激流植物群落生态学研究

本文根据6年定位研究结果,讨论了北温带山溪激流植物群落生态学方面的问题.文中分析了激流群落的种类组成、数量特征、外貌、结构、分布格局、动态与功能等.根据种-面积曲线确定样地最小面积;分析群落自然高度与绝对高度的相关性;探讨了群落的垂直分层与水平镶嵌;划分了群落的生态种组和生态差型;建立了群落的物候型谱和生物量成层模型;阐述了群落的建成过程和演替类型;最后,按照水毛茛对于扰的适应机制分析了其繁殖策略;提出了内陆黑潮并分析了其对群落演替所发生的影响.       

植被演替过程中种群格局动态的分形分析

该文根据“空间代替时间”的原则和对马尾松(Pinus massoniana)种群的重要值-平均胸径的变动趋势的分析,确定5个森林群落为广东省黑石顶自然保护区森林群落演替的一个时间序列;并在此基础上,运用分形理论的计盒维数和信息维数,对演替过程中马尾松种群空间格局的动态进行了分形分析。结果表明,马尾松种群的计盒维数和信息维数2个参数值均呈递减趋势,与其个体数、重要值变动趋势一致。在群落的演替过程中,马尾松种群的空间占据能力不断下降,种群呈衰退趋势。随其在群落中的优势地位逐渐被其它种群取代,群落将由以马尾松占绝对优势的单优群落演替为多优常绿阔叶林群落。分析结果同时表明,分形分析是群落演替过程中种群空间格局动态研究的有效方法,分形维数则能反映种群格局的尺度变化规律。     

退化次生林恢复过程中群落结构和生态位动态

在海南白沙县南开乡按人为干扰程度的不同依次选取次生演替中植被恢复初期、早期、近中期和后期4个典型群落,分别对群落结构、树种组成、重要值和生态位宽度等指标进行研究。结果表明:中前期次生演替过程中优势种作用明显,具有最大的生态位宽度;随着次生演替的进行,种群生态位宽度趋于均衡,群落表现出物种丰富度和多样性增加、林分结构复杂化、树种的优势作用弱化等正向演替的趋势;此外,该地区由于经营史的特殊性,中前期次生群落保留了很多原始林的痕迹,出现了一些本应在原始林内出现的生态稳定种,这些物种在中前期次生群落中数量少,生态位宽度小,却表现出强大的生活力;在演替中前期次生林的经营中,最大程度地发挥优势树种的作用、增加林内生态稳定种的数量是该地区次生林恢复经营的重要技术方向。     

内蒙古草原退化群落恢复演替的研究II. 恢复演替时间进程的分析

 根据内蒙古典型草原地带的羊草+大针茅草原退化变型一冷蒿群落封育12年(1983—1994)的动态监测数据进行分析,对群落恢复演替轨迹取得以下认识： 1．依据群落优势种的更替及主分量分析结果可将恢复演替过程划分为冷蒿优势阶段、冷蒿+冰草阶段、冰草优势阶段、羊草优势阶段。 2;退化草原群落在恢复演替过程中,群落生产力的变化表现出阶梯式跃变和亚稳态阶面相间的特点。第一次跃变发生在1984年,上升到第二个阶面,第二次跃变发生在1990年,进入了第三个阶面,已接近于原生群落的生产力。 3．群落生产力与水资源量的关系因恢复演替阶段不同而异。第一亚稳态时期,群落地上现存生物量大体处于166g·m-2的水平上,生长季降水量达176mm以上时,增加降水对群落生产力的提高不发生显著影响。第二亚稳态时期,群落生物量与降水量之间的相关性显著。可推算出群落于物质生产用水量介于1.1～1.6mm·g-1之间。此值在1.1mm·g-1时,群落对水资源的利用效率最高,而在1.6mm·g-1时群落生物量达到最大值。 4．在恢复演替进程中,群落密度的位点常数约为271.5株·m-2,循此常数上下波动,表现出拥挤与稀疏交替发生的过程,构成了恢复演替的节奏性变化。群落生物量的跃变与亚稳态的形成,以及群落密度的拥挤与稀疏交替作用是群落恢复演替的内在机制。恢复演替的速度,到第10年发生了1.78个半变的生态距离。5．草原退化群落恢复演替过程中,按照其节奏性及生产力跃变与亚稳态的规律,调控放牧利用强度或采取技术措施,调节群落拥挤和稀疏的交替过程可加速恢复演替进程。     

