青海湖湖盆南岸植物群落的生态优势度与海拔梯度

利用Ｓｉｍｐｓｏｎ优势度指标对青海湖湖贫南岸的植物群落优势度进行了测定,并讨论了群落生态优势与海拔梯度之间的相互关系。结果表明,海拔梯度是通过影响群落内和中群组成影响群落的生态优势度,群落生态优势度与群落内植物种群数呈相关,群落内种群越丰富,群落生态优势度就越小,反之越大。     

金佛山方竹经营对扁刺栲群落物种多样性和优势种种群结构的影响

为探讨金佛山方竹经营对扁刺栲群落物种多样性和优势种种群结构的影响,该研究以金佛山的扁刺栲自然群落和金佛山方竹经营群落为对象,分析了两类群落的物种组成特征、物种多样性及优势种种群结构。结果表明：(1)两种群落内共记录维管束植物84种,隶属于40科63属,以樟科、蔷薇科、壳斗科、山茶科物种为主;扁刺栲为群落优势种,中华木荷和灰柯为次优势种,金佛山方竹为灌木层优势种,扁刺栲群落组成与亚热带其他地区的扁刺栲群落组成相似。(2)金佛山方竹经营群落的灌木层物种丰富度显著低于自然群落,草本层Shannon-Wiener指数和Pielou指数均显著低于自然群落。(3)扁刺栲和灰柯在自然群落中为稳定型种群,而在金佛山方竹经营群落中为衰退型种群,中华木荷在两类群落中均为衰退型种群。(4)自然群落中扁刺栲、中华木荷、灰柯种群的萌枝率、有萌个体率和幼苗相对优势度均高于金佛山方竹经营群落。综上认为,金佛山方竹经营对金佛山扁刺栲群落灌木层和草本层物种多样性产生了负面影响,并显著影响扁刺栲群落优势种种群更新和维持。     

神农架极小种群植物庙台槭群落特征及种群动态

种群和群落特征分析是揭示物种濒危处境最有效的途径之一。庙台槭(Acermiaotaiense)是极小种群野生植物,被列为国家二级保护植物。然而,由于对神农架地区庙台槭资源状况和群落特征不清楚,严重制约该物种的保护成效。该研究对神农架地区庙台槭种群及其所在的群落开展调查,揭示群落的物种组成和群落结构;通过分析庙台槭种群的径级结构,绘制静态生命表和存活曲线,并分析种群动态变化指数,揭示庙台槭的种群动态。结果表明:(1)群落内共有木本植物33种,隶属于15科20属,群落内优势种为胡桃楸(Juglansmandshurica)、千金榆(Carpinuscordata)、金钱槭(Dipteroniasinensis)和华榛(Coryluschinensis);(2)庙台槭的相对优势度为2.23%,非群落内优势种;(3)神农架庙台槭分布范围十分狭窄(面积约1.7hm2),种群规模小(79株);(4)庙台槭种群内幼龄个体占比较高(79.75%),更新较好;(5)物种存活曲线属Deevey-II型,种群各龄级的死亡率基本相同,但在幼树阶段死亡率增高,在大树阶段(12.5cm≤胸径<17.5cm)...     

干热河谷次生稀树灌木林物种组成变化及群落结构动态

为揭示四川攀枝花苏铁国家级自然保护区干热河谷次生稀树灌木林群落演替动态规律,该研究以2015年群落内建立的1 hm²永久固定样地为研究对象,经2020年首轮复查,对物种组成、群落多样性、重要值、死亡率、补员率以及胸径(DBH)进行调查研究,以分析5年间群落物种组成及结构动态。结果表明:(1)2020年,群落木本植物共18种,隶属15科18属,较2015年新增1属1种,优势物种组成并无变化,但优势度变化显著。与2015年相比,在重要值(IV)> 1的6个种群中,5个树种IV增高,仅攀枝花苏铁种群IV降低,但其仍为群落优势建群种,铁橡栎和滇榄仁等乔木种群优势度显著增加。(2)2020年,群落中DBH≥1 cm的木本植物个体数增至1 710株,平均胸径由11.10 cm增至11.17 cm。群落年死亡率0.29%,死亡个体平均胸径11.84 cm,年补员率2.75%,补员个体平均胸径4.96 cm。与2015年相比,群落中7个种群出现个体死亡,9个种群出现补员个体。(3)虽然沙针种群规模缩小,但仍有9个种群规模扩大,4个种群规模保持稳定。只有攀枝花苏铁和沙针种群平均胸径减小,其余种群平均胸径均有不同程度的增大。随着森林演替的进行,群落内种间竞争的重要性将逐渐增大,铁橡栎和滇榄仁等乔木树种将在未来演替进程中占据优势地位,但短期内并不会威胁攀枝花苏铁种群优势地位,大径级植株个体的死亡是其优势度显著降低的主要原因。在未来群落演替进程中,攀枝花苏铁将与铁橡栎、滇榄仁等乔木树种组成以乔木树种逐渐占据优势的干热河谷次生稀树灌木林向气候顶极群落演替的过渡型次生林群落。     

