线源入流入渗法在生物结皮渗透性研究中的应用

土壤水分入渗的观测方法很多,但在测定坡地生物结皮土壤水分入渗时均存在一定的缺陷。线源入流入渗法是可用于无结皮的坡地土壤水分入渗较为简便快捷的观测方法。以裸土为对照,采用线源入流入渗法和模拟降雨法测定了黄土丘陵区多藻少藓、半藻半藓、多藓少藻等不同类型生物结皮土壤水分入渗过程。结果表明:(1)线源入流入渗法可在不干扰生物结皮的情况下,快速、完整地反映土壤水分入渗过程,获取初始入渗速率、平均入渗速率及稳定入渗速率等重要参数;(2)线源入流入渗法所得研究区不同类型生物结皮的初始入渗速率范围为3~12 mm/min,平均入渗速率范围为0.5~4.5 mm/min,稳定入渗速率范围为0.3~1.8 mm/min,随着藓盖度的增加,其初始、平均、稳定入渗速率均呈现出显著差异;(3)线源入流入渗法测定的生物结皮土壤稳定入渗速率(y,mm/min)与人工模拟降雨试验所得入渗速率(x,mm/min)呈显著的线性相关关系(y=1.73x-1.24,R^2=0.376 8,ρ=0.539~*)。研究结果为坡地生物结皮土壤水分入渗速率的测定提供一种简单易操作的测定方法。

Application of Line Source Infiltration Method in the Study of Biological Soil Crust Permeability

There are many methods to measure soil permeability, however, each method shows some defects when used on the biocrustal(biological soil crusts) soil on slope lands. Line source infiltration method is a simple and rapid method for the measure of infiltration on slope land without biocrusts. In this study, the water infiltration processes of bare soil(control) and different types of biocrusts, including cyanobacteria dominated, cyanobacteria-moss mixed and moss dominated biocrust soil in the Hilly Loess Plateau region were tested by using line source infiltration method. Meanwhile, the simulated rainfalls were applied on the same plots to get the permeability of the soils. The results showed that:(1) The line source infiltration method can describe the water infiltration process quickly and completely without disturbing the biocrusts. Meanwhile, the parameters such as initial infiltration rate, average infiltration rate and stable infiltration rate were observed stably.(2) The initial infiltration rate range of different types of biocrust obtained by the line source infiltration method in the study area was 3 ~ 12 mm/min, the average infiltration rate range was 0.5 ~ 4.5 mm/min, and the stable infiltration rate range was 0.3 ~ 1.8 mm/min. With the increase of moss coverage, the initial, average and stable infiltration rates were significantly different.(3) There was a significant linear correlation between the stable infiltration rates of biocrusts soil measured by the line source infiltration method and those of the simulated rainfall(y=1.73x-1.24, R^2=0.376 8, ρ =0.539~*). This study provides a simple and easy method for the determination of water infiltration rate in biological crusts soil on slope lands.