An assessment of the aquatic and wetland vegetation of the Upper Mississippi River

Illinois, Iowa, Minnesota, Missouri, and Wisconsin have strong botanical traditions that have resulted in a macrophyte literature which documents the identity, taxonomy, floristics, and ecology of aquatic macrophytes and wetland vegetation of the Upper Mississippi River and its floodplain. These findings are reviewed with respect to floristics, vegetation dynamics (patterns, history, production and management), and environmental changes that impact vegetation. Aspects requiring future study are noted to direct subsequent investigations.     

中国喀斯特植被分类系统

我国喀斯特地貌分布广泛,是全球喀斯特集中分布区面积最大且岩溶发育最强烈的典型区域。喀斯特植被物种组成独特,生物多样性丰富,群落结构复杂,植被类型极其丰富。该文对已发表的喀斯特植被类型和近期的调查资料进行系统整理,依据《中国植被志》的分类原则,在群系尺度上编制了中国喀斯特植被分类系统,包括3个植被型组、13个植被型和554个群系。探讨了喀斯特植被的分类系统与原有分类系统的衔接,并依据相关资料,对喀斯特生境专性群系进行了识别和判定,以期为喀斯特区域的石漠化治理、植被修复提供科学参考。     

Flowering phenology in the vegetation of Shervaroys,South India

Flowering phenology of 475 herbaceous and 348 arborescent taxa that form the vegetation of Shervaroys (Eastern Ghats: South India) was studied in relation to growth form, altitude and vegetation type. It was found that the majority of the herbaceous taxa flowered following rains while the arborescent taxa bloomed predominantly during the dry period irrespective of altitude and vegetation type.     

江苏省海滩植被演替的研究

江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。     

乌兰布和沙漠东北缘荒漠-绿洲过渡带植被地上生物量估算

干旱区荒漠植被地上生物量是植被生长状况评价与荒漠化监测的重要指标。在乌兰布和沙漠东北缘的荒漠-绿洲过渡带选取典型区,基于地面调查数据构建主要植物种的异速生长方程,对样方内的植被地上生物量进行估算;基于样方调查数据和Quick Bird影像数据,分别建立植被指数与人工固沙林和荒漠植被地上生物量的回归模型,并对研究区植被地上生物量进行估算。结果表明:植冠体积V是较好的预测变量,所得荒漠植物异速生长方程精度较高,能够满足样方内荒漠植被地上生物量估算需要;采用RVI对数模型估算人工固沙林地上生物量的效果最好(R~2=0.72,RMSEP=56.15),采用RVI线性模型估算荒漠植被地上生物量的效果最好(R~2=0.82,RMSEP=15.07);研究区内荒漠植被和人工固沙林的单位面积地上生物量分别为90.73g/m~2和105.28g/m~2。该研究可以为荒漠化监测和荒漠植被遥感信息提取提供参考。     

基于TM遥感影像的陕北黄土区结构化植被因子指数提取

根据结构化植被因子指数的概念,以TM影像为信息源,探讨了利用遥感技术提取陕北黄土区结构化植被因子指数（C_s）的途径与方法.结果表明：在陕北黄土区,C_s能更好地描述植被群落的水土保持效益,其与绿度植被指数（归一化植被指数NDVI、修正土壤调整植被指数MSAVI）和黄度植被指（归一化差异衰败指数NDSVI、归一化耕作指数NDTI）等单一的遥感植被指数虽然均存在良好的相关关系,但用绿度与黄度植被指数相结合可综合反映植被的水土保持功能,能较好地克服单一指数在描述植被控制水土流失中的不足;MSAVI、NDTI分别是基于遥感影像提取C_s较为理想的绿度和黄度植被指数;根据群落结构化植被因子指数与遥感植被指数的关系推算区域尺度上的结构化植被因子指数是可行的,但由于不同地区植物物候期的差异,要使该方法在其他地区适用,仍需开展相应的率定和验证工作.     