皖大别山区虫生真菌群落多样性研究

选用物种丰富度(S)、Shannon-Wiener多样性指数(H')、Pielou均匀度(E)和优势度曲线(K—dominance)等指标,对安徽大别山区虫生真菌群落多样性进行了测定．结果表明,群落的多样性指标能较客观地反映群落的结构状态,揭示各群落间的关系．利用极点排序和系统聚类,可将安徽大别山区虫生真菌区系划分为3个垂直生态类群：温湿低山气候类型(海拔900m以下)、凉湿中山气候类型(海拔900～1200m)和寒湿山顶气候类型(海拔1200m以上)．     

坝王岭热带山地雨林群落种群垂直分布

应用中心点,四分法取样技术于海南岛坝王岭的热带山地雨林,并根据群落以及部分优势种的特性,人为划分群落和各个种的层次高度范围,研究了一部分种群在群落中的垂直空间分布。结果表明,整个群落的个体垂直空间分布均匀度较高,群落下层的物种多样性指数稍高于上层,而均匀度则稍低。各个种群的垂直空间分布多度不等,有利于揭示种群在群落结构、演替过程的作用.种群的垂直空间分布格局呈随机型或集群型。     

重度砍伐后极小种群野生植物崖柏群落结构动态

砍伐导致濒危植物种群个体数量减少, 群落结构改变, 加剧物种灭绝风险。崖柏(Thuja sutchuenensis)为典型极小种群野生植物, 森林砍伐是导致其种群数量急剧下降的主要原因。但是, 到目前为止, 有关崖柏种群及其群落对砍伐的响应鲜有报道。本研究以重度砍伐后的崖柏群落为研究对象, 基于对崖柏群落固定样地的调查和两次复查, 对比分析了伐后崖柏种群径级结构、种群生存力、物种多样性及其群落结构动态等特征。结果表明: 崖柏残存群落伐后13年崖柏种群个体数量增加了22.58%, 其中幼苗幼树占85.71%, 而崖柏种群生存率下降25.43%, 种群死亡密度和危险率分别增加了24.12%和28.62%。崖柏群落物种丰富度和Shannon-Wiener指数分别增加96.43%和33.35%。研究结果表明, 砍伐使崖柏种群生存力及其在群落中的优势度持续下降, 崖柏占优势的针阔混交林有向阔叶林演替的趋势, 崖柏种群受到严重威胁, 亟需采取紧急保护措施。     

大青沟自然保护区主要森林群落优势种的种群分布格局

选择大青沟国家级自然保护区的水曲柳群落、蒙古栎群落和大果榆群落进行野外群落学调查,应用理论分布模型和聚集强度指标对其优势种水曲柳种群、蒙古栎种群和大果榆种群不同发育阶段、不同取样尺度下的聚集强度进行研究。结果表明:除了水曲柳种群在第Ⅱ、Ⅳ龄级,大果榆种群在第Ⅲ、Ⅳ龄级为随机分布外,3个优势种在4个发育阶段、4个不同取样尺度分布格局均为聚集分布。不同发育阶段和不同取样尺度对其分布格局和聚集度均有不同程度的影响。随着径级的增大或年龄的增加,3个优势种种群的聚集度均降低,除蒙古栎种群为聚集分布外,水曲柳种群和大果榆种群均呈现随机分布的趋势。随着研究尺度的增大,同一种群同一发育阶段的聚集强度呈下降的趋势。     

马衔山林区优势植物种群竞争的初步研究

本文采用点—四分法对马衔山林区阴坡半阴坡一定垂直带(2200—2700米)的植物群落进行了调查。把该林区优势植物种群山杨(Populus tremula var．davidiana),白桦(Betula platyphylla),青杆(Picea wilsonii)在不同群落中的相对优势度作为生态位重叠的计量,以优势植物种群在正常纯林中的优势度作为它的容纳量,应用Lotka-Volterra竞争方程描述了优势植物种群的竞争结局。1．优势植物种群的竞争是进展演替的主要动因。2．优势植物种群竞争的结局与每个种群的内禀增长力(r)和初始状态无关,只与种群间的竞争系数(α)和每个种群的容纳量(K)有关。3．优势植物种群间的竞争可作为研究植物群落的数学理论和一种方法。     

