【作者】 寇韬；

【导师】 李春燕； 宫照红；

【作者基本信息】 西藏大学 ， 森林培育， 2010， 硕士

【摘要】 拉萨河谷气候干燥、降雨量小,沙化严重。为了改善当地的生态、居住和放牧环境,需要进行人工植被恢复,建设防风固沙、防止水土流失的生态防护屏障。本文在拉萨河谷选择出四块具有代表性的实验地,调查了各实验地的地形、土壤、水分和植被等情况,应用主成分分析、聚类分析,构造立地质量评价指标体系,得到下面的研究结果:1.六级立地分类系统。根据《中国森林立地分类》,把拉萨河谷的立地分为:藏西南山地温暖半干旱灌丛草原立地区域,雅鲁藏布江中游立地区,雅鲁藏布江中游谷立地亚区,拉萨河河谷立地类型小区,下面再划分出立地类型组和具体的立地类型,共6级分类系统。2.根据拉萨河谷不同的地形确定四个立地类型组:河滩地立地类型组、台(阶)地立地类型组、山麓坡地立地类型组、洪积扇立地类型组。3.立地因子的主成分分析。对调查的指标做因子分析,选出其中的主导因子。河滩地筛选出3个主成分,累计方差贡献率占82.117%;台(阶)地、山麓坡地、洪积扇筛选出3个主成分,累计方差贡献率占85.801%。4.在spss13.0中用最短距离法聚类得到河滩地、台(阶)地、山麓坡地立、洪积扇的立地类型。5.土体构型研究(立地亚类型)。拉萨半干旱河谷土体构型可以分为五类:均质型、底型、体型、三段型和心型。均质型中的卵石滩地最差,其他的剖面土壤厚,地表植被丰富,土体构型较好。体型、三段型和心型的土体构型一般,土壤厚度差异大,需要适量客土,其中土壤薄的需要大量客土。6.结合聚类和土体构型研究的结果,分为16个立地类型:河滩地低水位中厚层粗沙质立地类型、河滩地低水位薄层粗沙质立地类型、河滩地低水位中厚层细沙质立地类型、低水位卵石滩地立地类型、河滩地低水位厚层砂壤质立地类型、河滩地中水位厚层砂壤质立地类型、河滩地高水位厚层砂壤质立地类型、山麓坡地下坡厚层粉沙质立地类型、山麓坡地中坡厚层粉沙质立地类型、山麓坡地上坡厚层粉沙土立地类型、台(阶)地下坡厚层粉沙质立地类型、台(阶)地中坡厚层粉沙质立地类型、台(阶)地上坡厚层粉沙质立地类型、洪积扇下坡厚层粗沙质立地类型、洪积扇中坡厚层粗沙质立地类型、洪积扇上坡厚层粗沙质立地类型。7.立地质量评价。采用层次分析法,建立拉萨半干旱河谷立地质量评价指标体系,结果表明:拉萨河谷立地只有极少数评分是优和极差。大部分评分为优、良和中,占整个样地的79.7%。评分极差的卵石滩地不能造林,评价优的可以直接造林,其他的立地需要采取改善措施才能造林。8.造林对策。针对不同立地类型的土体构型和立地质量评价结果,对立地评价为优的可以直接造林,对立地评价为良和中的需客土、使用保水剂后造林,对立地评价为差和极差的立地,需要彻底的改变立地条件才可以植树,此外还要选择抗旱、耐旱树种,以保证成活率。更多还原

【Abstract】 The climate of Lhasa valley is dry, little rainfall, desertification seriously. In order to improve the local ecological, residential and grazing environment, we need for artificial vegetation restoration, construction sand-fixing, erosion of ecological safety net. In this paper, choosed the four representative experiments of Lhasa river valley, surveyed the experimental land topography, soil, water and vegetation, etc., by using principal component analysis, cluster analysis and AHP, we had the results as follows:1. 6 Site Classification System. According to "China Forest Site Classification", the Lhasa Valley’s site is divided into: the Brahmaputra River established areas, the Brahmaputra River valley sub-district site, Lhasa River valley site type cell, and then divided into the following groups and specific site type site type, a total of 5 level classification system.2. The topography of Lhasa valley determines the four different site type group: flood land group of site type, platform group of site type, slope group of site type, alluvial fan group of site type.3. Principal component analysis of the site factors. The purpose of the analysis is to select one of the dominant factors. Flood land selected three main components, the cumulative contribution rate of variance accounted for 82.117%; platform, the slope, alluvial fans selected three main components, the cumulative contribution rate of variance accounted for 85.801%.4. By classify analyze with the shortest distance method in spss13.0, had flood land, platform, foothills slope stand, and alluvial fan’s site type.5. The study of soilmass structural patterns.Lhasa semi-arid valley’s soilmass structural patterns can be divided into five categories: homogeneous type, bottom type, size type,heart-shaped type and three-section type. Homogeneous type of Pebble Beach to the worst, the other thick soil profile, rich in vegetation, soil configuration is better. Size, three-section type and heart-shaped configuration of the soil is general,and it’s soil has many differences, which of thin soil needs a large number of foreign soil.6. From the study of the clustering and soil configuration’s results,we can divide the Lhasa valley into 16 site types.The 16 site types are the basis of the site classification in Lhasa valley.7. Site Quality Evaluation. AHP method is used to establish the site quality evaluation index system of Lhasa semi-arid valley.The results showed that: only a handful of Lhasa Valley site is excellent and poor ratings. Most’s score is the good, accounting for 79.7% of the samples. Score very poor pebble beach can not to reforest.The result of evaluating being the superior can afforest directly, the other sites need soil improvements before planting.8. Afforestation measures. Different types of site type and site quality evaluation results need different method.Evaluation of antagonism can planting for the excellent, good ,and the opposition,the site of bad scores need for the foreign soil.更多还原