水蚀风蚀交错区退耕植被演替过程研究

发布时间：2018-08-31 14:59

【摘要】：为研究人工草地和弃耕地植被在自然封禁恢复过程中植被群落各生态指标的变化特征和演替规律,分别选取位于黄土高原水蚀风蚀交错区的陕西省榆林市神木县六道沟流域紫花苜蓿人工草地和弃耕地为研究对象,以空间代替时间的方法研究了紫花苜蓿人工草地和弃耕地封禁后的群落植被演替过程。在此基础上,分析了不同植被类型样地土壤水分特征和地上生物量差异,提出在植被恢复建设过程中构建复合植被可以更合理有效利用有限水资源、缩短植被恢复建设进程和防控土壤侵蚀。主要对紫花苜蓿人工草地进行回访调查,对弃耕地进行群落特征调查,测定植被的株高、盖度、密度、物种丰富度等指标;同时对选取的不同植被类型样地进行植被冠层高度、地表植被盖度、叶面积指数、地上生物量、物种丰富度、土壤含水量、表层土壤容重和土壤饱和导水率等指标的测量。结果表明:(1)紫花苜蓿人工草地在经过11年的自然恢复演替,除Margalef指数外,Gleason指数、Shannon-Wiener指数和均匀度指数均具有相似的变化趋势,即2014年的调查结果普遍高于2004年的调查结果,群落物种丰富度、物种多样性和均匀度均有显著提高;样方内共出现高等植物42种,增加了10种,其中豆科6属7种,减少了2种;菊科6属9种,增加了2种;禾本科8属9种,增加了3属4种;群落内豆科、菊科和禾本科三大科合计分别占属种总数的58.8%和59.5%。(2)根据自然恢复40年左右的紫花苜蓿人工草地植物群落优势种与植物多样性的变化特征,发现在水分条件较好的阴坡出现向铁杆蒿-长芒草半灌木次生天然草地演替的趋势,而阳坡的演替趋势仍为长芒草次生天然草地。(3)不同年限弃耕地调查样方内共出现高等植物38种,分属于13科34属,其中豆科6属7种、菊科9属10种、禾本科7属7种,三大科植物在弃耕地自然恢复演替过程中占据主要地位。在恢复演替的12年和21年,阴坡弃耕地科属种的数量和物种丰富度指数(Gleason指数和Margalef指数)、物种多样性指数(Shannon-Wiener指数)以及均匀度指数均高于阳坡弃耕地,群落科属种数量增加的主要原因在于群落物种丰富度的增加。(4)在种植紫花苜蓿人工草地和弃耕地自然撂荒封禁两种植被恢复方式下,种植紫花苜蓿人工草地这一恢复方式要早于弃耕地的自然恢复演替进程。(5)在黄土高原水蚀风蚀交错区的六道沟流域内,深根性植物与浅根性植物复合后其冠层高度、地表植被盖度、叶面积指数和地上生物量均显著提高;土壤表层含水量显著增加;物种丰富度也呈现增加趋势。影响复合植被和单一植被地上生物量差异的主要因素是复合植被根系和单一植被根系对水分的吸收利用差异,以及深根性灌木和浅根性草本植物对不同深度土壤水分的利用差异。(6)在植被恢复建设过程中,深根性植物宜与浅根性植物搭配种植营造复合植被,可以合理有效利用有限水资源,提高植被地上生物量、冠层高度和地表植被盖度,加速植被恢复建设进程,从而可以有效控制该区的水蚀与风蚀作用。
[Abstract]:In order to study the variation characteristics and succession law of the ecological indices of the vegetation community in artificial grassland and abandoned farmland during the process of natural closure and restoration, the alfalfa artificial grassland and abandoned farmland in Liudaogou watershed of Shenmu County, Yulin City, Shaanxi Province, located in the water erosion and wind erosion crisscross region of the Loess Plateau, were selected as the research objects. Methods The succession process of community vegetation in alfalfa artificial grassland and abandoned farmland was studied. On this basis, the soil water characteristics and aboveground biomass differences of different vegetation types were analyzed. It was suggested that the construction of composite vegetation could make more rational and effective use of limited water resources and shorten the vegetation restoration process. The main purpose of this study is to investigate the community characteristics of abandoned farmland and determine the plant height, coverage, density and species richness of the vegetation. Meanwhile, the canopy height, surface vegetation coverage, leaf area index and aboveground biomass of different vegetation types were measured. Species richness, soil water content, surface soil bulk density and saturated water conductivity were measured. The results showed that: (1) After 11 years of natural restoration succession, except for Margalef index, Gleason index, Shannon-Wiener index and evenness index had similar trends, that is, the results of 2014 survey. The community species richness, species diversity and evenness were significantly improved. There were 42 species of higher plants in the sample plot, including 6 genera, 7 species of Leguminosae, 2 species of Leguminosae, 9 species of Compositae, 2 species of Compositae, 8 genera, 9 species of Gramineae, 4 species of Leguminosae, Compositae and Gramineae. (2) According to the variation characteristics of dominant species and plant diversity in alfalfa artificial grassland which had been restored for 40 years, it was found that there was a trend of succession from the shady slopes with better water conditions to the secondary natural grassland with Artemisia sinensis-Elymus elongata, while the trend of succession in the sunny slopes was still long. (3) There are 38 species of higher plants belonging to 13 families and 34 genera in the sample plots of abandoned cultivated land in different years. Among them, 6 genera and 7 genera of Leguminosae, 10 genera of Compositae, 7 genera of Gramineae, and 7 genera of Gramineae are dominant plants in the natural restoration succession of abandoned cultivated land. Quantity and species richness index (Gleason index and Margalef index), species diversity index (Shannon-Wiener index) and evenness index were higher than those of abandoned farmland on sunny slopes. The main reason for the increase of community species richness was the increase of community species richness. (4) The forbidden cultivation of Alfalfa artificial grassland and abandoned farmland by natural abandonment. Under the two vegetation restoration modes, the Alfalfa Planted artificial grassland was earlier than the natural restoration succession of abandoned farmland. (5) In the Liudaogou watershed of the water erosion and wind erosion crisscross region of the Loess Plateau, the canopy height, surface vegetation coverage, leaf area index and aboveground biomass of the deep-rooted and shallow-rooted plants were significantly higher than those of the shallow-rooted plants. The main factors affecting the above-ground biomass differences between the composite vegetation and the single vegetation are the differences in water absorption and utilization between the composite vegetation roots and the single vegetation roots, as well as the water content of deep-rooted shrubs and shallow-rooted herbs at different depths. (6) In the process of vegetation restoration and construction, deep-rooted plants and shallow-rooted plants should be planted together to construct complex vegetation, which can make rational and effective use of limited water resources, increase aboveground biomass, canopy height and surface vegetation coverage of vegetation, accelerate the process of vegetation restoration and construction, and thus effectively control water erosion and wind erosion in this area. Use.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157.43

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