薇甘菊对香港郊野公园植物群落危害的分析

从薇甘菊(Mikania micrantha)对不同类型群落的危害,群落中各植物种类受薇甘菊危害的程度,以及薇甘菊与群落中主要乔木和灌木的种间联结性等方面,对香港郊野公园植物群落受薇甘菊危害状况进行了分析。研究样地所在的植被受薇甘菊的危害严重,草灌丛中薇甘菊的平均覆盖率高达80%,灌木群落中薇甘菊的平均覆盖率为60%左右,常绿阔叶林中的薇甘菊覆盖率平均约为30%。对香港郊野公园受薇甘菊危害的植物种类分析表明:受薇甘菊危害最大的主要是乔木和灌木,草本和藤本的受害比例和受害程度相对较小。受薇甘菊危害的乔木有30种,占群落中乔木的62.50%;受薇甘菊危害的灌木有29种,占群落中灌木的70.73%;受薇甘菊危害的草本植物有10种,占群落中草本植物的33.33%。通过无样方法采用2×2列联表的χ2检验对薇甘菊与群落中主要乔木和灌木的种间联结性分析表明:与薇甘菊呈正联结的乔木有12种,占主要乔木(28种)的42.86%,这些种大多是阳生性乔木;与薇甘菊呈负联结的乔木有16种,占主要乔木的57.16%。与薇甘菊呈正联结的灌木有11种,占主要灌木(19种)的57.89%,多是阳生性灌木;与薇甘菊呈负联结的灌木有8种,占主要灌木的42.11%,这些种大多数也是阳生性灌木,仅九节是耐阴性灌木。     

薇甘菊入侵对中小型土壤动物群落结构特征的影响

薇甘菊是菊科假泽兰属的恶性杂草,在我国华南地区已成功入侵并造成严重危害.为了解薇甘菊入侵对土壤动物的影响效应,采用野外样地试验法对广州市火炉山森林公园薇甘菊入侵群落的土壤动物进行了调查.2009年4次采样共获得中小型土壤动物5206头,隶属于4门10纲19类,其中线虫类为优势类群,蜱螨目、弹尾目和轮虫是常见类群.薇甘菊入侵地中小型土壤动物群落结构特征发生了改变,与其他样区相比,入侵区中小型土壤动物的总个体数以及线虫类、蜱螨目的个体数显著增加,但中小型土壤动物类群数的变化不明显;在群落多样性方面,薇甘菊入侵区土壤动物群落的密度-类群指数显著提高,物种丰富度、优势度指数亦有所上升,但差异不明显,而均匀度、Shannon指数趋于下降;在群落相似性方面,薇甘菊入侵区与群落交错区的相似程度较高,与土著植物区的相似程度较低.薇甘菊入侵所引起的局部气候环境、凋落物、根系分泌物与土壤理化性质的变化可能是造成中小型土壤动物群落结构特征改变的主要原因.     

薇甘菊入侵对中小型土壤动物群落 结构特征的影响

薇甘菊是菊科假泽兰属的恶性杂草,在我国华南地区已成功入侵并造成严重危害.为了解薇甘菊入侵对土壤动物的影响效应,采用野外样地试验法对广州市火炉山森林公园薇甘菊入侵群落的土壤动物进行了调查.2009年4次采样共获得中小型土壤动物5206头,隶属于4门10纲19类,其中线虫类为优势类群,蜱螨目、弹尾目和轮虫是常见类群.薇甘菊入侵地中小型土壤动物群落结构特征发生了改变,与其他样区相比,入侵区中小型土壤动物的总个体数以及线虫类、蜱螨目的个体数显著增加,但中小型土壤动物类群数的变化不明显;在群落多样性方面,薇甘菊入侵区土壤动物群落的密度-类群指数显著提高,物种丰富度、优势度指数亦有所上升,但差异不明显,而均匀度、Shannon指数趋于下降;在群落相似性方面,薇甘菊入侵区与群落交错区的相似程度较高,与土著植物区的相似程度较低.薇甘菊入侵所引起的局部气候环境、凋落物、根系分泌物与土壤理化性质的变化可能是造成中小型土壤动物群落结构特征改变的主要原因.     

