【作者】 王凯博；

【导师】 上官周平；

【作者基本信息】 西北农林科技大学 ， 生态学， 2008， 硕士

【摘要】 本文以黄土高原子午岭林区植被演替过程中出现的7种主要群落类型(4年弃耕地、白羊草群落、狼牙刺群落、沙棘群落、山杨群落、白桦群落、和辽东栎群落)为研究对象,通过野外调查和室内实验分析,研究了不同演替阶段群落的组成结构、区系特征、物种多样性、群落生产力和土壤理化性质的变化,以及演替过程中群落物种多样性与植被生产力和土壤环境因子的关系,结果表明:1、子午岭林区植被演替过程中共出现种子植物40科87属114种,其中乔木10种、灌木29种、草本71种、藤本4种;从植物区系组成来看,群落演替过程中出现的40科植物分属6种地理成分,出现的87属种子植物可分为9种地理成分,温带分布性质的科、属成分均在该区占优。对该区植被生活型谱分析表明,高位芽植物和地面芽植物在该区群落演替过程中占优,分别占总种数的42.1%和40.1%;其次为地下芽植物,占总种数的12.3%;地上芽植物和一年生植物在该区均较少分布,不足总植物种数的5%。2、群落总体α物种多样性随演替呈现上升趋势,从演替初期到演替末期,群落的Margalef丰富度指数增加了196%,Shannon-wiener指数增加了149%,Simpson指数增加了218%;群落的Sorensen指数和Jaccard指数依次降低,下降幅度分别为66.1%和70.3%,群落的Cody指数随着演替进行逐渐增大,增幅为150%。群落的分层α多样性测度结果表明,草本层的多样性指数前期相对较大,后期有所下降;灌木层的多样性指数随演替进行有增大趋势,且增加幅度为前期大于后期,各多样性指数最大值均出现在演替后期的顶级群落阶段。除Simpson指数外,乔木层各多样性指数均为顶级乔木群落阶段大于先锋乔木群落阶段。3、随演替进行,土壤有机质、全氮呈现增加趋势,土壤有效氮和土壤水分呈现波动变化,土壤容重小幅下降。0～20cm土层土壤有机质、全氮、有效氮和土壤水分随着演替进展增加趋势最为明显;20～40cm和40～60cm土层土壤有机质和全氮较0～20cm土层明显下降,土壤水分含量和土壤容重均较上层有所增加,而土壤有效氮在不同演替阶段出现较大波动。4、群落总生物量随演替进行呈现前期快速增长,后期逐渐稳定的趋势。不同演替阶段群落总生物量大小顺序为:先锋乔木群落阶段(57.75 t hm-2)>灌木群落阶段(56.48 t hm-2)>顶级群落阶段(45.90 t hm-2)>草本群落阶段(3.79 t hm-2)>弃耕地阶段(1.63 t hm-2)。群落生产力呈现先升高后降低的趋势,群落生产力变化范围为1.63 t hm-2 yr-1～6.42 t hm-2 yr-1,群落生产力大小顺序为灌木群落阶段>草本群落阶段>先锋乔木群落阶段>顶级群落阶段>弃耕地阶段。5、演替过程中表层土壤环境因子与群落物种多样性关系最为密切,二者相关性随土层深度逐渐减弱。0～20cm土层土壤全氮和有机质与物种多样性指数呈显著或极显著正相关,土壤水分、土壤有效氮与物种多样性指数相关性次之,土壤容重相关性最弱;20～40cm土层土壤全氮和土壤有机质与群落物种多样性指数表现出弱相关性;40～60cm土层土壤环境因子与群落物种多样性指数未表现出相关关系。更多还原

【Abstract】 The component structure, floristic characteristics, species diversity, community productivity, soil physical-chemical properties, and the relationship between species diversity, community productivity and soil factors was tudied in vegetation succession in Ziwuling area on the Loess Plateau. The results are as followed:1. There are 114 species in 87 genera and 40 families including 10 species of trees, 29 species of shrubs, 71 species of herbs and another 4 species of liana in vegetation successional in Ziwuling area. As to the plant floristic composition, the 40 families belong to 6 geographical elements and the 87 genera belong to 9 geographical elements in vegetation succession. Both the family and genera with temperate distribution are dominant in this area. The analysis of life form spectrum of flora shows that the phaenerophyte and phaenerophyte are the dominant life form which account for 42.1% and 40.1% respectively, followed the geocryptophytes with 12.3%. The chamaephytes and therophyte less distributed in the area that is no more than 5%.2. The species diversity increased with vegetation succession. From the initial stage to the end, the Margalef index increased by 196%, Shannon-wiener index increased by 149% and Simpson index increased by 218 percent. With community succession, the Sorensen index and Jaccard index had a decrease of 66.1% and 70.3%, while the Cody index gradually increased by 150%. The layeredαdiversity indicated that the species diversity index of herbs in the initial stages were larger than latter, the species diversity index of shrubs increased with succession and the increased range were greater in early stage, furthermore, all other species diversity indexes of trees in climax community were bigger than in Pioneer arbor community stage except Simpson index.3. With the succession, soil organic matter and total nitrogen showed an upward trend, soil available nitrogen and soil moisture were fluctuating, and soil bulk density decreased slightly. The soil organic matter, total nitrogen, available nitrogen and soil moisture of 0 ~ 20 cm layer significantly rise with the succession. The soil organic matter and total nitrogen of 20 ~ 40 cm and 40 ~ 60 cm layer declined markedly and soil moisture and soil bulk had little increase compared to 0 ~ 20 cm layer. The soil available nitrogen had greater fluctuation in different succession stage. 4. The community species diversity and surface soil environmental factors have closely relationship that gradually weakened with the soil depth in the succession process. The soil organic matter and total nitrogen are significant or very significant positive correlation with species diversity, then soil moisture and soil available nitrogen, the correlation between soil bulk density and species diversity are the weakest. The 20 ~ 40cm layer of soil organic matter and soil total nitrogen showed weak correlation with community species diversity and the 40 ~ 60 cm layer of soil environmental factors showed no correlation with community species diversity.更多还原