半干旱区采煤沉陷对地表植被组成及多样性的影响

对神府-东胜矿区6个矿3种不同地貌下2个不同沉陷年份及对照区地表植被进行了调查,计算并分析了各样地植物种的重要值、物种多样性指数和均匀度等.结果表明:(1)神府-东胜矿区植物种类总体上来看较为稀少,生态较为脆弱;在调查区内共出现植物30科 82属 114种.(2)6个矿中以上湾、大柳塔和活鸡兔3矿区植物种类较丰富,补连塔和乌兰木伦矿区物种相对单一.(3)经沉陷干扰后,植物群落主要组成成分没有发生明显变化,群落的建群种没有改变;除生态十分脆弱的乌兰木伦矿区外,其余矿区地表沉陷后物种多样性与对照相比没有显著性差异;(4)沉陷后群落组成成分较沉陷前增多,且沉陷1年区比沉陷当年区物种数多,它们之间具有明显的相关性.     

巴丹吉林沙漠南缘植被物种多样性及其与土壤特性的关系

通过对巴丹吉林沙漠南缘地区植被的野外调查,探讨了植被物种组成与物种多样性对样地沿距沙漠中心的距离变化的响应,以及物种多样性与土壤因子间的关系。结果表明:(1)研究区主要物种共计10科18属20种,植物种类以沙漠旱生植物为主,样地的植被群落类型都是灌木与草本植物群落。(2)随着样地向沙漠外缘的延伸,植物种类和数量逐渐增多,群落结构更加复杂化和多样化;样地Shannon-Wiener指数和Simpson指数呈上升趋势,优势度指数逐渐下降;灌木层与样地的α多样性指数变化趋势一致,草本层变化幅度较小;β多样性指数中BrayCurtis指数呈下降趋势,说明植物群落之间的物种替换速率降低。(3)物种多样性指数与土壤因子的相关关系及逐步回归分析表明土壤有机质和土壤全氮含量对植被的影响显著,土壤表层20~40cm中的土壤速效磷与样地物种多样性和草本层物种多样性之间具有显著相关关系。     

子午岭植被自然演替中植物多样性变化及其与土壤理化性质的关系

在野外样方调查和室内实验分析的基础上,采用相关性分析和多元逐步回归方法,分析了黄土高原子午岭地区不同演替阶段群落物种多样性、土壤理化特性以及二者的相互关系.结果表明:群落物种多样性随演替进展呈增长趋势,但其增长并非完全线性,主要表现为草本群落演替阶段物种多样性指数高于灌木演替阶段.0~20 cm和20~40 cm土层土壤的全氮、有效氮和有机质等土壤养分指标随着植被演替不断增大.在演替过程中,土壤含水量变化虽有波动,但总体上升,土壤容重波动下降,说明演替过程中土壤环境在不断得到改善.40~60 cm土层土壤理化性质变化未表现出一定规律,说明其与植被演替没有必然联系.物种多样性指数与土壤因子的相关性分析表明,群落演替过程中物种多样性变化与土壤因子存在一定相关性,其中0~20 cm土层土壤的全氮和有机质与物种的多样性指数呈显著正相关.随着土层加深,物种多样性对土壤理化性质影响表现出减弱趋势.     

蒋家沟流域不同海拔灌草层群落特征与土壤关系的研究

为了解干热河谷区不同海拔梯度植物群落灌草层物种多样性与土壤养分、水分之间的关系,该文选择干热河谷典型流域——蒋家沟流域作为研究区域,在流域内海拔1 400～3 000 m范围设置样带,对样带内8个海拔梯度的植物群落进行样方调查,统计不同海拔梯度灌草层的物种组成,测定土壤养分、土壤含水量和持水量,并将土壤指标与植被多样性指数进行主成分分析和皮尔逊相关性分析。结果表明:流域内样地共发现灌草层植物32科77属80种,且灌草层植物群落组成、土壤有机碳(SOC)含量、全磷(TP)含量、土壤含水量和持水量均受海拔梯度的影响显著(P<0.05)。其中,土壤含水量、持水量、植物群落的丰富度指数和多样性指数均随着海拔升高不断增加,且高海拔区域SOC含量显著高于中低海拔区域(P<0.05)。土壤TP含量与Pielou指数、土壤含水量与Margalef指数、Shannon-Wiener指数和物种数均呈显著正相关(P<0.05),说明除海拔梯度外,土壤养分、水分含量是影响植物群落灌草层组成和多样性的关键因子。     

