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首页> 外文期刊>Remote Sensing >Experimental Evaluation of Several Key Factors Affecting Root Biomass Estimation by 1500 MHz Ground-Penetrating Radar
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Experimental Evaluation of Several Key Factors Affecting Root Biomass Estimation by 1500 MHz Ground-Penetrating Radar

机译：影响1500 MHz探地雷达估计根生物量的几个关键因素的实验评估

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Accurate quantification of coarse roots without disturbance represents a gap in our understanding of belowground ecology. Ground penetrating radar (GPR) has shown significant promise for coarse root detection and measurement, however root orientation relative to scanning transect direction, the difficulty identifying dead root mass, and the effects of root shadowing are all key factors affecting biomass estimation that require additional research. Specifically, many aspects of GPR applicability for coarse root measurement have not been tested with a full range of antenna frequencies. We tested the effects of multiple scanning directions, root crossover, and root versus soil moisture content in a sand-hill mixed oak community using a 1500 MHz antenna, which provides higher resolution than the oft used 900 MHz antenna. Combining four scanning directions produced a significant relationship between GPR signal reflectance and coarse root biomass ( R 2 = 0.75) ( p < 0.01) and reduced variability encountered when fewer scanning directions were used. Additionally, significantly fewer roots were correctly identified when their moisture content was allowed to equalize with the surrounding soil ( p < 0.01), providing evidence to support assertions that GPR cannot reliably identify dead root mass. The 1500 MHz antenna was able to identify roots in close proximity of each other as well as roots shadowed beneath shallower roots, providing higher precision than a 900 MHz antenna. As expected, using a 1500 MHz antenna eliminates some of the deficiency in precision observed in studies that utilized lower frequency antennas.
机译：在不干扰的情况下准确定量粗根代表了我们对地下生态学的理解的空白。探地雷达（GPR）已显示出对粗略的根部进行检测和测量的巨大希望，但是根部相对于扫描断面方向的方向，确定死根质量的难度以及根部阴影的影响都是影响生物量估算的关键因素，需要进一步研究。具体而言，尚未针对整个天线频率范围测试GPR适用于粗根测量的许多方面。我们使用1500 MHz天线在沙丘混合橡树群落中测试了多个扫描方向，根交叉以及根对土壤水分含量的影响，该天线提供的分辨率比通常使用的900 MHz天线更高。组合四个扫描方向会在GPR信号反射率和粗根生物量之间产生显着的关系（R 2 = 0.75）（p <0.01），并且当使用较少的扫描方向时会减少变异性。此外，当允许其水分含量与周围土壤相等时，能正确识别的根系要少得多（p <0.01），为支持GPR无法可靠地识别死根质量的说法提供了证据。 1500 MHz天线能够识别彼此紧靠的根以及阴影较浅的根下方的根，从而提供比900 MHz天线更高的精度。不出所料，使用1500 MHz天线可消除在使用低频天线的研究中观察到的精度不足。

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