【作者】 孙杰；

【导师】 王乃昂；

【作者基本信息】 兰州大学 ， 地球系统科学， 2018， 博士

【摘要】 沙漠中生物多样性及濒危物种丰富,且属于脆弱生态系统,同时,世界6%的人口居住并依靠沙漠生态及其服务生存。生物多样性为生态系统提供服务功能,而生态系统服务取决于生态系统健康。我国沙漠分布广泛,主要位于北方各省(区),但沙漠生态系统的保护基金及研究却非常缺乏。本文以阿拉善高原主体分布的3大沙漠为研究区域,研究沙漠生态系统植物群落物种多样性、植被分布格局及土壤因子对其影响、生态系统物种多样性及健康评价。主要结论如下:(1)基于290个样地、479个样方和21条样线的阿拉善沙漠植物物种多样性研究结果表明:阿拉善沙漠植被群落结构较为简单,共计196种植物,其中在所有样方中仅出现两次及以下的稀有种有22种,隶属35科,108属,其中以菊科、禾本科、藜科植物为最多,物种数占研究区总物种数的50.29%,豆科次之。巴丹吉林沙漠植物物种包含26科,73属,109种;腾格里沙漠植物物种包含27科,83属,118种;乌兰布和沙漠调查样方中物种包含12科,39属,52种。腾格里植物物种数最为丰富,巴丹吉林沙漠次之,乌兰布和沙漠相对较少。由样方中物种重要值-样方矩阵为数据基础,TWINSPAN、PCA排序及经典分类结合的分类结果显示:数量生态学方法和经典分类法的结果基本相互吻合,研究区植物群落分为5种植被型:荒漠、草原、草甸、灌丛和落叶阔叶林,5种植被亚型,8个群系组,15个群系类型,以旱生、耐盐碱植物为主。阿拉善沙漠植被图说明巴丹吉林沙漠主要为沙蒿+沙拐枣、沙蒿+膜果麻黄荒漠,乌兰布和和腾格里沙漠主要为沙蒿+油蒿荒漠。因此,阿拉善沙漠植被类型属于温带荒漠中的半灌木、小半灌木荒漠。(2)根据群系分类结果选取的174个代表样地物种多样性指数表明:腾格里沙漠植物群落的Shannon-Wiener、Simpson指数和物种丰富度较高,均匀度相对较低,分别为0.83,0.40,6.41,0.51;巴丹吉林沙漠Shannon-Wiener、Simpson指数和物种丰富度较低,均匀度较高,分别为0.71,0.36,4.41,0.56。研究区物种多样性指数水平较低,灌木、灌木-草本多样性指数均最高,Shannon-Wiener指数为0.79,Simpson指数为0.39,丰富度指数分别为5.40、5.97;均匀度指数均较低,为0.56、0.48。该类型植被具有物种丰富、优势种明显的特征,显示了沙漠生态系统植物群落特征。阿拉善沙漠生物量较大的群丛依次为:膜果麻黄群丛、红砂群丛、芦苇群丛、白刺群丛、沙蒿群丛、油蒿群丛。因此,阿拉善沙漠的沙蒿+沙拐枣、沙蒿+膜果麻黄和沙蒿+油蒿荒漠,植被生长状况较为良好。(3)不同植被群落下的2313份土壤分层样品,及从中挑选测试的样品土壤含水量、容重、比重、孔隙度、粒径、有机质、全氮、速效磷、速效钾含量、pH、电导率等土壤特性结果显示:灌木-草本群落下的土壤水分含量最大,为4.1%;灌木-草本群落下各种土壤养分状况仅次于包含有部分分布于湖泊或干湖盆周围的芦苇群系的草本。植物群落分布特征与土壤因子之间关系的DCCA排序、物种多样性指数与土壤因子之间的RDA排序、相关性分析结果显示:在土壤因子中,土壤养分、电导率、土壤粒径是对于植物群落分布有较大影响的因子,土壤速效磷、速效钾、有机质、电导率是对群落物种多样性有较大影响的土壤因子。(4)根据综合指标评价法,在区域尺度,阿拉善3大沙漠物种多样性评价结果显示,腾格里沙漠物种多样性相对较为丰富,物种多样性评价等级为“高”;在群丛类型尺度,不同植物群丛健康评价中,沙拐枣、芦苇群丛健康评价值为82.93、80.14,均属于“很健康”,膜果麻黄等灌丛类型的植物群丛生态系统健康情况也较好,为“健康”,评价值高于其他类型植被。以生态系统健康、物种多样性、植被及土壤环境状况为依据,建议栽植沙拐枣、膜果麻黄、沙蒿、芦苇,以形成沙蒿+沙拐枣、沙蒿+膜果麻黄、沙蒿+油蒿荒漠和芦苇草甸,可有效进行沙漠生态系统保护和恢复。更多还原

