洪河自然保护区典型湿地植物群落组成及物种多样性梯度变化

以洪河自然保护区两类典型湿地——河漫滩湿地与碟形洼地湿地的植物群落为研究对象,探讨其物种组成及物种多样性的梯度变化规律。结果表明,由沼泽至岛状林的梯度上:(1)各群落建群种、优势种和伴生种的种类及其优势度,地表覆盖藓类等组成特征均变化明显;(2)群落的物种丰富度呈逐渐增加格局,丰富度指数分别为26、41、51、68和82;(3)群落的α多样性的变化格局与丰富度格局不太一致,Shannon-Wiener多样性与Pielou均匀度的变化格局基本一致,呈不规则"N"型格局,Simpson优势度的变化格局正好与它们相反,呈不规则倒"N"型格局;上述格局的两个"拐点"出现在沼泽化草甸群落和湿草甸群落中;(4)群落的β多样性——相异性系数和Cody指数均呈先降后升的格局,二者的最小值出现在沼泽化草甸群落和湿草甸群落之间,最大值出现在灌丛草甸和岛状林群落之间;研究认为,典型湿地植物群落物种组成和物种丰富度的梯度变化主要于生境的变化有关,α多样性的变化格局主要与生境的变化和优势种的生物学特性有关,β多样性的格局的原因比较复杂,尚需进一步探讨。     

北方典型沼泽湿地高低土壤水分下植物群落特征

北方沼泽湿地在水源供给、缓解水土流失、遏制草地沙化等方面具有重要作用,明确其植物群落物种组成和多样性特征对提升其生态系统服务功能具有重要意义。目前,在北方地区开展大尺度湿地植被调查的研究仍相对较少。土壤水分是驱动植物群落发展的主导环境因素之一,为了解高低土壤水分背景下湿地植物群落特征差异及关键驱动要素,对我国7个北方典型沼泽湿地的植物群落物种组成及多样性特征进行了调查,分析了植物群落物种组成及多样性特征与环境因子的关系,以及沼泽湿地植物群落内克隆植物的分布特征。研究结果发现不同沼泽湿地的植物群落物种组成和多样性差异显著,但无明显的地带性分布规律,物种分布呈现区域性。群落物种多样性受降水、温度、土壤养分等多种环境因素的共同影响。沼泽湿地高低土壤水分背景下植物群落的物种组成和多样性差异显著,低土壤水分下植物群落物种多样性指数显著高于高土壤水分下植物群落。低土壤水分下物种多样性主要受降水和总氮影响,而高土壤水分下物种多样性主要受温度和总磷的影响。高土壤水分下克隆植物物种数和盖度在沼泽湿地植物中占有较高的比例,表明克隆植物比非克隆植物更适应高土壤水分环境。研究结果表明了7个沼泽湿地植被的区域性...     

旅游干扰对喀纳斯自然保护区植物群落的影响

研究不同强度旅游干扰对喀纳斯自然保护区西伯利亚云杉(Picea obovata)林、草甸群落和金露梅(Potentilla fruticosa)灌丛的群落物种组成、物种多样性以及土壤理化性质的影响.结果表明:(1)在不同强度干扰下,云杉林中灌木层与草本层物种组成存在较大差别,随着干扰强度的增大,群落物种多样性呈先上升后下降的变化;(2)草甸群落Shannon-Wiener多样性指数随干扰强度的增大有下降趋势,土壤理化性质也受到了影响;(3)围栏内外两个金露梅灌丛群落在不同的干扰强度下,群落优势度和均匀度具有显著差异(P<0.05),土壤理化性质也存在显著差异.土壤理化性质的改变在一定程度上也改变了群落的物种多样性.     

