【作者】 胡江波；

【导师】 杨改河；

【作者基本信息】 西北农林科技大学 ， 作物栽培学与耕作学， 2007， 硕士

【摘要】 经过退耕还林还草,植被恢复,渭北旱塬黄土丘陵沟壑区地表植被覆盖度有了明显提高,水土流失得到了有效的控制,生态环境逐步改善。本研究以陕西省千阳县冉家沟流域为研究对象,采用野外调查,定点观测与室内分析相结合的方法,研究分析了该区不同植被恢复模式下的水土保持效果及土壤水肥生态效益,评价了不同植被恢复模式的效应和功能,以期为该区退耕地的植被恢复、林草的合理配置与布局以及为正在开展的西部生态环境建设和黄土高原退耕还林还草工程提供理论依据。通过研究分析,得出以下主要结论:(1)封育和刺槐两种模式的水土保持效果比农田有明显改善,其中封育模式的水土保持效果优于刺槐林。(2)分别对封育和刺槐两种植被恢复模式的生物量与各自对应的径流比和泥沙比作相关性分析,得出不同植被恢复模式的生物量与径流比和泥沙比呈负相关。说明植被生物量的提高能有效地减少林下的地表径流量和径流中的泥沙含量,从而减少坡耕地的侵蚀量。(3)土壤含水量在不同地形上具有较大的分异性,并因植被类型、退耕年限、恢复方式及生物量的不同而存在差异。(4)几种不同植被恢复类型与对照农田土壤水分的季节动态变化有着较一致的趋势,呈现明显的“V”型,封育模式下的土壤含水量在整个生长季节均明显高于其它几种植被恢复模式;不同植被恢复类型引起土壤水分垂直分层差异,同时也会影响土壤水分垂直方向上的季节变化;不同植被恢复类型各层土壤水分变异系数不同,而变异系数的垂直变化也因植被恢复类型的不同存在差异。(5)退耕还林还草地上层土壤容重显著地高于农田,而下层土壤容重显著地低于农田。(6)退耕还林还草地土壤团聚体的总数量及各粒级均超过对照农田,退耕后土壤有机质积累迅速增加,促使了大团聚体的形成,提高了土壤的胶结性能和抗蚀性。(7)大多数标准样地的上层土壤速效养分高于中下层,土壤速效养分含量在土壤不同层次表现各异;9个标准样地间土壤上、中、下三层土壤全量养分含量均有极显著的差异,土壤全量养分含量在土壤不同层次表现各异。(8)9个标准样地间土壤上、中、下三层土壤有机质含量均有极显著的差异。其土壤有机质含量均随土层深度的增加而递减,其中荆条、侧柏和封育3种模式土壤有机质含量随深度递减最为剧烈,表现出明显的表聚性。(9)在系统分析比较土壤肥力状况的基础上,采用聚类分析方法,筛选出苹果、刺槐和封育作为该区退耕还林还草、植被恢复的主要推荐类型;荆条和侧柏作为不推荐类型;苜蓿在该区有较广泛的推广价值。更多还原

【Abstract】 With the implementation of grain for green project,surface vegetation coverage has been greatly improved; Water loss and soil erosion have been under effectively controlled and the ecological environment have been improved step by step in Weibei plateau. This research regards ranjiagou watershed of qianyang county of Shaanxi province as to study subject,adopting field investigation, fixed-point observation and indoor analysis methods,researching and analyzing the effect of soil and water conservation and ecological effect of water and fertilizer on soil under different vegetation restoration patterns , evaluating functions and effects of different vegetation restoration patterns, this thesis provides a theoretical basis for vegetation restoration of abandoned lands, for the rational allocation and distribution of forest and grass, for ecological environment construction of western regions under taking and for the project of returning farmland to forest and grassland in Loess Plateau. After the research and analysis,the main conclusion were drawn as following:(1) It is evident that the effect of soil and water conservation of enclosure and locust has improved greatly than that which is in farmland. The effect of soil and water conservation of enclosure was better than locust.(2) Through the correlation analysis between biomass of enclosure and the surface runoff ratio and sediment ratio on vegetation restoration pattern (same to locust), we can draw the conclusion that negative correlation between biomass of different vegetation restoration patterns and the surface runoff ratio and sediment ratio. It was showed that improvement of biomass could reduce efficiently the surface runoff and sediment content. Consequently, soil erosion of slope cultivated land was reduced. (3) The soil water content has biggish difference because of different topography, and was different types of vegetation, different restoration time, different vegetation restoration patterns, and different biomass.(4) The soil water’s seasonal dynamic change of several different vegetative restoration types and farmland showed the consistent tendency, which presented obviously "V",the soil water content of enclosure was obviously higher than the other’s. Different exploitation of soil moisture made the soil average moisture content as well as the soil moisture profile different. Each layered variation coefficients of different vegetative restoration types was different, and vertical change of variation coefficients was also different because of various restoration types.(5) As far as super stratum soil bulk density, the land of converting agriculture land into forest and grass was much significant higher than contrasting farmland, but the substrate soil bulk density was much significant lower than contrasting farmland.(6) The total quantity and each particle fraction of soil aggregate all exceeded the farmlands after returning the grain plots to forestry and grass. Restoration of vegetation causes soil organic matter accumulated rapidly and soil’s cementation characteristics and corrosion resistance improved.(7) Most of standard sample land’s soil available nutrients in super stratum soil were higher than that in middle or lower part of soil. Among nine standard sample lands, there was much marked difference in the whole nutrient contents in all layers. The soil available nutrients were different in soil profile layers, and were the whole nutrient contents.(8) Among nine standard sample lands, there was much marked difference in content of organic matter in all layers. Soil organic matter contents were all decreased with soil deep increased, which was more obvious for vitex negundovar.heterophylla、arborvitae and enclosure.(9) On the basis of system analysis of soil fertility, using clustering analysis, the author have selected apple, locust, enclosure three kinds of styles as the primary types in converting agriculture land into forest and grass; vitex negundovar.heterophylla and arborvitae two kinds of types as the wash out types; alfalfa has also relatively broad value of popularization.更多还原