《中国植被志》的植被分类系统、植被类型划分及编排体系

植被志(vegegraphy)是基于植被调查资料, 全面记叙植被的群落外貌、种类组成、结构和功能、生境条件, 以及地理分布等特征, 并对同类植被进行归纳和总结的志书。“植被志”的英文译为“vegegraphy”, 是本文的新造词, 它是由“vegetation”的词头“vege-”和英文后缀“-graphy” (记叙之意)组成的合成词。《中国植被志》的研编是一项时间紧迫、内容复杂、工作量浩繁的重大科学工程。它的完成将极大提升中国植被科学和生态学的研究水平, 并为中国植被资源的合理利用、生物多样性保护及生态环境治理等提供不可或缺的基础资料。本文首先简述了植被的基本特征(主要包括外貌特征、种类组成、群落结构以及动态变化等)和国内外植被调查的进展情况, 简要回顾了中国植被分类系统的研究历史, 并对以往的分类系统进行了若干修订。在此基础上, 着重讨论并提出了《中国植被志》卷册编排体系和用于《中国植被志》研编的植被类型划分方案。在对植被分类系统的修订方面, 主要对高级分类单位及相对应的英文名称进行了讨论和修订。按照本文修订的分类系统, 中国植被的分类单位及其对应的英文名称分别是: 植被型组(Vegetation Formation Group)、植被型(Vegetation Formation)和植被亚型(Vegetation Subformation)、群系组(Alliance Group)、群系(Alliance)和亚群系(Suballiance)、群丛组(Association Group)以及群丛(Association)。在植被型组中, 划分为9类: 森林、灌丛、草本植被、荒漠、高山冻原与稀疏植被、沼泽与水生植被、农业植被、城市植被及无植被地段。关于《中国植被志》的卷册编排和“植被类型”划分, 首先按高级分类单位——植被型划分相应的“卷”; 在此框架下, 模糊“植被亚型”、“群系组”和“群系”的概念, 确定“植被类型” (Vegetation type), 并将其作为植被志各卷中的“册”。这样处理不仅保证了研编工作的可操作性, 也保持了同一卷册中特定植被类型的完整性。《中国植被志》编排体系中的“植被类型”的划分很重要, 它是指具有相同建群种及相同优势类群(如种、属)的植被组合, 但它不是严格意义上的植被分类单位。“植被类型”的划分遵循“优势类群及生活型的同一性, 生境条件的相对重要性, 植被特征及用途的差异性, 以及突出植被志的应用性”等原则。按该编排体系, 《中国植被志》将由48卷约110册组成。     

Reconstructing pre-impact vegetation cover in modified landscapes using environmental modelling, historical surveys and remnant vegetation data: a case study in the Fleurieu Peninsula, South Australia

Aim To investigate the application of environmental modelling to reconstructive mapping of pre‐impact vegetation using historical survey records and remnant vegetation data. Location The higher elevation regions of the Fleurieu Peninsula region in South Australia were selected as a case study. The Fleurieu Peninsula is an area typical of many agricultural regions in temperate Australia that have undergone massive environmental transformation since European settlement. Around 9% of the present land cover is remnant vegetation and historical survey records from the ad 1880s exist. It is a region with strong gradients in climate and topography. Methods Records of pre‐impact vegetation distribution made in surveyors’ field notebooks were transcribed into a geographical information system and the spatial and classificatory accuracy of these records was assessed. Maps of remnant vegetation distribution were obtained. Analysis was undertaken to quantify the environmental domains of historical survey record and remnant vegetation data to selected meso‐scaled climatic parameters and topo‐scaled terrain‐related indices at a 20 m resolution. An exploratory analytical procedure was used to quantify the probability of occurrence of vegetation types in environmental domains. Probability models spatially extended to geographical space produce maps of the probability of occurrence of vegetation types. Individual probability maps were combined to produce a pre‐impact vegetation map of the region. Results Surveyors’ field notebook records provide reliable information that is accurately locatable to levels of resolution such that the vegetation data can be spatially correlated with environmental variables generated on 20 m resolution environmental data sets. Historical survey records of vegetation were weakly correlated with the topo‐scaled environmental variables but were correlated with meso‐scaled climate. Remnant vegetation records similarly not only correlated to climate but also displayed stronger relationships with the topo‐scaled environmental variables, particularly slope. Main conclusions A major conclusion of this study is that multiple sources of evidence are required to reconstruct past vegetation patterns in heavily transformed region. Neither the remnant vegetation data nor historical survey records provided adequate data sets on their own to reconstruct the pre‐impact vegetation of the Fleurieu Peninsula. Multiple sources of evidence provide the only means of assessing the environmental and historical representativeness of data sets. The spatial distribution of historical survey records was more environmentally representative than remnant vegetation data, which reflect biases due to land clearance. Historical survey records were also shown to be classificatory and spatially accurate, thus are suitable for quantitative spatial analyses. Analysis of different spatial vegetation data sets in an environmental modelling framework provided a rigorous means of assessing and comparing respective data sets as well as mapping their predicted distributions based on quantitative correlations. The method could be usefully applied to other regions where predictions of pre‐impact vegetation cover are required.     