不同演替阶段东方水韭群落特征初步研究

采用"空间代替时间"的方法,对处于不同演替阶段的东方水韭(Isotes orientalis H. Liu et Q. F. Wang)群落进行了物种组成、群落生态学数量特征、物种多样性及繁殖方式的比较分析,结果表明,在演替初期,群落的多样性(物种丰富度、Shannon-Wiener指数、Pielou均匀度指数和β多样性指数)最低,群落中东方水韭的多度、盖度、重要值和生态位宽度均最大,是明显的优势种;演替中期,东方水韭的多度、盖度、重要值和生态位宽度降低,但群落的物种多样性最高,是东方水韭的顶极群落;演替后期,群落中东方水韭的多度、盖度、重要值和生态位宽度均最低,多年生草本植物细叶芒(Miscanthus sinensis Anderss. )和菰[Zizania latifolia (Griseb. ) Turcz. ex Stapf]等逐渐占据重要地位.随群落的演替,群落中营无性/营养繁殖方式的物种数量逐渐增加,群落的繁殖策略由有性繁殖为主转为以无性/营养繁殖为主.研究结果显示,在东方水韭群落演替过程中,群落物种组成的改变、物种多样性的提高、物种繁殖策略的变化以及生境中生化,可能是导致东方水韭种群衰退的主要原因.     

长白山红松阔叶林不同演替阶段优势种的变化

以皆伐后长白山红松阔叶林4个不同演替阶段的林分为对象,分析其群落和优势树种的变化特征.结果表明:在长白山红松阔叶林不同演替阶段中,乔木树种的丰富度、Shannon多样性和Simpson优势度变化较小,多度和均匀度变化较大.随着演替的进程,群落的优势树种组成发生变化,种数逐渐减少,优势种的胸高断面积加和和最大重要值逐渐增加,说明不同演替阶段群落的优势种地位不断提高.长白山红松阔叶林的演替过程是白桦、山杨、黄檗、春榆等阳性或半阴性树种不断减少,而紫椴、水曲柳、红松、色木槭等阴性树种不断增加的过程.     

粤北天然林优势种群生态位研究

基于粤北始兴县罗坝保护区内2个2500m^2样地的群落分层频度调查数据,以不同林层作为一维资源位状态,以个体多度为生态位计测的资源状态指标,对天然常绿林群落中的12个优势树种（栲树、马尾松、茶木、枫香、罗浮柿、杨梅、鹿角栲、黄瑞木、甜锥、山杜英、牛耳枫及鸭公树）进行了生态位的计测和分析。结果表明,大部分的耐荫树种具有较大的生态位宽度值;而阳性树种（如马尾松等）同表现为较小的生态位宽度值。其中马尾松和枫香的生态位宽度值为0,与这两个种在群落演替中的衰退地位相一致,各优势树种,无论是耐荫种类抑或是阳性种类,均表现出一定程度的对现有环境适应的相似性。群落1中相似性比例在0.5以上的占54.5%;也表现出一定程度的生态位重叠,群落1中重叠值大于0.2的占51.5%。结合经典的森林群落分层频度分析,则可以更准确地判定种群在群落中的地位和更新发展潜力;另一方面,把群落分层作为资源位,考虑不同的个体多度的分层中的分布情况,这些分析结果也从一个侧面反映树种对生境的要求情况,不同的群落由于其中树种组成结构不同,使树种生态位宽度值产生变化,从而影响树种之间的生态位相似比例和生态位重叠值。     

