Dissertation > Agricultural Sciences > Forestry > Forestry basic science > Forest soil science

Study on Artificial Forest Ecological Character and Its Soil and Water Conservation Mechanism in Red Soil Hilly Region

Author DingJun
Tutor WangZhaoZuo
School Zhejiang University
Course Ecology
Keywords Artificial soil conservation forest Effect of Soil and Water Conservation Canopy interception : hydrological effects : litter Enhance the value of soil erosion Soil physical properties Water-stable soil aggregate structure Woodland microclimate Effective root density
CLC S714
Type PhD thesis
Year 2003
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Southern red soil hilly region belongs to a very serious soil erosion areas in the region to carry out artificial soil and water conservation forest construction is a very urgent task. April 2001 - July 2002 period in Lanxi Soil and Water Conservation Station, Lin Jiancheng and Water Conservation Effect of artificial soil and water conservation, plantation canopy interception precipitation patterns, the annual change in litter and hydrological effects, plantation root enhancement effect on soil erosion, soil physical properties of plantation spatial variation and planted a small feature six aspects of climate change, Southern Red hilly area and water conservation forest ecological characteristics and soil and water conservation mechanism was studied, research The results are as follows: 1, Lin Jiancheng artificial soil and water conservation and soil and water conservation effect (a) of the test area to increase the height of trees, tree diameter at breast enlargement and elevated canopy closure, the overall trend is consistent with the growth of time are a corresponding increase in the extension. However, the different types of districts because trees also showed a greater difference in the average annual increase in slow bamboo forest, tree DBH maintained at a relatively stable level, the peak concentration in leaves 4 to May; mixed forest and tree diameter at breast height of trees increased expansion is relatively slow, the annual change in canopy density variation consistent with defoliation anniversary; fir tree height increased relatively fast, while the relatively slow expansion of DBH, annual average canopy density is low; citrus tree trunks low interannual did not change significantly, the growth mainly manifested as canopy expansion and canopy density increases. (2) The test area with trees growing erosion showed decreased rapidly at first, then slowly declining, the last stable equilibrium trend. Specifically manifested in several indicators of soil erosion on: first, the bamboo forest, mixed forest and Chinese fir plantation three years after the runoff does not appear obvious, conventional citrus groves and citrus groves in the dense built during the course of action is relatively slow surface runoff weak, surface runoff in six years after planting will no longer produce. Second, from the soil of suspended sediment dynamics point of view, with the completion of woodland time, the amount of suspended sediment yield decreases. Different soil test area of ??suspended sediment dynamics there are significant differences, in general, showed two categories, one is bamboo forest, mixed forest and fir forest, they suspended sediment dynamic change has obvious demarcation point, roughly in order to plant trees the first two years for the sector, the first two years ago the amount of suspended sediment accounted for 9 years to 93.7% in total over the first two years after the amount of suspended sediment drastically reduced to five years there will be no suspended sediment production. The other is conventional citrus groves and dense citrus groves, they suspended sediment change the demarcation point for the first three years, the first three years before the quality of its nine years suspended for 76.7% of the total over the first three years later to maintain more gradual reduction in the ninth year there is a small amount of production. Third, the dynamic changes of soil bedload and suspended sediment soil dynamic changes of different trends in each test area consistent with the first two years after passage of the test area are not mass produced. Fourth, suspended sediment and soil quality over quantity in the soil erosion in the proportion of the size, determines their effect on soil erosion modulus dynamic changes affecting the degree of severity. From three years of suspended sediment and soil soil bedload dynamic change of view, in the first year of plantation soil erosion mainly in the form of bedload, later dominated by the quality of the soil goes gradually to the soil as suspended sediment main transition, to three years later in the test area of ??soil erosion are suspended sediment based. Two different plantation canopy interception rainfall patterns (1) canopy interception surface has the following characteristics, namely the existence of a surface saturation point, when rainfall is below the surface saturation point, the entire crown level gradually increases the amount of rainfall interception retention rate decreases, when the rainfall over the surface saturation point, the entire amount of rainfall interception by the canopy remained unchanged, while the rejection rate decreases rapidly; Second canopy level summary of a 2 a saturation point dynamic, with canopy canopy density increases, the saturation point rise, with canopy density decreases, the saturation point is lowered; Third rainfall longer the interval, the greater the surface rainfall interception, interception rate is higher, contrary rainfall shorter the interval, The smaller surface rainfall interception, interception rate is lower. (2) vertical canopy interception has the following four characteristics: First, the delay start time rain forest: a second, ending prolonged rain forest; Third, reduce start 30 minutes (I3.) Rainfall intensity; fourth, less Little rainfall milky. (3) the lateral canopy interception showing: less than 10mm in the case of rainfall, canopy interception on rainfall increased with increasing distance from the base of the trunk interception relative reduction in the amount of each forest type to reduce the size of the order of citrus groves , bamboo forest, mixed forest and fir. Rainfall greater than Zomm case, it showed with increasing distance from the base of the trunk interception relative increase in the amount of each forest type interception increase the size of the order for the fir forest, bamboo forest, mixed forests and citrus groves. 3, the annual variation of litter and hydrological effects of the leaves of each test area there are two peak periods (May and December). Pubescens deciduous evergreen species mainly concentrated in the May peak, pine, citrus and deciduous mixed forest peak mainly in December. Annual litter decomposition variation can be seen from the whole, the decomposition rate of citrus groves gt; fir gt; pubescens gt; mixed. From each of the test area annual savings amount of litter dynamics of view, the bamboo forest stock volume of litter highest in May, while the other test area each litter accumulation peaked in December. The test area litter variation of the maximum water holding capacity and the amount of their respective annual savings consistent. Moso bamboo litter maximum water holdup at various times were the highest in the other test area showed a seasonal litter over water holding capacity increases first and then decreases gradually while, but they are a turning point at different seasons, mixed forests and fir turning point in October, while the citrus groves turning point in July. 4, plantation roots on soil erosion enhancement effects (l) soil profile observations found that root density with increasing soil depth drastically reduced, the effective root density in woodland (Diameter Cluster 1. Roots) there is a difference, wool Bamboo 65% are located in O a 3Ocln soil, and 0 a loc two at most, 33% of the total; mixed concentrate on. A ZoC. Soil roots, accounting for 61% of the total number of roots a 72%; fir to about 43% of the root distribution in O ~ ZOC. Soil; citrus groves root distribution to 0 a 10. . Dominated, accounting for 45% of the total. Root dry weight and root density distribution also has a variation of the same

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