广西陆川不同树种人工林的薇甘菊入侵程度变化

探索薇甘菊入侵与人工林环境因子关联性对薇甘菊防治和疫区合理选择造林树种具有重要意义。在广西陆川薇甘菊(Mikania micrantha)严重危害地区对造林0.5-3.5年的杂交相思(Acacia mangium × Acacia auriculiformis)、马占相思(Acacia mangium)、火力楠(Michelia macclurei)、巨尾桉(Eucalyptus grandis × Eucalyptus urophylla)人工林进行了系统抽样调查, 在3个不同生境的6个林分记录了100个样方的上层林冠盖度、林下植被盖度、薇甘菊盖度、物种丰富度、坡度、流径长、距林缘距离、朝向等因子。以薇甘菊盖度为响应变量、林分因子为随机截距的线性混合效应模型分析表明, 薇甘菊盖度与林下植被盖度极显著正相关(P < 0.000), 与上层林冠盖度(P < 0.027)和朝向(P < 0.028)显著负相关。上层林冠盖度是抑制薇甘菊盖度扩大的主要因素, 越是在干热的立地, 上层林冠盖度对薇甘菊入侵的阻止效应越明显。薇甘菊开花数量与上层林冠盖度极显著负相关(P < 0.01), 二元协方差分析则表明上层林冠盖度对薇甘菊是否有花具略微显著负效应(P = 0.081)。薇甘菊疫区造林宜选择能够形成浓密乔木林冠的树种。由于桉树成龄叶垂直悬挂的着生方式, 成龄桉树的林冠稀疏, 不能抵御薇甘菊入侵, 建议薇甘菊疫区不宜种植速生桉。     

薇甘菊在广东的传播及危害状况调查

薇甘菊在广东主要分布在珠江三角洲地区及东部沿海地区,以深圳为中心向东部、北部和西部逐渐传播开来。薇甘菊多定居在开旷和具有丰富有机质的潮湿环境,富含有机质的生活垃圾、堆积淤泥的水沟边及肥沃的弃耕地常为侵入薇甘菊的分布中心,大量的种子和快速的营养繁殖使其由定居地向外扩散和蔓延。长途交通运输等人为因素是造成薇甘菊远距离传播的主要原因。薇甘菊对灌木的危害最大,受人为干扰的次生林在一定程度上受其危害,果园的人工除草和施肥加速了薇甘菊的危害。     

入侵种薇甘菊防治措施及策略评估

薇甘菊Mikania micrantha H.B.K.是入侵中国南部地区的一种危害极大的外来入侵种。防治薇甘菊的措施和策略,应根据薇甘菊的物种特性及所能支配的防除资源,综合考虑、统筹安排。薇甘菊能快速生长覆盖其他植物,其残株断枝易成为独立生长的新个体、种子量巨大且极易扩散,喜入侵次生植被。物理清除适用于小面积,对大面积出现的薇甘菊不应采用。化学防除主要用于应急,但未能改变适于薇甘菊生长的生境,薇甘菊仍可能在数年后再次为害。田野菟丝子Cuscuta campestris控制薇甘菊适用于大面积危害区域,当只以控制而不以根除自然群落的薇甘菊为目标时效果很好。群落改造能一劳永逸地解除薇甘菊的危害,但只适用于宜林地,且成本较高。天敌控制和植物化感防治都尚在探索阶段。未来还应发掘有效天敌,研发综合防治措施,揭示宏观分布规律。薇甘菊防治的正确策略是:对于已形成区域性危害的薇甘菊,根除已经不可能,应采取持久战而非速决战,防止薇甘菊入侵新区域是防治的重中之重,必须优先治理轻度入侵地和能向周边区域甚至是遥远区域扩散的传播源,建立防治示范区或样地。     