岷江冷杉林皆伐后次生群落结构和物种多样性的演替动态

为阐明岷江冷杉林皆伐后次生群落的演替过程,采用空间代替时间的方法,在川西米亚罗林区海拔3100—3600 m的阴坡选择岷江冷杉林皆伐后次生演替10、20、30、40和50a阶段的次生群落作为研究对象,对其群落结构和物种多样性的动态进行了研究。不同演替阶段的树木均呈显著聚集分布。按群落中优势种的重要值将该演替序列划分为3个类型:悬钩子-蔷薇灌丛、白桦阔叶林和桦木-岷江冷杉针阔混交林。随次生演替,乔木和灌木种的物种丰富度趋于增加,而草本种的物种丰富度趋于减少;乔木和灌木种的Shannon-Wiener多样性指数趋于增大,而草本的Shannon-Wiener多样性指数趋于减小;乔木、灌木和草本层的Pielou均匀度指数均趋于增大;乔木层的Simpson优势度指数趋于减小,灌木和草本层的Simpson优势度指数在演替0—40年阶段趋于增大,而在演替50a阶段趋于减小。在该演替序列中,乔木、灌木和草本层的物种组成均呈耐荫种替代非耐荫种的趋势。     

公路碾压干扰下群落植物多样性——以藏北矮嵩草草甸为例

运用时空替换法,以空间变换替代时间变换,对公路碾压干扰下藏北矮嵩草草甸恢复演替中不同阶段群落植物多样性进行研究.结果表明：各草地群落样方中共出现高等植物33种,其中菊、豆、禾本科和蔷薇科合计16种,占48.48﹪,在其自然恢复演替所起的作用最大;莎草科植物作为顶级群落的建群种具有重要作用.物种构成具有明显的阶段性特征：演替前期以1年生和2年生植物为主;中期多年生草本植物逐渐占据优势;后期矮嵩草成为单优势种;菊叶萎陵菜和二裂萎陵菜几乎贯穿始终.物种积聚主要是在演替前期和中期完成,其积聚过程符合二次曲线.演替后期群落植物多样性程度最高,多样性随演替进程表现为逻辑斯谛增长规律：前期群落物种丰富度较低,均匀度较高,生态优势度？也比较高,但综合多样性较低;中期群落的均匀度下降,生态优势度也同时下降,综合多样性高;后期矮嵩草成为群落的单优势种,群落的均匀度和生态优势度均下降,综合多样性仍然增加.     

植物群落演替与土壤发展之间的关系

本文运用植物群落中植物优势种的重要值与相对应子群落的土壤特征值直接相关联的分析方法,对湖北宜昌大老岭的桦(Betula)、栎(Quercus)、栗(Castanea)七个群落类型的三个演替途径的土壤动态进行分析,结果表明:在植物群落的演替过程中,土壤中的Ca、pH值减少;离子代换量增加;Na、Mg、NH_4+-N、速效P、速效K、有机质的含量是随着物种的变化而呈不同的趋势。因此,植物群落的演替是生态系统的动态过程。     

东太湖水生植物群落结构的演变及其沼泽化

2002年东太湖水生植被调查结果表明,沉水植被和浮叶植被是该湖水生植被的主要生态类型,分布面积分别占全湖总面积73.6%和18.3%。东太湖水生植被主要有9个群丛,其中沉水植被主要的5个群丛是伊乐藻(外来种)群丛、金鱼藻群丛、伊乐藻 微齿眼子菜群丛、菜-伊乐藻 微齿眼子菜群丛、苦草 竹叶眼子菜 黑藻群丛,其分布面积分别占东太湖植被总面积的30.7%、17.2%、16.7%、15.8%、9.3%。随着对东太湖的不断改造和资源的不断利用,20世纪60年代东太湖人工种植沼泽植被菰群丛,20世纪80年代初环湖水陆交错带被围垦而芦苇群丛消失,微齿眼子菜替代竹叶眼子菜而占据东太湖40%的水面。近10a来,东太湖网围养蟹迅速发展,占全湖总植被面积25.6%的沼泽植物——菰群丛及其占40%的微齿眼子菜群丛被清除,外来种伊乐藻和无根植物金鱼藻分布面积达90%的湖区。东太湖水生植被由20世纪50年代的原生演替到现在的次生演替,群落演变激烈,同时东太湖沼泽化进程加剧。     