三江平原沟渠土壤种子库特征及其与地上植被的关系

为了探究三江平原沟渠土壤种子库在湿地植物保护中的作用及其在湿地恢复中的潜力,该文采用幼苗萌发法与样方调查相结合的方法,对三江平原不同开挖年限沟渠的土壤种子库特征及其与地上植被的关系进行了研究。结果表明:沟渠具有较大规模的土壤种子库,边坡种子库显著大于底泥种子库,边坡种子库密度为8 973–25 000 seeds·m–2,底泥种子库密度为506–1 488 seeds·m–2。开挖10年、20年和30年的沟渠土壤种子库共有50种植物萌发,隶属于20科41属。开挖10年、20年和30年的沟渠土壤种子库萌发物种数分别为37种、34种和33种,地上植被物种数分别为25种、33种和22种。土壤种子库和相应地上植被的相似性系数分别为38.7%、35.8%和32.7%。随着植物群落演替的进行,地上植被的Simpson指数、Shannon-Wiener多样性指数和Pielou均匀度指数均逐渐增大。三江平原沟渠土壤种子库和地上植被中保存了大量湿地植物,表明沟渠具有保护植物物种多样性的作用,沟渠土壤种子库具有湿地恢复的潜力。随着沟渠开挖年限增加,沟渠植物群落呈现退化特征,建议对沟渠系统加强管理。     

黄河首曲湿地植物群落生产力、物种多样性及其与生境的关系

近年来，在气候变化与人为干扰等因素的驱动下，高寒湿地退化导致生物多样性的丧失如何影响生态系统功能尚无共识。以黄河首曲高寒湿地为研究对象，基于野外采样数据和植物群落多样性指数，重点分析植物物种多样性、地上生物量空间分布格局及其与土壤因子关系。结果表明：首曲湿地存在一定程度退化，植物群落组成主要集中在菊科和禾本科，莎草科和豆科植物较少；植物群落物种多样性和地上生物量未表现出显著的经纬度和海拔梯度变化；Patrick丰富度指数(R)和Shannon-Weiner多样性指数(H)与地上生物量呈显著正相关，说明保护区植物多样性的保护有利于生产力维持；土壤含水量影响着高寒湿地植被群落结构，与多样性指数呈显著相关性，是高寒湿地植被恢复和重建的关键性因子。该研究结果对于认识黄河首曲高寒湿地植物生物量和物种多样性及土壤因子的空间分异规律具有一定的参考价值，同时为高寒湿地退化生态系统功能的恢复及生物多样性的保护提供科学依据。     

不同恢复措施对内蒙古乌拉特中旗荒漠草原植物群落的影响

处于干旱地区的内蒙古荒漠草原，在防风固沙、生物多样性保育等方面发挥着重要的生态功能。近年来由于人类活动的干扰及气候变化的影响，内蒙古荒漠草原生态系统发生了严重的退化。如何有效恢复荒漠草原的生态功能是当前亟待解决的问题，科学合理地进行人为定向培育是荒漠草原植物群落恢复与重建的重要措施。本研究以乌拉特中旗荒漠草原为对象，通过控制实验探讨了不同退化程度下植物群落结构及地上生物量对不同恢复措施的响应。结果表明：在重度退化的荒漠草原生态系统，短期封育提高了杂类草的相对盖度，使群落地上生物量增加2.11倍；添加有机肥提高了禾草物种丰富度，使群落地上生物量提高了3.97倍；补播显著提高了植物群落的盖度、密度，使群落地上生物量提高了9.76倍。在重度沙化区，补播显著提高了群落的盖度、密度、地上生物量，但对物种多样性无显著影响。在中度退化区，添加复合肥显著降低了短花针茅群落杂类草物种数，提高了禾草及植物群落的地上生物量；添加复合肥显著提高了柠条锦鸡儿-丛生禾草群落中禾草物种丰富度，但对植物群落盖度、密度及地上生物量无显著影响；喷施叶面肥显著降低了藏锦鸡儿-灌丛化禾草群落杂类草的盖度和密度，提高了禾草的地...     