海岛矿区岩质边坡植物群落演替中物种多样性的变化

通过植物群落调查,采用Shannon多样性指数、Simpson优势度指数、Margalef丰富度指数和Pielou均匀度指数,结合DCA排序和一元线性回归分析,考察了舟山海岛矿区岩质边坡植物物种构成特征,研究了植物群落演替过程中生物多样性的变化。结果表明:研究区可划分为3个植物群落演替阶段(草本植物群落阶段、灌丛群落阶段和灌乔群落阶段);演替过程中,物种丰富度指数显著上升,多样性指数和优势度指数逐渐升高;具有矿区特殊生境适应性的植物配置在边坡植被恢复进程中与自然植被表现出一定的差异,演替过程依次为迁入物种生长期、迁入物种与人工导入种竞争期、迁入物种与人工导入种稳定共存期;人工导入群落演替后期的植物种大大加速了群落演替进程;合理的植物配置更能促进群落向正演替方向发展。     

干旱砾漠区露天采煤对草地植物群落特征及其稳定性影响

露天煤炭开采对区域地形地貌、水文循环和土壤植被等生态环境因子产生了较大干扰,但干旱砾漠区露天开采对周边植物群落及其稳定性的影响范围和程度仍有待深入研究,这个问题的探明才能为矿区植被恢复的精准施策提供科学依据。该文通过定量比较距露天开采区不同距离植物群落组成、多样性、生产力和稳定性变化特征,分析干旱砾漠区露天采煤对植物群落的影响范围和程度,并结合土壤性状和微气象因子的测量,探究影响干旱矿区植物群落特征的主导因子。结果表明:(1)干旱砾漠区露天开采排土场原始植被消失殆尽,开采区外围0~500 m范围内原优势物种重要值降低,伴生物种重要值增加,500 m后随着距开采区距离的增加优势植物重要值逐渐增加,至开采区800 m外植物群落组成趋于稳定;(2)开采区外围0~500 m范围内植物群落地上生物量、多样性和群落稳定性较5000 m处分别平均下降了53%、70%和37%,开采区500 m以外上述群落指标整体上变化不明显,而植被覆盖度在开采区外围不同距离并未表现出显著变化趋势;(3)土壤水分、有机质、有效氮磷钾、可溶性盐与植物群落地上生物量、多样性和稳定性呈正相关关系,而土壤pH、光照强度和地表温度与上述植物群落指标呈负相关关系。因此干旱砾漠区露天开采排土场及开采区外围0~500 m范围是矿区生态修复过程中重点考虑区域,同时研究表明干旱砾漠区植被主要分布在砾漠戈壁浅沟和季节性河道等生境相对良好的凹陷微地形条件下,综合可得出干旱砾漠区植被修复过程中可通过微地形塑造、土壤改良和乡土物种繁殖促进,以实现干旱矿区生态系统的稳定和可持续发展。     

榆靖沙漠高速公路沿线植被特征及其多样性

以野外植被调查、物种多样性计算和土壤含水量测定为基础,分析了榆靖沙漠高速公路沿线植被特征,物种多样性指数及其与土壤含水量之间的关系。结果表明:(1)研究区主要物种共计16科39属49种,油蒿为分布最广泛的优势种,植物群落以油蒿群落最为常见;各区域重要值大于0.1的物种中灌木和半灌木占优势。(2)12个小研究区的Shannon指数平均值1.42~2.05,其中研究区E最高,研究区G最低;由于黄土覆盖区(采样线5)土壤养分含量良好,植物生长发育良好,植被覆盖度较高,其Shannon指数和Sorenson相似性指数高于其他3种生境条件的研究区。(3)Pielou指数与0~10 cm土层的含水量呈显著负相关,而物种丰富度与20~30 cm土层的含水量呈显著正相关。     

彬长矿区不同地表沉陷类型下植物群落特征

地表沉陷是煤炭开发过程对生态环境造成严重损害的形式之一,直接或间接地影响植物分布与群落结构。本研究以陕西彬长矿区不同地表沉陷类型下植物群落为对象,调查植物群落组成、生产力和多样性等变化特征,探讨不同沉陷类型植物群落特征的变化规律及其机理。结果表明:1)彬长矿区植被以菊科、禾本科、豆科植物为主,植物生长型构型以多年生草本为主,水分生态类型以中旱生植物为主;沉陷扰动造成了一年生草本、多年生草本和中旱生植物比例增加,中生植物比例显著下降,而灌木和乔木比例变化不明显。2)不同沉陷类型下塬面裂缝区植物群落结构变化不显著,塬面台阶状沉陷区、沟谷边缘裂缝区和台阶状沉陷区植物群落物种数、盖度、生物量、物种密度、物种多样性显著下降。3)依据植物群落损害程度,将彬长矿区不同沉陷类型分为3类:轻微损害区,包括塬面裂缝区;中等强度损害区,包括塬面台阶状下沉区和沟谷边缘裂缝区;强烈损害区,包括沟谷边缘台阶状下沉区。     

