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枯落物含水率测定在森林水文学、碳循环、林火蔓延以及火险等级评估等研究中具有重要作用。本文提出了一种基于驻波率(SWR)原理的森林枯落物含水率测量方法,所设计的SWR水分传感器具有复用双环式探头结构,可分时测量枯落物或土壤的含水率和电导率。实验结果表明,传感器输出电压与半分解、全分解枯落物和土壤含水率呈现良好的线性关系。与商品化TDR水分传感器相比,SWR传感器测量枯落物和土壤含水率的平均绝对误差较小,且在厚度小于10 cm的枯落物含水率测量以及测量成本方面具有明显优势。在对枯落物含水率进行长期原位测定时,SWR传感器可通过测量电导率来判断半分解的枯落物是否随时间推移而完全分解,以便及时调整传感器水分测量的标定曲线,最大程度降低因枯落物成分改变对传感器测量精度造成的影响,为准确测量森林地表枯落物含水率奠定基础。
The determination of the moisture content of litter plays an important role in the research of forest hydrology, carbon cycle, spread of forest fires, and the assessment of fire risk grade. In this paper, a method for measuring moisture content of forest litters based on the principle of standing wave rate (SWR) is proposed. The designed SWR moisture sensor has a double loop probe structure which can measure the moisture content of litter or soil and Conductivity. The experimental results show that the output voltage of the sensor shows a good linear relationship with the semi-decomposition, the total decomposition of litter and the soil moisture content. Compared with the commercial TDR moisture sensor, the average absolute error of the SWR sensor in measuring litter and soil moisture content is small, and it has obvious advantages in measuring the moisture content of the litter less than 10 cm in thickness and measuring the cost. In the long-term determination of the moisture content of litter in situ, SWR sensors can be used to determine whether the semi-decomposed litter is completely decomposed over time by measuring the conductivity, so as to adjust the calibration curve of the sensor moisture measurement in time to minimize The influence of the change of the composition of the litter on the measurement precision of the sensor lays the foundation for accurately measuring the moisture content of the forest surface litter.