山东省渤海沿岸滨海湿地草本植物群落物种组成及多样性研究

以山东省渤海沿岸滨海湿地草本植物群落为研究对象, 探讨其物种组成及其群落多样性变化规律。结果表明: 研究区域内共有草本植物83 种, 隶属23 科62 属, 其中, 禾本科和菊科种类最多, 占所有植物种类的34.94%。研究区内植物科属分布以世界分布和泛热带分布为主; 草本植物以芦苇最为常见, 出现频率高达66%。采用Ward 最小方差法进行聚类, 将50 个样地划分为12 类植物群落, 包括芦苇群落、芦苇+碱蓬群落、芦苇+盐地碱蓬群落、碱蓬群落、盐地碱蓬群落、中亚滨藜+长芒稗群落、芦苇+荻群落、盐角草群落、互花米草群落、白茅群落、芦苇+獐毛群落和芦苇+柽柳+假苇拂子茅群。物种丰富度指数的变化范围为3-40, Shannon-Wiener 多样性指数和Simpson 多样性指数的变化范围分别是0.14-2.20 和0.05-0.84, 不同植物群落类型的物种多样性指数差异显著; 物种均匀度指数的变化范围是0.12-0.83, 整体起伏较大, 优势种不明显。目前植物多样性的现状主要受由气候变暖、河流断流等自然因素和人类对湿地的不合理开发利用等人为因素影响, 并指出应该建立和完善相应的湿地保护法律法规, 增加湿地修复与重建工作, 加强宣传教育, 合理开发利用湿地, 促进滨海湿地生态系统可持续发展。     

三江平原小叶章群落近30年的动态变化

由于生境的改变,三江平原沼泽湿地典型植物群落中小叶章群落内部发生了显著的变化。本文以定点观测和典型湿地植物调查为基础,分析了近30年来小叶章群落的动态变化。结果表明,小叶章群落的物种频度符合Raunkiaer频度定律,即5个频度级的关系都具有A〉B〉C≥D〈E的规律性。小叶章群落的物种构成发生了明显变化,灌木类型植物逐渐增多。植物物种多样性减少。小叶章的多度、分盖度和高度都有降低趋势。     

优势种去除对崇明东滩盐沼湿地生态系统的影响

盐沼生态系统环境梯度明显,物种组成较简单,是研究生物多样性与生态系统功能关系的理想对象。本研究以崇明东滩盐沼湿地为研究区域,研究优势种去除对植物群落结构以及底栖动物群落的影响。结果表明:(1)去除处理仅对植物群落分株密度有极显著效应(P0.01)。去除组和对照组物种组成差异随时间增加而减小,处理效应逐渐减弱。(2)去除组底栖动物密度均低于对照组,但差异不显著。(3)盐沼植物群落特征与底栖动物群落有密切关系,植物密度、冠层高度与底栖动物密度相关性极显著。去除优势种后,植物群落分株密度升高,群落内剩余物种占比有所上升,次优势种对群落的补偿效应具有较大贡献;而底栖动物群落密度下降,其生物量和多样性指数的变化趋势与密度并不一致。上述结果表明生物多样性变化影响了盐沼湿地生态系统植物群落和底栖动物群落结构,进而可能影响物质循环和能量流动过程。     

水淹干扰下水库水滨带植物群落谱系结构与物种多样性格局

群落谱系结构将物种系统发育信息整合到群落中，给生物多样性研究提供了全新视角。为探讨水淹干扰下水库水滨带植物群落物种多样性维持机制，以丹江口水库水滨带为研究区域，以南水北调中线一期工程运行前的原有水滨带植被为研究对象，分析不同水淹干扰强度下群落谱系结构和物种多样性及其与环境因素的关系。结果表明：(1)随着水淹干扰强度增加，群落物种丰富度、物种多样性和谱系多样性显著降低。谱系结构指数虽无显著差异，但随着水淹干扰强度增加呈现由发散到聚集的变化趋势。表明水滨带植物群落物种多样性维持机制是生境过滤和生态位分化共同驱动的结果，并且随着水淹干扰强度增加呈现生境过滤作用增加、物种间竞争排斥作用减弱的生态过程影响规律。(2)坡度、土壤质地、速效氮和全氮含量对整个水滨带植物群落物种丰富度、物种多样性和谱系多样性影响显著。此外，土层厚度和速效磷对物种丰富度和土层厚度对谱系多样性也影响显著。而仅有速效氮含量对谱系结构指数影响显著；轻度水淹干扰下坡向、速效磷含量与多样性指数显著相关；中度水淹干扰下坡度、土层厚度、土壤质地、土壤总氮含量与多样性指数显著相关，土壤pH、全氮和全磷含量与谱系结构指数显著相关；重度水淹...     