牛洛河自然保护区东京龙脑香林群落特征研究

东京龙脑香(Dipterocarpus retusus)是国家I级重点保护野生植物,是东南亚热带雨林的标志性树种,目前有关该群落学的研究尚处于空白。该研究通过实地踏查,采用典型选样法布设4个30 m×30 m的群落样地、20个10 m×10 m的种群样方,记录样地内的物种及其株高、胸径、数量,群落特征等,并通过分布区类型划分、群落物种多样性分析及种群年龄结构划分等方法,分析了东京龙脑香林群落学与种群学特征。结果表明:(1)样地中共记录种子植物181种,隶属76科143属,其中热带性质科有58科、热带性质属有126属、热带性质种有162种,科、属、种热带成分比例分别为76.32%、88.11%、89.50%,表明该群落具有强烈的热带性质。(2)该群落物种多样性指数整体较高,多样性指数(d_(Ma)、H')在群落不同层次中均表现为灌木层乔木层草本层的特征;均匀度指数(J_(sw))在不同层次中比较接近;优势度指数(D)表现为草本层乔木层灌木层。(3)从乔木层重要值来看,东京龙脑香的最大,为26.85,显示出绝对的优势,是该群落的优势种、建群种。(4)该种群年龄结构为正金字塔型,表明该种群处于增长时期,为增长型种群。     

长白山高山冻原种子植物的调查

通过多次对长白山高山冻原的实地考察,统计得到冻原种子植物共计34科、94属、146种,有6种属的分布区类型(包括3个变型),北温带分布类型最多,占总属数的68.09%。在整个冻原上,草本有125种,占总数的85.62%,其中多年生草本124种。高山冻原植物中具有多种生态,生理适应方式,低矮平卧状植株、极矮小草本、密集丛生是植物的重要适应方式,细长密集须根是冻原上主要的适应方式,占植物总数的54.94%。果实中干果共计137种,其中蒴果56种。由于高山冻原上生态环境十分残酷,极易受人为因素的影响。     

Where do the treeless tundra areas of northern highlands fit in the global biome system: toward an ecologically natural subdivision of the tundra biome

According to some treatises, arctic and alpine sub‐biomes are ecologically similar, whereas others find them highly dissimilar. Most peculiarly, large areas of northern tundra highlands fall outside of the two recent subdivisions of the tundra biome. We seek an ecologically natural resolution to this long‐standing and far‐reaching problem. We studied broad‐scale patterns in climate and vegetation along the gradient from Siberian tundra via northernmost Fennoscandia to the alpine habitats of European middle‐latitude mountains, as well as explored those patterns within Fennoscandian tundra based on climate–vegetation patterns obtained from a fine‐scale vegetation map. Our analyses reveal that ecologically meaningful January–February snow and thermal conditions differ between different types of tundra. High precipitation and mild winter temperatures prevail on middle‐latitude mountains, low precipitation and usually cold winters prevail on high‐latitude tundra, and Scandinavian mountains show intermediate conditions. Similarly, heath‐like plant communities differ clearly between middle latitude mountains (alpine) and high‐latitude tundra vegetation, including its altitudinal extension on Scandinavian mountains. Conversely, high abundance of snowbeds and large differences in the composition of dwarf shrub heaths distinguish the Scandinavian mountain tundra from its counterparts in Russia and the north Fennoscandian inland. The European tundra areas fall into three ecologically rather homogeneous categories: the arctic tundra, the oroarctic tundra of northern heights and mountains, and the genuinely alpine tundra of middle‐latitude mountains. Attempts to divide the tundra into two sub‐biomes have resulted in major discrepancies and confusions, as the oroarctic areas are included in the arctic tundra in some biogeographic maps and in the alpine tundra in others. Our analyses based on climate and vegetation criteria thus seem to resolve the long‐standing biome delimitation problem, help in consistent characterization of research sites, and create a basis for further biogeographic and ecological research in global tundra environments.     