广东内伶仃岛薇甘菊危害与生态因子的关联度分析

用灰色关联度分析对广东内伶仃岛草本群落、草灌(或灌草)丛群落和灌木林受薇甘菊危害与环境因子的关联性进行分析。结果表明薇甘菊对草本群落的危害与环境因子的关联度中主要受土壤水分和电导率的影响较大,对草灌丛群落的危害与各环境因子的关联度差异不大,但其中受土壤含水量、pH值和群落透光度的影响稍大些,对灌丛群落的危害与各环境因子的关联度差异也不大,其中受土壤有机质、群落透光度和土壤含水量的影响较大。各环境因子对不同群落受薇甘菊危害的影响由强到弱的顺序为土壤含水量>土壤pH值、有机质含量>群落透光度、土壤养分。     

宁夏黄土丘陵区不同生态恢复生境地表甲虫多样性

为了解宁夏黄土丘陵区不同生境地表甲虫群落多样性变化规律及与环境因子的关系, 并探讨不同生态恢复措施对维持地表甲虫群落多样性的影响, 2013年7-8月, 作者利用陷阱法调查了该区6种生境内的地表甲虫群落多样性。结果表明: 灌草混交林地、乔灌混交林地、生态薪炭林地中地表甲虫物种丰富度和个体数量均较高, 天然封育草地、生态经济林地和水平农田中物种丰富度较低, 生态经济林地和水平农田中甲虫个体数量显著高于天然封育草地。不同生境间, 灌草混交林地、乔灌混交林地与生态薪炭林地之间、生态经济林地与水平农田之间甲虫群落组成相似性较高。多元回归分析表明, 草本层生物量、灌木层盖度及土壤含水量是影响甲虫物种丰富度的决定因素, 林冠层盖度和枯落物厚度是决定地表甲虫个体数量的重要因素。CCA分析表明, 枯落物盖度、枯落物厚度、林冠层盖度及草本层盖度是影响地表甲虫群落组成的重要环境因子。研究表明, 灌草混交林地为地表甲虫群落多样性维持较好的生境类型, 是宁夏黄土丘陵区典型生态恢复的最优模式。     

海南岛霸王岭两种典型热带季雨林群落特征

热带季雨林为海南岛的隐域性植被类型,分布在与热带低地雨林相似的海拔范围但生境条件较差的局部地段,在旱季其大部分的乔木种类和个体都会落叶.海南岛霸王岭林区分布着海南岛最为典型且大都保存较为完好的热带季雨林原始林,按照其优势树种可划分为海南榄仁(Terminalia hainanensis)季雨林和枫香(Liquidambar formosana)季雨林两种群落类型.通过对霸王岭林区两种典型的热带季雨林老龄林群落的样地调查,比较分析了其物种组成、大小结构、多样性、季相变化等特征.结果表明:海南岛热带季雨林群落中物种优势度明显,具有明显的标志种--海南榄仁和枫香.海南榄仁群落具有较高的灌木物种丰富度、个体多度及较低的乔木物种丰富度、个体多度和多样性;海南榄仁群落在小径级和低高度级中具有较高的植物个体多度,同时在低高度级中具有较低的物种丰富度,但其它径级和高度级两个群落物种丰富度及个体多度差异均不显著;除灌木落叶物种丰富度海南榄仁群落显著高于枫香群落外,其余各生长型落叶物种丰富度及个体多度两个群落之间均无显著差异;在具刺木质藤本物种丰富度和个体多度上海南榄仁群落与枫香群落差异不显著,但乔木、灌木和木本植物具刺物种丰富度及个体多度海南榄仁群落均显著高于枫香群落.总体来看,海南榄仁群落比枫香群落的季雨林特征明显,是海南岛最为典型的季雨林群落类型.     

