Monitoring of moisture content in soil and evaluation of transpiration segmentation model based on Actively Heated Fiber Optic method

The transpiration of plants will change the matric suction of soil and affect the mechanical properties of soil. In this paper, three kinds of plants are chosen with different transpiration rate: ivy tree bark, scindapsus aureus and Ivy League, active heating fiber optic (hereinafter referred to as AHFO), and are adopted to test on the moisture content of soils distributed around the plant roots. This paper also examines the hydraulic effect in the process of transpiration and evaluates the transpiration segmentation model which is commonly used to describe hydraulic interaction between plants and soil. The experimental results show that (1) the influence of plants on soil moisture content can effectively be described by the transpiration segmentation model, and the change in water content is affected by the plant leaf area, root density, soil depth and transpiration time. (2) The leaf area index and root density of ivy tree bark and scindapsus aureus are similar, and the change value of water content in soil around the root is similar (0.075 m³/m³). The leaf area index and root density of Ivy League are much higher than those of ivy tree bark an scindapsus aureus. Therefore, the change value (0.125 m³/m³) of moisture content in the soil around the root caused by Ivy League is much higher than the other two plants. (3) In this experiment, the depth influenced by plants on the water transport in soil ranges mainly from 10 to 15 cm, and the water field at depth is almost not affected by plants. (4) After wetting, the influence of plants on soil moisture content is most obvious at the early stage of drying, which is mainly caused by the passive water absorption of plants.