Variation in species composition and diversity of wetland communities under different disturbance intensity in the Sanjiang plain

In this study, ditch density was chosen as an indicator of disturbance intensity, and four sites with different ditch density were chosen to compare species composition and diversity among them. Four transects and sixty-seven quadrats were sampled along the ditch density gradient. The results showed that there existed a significant negative relationship between disturbance intensity and species parameters, while species diversity did not differ greatly among sites, but species composition varied considerably. With increasing disturbance intensity, the wetlands tended to be reduced in plant species diversity, and an increasing loss of indigenous wetland species was paralleled with an increasing invasion of upland species. The results also show that the rate of species turnover within communities differed among communities under different disturbance intensities. The communities with intermediate ditch density (0.6-1.2 km/km²) had higher rates than the other communities.     

Contrasting responses of plants and pollinators to woodland disturbance

Preserving species diversity is critical to ensure ecosystem functioning; however, different components of diversity might respond to human disturbance in different ways. Similarly, trophic levels might have uncoupled responses to the same disturbance, thus ameliorating or aggravating the persistence of ecological communities. In this study, we analysed how the density, richness and evenness of flowers and pollinators respond to four levels of woodland thinning intensity (0, 30, 50 and 70% of woodland basal area removed) over 2 years in three contrasting sites. We found a mismatch in the response of flowers and pollinators to thinning. Flower density and richness had disparate responses, depending on the site and year, while evenness did not change with thinning. In contrast, pollinator density and richness, but not evenness, consistently increased with thinning among years and sites. These results suggest that thinning has a great influence on pollinators through changes in abiotic conditions and, perhaps, flower attractiveness rather than through small‐scale changes in flower density and richness. At the site where tree flowers were absent, bee pollinator community composition was impoverished, suggesting that trees provide important floral resources to pollinators. Our findings indicate that disturbance may diminish local plant abundance and richness, but pollinator abundance and richness are enhanced after intense thinning at small scales.     

茂县土地岭植被恢复过程中物种多样性动态特征

植被恢复是退化生态系统重建的重要途径,植被恢复过程物种多样性的变化反映了植被的恢复程度.通过群落调查和多样性分析,研究了岷江上游土地岭植被恢复过程中群落物种多样性特征.结果表明： 恢复过程中6类不同类型群落分别表现其对于不同环境特征、干扰及更新方式等的响应;森林是较灌丛更适合当地环境状况的植被类型;人工恢复无干扰和轻度干扰群落的多样性相对较高,是较好的恢复模式.重度干扰使得1年生植物与地下芽植物比例增加,其它口食性较好的多年生草本减少.较强的干扰是群落无法更新、长期处于灌丛阶段且多样性较低的重要原因.本地区人工恢复群落在更新进程和多样性维持上优于自然更新群落,种植华山松加速了本地区植被演替进程.建议以适合恢复区域的多种恢复配置方式进行造林,并避免较强干扰,可以加速群落演替进程并保持恢复群落较高的物种丰富度与多样性.     

Structure,diversity, and regeneration of tropical dry deciduous forest of northern India

This study examined the impact of disturbance on the pattern of diversity, forest structure and regeneration of tree species in the Vindhyan dry tropical forest of India. A total of 1500 quadrats distributed over five, 3-ha permanent plots in five sites, differing in degree of disturbance, were used to enumerate and measure the tree species. A total of 65 species with 136,983 individuals were enumerated in the total 15-ha area for stems 30 cm height. The number of species and number of stems ranged from 12 to 50 and 8063–65331 per 3-ha area. The number of species and stems for trees 10 cm dbh ranged from 3 to 28 species, with a mean value of 16 species ha^–1, and from 16 to 477 stems, with a mean value of 256 stems ha^–1, respectively. The adult based PCA ordination indicated uniqueness of sites in terms of species composition and habitat characteristics. PCA ordination also showed uniqueness of sites in terms of seedling composition, but the seedling and adult distributions were not spatially associated. The distinct species composition at the different sites and at the two life-cycle stages on the same site is indicative of marked spatio-temporal dynamics of the dry tropical forest. The density–diameter semi-logarithmic curves ranged from a near linear to an overall concave appearance with a limited plateau in the mid-diameter ranges. The -diversity and its components decreased with increasing disturbance intensity, reflecting enhanced utilization pressure with increasing disturbance. The site-wise and species-wise regression analyses of the number of individuals in different stages of the species revealed that both the level of disturbance and the nature of species strongly affect the regeneration. In conclusion, although the forest is relatively species-poor, the differential species composition on different sites and the temporal dynamics lend a unique level of diversity to the tropical dry deciduous forest.     