塔里木荒漠河岸林异质生境物种多样性比较与其测度指标筛选及评价

选择合适的物种多样性测度指标与多样性指数是进行群落多样性研究的基础工作。依据塔里木河上游荒漠河岸林样地调查资料,分别采用重要值、盖度和多度为测度指标比较了反映群落物种丰富度、多样性、均匀度和优势度12种多样性指数与异质生境群落多样性特征,并对多样性指数进行了相关分析与评价。结果表明,荒漠河岸林异质生境群落物种组成种类差异明显,轮南镇胡杨群落物种丰富度与多样性指数最高,水工三连灰胡杨群落多样性最低,土壤水盐的空间异质性是引起荒漠植被空间分布与群落多样性差异的主导因子。表征荒漠群落多样性以重要值和盖度为测度指标优于多度指标,其中以重要值为测度指标来反映群落多样性更为合理。相关与主成分分析表明,均匀度与多样性指数间的相关性高于丰富度与多样性指数,且多样性指数受均匀度、优势度指数受丰富度影响较大,反映出荒漠河岸林群落多样性主要决定于物种分布的均匀程度。12种多样性指数中Margalef丰富度指数（Ma）、Shannon-Weiner多样性指数（H）与Simpson多样性指数（D）能客观真实地反映异质生境荒漠植物群落多样性。同时,针对高度生境异质性的荒漠植物群落,还应综合考虑群落物种组成与生境特征,选择合适的多样性指数组合可更客观地反映荒漠河岸林群落多样性变化。     

不同生境和森林内薇甘菊的生存与危害状况

对薇甘菊（Ｍｉｋａｎｉａ ｍｉｃｒａｎｔｈａ Ｈ．Ｂ．Ｋ）在不同生境下生长状况及其对其它植物的危害程度的研究表明,这种热带杂草是喜光、好湿的。薇甘菊伴生物种以藤本植物居多。其中葛藤和五爪金龙出现的频度最大。薇甘菊及其伴生种通过攀爬树冠,形成盖幕作用而对其它植物造成危害。在森林内薇甘菊危害的对象主要是低矮的乔木对高大乔木影响不大。     

北京城区公园的植物种类构成及空间结构

对植物种类构成及空间结构的研究,可为公园植物多样性保护及公园的科学管理提供重要依据.采用分层随机抽样调查法,调查了北京市五环以内的53处公园,共记录维管束植物96科283属492种.基于研究区乔、灌、草共21个调查项目的大量数据及相关统计分析,对北京城区公园绿地各层植物的常见结构型式进行了阐述.结果表明：北京城区公园植物中,本地种占5386%,植物属的区系地理分布很广泛,优势植物的优势性明显;研究区大部分公园的草本植物种类较为丰富、盖度较高,而灌木盖度偏低、树冠下的灌木也偏少,乔灌植物种类丰富度和密度不高,乔木冠幅、胸径、灌幅及乔灌高度基本在2级水平,但乔木冠层结构比较丰满、受光良好、生长状况良好,灌木叶层缺失不明显.通过相关分析和北京市园林绿化史调研结果推测,北京城区公园植物种类构成及其空间结构主要受园林设计、植物引种、种植管理的影响.     

Environmental effects on Neotropical liana species richness

Aim Lianas differ physiologically from trees, and therefore their species‐richness patterns and potential climate‐change responses might also differ. However, multivariate assessments of spatial patterns in liana species richness and their controls are lacking. Our aim in this paper is to identify the environmental factors that best explain the variation in liana species richness within tropical forests. Location Lowland and montane Neotropical forests. Methods We quantified the contributions of environmental variables and liana and tree‐and‐shrub abundance to the species richness of lianas, trees and shrubs ≥ 2.5 cm in diameter using a subset of 65 standardized (0.1 ha) plots from 57 Neotropical sites from a global dataset collected by the late Alwyn Gentry. We used both regression and structural equation modelling to account for the effects of environmental variables (climate, soil and disturbance) and liana density on liana species richness, and we compared the species‐richness patterns of lianas with those of trees and shrubs. Results We found that, after accounting for liana density, dry‐season length was the dominant predictor of liana species richness. In addition, liana species richness was also related to stand‐level wood density (a proxy for disturbance) in lowland forests, a pattern that has not hitherto been shown across such a large study region. Liana species richness had a weak association with soil properties, but the effect of soil may be obscured by the strong correlation between soil properties and climate. The diversity patterns of lianas and of trees and shrubs were congruent: wetter forests had a greater species richness of all woody plants. Main conclusions The primary association of both liana and tree‐and‐shrub species richness with water availability suggests that, if parts of the Neotropics become drier as a result of climate change, substantial declines in the species richness of woody plants at the stand level may be anticipated.     