【Abstract】 Biodiversity and endangered species are abundant in the desert ecosystem,which belongs to fragile ecosystems.Deserts are home to 6% of the world’s population.These population rely on desert ecology and its service to survive.Ecosystem services depend on ecosystem health,ecosystem health has the function of maintaining biodiversity and ecosystem services.Desert ecosystem protection funds and research are very scarce.Deserts are widely distributed in China,mainly in the northern provinces.This paper takes three deserts of Alxa Plateau as the research area,investigated several aspects of phytocoenosium in desert ecosystem,including diversity of species,vegetation distribution pattern and its response to soil factors,and then accomplished its biodiversity and health assessments.This research coms to the following conclusions:(1)A total of 290 sample plots in the Alxa Deserts have been set.479 quadrats and 21 transect lines show that vegetation community structure in Alxa deserts is relatively simple,with a total of 196 species(within 22 rare species,appeared twice and below in all the quadrats),under 35 families,108 genera.Among them,Compositae,Gramineae and Polygonaceae have the maximum number of species,accounting for 50.29% of the total in the study area,followed by Legumes.The plants in Badain Jaran Desert are under 26 families,73 genera,109 species.The plants in Tengger Desert are under 27 families,83 genera,118 species,and that in Ulan Buh Desert are under 12 families,39 genera,52 species.The number of species in Tengger is the most abundant,followed by that in Badan Jaran Desert,andspecies in Ulan Buh Desert are relatively few.Based on the Important Value – Sample Quadrat Matrix data,the classification result of TWINSPAN,PCA sorting combined with classical plant taxonomy reveals that the outcome of quantitative ecology method basically conform with that of the classical plant taxonomy method.The plant in Alxa deserts are divided into 5 vegetation type: desert,grassland,meadow,shrub and deciduous broad-leaved forest,15 formations.Drought-resistant and salt-tolerant plants are in majority.Spatial distribution map illustrates that the Badan Jaran Desert is dominated by Artemisia arenaria + Calligonum arborescens,Artemisia arenaria + Ephedra przewalskii deserts.The Ulan Buh Desert and Tengger Desert s are mainly Artemisia arenaria + Artemisia ordosica deserts.Therefore,the vegetation type in Alxa deserts belongs to semi-shrubs and small shrubs in temperate deserts.(2)174 representative samples for calculation of the Shannon-Wiener,Simpson,uniformity and species richness index show that the species diversity index in the study area are relatively low,shrubs,shrubs-herb have the maximum diversity indexes and minimum uniformity index,shows the characteristics of desert ecosystems.The communities with large biomass in Alxa desert are successively: Ephedra przewalskii,Reamuria soongorica,Phragmites communis,Nitraria tangutorum,Artemisia arenaria and Artemisia ordosica.They have good vegetation growth conditions.(3)2313 soil layered samples are collected under different community types,the soil moisture content,bulk density,specific gravity,porosity,particle size,organic content,total nitrogen,available phosphorus,available potassium content,pH,conductivity,and other soil properties are experimented.The soil moisture content under shrub-herb communities is maximum,4.1 %.The soil nutrients under shrub-herb communities rank only second to the Phragmites communis communities distributed around lakes and dry lakes.Through the Detrended Canonical Correspondence analysis(DCCA)of plant community species and environmental factors,Soil moisture,total nitrogen,organic matter content have great influences on the distribution of vegetation.As to the RDA analysis and Pearson correlation analysis of the Shannon-Wiener,Simpson Index,Uniformity,Species Richness and the environmental factors,there is a relatively strong positive correlation between biodiversity and soil available phosphorus content,followed by rapid availability of potassium,organic content and the conductivity again.(4)Ecosystem assessments: at the regional scale,the biodiversity in 3 deserts are evaluated and that in the Tengger Desert is relatively abundant.At the community scale,ecosystem health assessment is conducted on different community types.The health status of the Calligonum arborescens community and Phragmites communis community are “very health”.Their evaluation values are 82.93 and 80.14,which are higher than other types of vegetation communities.According to this article,it is recommended that,when necessary,species with good vegetation,soil environment and good evaluation results can be planted for desert ecosystem protection and restoration,like Calligonum arborescens,Ephedra przewalskii,Artemisia arenaria and Phragmites communis to construct Artemisia arenaria + Calligonum arborescens,Artemisia arenaria + Ephedra przewalskii,Artemisia arenaria + Artemisia ordosica deserts and Phragmites communis meadow.更多还原