《中国植被志》研编内容与规范

植被志是基于植被(或植物群落)调查资料, 全面记叙植被的外貌、物种组成、结构和功能, 以及地理分布和生境条件等特征, 并对同类植被进行归纳和总结的志书。《中国植被志》是第一部对中国植被进行全面记述的志书, 预计完成约48卷110册。在借鉴《中国植被》(1980)(简称“80方案”)植被分类基本原则的基础上,《中国植被志》将对中国植被分类系统的高级分类单位(植被型组、植被型和植被亚型)进行归纳和总结, 对中级和低级分类单位(群系组、群系、亚群系, 群丛组、群丛)进行详细描述。植被高级分类单位的描述具有概括性质, 是在中国植被分类系统中级和低级分类单位描述的基础上, 对其在全球和中国境内的地理分布、自然环境、群落外貌、植被类型及多样性、优势种或共优势种、生物多样性保育价值以及资源现状等进行概述, 并对“80方案”相关内容进行修订和拓展, 将提供对中国植被基本特征客观、准确的记述。在植被中级和低级分类单位中, 群系组描述的内容包括地理分布、自然环境、群落外貌、植被类型以及价值与保育等内容; 群系描述的主要内容包括地理分布、自然环境、生态特征、物种组成、群落结构、群丛组和群丛的分类与描述、优势种的生物学特性、生物量与生产力、植被动态与演替以及价值与保育等方面。作为植被志研编的核心内容, 群丛组和群丛的分类与描述主要基于植被调查资料, 采用数量分类方法, 根据群落结构和物种组成的差异划分出不同的植被类型, 并对其基本特征进行定量描述和归纳。其中, 群落的层片结构、特定植被分类单元的特征种或特征种组的筛选与甄别是植被类型划分的关键环节; 而群落外貌, 群落结构, 物种组成, 各类物种的生长习性、生境的偏适性等是群丛组和群丛描述与归纳的重点内容。该文提出了中国植被中级和低级分类单位的命名方案, 其特点在于植被类型的科学名称中同时体现了植被分类单元特征种或优势种的名称及其所属的高级植被分类单位(植被型组或植被型)的名称, 兼顾了植被名称的规范性与实用性。《中国植被志》的研编工作由文献整编、群落调查、数据分析与整理、文本撰写等环节组成。该文对植被样方的调查与收集, 文献收集与整编, 气候、土壤、地形等相关数据的来源及其整理方法, 植被分类方法, 植被命名, 植被分类单元描述的内容, 植被志章节编写大纲、体裁及撰写等多个规范进行了详细的阐述或示例。     

海南岛热带森林植被的类群及其特征

对海南岛热带森林植被的历史变迁进行了回顾。讨论了海南岛热带森林植被类型的分类单位与等级 ,提出了海南岛热带森林的植被分类系统 ,海南岛热带森林植被可分为 2个植被型组 ,7个植被型 ,4个植被亚型 ,35个群系 ,2 1个亚群系 ,1 0 9个群丛组或群丛 ;并对代表类群进行了描述     

湖北省植被分类的研究 Ⅰ.自然植被

本文论述了湖北植被分类的原则、依据,植被分类的单位和命名,并拟订了5级分类系统,以植被型、群系、群丛作为主要分类单位。根据多年来全省野外调查资料分析,湖北植被划分为8个植被型组、13个植被型、66个群系组、152个群系、10个群丛。     

