Subjects: Geosciences >> Geography submitted time 2024-04-29 Cooperative journals: 《干旱区研究》
Abstract： Root biomass is an important part of the soil ecosystem, however, due to the limitations of measurement techniques and methods, it is impossible to rapidly assess it. The ground penetrating radar (GPR) is an efficient and nondestructive geophysical tool through which root information can be obtained without damaging the soil environment. However, accuracy during the detection and identification of underground roots by GPR is significantly affected by many factors such as soil water content, root roughness, length, and extension direction. In particular, soil water content has an obvious effect on root detection. In this study, in situ root embedding detection experiments were carried out to investigate the influence of soil water content on root detection via GPR. Combined with the changes in wave velocity, amplitude, and the root reflection coefficient of the GPR, the root point identification rate and root point distance root point root mean square error were analyzed under different average soil water content. The results showed that (1) the wave velocity and amplitude of the GPR were important parameters to determine variations in soil water conten during root detection; (2) the GPR’s velocity decreased and the radar amplitude flattened with the increasing soil water content; (3) as the root diameter increased at different soil depths, the GPR’s wave velocity also increased and the GPR’s amplitude tended to be drastic changes; (4) the root point recognition rate and soil water content were negatively correlated (P
Subjects: Geosciences >> Geography submitted time 2021-08-11 Cooperative journals: 《干旱区研究》
Abstract：为了阐明不同土地利用方式对土壤理化性质和生态化学计量特征的影响，以晋西黄土区典型人工混交林地、刺槐纯林地、经济林地、农田、荒草地为研究对象，测定了0~10 cm、10~20 cm、20~30 cm、30~40 cm、40~50 cm、50~60 cm土层的容重、孔隙度以及有机质（TC）、全氮（TN）、全磷（TP）含量，分析土地利用方式与土壤理化性质及生态化学计量特征的关系，以期为土地资源的合理利用与生态服务功能提供依据。结果表明：（1）人工混交林地、刺槐纯林地、经济林地的容重（1.17 g·cm-3、1.19 g·cm-3、1.20 g·cm-3）显著小于农田（1.31 g·cm-3）和荒草地（1.38 g·cm-3），刺槐纯林地TC和TN含量最大（9.94 g·kg-1、0.88 g·kg-1），农田最小（7.26 g·kg-1、0.63 g·kg-1），TP无差异（P>0.05）。随着土层深度的增加，容重逐渐增大，孔隙度逐渐减小，TC和TN逐渐减小，TP保持相对稳定。（2）人工混交林地、刺槐纯林地、经济林地的C:P（25.69、20.51、19.41）和N:P（2.23、1.82、1.58）大于农田（18.57、1.62），C:P和N:P随土层深度的增加而减小，C:N保持稳定。（3）C:N与总孔隙度正相关（P<0.05），C:P和N:P与土壤容重极显著负相关（P<0.01），与总孔隙度、非毛管孔隙度、TC、TN、C:N显著正相关（P<0.05）。通过各土地利用方式的土壤理化性质比较，林地的土壤养分状况显著高于农田，尤其以人工混交林地效果最佳，退耕还林有助于提高土壤质量。因此，在退耕还林还草过程中应多注意树种之间的搭配，而避免大面积营造单一林种。
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