| The rocky mountain area in Northern China plays an important role in forestry construction. Because of the soil layer of this area is too thin, and lack of soil water and nutrition, which have bad effect on the forest growth. And forest management can effectively promote forest growth, improve and enhance forest ecosystem. Among them, the forest management of the ecosystem water cycle, affecting water balance is one of,the main concerns of scholars. Therefore, based on above-mentioned, Badaling,artificial pine forest is treated as study object in this paper, observation on infiltration in wild, data collection, and data analysis,models simulation are main methods of study in this paper, comparing infiltration process of three different forest densities; the impact of physical factors on soil infiltration, and model simulation are studied in this paper. The main conclusions are as follows:(1)As the forest densities increasing, soil moisture heteromorphosis coefficient tend to be high at low and high densities, the difference among the low density, medium density and high density is significant and obvious. Bulk density grows, but not dramatically. Soil total porosity and capillary porosity also increase, non-capillary porosity is affected by many factors, which makes the situation is complicated.(2) Due to the distribution of root system increasing in sample plot which has relatively high density, the soil porosity will increase, the permeability will be better on condition that the porosity become increasingly big, makes the soil initial infiltration rate(i0) tend to increase.1058p/hm2(9.56±8.83mm/min)<1444 p/hm2 (12.11±5.89 mm/min)<1746p/hm2 (14.69±5.59 mm/min); Soil stable infiltration(ic) turns to rise as well as the initial infiltration.1058 p/hm2(6.33±5.86mm/min)<1444 p/hm2(6.33±4.04 mm/min)<1746 p/hm2(10±5.51 mm/min); Meanwhile, the soil infiltration rate will be more. The stable infiltration time(t) will be longer gradually: 1058 p/hm2(16.52min)、1444 p/hm2(18min)and 1746 p/hm2 (20min), this is mainly due to the low initial soil moisture in high density, which resulting the wetting front infiltration process is weak that makes the time of infiltration delayed in high density sample ground. Principal component analysis showed the infiltration capacity in high density is best while the low density plot is worst (the comprehensive discrimination value of low; medium; high densities is -0.8467;-0.2554 and 1.10300, respectively).(3) The factors that affect average infiltration are shown as follows:bulk density, total porosity,initial soil moisture, organic matter, non-capillary porosity and sand content.The main factor that affect initial infiltration and stable infiltration in low density is initial soil moisture while in high density is capillary porosity. The main reason is that the significant high initial soil moisture in low density, which have high wetting front and absorption capacity, that promote the infiltration rate; while high density plot have large amount of porosity significantly than low and medium densities, which will increase the infiltration path and then promote the infiltration rate.(4)Comparison of Horton model; Kostiakov model and Philip model, the Horton model average fitting accuracy(R2=0.9630) is most high and the error (ε=0.4132)is most low compared with other two models. The procedure of infiltration simulation by Horton model indicates that the soil infiltration rate increase dramatically when the forest density grows. |
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