TDR calibration of organic forest floor media
TDR calibration of organic forest floor media
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DOI：
10.1016/s0933-3630(96)00128-6
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发表时间：
1997-06-01
期刊：
影响因子：
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通讯作者：
Heimovaara, TJ
中科院分区：
文献类型：
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作者：
Schaap, MG;deLange, L;Heimovaara, TJ
对5个不同林分的25个森林地表样品进行了时间域反射仪(TDR)标定。根据折光率用线性回归方法估计体积含水率。由于束缚水的存在，用折射率混合模型不可能根据理论值来预测标定线参数。然而，当考虑水的视介电常数时，由于低的森林地面容重导致校准线斜率和偏移量几乎成反比，因此可以预测偏移距参数。给出了不同林地材料的标定参数。允许较高的误差范围，我们还可以建立与公布的校准曲线非常一致的一般校准曲线(Malicki等人，1994)。误差分析表明，有机物的分解、残余水分和温度的影响对校准参数的影响可以忽略不计。有机材料的收缩对体积含水率和TDR反射时间都有显著影响。如果不进行校正，对于强烈收缩的H层，这两种影响都会产生大约0.02厘米(3)厘米(-3)的系统误差。
We carried out a time domain reflectometry (TDR) calibration for 25 forest floor samples of five different forest stands. Linear regression was used to estimate the volumetric water content from the refraction index. Due to the presence of bound water, it was impossible to predict the calibration Line parameters from theoretical values with a refractive mixing model. However, when the apparent dielectric constant of the water was considered, it was possible to predict the offset parameter because the low forest floor bulk density caused the calibration line slope and offset to be almost reversely proportional. Calibration parameters for different forest floor materials are presented. Allowing a somewhat higher margin of error we could also establish general calibration curves which were in close agreement with a published calibration curve (Malicki et al., 1994). An error analysis showed that decomposition of organic matter, residual water and temperature effects have negligible effects on the calibration parameters. Shrinkage of the organic material significantly influenced both the volumetric water content and the TDR reflection times. If not corrected, both effects yielded systematic errors of approximately 0.02 cm(3) cm(-3) for a strongly shrinking H horizon.