汉江中下游水生植物群落及演替

水生植物是河流生态系统的重要组成部分, 研究河流水生植物群落组成及演替对于河流生态系统健康诊断具有重要意义。该研究采用野外生态学研究方法, 于2013年9月和2014年6月2次对汉江中下游12个典型代表性江段的水生植物群落的组成、分布和生物量等进行调查。调查结果表明, 现阶段汉江中下游的主要水生植物共有69种, 隶属28科49属, 其中优势种主要是穿叶眼子菜(Potamogeton perfoliatus)、竹叶眼子菜(P. malaianus)、芦苇(Phragmites australis)、南荻(Triarrhena lutarioriparia)和喜旱莲子草(Alternanthera philoxeroides)等。结合早期的研究表明, 汉江中游江段沉水植物优势群落变化明显; 下游则呈现出由沉水植物群落向挺水植物群落演替的格局。挖沙和污染等人类干扰以及水位波动、河流底质和植物繁殖策略等自然因素可能是导致汉江中下游水生植物优势种变化和群落演替的主要因素。该研究结果可为汉江中下游的水生植物多样性保护和生态修复提供科学依据。     

洪泽湖大型水生植物群落结构和时空格局的GIS模拟

2010—2011年对洪泽湖大型水生植物进行了4个季度全面的调查和研究, 共发现大型水生植物8科12种, 其中沉水植物9种, 挺水植物1种, 浮叶植物2种。马来眼子菜(Potamogeton malaianus)、微齿眼子菜(P. maackianu)、篦齿眼子菜(P. pectinatus)和菹草(P. crispus)为全年优势度较高的水生植物, 但4个季节大型水生植物的优势种类组成差异明显。秋季的水草生物量最高, 其次为夏季和冬季, 春季最低。结合GPS (Global Position System)和GIS (Geographic Information System), 利用GIS的Kring插值法对洪泽湖大型水生植物总生物量及主要优势物种的时空分布进行了可视化模拟。结果发现洪泽湖现阶段大型水生植物分布区域主要集中在湖区北部水质较好、透明度较高且相对封闭的成子湖区。文章也分析了洪泽湖大型水生植物变迁的潜在影响因子, 为水生植物保护和生态系统健康提供了基础依据。     

新疆开都河流域水生植物多样性及其影响因素

河流是一个连续的、流动的、独特而完整的系统,研究河流生态系统中水生植物的多样性分布格局及其影响因素对河流生态学研究具有重要意义。本文通过野外调查,研究了新疆开都河流域水生植物多样性、主要水生植物群落特征及与环境因子之间的关系,并利用水分-能量动态假说和栖息地异质性假说对该流域水生植物物种多样性的地理格局进行解释。结果表明: 开都河流域共有水生植物71种,隶属于24科39属;聚类分析可将开都河流域水生植物群落划分为10个主要群落类型,其中芦苇群落物种丰富度最高,狭叶香蒲群落和金鱼藻群落物种丰富度最低;流域水生植物群落Shannon指数与pH呈显著负相关,Simpson指数与pH、经度呈显著负相关,与海拔呈显著正相关;流域水生植物群落类型主要受海拔、水深及水温的影响;流域水生植物物种多样性随经纬度无明显变化规律。水分-能量动态假说和栖息地异质性假说共解释开都河流域水生植物多样性格局变量的31.4%,表明这两个假说对于该流域水生植物多样性格局的解释力并不高。     

Assessing the responses of aquatic macrophytes to the application of a lanthanum modified bentonite clay,at Loch Flemington,Scotland, UK