陕西子午岭生态因素对植物群落的影响

为探讨生境对植被格局分布的影响,对黄土高原马栏林区60块样地进行植被学调查的基础上,采用17个环境指标刻画植物群落的空间位置、地形和土壤特征;利用双向指示种分析(TWINSPAN)划分了该区不同演替阶段的植物群落类型;利用前向选择法(forward selection)及Monte Carlo检验对不同演替阶段植物群落物种组成影响显著(p＜0.05)的环境因子进行筛选;利用去势典范对应分析(DCCA)排序方法分析不同演替阶段植物群落分布格局与环境的关系;利用偏典范对应分析(partial CCA)定量分离环境、空间及其交互作用对植被格局总体变异的影响.结果表明:(1)马栏林区的植物群落可划分为13个类型,分别属于4个不同的演替阶段;(2)对演替初期阶段群落影响显著的环境因子是土壤含盐量和碱解氮,对演替过渡阶段群落影响显著的环境因子是海拔和腐殖质厚度,对演替亚顶级阶段群落影响显著的因子是海拔、坡向、枯落物厚度、腐殖质厚度和pH值,而对演替顶级阶段群落分异影响显著的因子是海拔、坡向、pH值和速效磷;(3)不同演替阶段群落的生态学特性和分布规律与环境空间的生态梯度格局吻合较好;(4)随着演替的进行,环境因子单独对植物群落的影响越来越大,而样地位置单独作用和样地位置与环境因子的交互作用之和越来越小.     

黄土丘陵区植物群落多样性及生物量随土壤水分梯度变化特征

了解土壤水分与物种多样性及生物量的关系对探究植物群落特征与分布具有重要意义。以陕北黄土丘陵区吴起、米脂、府谷、定边4个典型区域为研究对象,对比分析降水量影响下的土壤水分梯度对自然恢复植物群落多样性、生物量的影响,为黄土丘陵区植被恢复和生物多样性管理提供科学依据。结果表明:随降水量自东南向西北逐渐减少土壤水分呈降低趋势,吴起、米脂、府谷和定边平均土壤含水量分别为9.77%、9.40%、7.91%和6.40%;4个区域调查统计到植物24科56属71种,其中禾本科、菊科、豆科植物占多数且以草本植物为主;随着土壤含水量降低,4个典型区域植物群落物种组成具有较低的相似性,说明物种组成随土壤水分变化而更替;同时,群落生物量、Margalef指数、Shannon指数以及Pielou指数均表现出逐渐降低趋势,且群落生物量、Margalef指数、Shannon指数与浅层土壤含水量呈显著正相关。研究表明,土壤水分变化对群落物种组成、植物群落多样性及生物量有重要的影响,研究区植被恢复建设必须要考虑土壤水分承载力。     

岷江干旱河谷灌丛土壤种子库及其自然更新潜力评估

为了解岷江干旱河谷区灌丛植被土壤种子库的特征及预测灌丛植被自然更新的潜力,利用土壤种子库"萌发法"(每个地段15个2m×2m样方内分土表层、0-5cm土层和5-10cm土层采集土样)及野外植被调查方法(每个地段15个1m×1m的调查样方),研究了岷江干旱河谷3个地段(河谷下游边缘汶川地段、核心茂县地段以及上游边缘松潘地段)阳坡灌丛植被土壤种子库及其与地上植物群落的关系。发现:土壤种子库发芽试验共观察到4274株幼苗,分属于113个物种。土壤种子库密度在102—103ind./m2,物种数在12—23种/0.06m2,边缘地段的土壤种子库平均种子密度(ind./m2)和平均物种数(种/0.06m2)均比中心地段(茂县)高。3个地段土壤种子库和地上植被的组成物种均多为多年生植物,地上灌丛与其土壤种子库的密度及物种数均呈不显著相关性;物种组成的Sorensen相似性指数较低,不足30%,但土壤种子库均比地上植被具有更高的物种丰富度。综合分析表明,岷江干旱河谷灌丛具有依靠土壤种子库实现自然更新的潜力,但由于物种组成相似性较低,现存灌丛植被一旦遭到破坏后,单依靠土壤种子库自然恢复到现存植被是困难的,需要在自然恢复潜力评估基础上积极充分采取人工促进自然恢复的策略,同时也应充分考虑干旱河谷植被及其自然更新潜力的空间异质性。探明岷江干旱河谷区灌丛植被的土壤种子库特征,是认识灌丛植被自然更新潜力的基础,是合理制订该区植被恢复与管理措施的重要依据。     

