collected on June 23 and 24, when taking the measured values from the field whole-tree container weighing method under natural growth conditions of the poplar stands as the reference, the calculated values of Granier's original formula were underestimated by 68.90%, while the calculated values of the calibration formula fitted by the whole-tree container weighing method were only underestimated by 2.95%, and those of the calibration formula fitted by the excised stem segment weighing method were underestimated by 15.75%.

Granier's original formula suffers from severe underestimation when calculating the sap flux density of 107 fast-growing poplar stems, resulting in considerable errors. However, the calibration formulas can reflect the relationship between sap flux density and K value, and accurately represent the actual sap flow. Therefore, the sap flux density of 107 fast-growing poplar calculated using the Granier formula calibrated by the whole-tree container weighing method exhibits high accuracy.

搜集汇总

背景与挑战

背景概述

该数据集研究了Granier原始公式在测算107速生杨树干液流通量密度时的误差，发现公式存在严重低估（误差率高达-74.3%），并通过建立基于整树容器称重法和离体茎段称重法的校正公式（如Fd = 0.0108K^0.5666）来提升精度，验证表明校正后误差可降至2.95%，适用于植物学研究和林业技术应用。