| The relationship of forest between hydrogen is a hot topic in global ecology. The water conservation benefit and its influencing factors were studied in spruce (Picea asperata) plantations with the stand age of 5～70 and natural stands by using space taking the place of time. Theory model was fitted through analyzing different age gradations and age groups and the protective maturity period of regeneration in spruce plantations was determined as well as. It gives the theory to the sustainable management of water conservation forest for spruce plantations. The results were as follows:Litter cumulate mass, maximal water holding capacity and max water-holding rate alone with stand age of increasing, the range of 10.16～25.75 t/hm~2, 1.49～23.42 t/hm~2, 145～928 %. Litter cumulated mass, maximal water holding capacity and max water holding rate of increase in age, the range of 18.73～30.38 t/hm~2, 3.65～20.26 t/hm~2, 280～903%. Three factors of natural forest were bigger than plantations'.The Soil Organic Matter (SOM) of the surface layer (0～10 cm) is bigger than the layer of 10～20 cm. And the TOM (Total Organic Matter) of surface layer will increase by 1.76～9.47 percent with the increase of the age of trees planted in the site. In the age phases of 10～15, 30～35 and 50～55 a, the SOM content will decrease by 0.21%, 0.53%, 0.41% respectively. SOM of surface layer will increase with the age of trees by the range between 2.57 to 8.93 percent. SOM in nature forest will bigger than plantation in the different related layer.The total soil moisture storage (TSMS) will increase by the increase of the age of trees, and will up to maximal value of 3536.13 t/hm~2 in the age of 40 a in the age range of 5 to 40 a. However, TSMS will decrease from 3536.13 t/hm~2 to 3284.67 t/hm~2, with the increase of the age of trees from the age range of 40 to 70 years, and in the age of mature(61～80 a), the TSMS will up to their max or 3503.90 t/hm~2. Natural forest is higher than plantations'.By analyzing the physical properties of soil at all levels with variance, the results showed that the upper soil bulk density was significantly lower than the bottom when the age of the stand was 15～40. Yet the other was no significant difference. The upper soil total porosity, maximal water-holding capacity and minimum water holding capacity only in some age is significantly lower than the bottom. But the upper moisture storage in every age was significantly higher than the bottom, the upper soil bulk density in young(≤20 a),middle age (21～40 a) and pre-mature (41～60 a) was significantly lower than the bottom. But the mature was no significant difference. The minimum of water holding capacity in young, middle-age was significantly higher than the bottom, the other was no significantly difference. The upper total porosity, the Maximal water-holding capacity and the soil moisture storage in every age was significantly higher than the bottom.The results showed that the upper soil permeability rate was higher than the bottom's. With the age grads on, the upper soil permeability rate increases. The minimum was 3.78 mm/min at the age of 25, and the maximum was 15.67 mm/min at the age of 30. With the growth of age group, the upper soil permeability rate was normal distribution. From young to middle age, the upper soil permeability rate went up.The maximum was 9.88 mm/min at the middle age. From middle age to mature, the upper soil permeability rate was descended. All soil permeability rate of the natural forest soil were higher than the plantations'.Throughfall amounts increased with the increase of the precipitation amounts and precipitation intensity in spruce plantation. The throughfall amounts and through snowfall were 1.03～12.51 mm and 0.17～2.85 mm, respectively. Canopy interception amounts increased with the increase of precipitation intensity with the interception rainfall and interception snow were 0.26～2.61 mm and 0.03～2.55 mm. Canopy interception rainfall capability showed irregular variation and the maximum was 21.1% in 6.1～8.0 mm. Canopy interception snow capability increased with the increase of snowfall and snow intensity. Canopy interception snowfall was more capable than canopy interception rainfall. Stem-flow amounts increased with the increase of precipitation, however stem-flow accounted for 0.01% of the precipitation which could be negligible as for precipitation event. The canopy interception amounts was 5.74 mm.The water conservation benefit of spruce plantation in per unit accelerated with the stand age and the values were 1.22～3.53×10~4m~3/hm~2 and 1.57～3.49×10~4m~3/hm~2 with the increasing of age graduation and age group. Water conservation benefit of spruce natural stand was more than that of spruce plantation.To water conservation benefit in per unit of the main factor, protective maturity age (PMP) was determination. The results showed initializationthat age of protective maturity (IPMA) =35 a. the fitted quadratic equation between water conservation benefit in per unit and stand age in spruce plantation and natural stand were Q=-0.001a~2+0.1169a+0.3924 and Q=-0.0005a~2+0.0812a+0.8054, respectively. The maximum age of protective maturity (MPMA) was 58.5 years and the terminal protective maturity (TPMA) was 81.2 years. Combining the analysis of ecological function of spruce plantation, the best suitable regeneration age was 61.0～81.2 years for waterconservation forest of spruce. |
PDF Full Text Request