Density‐dependent Survival in Seedlings Differs among Woody Life‐forms in Tropical Wet Forests of a Caribbean Island

Negative density dependence contributes to seedling dynamics in forested ecosystems, but the relative importance of this factor for different woody plant life‐forms is not well‐understood. We used 1 yr of seedling survivorship data for woody seedlings in 17 different plots of lower to mid‐montane rain forests on the island of Dominica to examine how seedling height, abiotic factors, and biotic factors such as negative density dependence are related to seedling survival of five different life‐forms (canopy, midstory, and understory trees; shrubs; and lianas). Across 64 species, taller seedlings in seedling plots with higher canopy openness, greater seedling density, lower relative abundance of conspecific seedlings, and lower relative abundance of conspecific adults generally had a greater probability of surviving. Height was the strongest predictor of seedling survival for all life‐forms except lianas. Greater seedling density was positively related to survival for canopy and midstory trees but negatively related to survival for the other life‐forms. For trees, the relative abundance of conspecific seedling and adult neighbors had weak and strong negative effects on survival respectively. Neither shrub nor liana seedling survival was affected by the relative abundance of conspecific neighbors. Thus, negative density dependence is confirmed as an important structuring mechanism for tree seedling communities but does not seem to be important for lianas and shrubs in Dominican rain forests. These results represent the first direct assessment of controls on seedling survival of all woody life‐forms – an important step in understanding the dynamics and structure of the entire woody plant community.     

Structure and pattern in temperate seasonal forests

Demography, spatial pattern, and diversity of canopy and subcanopy trees, shrubs, and lianas were compared in two cool and two warm temperate North American forests, paired at 30° and 40° north latitudes. All woody stems 1 cm dbh in 16 randomly located, non-contiguous plots totalling 1 ha at each of the four sites were measured, mapped, and identified. Basal area and overall density did not differ between latitudes. Demographic and spatial analyses revealed remarkable similarity in spatial dispersion, irrespective of density or species composition. At all sites, dispersion of canopy trees was random but all understory stems were uniformly distributed relative to all canopy trees. Species diversity and vertical structure differed between the warm and cool temperate sites, especially in species composition of individual strata. Associations of understory species relative to canopy species were more random at 30° than at 40° north, where a higher degree of association between canopy and understory species' patterns, coupled with their size class distributions, suggested more lengthy regeneration cycles and an alternation of species assemblages. The forests at 30°, those subject to periodic canopy disturbance by hurricanes, had more vertical mixing of species (i.e., canopy species represented in all size classes), more tree saplings, and significantly more shrub and liana species.     

Spatiotemporal changes of beetle communities across a tree diversity gradient

Aim Plant and arthropod diversity are often related, but data on the role of mature tree diversity on canopy insect communities are fragmentary. We compare species richness of canopy beetles across a tree diversity gradient ranging from mono‐dominant beech to mixed stands within a deciduous forest, and analyse community composition changes across space and time. Location Germany’s largest exclusively deciduous forest, the Hainich National Park (Thuringia). Methods We used flight interception traps to assess the beetle fauna of various tree species, and applied additive partitioning to examine spatiotemporal patterns of diversity. Results Species richness of beetle communities increased across the tree diversity gradient from 99 to 181 species per forest stand. Intra‐ and interspecific spatial turnover among trees contributed more than temporal turnover among months to the total γ‐beetle diversity of the sampled stands. However, due to parallel increases in the number of habitat generalists and the number of species in each feeding guild (herbivores, predators and fungivores), no proportional changes in community composition could be observed. If only beech trees were analysed across the gradient, patterns were similar but temporal (monthly) species turnover was higher compared to spatial turnover among trees and not related to tree diversity. Main conclusions The changes in species richness and community composition across the gradient can be explained by habitat heterogeneity, which increased with the mix of tree species. We conclude that understanding temporal and spatial species turnover is the key to understanding biodiversity patterns. Mono‐dominant beech stands are insufficient to conserve fully the regional species richness of the remaining semi‐natural deciduous forest habitats in Central Europe, and analysing beech alone would have resulted in the misleading conclusion that temporal (monthly) turnover contributes more to beetle diversity than spatial turnover among different tree species or tree individuals.     