长白山高山冻原植被生物量的分布规律

从物种生物量、优势种器官生物量和植被生物量角度,探讨了长白山高山冻原生态系统生物量的空间变化规律．结果表明,在调查的43种长白山高山冻原植物中,单物种生物量排序前5种植物分别是牛皮杜鹃(Rhododendron chrysanthum)(159．01kg·hm^-2)、笃斯越桔(Vaccinium jiliginosum var．alpinum)(137．52kg·hm^-2)、高山笃斯(Vaccinium uliginosum)(134．7kg·hm^-2)、宽叶仙女木(Dryas octopetala var．asiatica)(131．5kg·hm^-2)圆叶柳(Salix rotundifolia)(128．4kg·hm^-2)．它们是长白山高山冻原生态系统的优势种．地下与地上生物量和地下与总生物量之比随海拔升高逐渐增加．植被生物量随海拔升高。总体呈逐渐减小的趋势。植被生物量与海拔高度呈显著负相关．长白山高山冻原生态系统平均生物量为2．21t·hm^-2,对调节长白山小气候、涵养水源、水土保持等生态服务功能的发挥有着重要的作用。同时对固定大气CO2起着汇的作用。     

退化中的长白山西坡灌木苔原优势种分布差异

长白山苔原带植被正在发生显著变化,灌木苔原中灌木植物分布范围萎缩,重要值下降。通过样方调查数据,分析灌木苔原中优势种的变化,灌木分布格局和灌木群落结构特征沿海拔的差异,旨在揭示长白山灌木苔原退化的区域差异,为明确其退化机理提供基础数据。研究表明:(1)长白山西坡灌木苔原退化严重,多种草本植物已经侵入,并成为优势种。目前7个优势种中灌木仅占2席,草本植物占据5席,与1979年的样方调查结果相比灌木优势种的数量和地位都明显下降。7个优势种均为聚集分布,各优势种分布呈现斑块化、分离化,统一的灌木苔原面临解体;大部分灌木苔原群落中,出现了草本层,苔原带下部灌木苔原中草本层高于灌木层,物种组成和群落形态接近草木苔原。(2)灌木在各海拔均仍有广泛分布,但其空间分布格局明显不同。在海拔2300m以下,灌木的分布产生较强的聚集现象,特别是在海拔2100m以下这种聚集分布现象更为突出;在海拔2300m以上灌木的聚集程度较弱。(3)长白山西坡灌木苔原退化的区域分异明显,在海拔2100m以下灌木苔原退化严重,成为草-灌苔原;在海拔2100—2300m之间,灌木苔原退化较严重,成为灌-草苔原;在海拔2300m以上,退化较轻,仍为灌木苔原。由此推断,长白山西坡灌木苔原的退化机理应包括两个方面:草本植物入侵,种间竞争导致灌木退化,以及环境变化导致灌木退化,二者皆可能是全球气候变化的结果。     

Dwarf pine invasion in an alpine tundra of discontinuous permafrost area: effects on fine root and soil carbon dynamics

Key message

Recent invasion of Pinus pumila , a highly productive shrub-like tree species, into alpine tundra does not significantly modify the dynamics of fine root and soil carbon in the tundra.

Abstract

Climate warming may directly and indirectly affect the large carbon stock in discontinuous permafrost soil at high latitudes. In recent decades, Siberian dwarf pine [Pinus pumila (Pall.) Regel] has been invading dry heath alpine tundra in the northern Amur region of Far East Russia. Siberian dwarf pine is known to have high aboveground productivity, comparable to that of tall coniferous trees. We hypothesised that the invasion of Siberian dwarf pine into alpine tundra could increase soil carbon stocks via an increase in fine roots. Contrary to our expectations, the invasion of dwarf pine did not significantly increase the fine root biomass and productivity of the tundra, probably due to the belowground competitive exclusion between the dwarf pine and alpine tundra plants. Furthermore, the invasion of the dwarf pine did not affect soil carbon in the alpine tundra ecosystem. These results show that the recent invasion of Siberian dwarf pine into tundra did not influence the fine root dynamics or the soil carbon stock in the study site. Together, these results implied that (1) it takes a long time for pine invasion to change the belowground ecosystem properties of tundra vegetation to that of pine thickets and therefore (2) the lack of an increase in soil carbon from recent tree invasion should be taken into account when modelling future carbon dynamics in alpine tundra.

     

Bryoflora of the Alpine Tundra of Changbai Mountain and Its Floristic Relationship to the Bryofloras of Arctic Tundras

The alpine tundra of Changbai Mountain is situa,ed in 41º53′–42º04′N, 127º57′–128º11′E and at elevations ranging from 1950(2000) –2749.2 m. There are 67 genera and 135 species of bryophytes in the alpine tundra, belonging to following five distribution types (DT): Cosmo-politan DT (50 genera, 29 species), North Temperate DT (14, 79), Eastern Asian-North American Discontinuous DT (1, 1), Eurasian Temperate DT (1, 10), Eastern Asian DT (1, 16). The alpine tundra of Changbai Mountain shares 55 genera and 103 species of bryophytes with arctic tundras.     

