科研之友
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摘要
The precipitation redistribution process of forest vegetation is an essential factor affecting regional water use efficiency and ecosystem productivity, which can also regulate the mechanism of water resource balance. The precipitation interception by vegetation during and after rain events is an important component of the hydrological cycle of forest ecosystems in arid and semiarid sandy grassland. Pinus sylvestris var. mongolica Litv. is the main water and soil conservation species in the semiarid sandy land. It plays a significant role in regulating regional hydrological processes. There was the water resource deficit and water level drop in Horqin Sandy Land, the precipitation interception by Pinus sylvestris var. mongolica planted forest can affect the regional ecological environment. We investigated the precipitation redistribution characteristics of Pinus sylvestris var. mongolica planted forest in Horqin Sandy Land from May to August in 2018. The study aims to analyze and quantize precipitation redistribution patterns (throughfall, canopy interception, stemflow, and litter layer interception) of Pinus sylvestris var. mongolica. Simultaneously, we calculated how many precipitation magnitudes distributed to the surface soil, to evaluate the regional soil water content and effective supply of groundwater in the planted forest of Pinus sylvestris var. mongolica. A canopy of Pinus sylvestris var. mongolica is the first layer affecting precipitation redistribution. Canopy interception rate decreased and then stabilized with the precipitation increase, which also can be linearly correlated with canopy closure and leaf area index, which is affected by its canopy structure. The atmospheric precipitation passes through the forest canopy to form throughfall, canopy interception, stemflow. Throughfall of Pinus sylvestris var. mongolica accounted for 86.45% of the total precipitation, and linearly increased with the precipitation (y=0.8994x-0.5655, R2=0.9961, P<0.0001). Throughfall occurred when the precipitation exceeded 0.63 mm. The canopy interception and stemflow accounted for 10.44% and 2.54% of the total precipitation, respectively. There was the power function relationship between canopy interception and precipitation (y=1.4978×(1-e-0.0526x), R2=0.8230, P<0.0001), and the positive linear relationship between stemflow and precipitation (y=0.0273x - 0.0324, R2=0.9491, P<0.0001), stemflow occurred when the precipitation exceeded 1.19 mm. The litter is the second active layer affecting the precipitation redistribution, the interception of the litter layer accounted for 12.37% of the total precipitation and increased with precipitation (y=4.1580×(1-e-0.0545x), R2=0.8536, P<0.0001). The average water absorption rate of litter in the range of 0-24 h was 1.83 mm·h- 1. The maximum water holding capacity was 3.23 mm, and the interception of the litter layer accounted for 42.37% of its maximum water holding capacity. The total interception from the canopy to the litter was 25.35%. The remaining 74.65% precipitation finally infiltrated into the soil surface from the litter layer to replenish soil moisture and groundwater. We obtained that the rainfall redistribution patterns of Pinus sylvestris var. mongolica forest varied with the precipitation characteristics (such as precipitation amount and intensity) and its canopy structure characteristics. The Pinus sylvestris var. mongolica forest can effectively intercept and store precipitation. Thus, increasing water effective recharge of forest land will improve the relationship between vegetation and precipitation to enhance the productivity of the forest ecosystem.
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