间伐强度对马尾松人工林间伐初期林下植被群落物种组成和多样性的影响

以川东低山区29年生马尾松人工林为对象,研究了不同间伐强度(0、10%、20%、30%、40%、50%)处理1年后林下植被群落物种组成与多样性分异特征初期响应。结果表明: 各间伐处理均能降低草本植物芒、芒萁的优势地位,而各处理灌木的优势物种组成较复杂,中等间伐强度(20%、30%、40%)处理泛化种较其他处理明显增多。各多样性指数随间伐强度增高呈现先增后降的变化趋势,草本植物较灌木的分异性更强,且各指数与土壤含水量均呈显著正相关。间伐强度与土壤理化性质对群落分异解释量为81%,中等间伐强度林下植被群落除全磷外与其他因子表现出正相关关系。间伐初期草本植物群落较灌木群落更能积极响应干扰;40%间伐强度处理与土壤环境因子关系紧密,群落稳定性高,物种最为丰富,为本试验条件下间伐措施的最佳处理。     

长白山北坡不同海拔及干扰程度下访花食蚜蝇群落的差异

本研究采用垂直面取样法,对中国长白山北坡不同海拔及干扰程度下访花食蚜蝇群落的物种组成、多度、丰富度及多样性进行了调查研究。我们选择了不同垂直带的两个样地,分别位于800~1 100 m和1 750 ~2 150 m;每个样地选取3种生境类型,每一生境类型采样面积为20 m×20 m。252组调查数据表明,共采到访花食蚜蝇42种2 540个体。不同海拔生境访花食蚜蝇的组成、多度、丰富度及多样性的差异分析结果表明: 低海拔样地内不同生境访花食蚜蝇的群落相似性高于高海拔样地;低海拔样地访花食蚜蝇的多度高于高海拔样地,而物种丰富度低于高海拔样地;不同生境类型访花食蚜蝇多样性指数存在差异,但高海拔样地与低海拔样地多样性差异不显著;过渡林生境（岳桦林带）与次生林生境（针阔混交林带Ⅱ）中访花食蚜蝇的多样性较高。保护珍稀植物物种的人工植物花园访花食蚜蝇多样性仅次于过渡林生境（岳桦林带）与次生林生境（针阔混交林带Ⅱ）,保护作用显著。     

Change within and among forest communities: the influence of historic disturbance,environmental gradients,and community attributes

Understanding how ecological communities change over time is critical for biodiversity conservation, but few long‐term studies directly address decadal‐scale changes in both the within‐ and among‐community components of diversity. In this study, we use a network of permanent forest vegetation plots, established in Great Smoky Mountains National Park (USA) in 1978, to examine the factors that influence change in community composition within and among communities. In 2007, we resampled 15 plots that were logged in the late 1920s and 15 plots that had no documented history of intensive human disturbance. We found that understory species richness decreased by an average of 4.3 species over the 30‐yr study period in the logged plots, but remained relatively unchanged in the unlogged plots. In addition, tree density decreased by an average of 145 stems ha^?1 in the logged plots, but was relatively stable in the unlogged plots. However, we found that historic logging had no effect on within‐community understory or tree compositional turnover during this time period. Instead, sites at lower elevations and sites with lower understory biomass in 1978 had higher understory compositional turnover than did sites at higher elevations and sites with higher understory biomass. In addition, sites with lower soil cation exchange capacity (CEC) and with lower tree basal area in 1978 had higher tree compositional turnover than did sites with higher soil CEC and higher tree basal area. Among‐community similarity was unchanged from 1978 to 2007 for both the logged and unlogged plots. Overall, our results indicate that human disturbance can affect plant communities for decades, but the extent of temporal change in community composition may nevertheless depend more on environmental gradients and community attributes.     