Effects Of Vegetation and Soil on Species Diversity of Soil Dwelling Diptera in a Heathland Ecosystem

The role of vegetation and soil factors on the biodiversity of two soil dwelling, saprophagous, fly families (Sphaeroceridae and Lonchopteridae) in a heathland ecosystem were investigated. The fly community is primarily affected by soil humidity and the amount of organic matter while the vegetation structure and species composition only indirectly influence the fly communities. There was no correlation between plant species richness and the fly diversity indices. Based on our results and literature data, we hypothesise that the direct effects of the vegetation is more evident for herbivorous insects than for species that do not feed on plants. The investigated families show a clear response to microhabitat differences in the soil factors, which makes them promising indicators for soil health and as tool for monitoring environmental changes.     

Soil nematode biodiversity in terrestrial ecosystems

A review of the literature on nematode diversity (=number of species identified) of soil inhabiting nematodes was undertaken and analysed with regard to distance from the equator, vegetation type and sampling effort. After applying a correction factor for sampling effort the results indicated that species richness was greatest in temperate broadleaf forest (61.7 species per sample) followed by cultivated soil, grassland, tropical rainforest, temperate coniferous forests and polar vegetation. The maintenance of high biodiversity in cultivated soils is unexpected but may reflect the impact of dominance in calculating many indices. Species richness was greatest between latitudes 30–40° (93.9 species per sample) and least above 70°, the mean richness near the equator (i.e. 0–10°) was 80.6 species per sample. While these data would suggest that nematode diversity is not necessarily greatest at the equator, and evidence to support a 'humped back' theory of species richness is not conclusive, they contradict the suggestion that nematode diversity increases with increased latitude.     

Soil Microfungi in Two Post-Mining Chronosequences with Different Vegetation Types

Soil microfungi were studied in the Sokolov (Czech Republic) post‐mining dumps afforested with Alnus glutinosa and in the Lusatian (Germany) post‐mining dumps afforested with Pinus sylvestris or P. nigra. Microfungi were isolated using the soil dilution plate method. Soil microfungi communities of two chronosequences were compared by species composition, frequency of species occurrence, and colony forming units of fungi (CFU‐counts). Differences in species occurrence were determined. More species of entomopathogenic microfungi were found from the Sokolov post‐mining area in comparison with the Cottbus post‐mining area. Absidia glauca, A. cylindrospora, Penicillium glabrum, and P. janthinellum were the most frequently isolated species from the Cottbus post‐mining area, while A. glauca, Geomyces pannorum, and Trichoderma koningii predominated at the Sokolov post‐mining area.     

Soil seed bank characteristics in Cameroonian rainforests and implications for post-logging forest recovery

The soil seed bank is considered as an important component for resilience of climacic vegetation. Whereas several related studies have been conducted in Asian, American and some African tropical forests, no investigation has ever been conducted in Central African rainforests, especially in logged forests where the soil seed bank could contribute to regeneration of timber of trees species. We studied the soil seed bank characteristics in relation to the standing vegetation in three Cameroonian forest zones with different disturbance regimes. There was no significant difference between sites in terms of density of the seed bank; the average mean density was 87.6 seeds m⁻². But dissimilarities of the floristic compositions between sites were quite high. Overall, seeds came from 43 species including three commercial tree species. Whereas the seedlings emerging from soil samples mostly came from weedy and short-lived pioneer species, climax species predominated in the extant vegetation, leading to a very weak similarity between soil seed flora and the surrounding vegetation: Sorensen's index ranged from 3.5 to 7.6%. Canopy openness could significantly affect the species richness of soil seed stocks but not the seed density. These results show that the soil seed bank contribution to the resilience of mature tropical forests is low. In particular, very few timber tree species could benefit from soil seed stocks for their regeneration. Therefore, the development of enrichment techniques including use of the soil seed bank as a source of tree regeneration in such a context would be irrelevant.     