Loch Flemington is a shallow lake of international conservation and scientific importance. In recent decades, its status has declined as a result of eutrophication and the establishment of non-native invasive aquatic macrophytes. As previous research had identified the lake bed sediments as an important source of phosphorus (P), the P-capping material Phoslock^® was applied to improve water quality. This article documents the responses of the aquatic macrophyte community by comparing data collected between 1988 and 2011. Summer water-column total P concentrations decreased significantly and water clarity increased following treatment. Aquatic plant colonisation depth increased and plant coverage of the lake bed extended. However, the submerged vegetation remained dominated by the non-native Elodea canadensis Michx. Aquatic macrophyte community metrics indicated no significant change in trophic status. Species richness and the number of ‘natural’ eutrophic characteristic species remained broadly similar with no records of rare species of conservation interest. Loch Flemington is still classified as being in ‘unfavourable no change’ condition based on its aquatic macrophytes despite the water quality improvements. The implications of these results are discussed in relation to the future management of Loch Flemington and in the wider context of trying to improve our understanding of lake restoration processes.     

Centennial‐scale changes to the aquatic vegetation structure of a shallow eutrophic lake and implications for restoration

1. We investigate long‐term (>200 years) changes to the composition and spatial structure of macrophyte communities in a shallow, eutrophic lake (Barton Broad, eastern England) and consider the implications for lake restoration. 2. Historical macrophyte data were assembled from a variety of sources: existing plant databases, museum herbaria, journal articles, old photographs and eyewitness accounts. Additionally, two types of sediment core sample were analysed for plant macro‐remains and pollen; bulk basal samples from multiple core sites analysed to provide information on ‘pre‐disturbance’ macrophyte communities and two whole cores analysed to determine historical change. 3. Prior to the late 1800s, macrophyte communities were diverse and included a multilayered mosaic of short‐stature submerged taxa and taller submerged and floating‐leaved species. With the progression of eutrophication after around 1900, the former community was displaced by the latter. Diversity was maintained, however, since an encroaching Schoenoplectus–nymphaeid swamp generated extensive patches of low‐energy habitat affording refugia for several macrophytes otherwise unable to withstand the hydraulic forces associated with open water conditions. When this swamp vegetation disappeared in the 1950s, many of the ‘dependent’ aquatic macrophytes also declined leaving behind a sparse, species‐poor community (as today) resilient to both eutrophication and turbulent open waters. 4. The combination of historical and palaeolimnological data sources offers considerable benefits for reconstructing past changes to the aquatic vegetation of lakes and for setting restoration goals. In this respect, our study suggests that successful restoration might often be better judged by reinstatement of the characteristic structure of plant communities than the fine detail of species lists; when nutrients are low and the structure is right, the right species will follow.     

Water table and species identity outweigh carbon and nitrogen availability in a softwater plant community

Performance of aquatic macrophytes is driven by many environmental factors, and a major challenge is to understand how aquatic macrophyte communities are structured in various environments. In softwater lakes in Western Europe, hydrological state (submersed/emersed), carbon dioxide and ammonium levels and species interactions are considered as driving forces in structuring amphibious plant communities. In this study we aimed at evaluating the relative importance of these factors for four species in a competitive neighbourhood. Softwater lake habitat was simulated during one growing season in laboratory conditions, mimicking water level fluctuation, photoperiod and temperature. Artificial communities consisted of small populations of four softwater macrophyte species: Luronium natans, Baldellia ranunculoides ssp. repens, Eleocharis multicaulis and Hydrocotyle vulgaris. These communities were subjected to two levels of carbon dioxide and ammonium. Additionally, monocultures of Baldellia and Eleocharis were grown at a higher nutrient level combination in order to measure their competitive response in a community. Time (hydrological state) and species identity turned out to be the only consistently significant factors determining community composition. Plant performance was clearly species-dependent, while carbon dioxide and ammonium did not have major effects. The competitive response was significant in both Eleocharis and Baldellia. Competition intensity was highest in the emersed state. Carbon dioxide had a supplementary effect on the within-species performance in Luronium, Baldellia and Eleocharis, with high carbon dioxide level mainly resulting in more flowers and more stolons. Community outcomes and competitive responses in aquatic macrophytes appear difficult to predict, because of mixed life strategies and morphological and functional plasticity. We conclude that hydrological state was the only important environmental factor. The identity of the species that were present—implying species interactions—largely determined community outcome.     

