| Chinese fir, widely distributed in the South of China, was one of the important timber trees. It could not only provide the material for our country’s economic construction, but also could play an important role in the ecological benefits, especially in the function of water conservation. Exploring the Chinese fir forest’s water conservation and soil and water conservation was not only cardinal significance to the Dagangshan area, but also for the whole South of China. Therefore,the paper choose the Chinese fir with various densities as the object.It detaily studied the characteristic of water conservation and storage of the canopy, litter layer and soil layer. The water conservation was evaluated by Topsis method,the paper could propose a reasonable suggestion for Chinese fir of afforestation and forest density for water conservation function,also it could Provide the basis and method of forest structure adjustment, could provide the theoreticalbasis of building and managing of Chinese fir,also its ecological function in the future. The main results were as follows:1. We observed10rainfall in experimental area.The totle rainfall was235.7mm.There were two light rains and four moderate rains and three heavy rains and1storm during the observation. The duration of rainfall were between38and580min. The intensity of rainfall was in0.06mm/min-0.37mm/min.2. Both throughfall and throughfall rate of N900were the maximum, which were161.62mm and69%, on the contrary in term of N4700, which were115.36mm、49%. Two rainfalls which were less than10mm were not produced stemflow.Both the canopy interception and interception rate had same order like N4700>N3500>N2700>N1700>N9oo.The canopy interception ranged from72.13to119.16mm, and the canopy interception rate changed from31%to51%. The canopy interception and rainfall had a good correlation.3. The total thickness with different density of Chinese fir litter ranged from2.8to3.3cm,and the litter accumulation fluctuates was between3.94and5.34t/hm2.Both the total thickness and litter accumulation had a same order such as N3500>N4700>N1700>N900. Maximum soil water-holding capacity of N3500was the maximum (12.60t/hm2), and highest water-holding proportion of N1700was the biggest(254.98%), however, both maximum water-holding capacity and highest water-holding proportion of N2700were the lowest, which were9.69t/hm2and229.07%. The litter layer effective retaining content of different densities of Chinese fir changed from5.18to6.35t/hm2, followed by N3500>N47oo>N1700>N900> N27oo.The relationships between water-holding rate and immersion time of whether semi-decomposed or un-decomposed litter in all different fir forests were significantly fitted by Logarithmic equation(Q=aln(t)+b). The relationships between water absorption speed rate and soaking time were described by power function(V=ktn).4. The total porosity and maximal soil water-storage of different fir forest had same sort order like N35oo>N47oo>N27oo>N1700>N9oo, however, the order was contrary in term of soil bulk density,which ranged from1.22to1.30g/cm3.Both soil capillary porosity and water storage of N3500were the highest(40.04%,3153.16t/hm2), and the smallest values of both the factors were found in forest stand of N900(38.56%,3059.76t/hm2). The soil non-capillary porosity changed from9.42%to11.33%, and was in a sequence of N47oo>N35oo>N27oo> oo, while effective water storage showed a order like N3500>N4700>N27oo>N9oo> N1700, and ranged from721.93to894.70t/hm2.Soil stable infiltration rate of different forests stand ranged from1.34to3.52mm/min,in an order of N47oo> N35oo> N27oo> Ni7oo> N900.5. It could calculate by Topsis evaluation method:the sequence of water conservation function with different density Chinese fir forest like N35oo>N47oo>N27oo>N1700>N9oo, which showed that the water conservation function of forest density in3500tree per hm2is superior to the other stand density. |
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