Dynamic influence of different density litter on moisture content in each soil layer during rainfall process

ObjectiveTaking the typical Pinus tabuliformis forest and Robinia pseudoacacia forest in the Loess Plateau of western Shanxi, northern China as the research object, the preliminary study was conducted on the hydrological effects of litter layer and soil layer in order to provide reference for the construction of water conservation forests and soil and water conservation forests in the area.

MethodAfter selecting the forest corresponding to litter of three densities, artificial rainfall was performed. The moisture content of 6 soil layers including 0-20 cm, 20-40 cm, 40-60 cm, 60-80 cm, 80-100 cm, and 100-120 cm was monitored in real time.

Result(1) At the same rainfall level, the interception of litters increased with the increase of density, and the time for the interception to reach saturation was also prolonged; the rate of interception decreased with the increase of rainfall, and increased with litter density. (2) During rainfall process, with the increase of litter density, the water content of the top soil (0-60 cm) of both types of forests gradually decreased. The 0-20 cm soil moisture content response to rainfall was the most direct and rapid, while the change of soil moisture content in 20-40 cm and 40-60 cm soil layers had a certain lag and extension, the soil moisture content in deeper soil layer (60-120 cm) had almost no response to the rainfall process. (3) After rainfall, the moisture content in all depths of the soil layers showed a continuous decrease with time. Within 24 hours after the end of rainfall, the soil moisture content under bare land and all litter with different densities was highest in the 0-20 cm layer. After 48 hours of rainfall, the highest soil moisture in bare soil occurred in 20-40 cm soil layer, however, for soils covered with litter, the moisture content in the 0-20 cm soil layer was always the highest within 48 hours after the end of rainfall, and as the density increased, the magnitude of the decrease over time decreased.

ConclusionThe relation between interception or its rate and duration of rainfall accords with the power function relation(R²>0.9). Before and after rainfall, the litter with different densities has a great influence on soil moisture content. The moisture content in different soil layer shows a significant differences in response to rainfall.