The intermediate disturbance hypothesis does not explain fire and diversity pattern in fynbos

The intermediate disturbance hypothesis is a widely accepted generalization regarding patterns of species diversity, but may not hold true where fire is the disturbance. In the Mediterranean-climate shrublands of South Africa, called fynbos, fire is the most importance disturbance and a controlling factor in community dynamics. The intermediate disturbance hypothesis states that diversity will be highest at sites that have had an intermediate frequency of disturbance and will be lower at sites that have experienced very high or very low disturbance frequencies. Measures of diversity are sensitive to scale; therefore, we compared species richness for three fire regimes in South African mountain fynbos to test the intermediate disturbance hypothesis over different spatial scales from 1 m² to 0.1 hectares. Species diversity response to fire frequency was highly scale-dependent, but the relationship between species diversity and disturbance frequency was opposite that predicted by the intermediate disturbance hypothesis. At the largest spatial scales, species diversity was highest at the least frequently burned sites (40 years between fires) and lowest at the sites of moderate (15 to 26 years between fires) and high fire frequency (alternating four and six year fire cycle). Community heterogeneity, measured both as the slope of the species-area curve for a site and as the mean dissimilarity in species composition among subplots within a site, correlated with species diversity at the largest spatial scales. Community heterogeneity was highest at the least frequently burned sites and lowest at the sites that experienced an intermediate fire frequency.     

More species,but all do the same: contrasting effects of flood disturbance on ground beetle functional and species diversity

The role of habitat disturbance on biodiversity is central as it promotes changes in ecological systems. That said, still little is known about the functional consequences of such changes. Functional diversity can be used to revealing more mechanistically the disturbance effects on communities by considering the richness and the distribution of traits among the species. Here we analyzed the response of functional and species diversity of ground beetles to flood disturbance to better understand the functioning of alluvial invertebrate communities. Ground beetles were sampled in periodically flooded grasslands along the Elbe River in Germany. We used generalized linear mixed effects models to unveil the relationships between flood disturbance, species and functional diversity, respectively. We measured different components of functional diversity (functional richness, evenness, dispersion, and divergence) and analyzed species diversity by means of rarefied species richness, abundances, evenness and Simpson's diversity. We found contrasting relationships in that most species diversity measures peaked at highest disturbance levels, while most functional diversity measures decreased with increasing disturbance intensities. Inversed relationships between species and functional diversity are rarely observed, as most studies report on positive correlations. We explain increasing species diversity with a higher amount of resources available in highly disturbed sites. Decreasing functional diversity is best explained through the convergence of species traits by flood disturbance and uneven resource exploitation in highly disturbed plots (low functional evenness), suggesting strong impacts from functionally different generalist species in floodchannels. We show that the amount of resources available, and how these resources are exploited, play major roles in the functioning of floodplain ground beetle communities.     

Vegetation restoration patterns and their relationships with disturbance on the Giant Panda Corridor of Tudiling, Southwest China

Human activities such as deforestation, cultivation, and overgrazing have contributed to the destruction of forest ecosystems in the upper Minjiang River basin for a long time, which has led to the reduction in forest coverage and biodiversity. On the Giant Panda Corridor of Tudiling in this basin, the effects of the existing disturbance regimes on plant communities after the vegetation restoration in the 1980s were assessed, and the community composition, the species diversity and their relationships with environmental factors significantly associated with the disturbance were analyzed using the transect sampling method, the two-way indicator species analysis (TWINSPAN) and the detrended canonical correspondence analysis (DCCA). The results were as follows: communities could be classified into six types, and species were clustered into four functional groups (responsive to disturbance, retarded disturbance, resistant to intermediate disturbance, and resistant to heavy disturbance) based on both TWINSPAN and DCCA. DCCA with species composition of plots is similar to that with species diversity of plots. The communities were separated into distinct groups along the DCCA axis, and this pattern was significantly correlated with environmental factors. Elevation differences, shape, slope, distance to roads, and the number of paths in the plots had an evident influence on the distribution of the species and communities. Environmental factors including slope, distance to roads, and the number of paths revealed the gradient of disturbance among the communities along the DCCA axis. High disturbance intensity caused significantly lower species diversity and inhibited the regeneration of vegetation compared with the more diverse undisturbed communities. Artificial restoration was more effective than natural restoration in maintaining high species diversity. The process of succession was inhibited in natural restoration because of the failure of tree establishment, growth, and survival during regeneration.