Macrophyte species drive the variation of bacterioplankton community composition in a shallow freshwater lake

Macrophytes play an important role in structuring aquatic ecosystems. In this study, we explored whether macrophyte species are involved in determining the bacterioplankton community composition (BCC) in shallow freshwater lakes. The BCC in field areas dominated by different macrophyte species in Taihu Lake, a large, shallow freshwater lake, was investigated over a 1-year period. Subsequently, microcosm experiments were conducted to determine if single species of different types of macrophytes in an isolated environment would alter the BCC. Denaturing gradient gel electrophoresis (DGGE), followed by cloning and sequence analysis of selected samples, was employed to analyze the BCC. The DGGE results of the field investigations indicated that the BCC changed significantly from season to season and that the presence of different macrophyte species resulted in lower BCC similarities in the summer and fall. LIBSHUFF analysis of selected clone libraries from the summer demonstrated different BCCs in the water column surrounding different macrophytes. Relative to the field observations, the microcosm studies indicated that the BCC differed more pronouncedly when associated with different species of macrophytes, which was also supported by LIBSHUFF analysis of the selected clone libraries. Overall, this study suggested that macrophyte species might be an important factor in determining the composition of bacterial communities in this shallow freshwater lake and that the species-specific influence of macrophytes on BCC is variable with the season and distance.     

The influence of flood duration on the surface soil properties and grazing management of karst wetlands (turloughs) in Ireland

This study tested the hypothesis that lake augmentation with well water impacts the distribution and abundance of aquatic plants in lakes. Water chemistry was measured from 14 wells, 14 augmented lakes, and 14 lakes without augmentation. Nine in-lake aquatic macrophyte abundance and species distribution metrics were measured in all lakes. Net photosynthetic rate (NPR) of nine submersed species was also measured in well and lake water. Augmentation increased alkalinity in receiving lakes, but total phosphorus was significantly lower, which resulted in lower chlorophyll and greater Secchi depths. Although measured NPR was higher for all plants incubated in well water, only one (emergent species richness) in-lake aquatic macrophyte metric was different in lakes with and without augmentation. Lake augmentation significantly changed water chemistry of receiving waters, but effects on aquatic macrophytes were minimal, suggesting that other environmental factors are limiting the distribution and abundance of macrophytes in the study lakes. The lower phosphorus levels in augmented lakes were unexpected because phosphorus concentrations in well water were significantly greater than in lakes with or without augmentation. Precipitation of calcium phosphate likely accounts for the reduced phosphorus levels in augmented lakes.     

Impacts of space,local environment and habitat connectivity on macrophyte communities in conservation lakes

Aim  To assess the relative impacts of spatial, local environmental and habitat connectivity on the structure of aquatic macrophyte communities in lakes designated for their conservation value. Location  Selected lakes of conservation importance all over Scotland, representing a wide variety of lake habitat types and associated macrophyte communities. Methods  Local environmental variables and species occurrence were measured in the field. Spatial variables were generated using principal coordinates of neighbour matrices (PCNM) analysis. Connectivity between each lake and its neighbours was defined as either (i) all lakes within a radius of 5, 10, 25, 50, 75 or 100 km; (ii) all lakes in same river system; or (iii) all lakes in the same catchment and upstream of the lake. Using variance partitioning within canonical correspondence analysis, the relative impact of E = local environment, S = space and C = lake connectivity was compared on submerged (n = 119 lakes) and emergent (n = 96 lakes) macrophyte assemblages. Results  Local environmental conditions, such as total phosphorus, alkalinity/conductivity and the presence of invasive species, as well as spatial gradients were key drivers of observed variation in macrophyte communities; e.g., for submerged macrophytes, a combination of local to moderate factors relating to water chemistry and broad‐scale gradients reflecting elevation and climate are important. Spatially structured environmental variables explained a large portion of observed variation. Main conclusions  Our findings confirmed the need to manage local environmental pressures such as eutrophication, but suggested that the traditional catchment approach was insufficient. The spatial aggregation of environmental and connectivity factors indicated that a landscape scale approach should be used in lake management to augment the risk assessment to conservation species from the deterioration of suitable lake sites over broad biogeographic areas.