Ecology of a steppe-tundra gradient in interior Alaska

Abstract. Subarctic steppe is currently restricted in interior Alaska and the Yukon Territory to steep, south-facing river bluffs. Paleoecological and biogeographic evidence suggests that some steppe taxa may have been more widespread during the Full-Glacial. We examined factors controlling the distribution of steppe taxa on an elevation gradient across a steppetundra ecotone; such analyses may help define potential Full-Glacial distributions of these taxa. Multivariate analyses suggest that species can be divided into four spatially distinct groups, but individualistic species distributions create considerable overlap among these groups. The steppe-tundra ecotone comprises a broad zone of mixing between steppe taxa and drought-tolerant alpine tundra taxa, followed by an abrupt shift to alpine shrub tundra. The transition from low steppe to tundra vegetation is primarily associated with a gradient of decreasing soil temperature. The more abrupt transition from mixed steppe-tundra to alpine shrub tundra vegetation is primarily associated with changes in soil depth and soil moisture. Variation in vegetation within steppe is associated with gradients in soil phosphorus and moisture. Greenhouse experiments on drought tolerance of two steppe and two tundra taxa suggest that the individualistic distribution of species along the ecotone is partly a function of physiological differences among species. Our analyses of vegetation-environment relationships support the hypothesis that some components of the steppe community could have been more widespread during the colder Full-Glacial.     

Habitat use by singing voles and tundra voles in the southern Yukon

Summary We investigated how far competitive interactions influence the use of habitats and relative abundance of two species of Microtus in the southwestern Yukon. We worked in the ecotone between alpine tundra and subalpine shrub tundra where populations of singing voles (Microtus miurus) and tundra voles (M. oeconomus) overlap little.We removed tundra voles from shrub tundra on one live-trapping area to look at the effect on the contiguous population of singing voles in alpine tundra. The removal of tundra voles did not affect the distribution or relative abundance of singing voles. The spatial distribution of these species and their movements within habitats suggest that they have a strong habitat preference.Populations of small mammals in the area are extremely dynamic and the relative importance of competitive interactions may change as density varies. At present we have no evidence that competition affects habitat use in M. miurus.     

长白山高山苔原带蛾类物种组成及其时间动态

长白山高山苔原带环境条件恶劣,通过对高山苔原带蛾类研究,揭示蛾类物种组成以及时间变化,可为研究蛾类对苔原极端生境的适应能力,以及蛾类在维持苔原带生态平衡中的作用提供依据。2005-2007年和2019年,每年的6、7、8月,在长白山高山苔原带利用灯诱采集蛾类标本,分析蛾类的物种组成以及时间动态。共采集蛾类1585头,隶属于13科126种,夜蛾科（Noctuidae）为优势类群,绿组夜蛾（Anaplectoides prasina）和一色兜夜蛾（Cosmia unicolor）为优势种,稀有种较多。蛾类的种-多度分布接近生态位优先假说。7月份蛾类的物种数、个体数最多,丰富度指数、多样性指数都最高,但均匀度指数却最低。不同种类对时间的反应表现出一定的差异,黄绿组夜蛾（Anaplectoides virens）对8月,厉切夜蛾（Euxoa lidia）对6月的适应力相对较强。各物种的顺序日期存在一定的差异性,只有10种蛾类在3个月份都被采集到。研究表明,长白山高山苔原带蛾类的多样性较低,成虫活跃期较短;不同类群的蛾类在苔原环境中显示出差异化的适应性,夜蛾科的适应能力超过其它类群,尺蛾科（Geometridae）的适应性相对较低,蛾类对时间的变化反应比较敏感。     

长白山高山苔原雪斑大白花地榆群落土壤氮素动态与生产力的关系

在高山苔原冬季积雪覆盖的群落生长季短, 但明显比周围群落生长茂盛。为了说明雪斑地段群落生长机理, 对长白山苔原雪斑土壤氮素动态以及大白花地榆(Sanguisorba sitchensis)群落生产力进行了连续测定。雪斑群落土壤冬季相对温暖, 最低日平均温度-1.4 ℃, 裸露地段-16.9 ℃, 全年水分条件充足; 积雪期凋落物分解和氮矿化均在进行, 土壤具有很高的氮素含量及矿化速率。大白花地榆地上部分净初级生产力为4 046 kg·hm^-2·a^-1。正是独特的水热条件和养分条件, 以及具有很大的叶面积同化器官, 高山苔原雪斑地段的大白花地榆群落才得以维持生存并表现出很高的生产力水平。