Objective Precipitation redistribution is an important hydrological process in forest ecosystems. Analyzing the precipitation redistribution characteristics of Pinus densiflora and Quercus mongolica can provide a reference for the analysis of ecological hydrological parameters and model establishment of typical forest stands in eastern Liaoning Province of northeastern China.
Method Taking the Pinus densiflora and Quercus mongolica forests in the Xianrendong Nature Reserve as the survey and observation objects, the selection of precipitation outside the forest (POF), throughfall (TF), stem flow (SF) and canopy interception (IF) were used as indicators. The regression analysis method was used to establish the equations of POF and various indicators, and the precipitation characteristics and their changes of the two forests were analyzed.
Result (1) In the Pinus densiflora forest, TF, IF and SF were 388.5, 215.3 and 66.5 mm, accounting for 57.96%, 32.12% and 9.92% of the POF, respectively. In the Quercus mongolica forest, TF, IF, and SF were 421.7, 119.0 and 55.5 mm, accounting for 70.73%, 19.96% and 9.31% of the POF, respectively. (2) At low intensity precipitation, the initial lag time of Pinus densiflora and Quercus mongolica forest was about 1 h, while for medium and high intensity rainfall, the lag time was shorter, significantly less than 1 h; and the canopy interception time of the Pinus densiflora forest was longer, the hysteresis was stronger, and the interception effect was better. (3) The rainfall outside the forest was significantly and linearly positively correlated with the penetration rainfall and stem flow (P < 0.001). The minimum rainfall producing TF and SF by Pinus densiflora forest and Quercus mongolica forest was 4.2 , 5.8 mm and 2.0, 2.5 mm. respectively. (4) The canopy interception of Pinus densiflora and Quercus mongolica showed a significant quadratic function relationship with rainfall (P < 0.001). Canopy interception occurs simultaneously with rain outside the forest. When the rainfall was greater than 90.0 and 70 mm, the canopy interception of Pinus densiflora and Quercus mongolica tended to be stable at about 10 and 7 mm, respectively. (5) The rainfall outside the forest had a very significant negative correlation with canopy interception rate (P < 0.001), showing a power function relationship. When the rainfall outside the forest was greater than 90.0 and 70 mm, the canopy interception rates of Pinus densiflora and Quercus mongolica forest tended to be stable, decreasing to about 20% and 10%, respectively.
Conclusion In the process of precipitation redistribution, the SF and IF of the Pinus densiflora forest is greater than Quercus mongolica forest, while the TF of Pinus densiflora forest is smaller than Quercus mongolica forest. Redistribution of Pinus densiflora forest is stronger. There is a significant delay in TF in the forest, the lag time is affected by rainfall intensity and stand type, and the lag time of Pinus densiflora forest is greater than Quercus mongolica forest. The POF is significantly positively correlated with SF, TF and IF, and it has a linear function relationship with tree SF and TF. It has a quadratic function relationship with the IF. There is a significant negative correlation between the POF and canopy interception rate, and it is a power function relationship.
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