放牧对草地群落与土壤特征的影响

针对放牧干扰对草地生态系统的影响,采用回归分析和典型对应分析(CCA)方法,研究放牧对草地植物群落物种多样性与生产力、土壤碳氮含量与生物量关系的影响。结果表明:(1)与休牧草地相比,放牧草地的地上生物量降低31.63%,凋落物生物量降低134.29%;放牧草地的禾草类生物量提高19.77%,而杂草类生物量和豆科类生物量分别降低31.09%和23.42%。(2)当物种多样性指数小于1.3时,休牧草地的生产力明显高于放牧草地;当物种多样性指数大于1.3时,放牧草地的生产力高于休牧草地。(3)CCA分析显示,家畜主要通过影响群落地上生物量、凋落物质量和土壤容重进而影响土壤的碳氮含量。(4)当群落地上生物量小于100g·m-2时,休牧草地的土壤有机碳和全氮含量高于放牧草地,当群落地上生物量大于100g·m-2时,放牧草地则略高于休牧草地。(5)当群落地下生物量小于1 200g·m-2时,放牧草地土壤有机碳、全氮含量高于休牧草地;当地下生物量大于1 200g·m-2时,放牧草地则略低于休牧草地。     

汾河流域中下游植物群落物种多样性与土壤因子的关系

于2011年4~10月对汾河流域中下游33个样地128个样方的植被进行样地调查和土壤取样分析,并运用双向指示种分析（TWINSPAN）进行群落分类,用典范对应分析法（CCA）分析7种土壤因子与汾河流域中下游植物群落的分布关系,以揭示汾河流域中下游植被的物种多样性与土壤因子的关系。结果表明:（1）汾河流域中下游地区共发现植物121种,隶属33科81个属,其中以菊科、禾本科、藜科和蓼科植物最多,分别占总数的24.79%、14.05%、8.26%和7.43%,且芦苇的分布频率最高,达到49%。（2）双向指示种分析表明,汾河流域中下游33个样地分为8个群落类型（Ⅰ~Ⅷ）。（3）汾河流域中下游植物群落的Patrick丰富度指数和Shannon-Wiener指数变化趋势相似,而Simpson指数则与Patrick丰富度指数和Shannon-Wiener指数呈相反的变化趋势;Pielou均匀度指数的变化趋势与其他3个指数均不同。（4）汾河流域中下游土壤含水量、速效钾含量在不同群落类型的不同样地间的差异大部分达到显著水平,土壤养分具有比较明显的空间分布中度不均的特点。（5）汾河流域中下游地区的土壤有机质含量与物种Simpson指数以及土壤全氮与Pielou均匀度指数均具有显著负相关关系。（6）CCA排序结果表明,土壤含水量及速效磷、速效钾含量是影响植被群落分布最重要的环境因子。     

Soil Nematode Diversity: Species Coexistence and Ecosystem Function

Soil nematode species diversity is often high, both at ecosystem and single soil-core scales. First, how can so many species coexist? There is evidence of niche partitioning, notably of physical space, but vast interspecific overlaps and trait plasticity seem equally common. It appears that coexistence of species with similar resource needs is made possible by small-scale disturbance and predation, which likely reduce local population sizes and interspecific competition. Regional processes such as dispersal, large-scale disturbance, and aggregation, which govern ecosystem level diversity, may also affect local species interactions and soil-core scale diversity. Second, what is the significance of having so many species, with so few trophic functions, for ecosystem processes? Focusing on bacterivore diversity, it is clear that species contributions to decomposition, likely to differ as a function of individual biologies, are concealed by the trophic group approach. However, considerable functional redundancy probably exists, which may explain why decomposition processes are maintained in highly disturbed soils despite the extinction of many species. Thus, soil nematode diversity is important for the long-term stability of soil functioning, and merits protection and further study.     

Responses of Pioneer and Later‐Successional Plant Assemblages to Created Microtopographic Variation and Soil Treatments in Riparian Forest Restoration

Riparian forest restoration generally involves introduction of later‐successional tree species, but poor species suitability to severely altered or degraded site conditions results in high mortality and poor community development. Additionally, while microtopographic heterogeneity plays a crucial role in the development of natural riparian forests, little is known regarding effects of restored or created microtopography on the development of introduced plant communities. The objective of this study was to determine the influence of created microtopography and soil treatments on early development of introduced pioneer and later‐successional plant communities in riparian forest restoration. Ridges, flats, and a mound‐and‐pool complex were created, and pioneer and later‐successional tree assemblages were planted within plots in each of these three microtopographic positions. Straw‐based erosion control mats were placed on half the plots as a source of mulch. After two growing seasons, growth and survival of the pioneer assemblage were equal among microtopographic positions, but survival of the later‐successional assemblage was significantly higher on ridges (59%) than on mounds and pools (22%) and flats (26%). A suitability index indicated that performance of the later‐successional assemblage on ridges was higher than that of the pioneer assemblage for all microtopographic positions. Flood duration explained much of the variation in plant assemblage survival, and erosion control mats had little influence on seedling survival. Restoring microtopographic features has the potential to enhance species survival and promote community development. Microtopographic restoration may be as important in riparian forest restoration as proper species selection and hydrologic reestablishment, especially at severely disturbed sites.