植被年际变化对蒸散发影响的模拟研究

利用通用陆面模式(CLM3.0)及其植被动力学模式(DGVM)研究植被覆盖度(FC)和叶面积指数(LAI)的年际变化对全球蒸散发的影响。设计两套实验方案,其植被的FC和LAI的气候态相同,但一套实验中植被的FC和LAI有年际变化,而对照实验中则没有。结果表明:(1)在草、灌木、树占优势的地区植被FC年际变化依次减小;LAI年际变化较大的地区集中在草和灌木覆盖的地区,在落叶林地区,春秋两季植被LAI的年际变化也较大。(2)全球树占优势的大部分地区,植被的年际变化使得年平均蒸散发和地表蒸发增加、冠层蒸发和蒸腾减少;而在灌木和草覆盖区,变化则大致相反。(3)低纬度地区蒸散发季节循环变化比较明显,而北半球中纬度地区,蒸散发变化明显区随着纬度增加而在时间上向后推延。(4)FC和LAI年际变化较大时,蒸散发及地表蒸发降低,而蒸腾增加;这些差异随FC和LAI年际变化的增加而增加。单点分析进一步表明植被年际变化不仅改变蒸散发的多年平均值,同时改变其分量间的相对比例。     

Understanding properly the `potential natural vegetation' concept

This is a response to critical comments concerning the inappropriate use of the potential natural vegetation (PNV) concept made in a recent contribution to the Commentary section of this journal. We consider that the PNV concept has been misinterpreted. PNV has been used extensively in several European countries since the mid‐1950s and was never intended to be used to make a prediction of what vegetation would dominate in an area if human influence were removed. PNV maps express hypothetical assumptions of what corresponds to dominant or natural vegetation in each area. Remnants of the vegetation of the past provided by palaeopalynology and other disciplines provide valuable information for interpreting modern vegetation, but natural changes and anthropogenic influences operating over the last millennia have to be taken into account. Annex I of the Habitats Directive provides a balanced list of habitat types for implementing conservation policies within the European Union.     

地表植被景观对PM2.5浓度空间分布的影响研究

我国当前城市日益频发的雾霾问题引发公众广泛关注,PM_2.5被认为是雾霾的主要成因。研究认为,在某一区域短时间尺度上（如日）,PM_2.5浓度主要受气象条件影响。但在较长时间尺度上（如季,年）,由于气象条件基本相似,则PM_2.5浓度主要受土地利用特别是地表植被景观的影响。如何耦合地表植被景观格局与PM_2.5浓度信息,定量分析其影响是当前相关科学研究的一个难点,需要引入新思路。首先基于季节气象条件基本相似的科学假设,采用土地利用回归模型分四季高精度模拟PM_2.5浓度空间分布。其次,采用像元二分模型分四季估算研究区植被覆盖度。在此基础上采用随机抽样法通过统计回归模型耦合植被覆盖度与PM_2.5空间分布,定量研究植被覆盖度对PM_2.5分布影响及其尺度效应。研究结果表明：1）植被覆盖度与PM_2.5浓度在本研究选择的空间尺度上,都显著负相关,说明植被覆盖度对PM_2.5具有显著影响;同一个季节不同尺度上,以及不同季节同一尺度上的植被覆盖度对PM_2.5浓度的影响存在一定差异。2）植被覆盖度对PM_2.5浓度的影响方式比较复杂,不同的季节的表现方式不同,总体来说PM_2.5浓度与植被覆盖度曲线回归模型的拟合度高于线性回归模型,说明植被覆盖度对PM_2.5的影响具有非线性特征。3）不同的PM_2.5浓度水平下,植被覆盖度对PM_2.5浓度的影响程度存在差异。PM_2.5浓度越高,植被覆盖度对其浓度的影响越明显。本研究提出的区域尺度耦合地表植被覆盖与PM_2.5浓度的思路与方法,有效的揭示了植被覆盖度对PM_2.5浓度分布的影响方式与尺度效应,为通过优化城市植被缓解大气污染提供一定参考。     

Floodplain vegetation phenology in the Southeast USA: Optimizing the timing of aerial imagery acquisition

Phenological patterns of wetland vegetation were studied on the Savannah River Site, Aiken, South Carolina, USA, to aid in delineation of wetland vegetation community types and plant species from aerial imagery. Relative phenology patterns were recorded for 16 dominant wetland plant species from May 1984 to June 1985 on the floodplains of three streams. These patterns were identified and compared with aerial photographs acquired in the same season as ground observations. Leafout and leaf senescence varied between and within floodplains. In spite of this variability, vegetation classes and individual species may be distinguished best during the late April leafout period.     