Direct and indirect effects of environmental factors,spatial constraints,and functional traits on shaping the plant diversity of montane forests

Understanding the relative importance of the factors driving the patterns of biodiversity is a key research topic in community ecology and biogeography. However, the main drivers of plant species diversity in montane forests are still not clear. In addition, most existing studies make no distinction between direct and indirect effects of environmental factors and spatial constraints on plant biodiversity. Using data from 107 montane forest plots in Sichuan Giant Panda habitat, China, we quantified the direct and indirect effects of abiotic environmental factors, spatial constraints, and plant functional traits on plant community diversity. Our results showed significant correlations between abiotic environmental factors and trees (r = .10, p value = .001), shrubs (r = .19, p value = .001), or overall plant diversity (r = .18, p value = .001) in montane forests. Spatial constraints also showed significant correlations with trees and shrubs. However, no significant correlations were found between functional traits and plant community diversity. Moreover, the diversity (richness and abundance) of shrubs, trees, and plant communities was directly affected by precipitation, latitude, and altitude. Mean annual temperature (MAT) had no direct effect on the richness of tree and plant communities. Further, MAT and precipitation indirectly affected plant communities via the tree canopy. The results revealed a stronger direct effect on montane plant diversity than indirect effect, suggesting that single‐species models may be adequate for forecasting the impacts of climate factors in these communities. The shifting of tree canopy coverage might be a potential indicator for trends of plant diversity under climate change.     

福建茫荡山黄枝润楠群落多样性比较研究

通过对黄枝润楠群落物种多样性测定,并与邻近区域的其它群落比较,结果表明,该群落显示较高的物种多样性指数,但物种多样性纬度梯度变化不明显,与中国中亚热带东部常绿阔叶林表现出的灌木层＞乔木层＞草本层的格局有所不同。     

Subordinate,not dominant,woody species promote the diversity of climbing plants

We aimed to determine which factors explain the relative abundances of climbing plants in a tropical sandy coastal plant community, locally called restinga, in SE-Brazil, where facilitation is an important mechanism controlling shrub and tree diversity. The factors examined were: associations with host trees and shrubs, environmental conditions, associations with herbs and space. We surveyed a total of 84 vegetation patches within two hectares of open restinga vegetation. Climbers, trees, shrubs and herbs were sampled using an adapted cover pin frame approach. Partial constrained ordination (pRDA) was used to partition the variation of climber species relative abundances into four sources: trees and shrubs relative abundances, herb species relative abundances, environmental variables (patch architecture and size), and the spatial coordinates. Linear models were used to model the relationship of climber diversity as a function of the environmental factors. A total of 12 climber species belonging to 5 families were recorded. Associations between climber species with subordinate trees and shrubs were the major determinants of climber presence in these vegetation patches. The support for growth created by these trees and shrubs had a secondary role in explaining these patterns. We found no relationship between tree dominance and climber species dominance in each patch. However, most climbers were associated with subordinate shrubs. Trellis availability at the first stratum was related to greater climber diversity suggesting that subordinate trees and shrubs may be crucial to promote climber diversity in this plant community. Space and associations with herbs had a minor contribution to overall variation. While 15 years of research in the site associated local floristic diversity to dominant trees, our results demonstrate that climber diversity in this community is governed by interactions with subordinate host woody species related to the environmental support for growth created by such trees and shrubs.