上海城市近自然森林的重建动态

近自然森林作为城市植被恢复的重要模式,已在我国多地开展了实践,并衍生了新的造林模式。为评估不同近自然森林建设模式的群落恢复进程,本研究以上海城市裸地上重建的近自然森林为对象,通过长期监测两处分别应用原"宫胁法"与新"异龄复层落叶—常绿混交林"种植模式的近自然森林重建过程,从物种组成、垂直结构、生活型组成和目标恢复物种4个方面解析恢复动态。结果表明:两种造林模式恢复的近自然森林,随恢复进程其物种组成逐渐趋同,在十多年内已形成了落叶—常绿垂直混交结构;"异龄复层落叶—常绿混交林"造林模式可更好地促进常绿阔叶树种的恢复,尤其是常绿建群种红楠与小叶青冈。本研究证实了近自然森林恢复技术可以缩短亚热森林群落向演替后期发展的时间,以及新造林模式的有效性,为近自然森林技术的应用与实施提供了科学依据。     

黄土丘陵区坡面植被盖度及其配置格局的水蚀效应模拟

黄土高原因土壤侵蚀严重被视为生态脆弱地带,探讨植被盖度及其所处坡位对土壤侵蚀的响应,对坡面侵蚀产沙的预测和调控具有重要意义。基于WEPP模型情景模拟,分析了分布广泛、耐旱性强的长芒草和典型恢复灌木植被柠条在不同雨强(0.5、1.0、1.5 mm/min)、不同植被盖度(20%、40%、60%、80%)和不同坡位(坡上、坡中、坡下)条件下的土壤侵蚀变化情况,运用双因素方差分析和相关贡献指数阐明坡面侵蚀产沙特征对坡位和植被盖度交互作用的响应,并提出植被配置的优化模式。结果表明:(1)提高植被有效覆盖度是减小土壤侵蚀的重要举措,且当植被分布在下坡位时坡面土壤侵蚀最少;(2)植被盖度可以有效减少产沙量。小雨强时,柠条和长芒草随盖度增加对泥沙的拦截率分别从38%增加到90%,64%增加到96%;中、大雨强时,植被盖度小于20%或者大于80%时,长芒草坡面产沙量大于柠条坡面。盖度为40%—60%时,长芒草坡面产沙量小于柠条坡面;(3)双因素方差分析表明:坡位和植被盖度对坡面侵蚀产沙量有极显著的影响(P0.001);当植被是长芒草时,坡位和植被盖度交互作用对坡面侵蚀产沙有显著影响(P0.01),植被是柠条时,坡位和植被盖度交互作用对坡面侵蚀产沙作用不显著;(4)通过模拟柠条和长芒草不同配置情景得出:长芒草分布在坡面下部产沙量较小,且当柠条和长芒草配比为1∶2时产沙量最小。     

Freshwater and wetland plant communities of Loch Lomond

Information on the aquatic and wetland vegetation of Loch Lomond, Scotland, is summarised for the period 1957–90. Aquatic macrophyte growth is estimated to occupy about 1% of the loch's total surface area, being limited to the 0–10 m euphotic zone, and probably excluded from much of this area by wave disturbance and unsuitable substrates. Aquatic vegetation is however abundant in sheltered bays and less-exposed shorelines, particularly in the South Basin of the loch. Although Littorella uniflora (L.) Aschers is the commonest, ubiquitous, submerged plant of the loch, three separate euhydrophyte communities have been identified within the loch. One of these is characterised by abundant stands of Elodea canadensis Michx., which appears to have invaded Loch Lomond some time between 1967–88, and has rapidly spread throughout the loch.