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1.
为评估皆伐迹地地表苔藓组成与特点,同时为苔藓生物多样性的保护与恢复提供理论依据,作者于2006年7–10月调查了四川省阿坝藏族羌族自治州地区壤塘二林场云杉(Picealikiangensis var.rubescens)林皆伐迹地自然恢复过程中苔藓植物和维管植物的组成和结构;采用方差分析法对苔藓层结构参数进行差异性检验,对苔藓层结构参数和环境因子作非参数Spearman相关性分析,并对显著性因子进行回归分析。结果表明:(1)在9–27年植被自然恢复过程中,不同阶段苔藓植物群落优势物种组成发生了更替。一些个体较小、易产生孢子、喜阳、抗干扰的顶蒴藓物种侵入并占据优势;而一些出现于早期采伐迹地、喜湿、对环境变化较敏感的侧蒴藓物种消失。(2)随着迹地植被自然恢复,苔藓植物群落物种丰富度、多样性指数和均匀度指数总体上呈下降趋势;迹地上样方间苔藓层盖度和生物量波动较大,但随着自然恢复进程而迅速减少,群落结构趋向简单化;(3)维管植物发育程度与苔藓层发育关系密切;草本层生物量对苔藓盖度和种丰富度起主导作用,草本层高度是对苔藓生物量有显著影响的主导因子。综合分析表明,早期采伐迹地的自然恢复进程中由维管植物群落结构变化导致的生境差异对苔藓植物发育影响较大。  相似文献   

2.
植物种子大小与幼苗生长策略研究进展   总被引:20,自引:0,他引:20  
种子大小和幼苗更新对策是植物生活史策略的重要组成部分.本文从不同侧面综述了当前国内外关于种子大小和幼苗之间关系的生态学研究,包括:种子大小对萌发出土的影响,种子大小与幼苗形态生长特性之间的关系,种子大小与幼苗存活、竞争能力之间关系等,并对今后的相关研究进行了展望.在不同的微环境和植被类型下,种子大小与幼苗生长之间的关系可能有所差异;种子大小对植物幼苗生长的影响导致种子大小不同的植物对植被幼苗更新补充的贡献不同;种子大小与幼苗生活史策略关系在大尺度的群落空间水平上和小尺度的物种间与物种内的研究对于天然植被的更新恢复研究具有重要意义.  相似文献   

3.
种子大小及其命运对植被更新贡献研究进展   总被引:14,自引:3,他引:14  
种子是种子植物的繁殖体.种子对后代的资源投入将会直接影响后代的适合度进而影响到植被群落的更新.一般较大种子物种在种子萌发和幼苗生长阶段是具有较大优势的;但较小种子物种在逃避被动物采食和形成持久的土壤种子库成为植被更新的后备动力方面具有较大的优势.在不同的选择压力下,不同大小种子在以后的生活史中具有不同的命运,对植被的更新也具有不同的贡献.本文主要从种子大小和种子的传播散布、种子萌发、种子存活以及种子土壤库等方面综述了国外关于种子大小及其以后命运对植被更新贡献的研究结果,并对国内的相关研究提出了一些建议:种子生态学研究需要结合群落特点以及微环境等,开展从种子生产到幼苗更新全过程的系统性研究,为植物物种多样性保育和退化植被恢复方面提出有科学依据的管理措施.  相似文献   

4.
浙江天童常绿阔叶林地被层的研究   总被引:10,自引:0,他引:10       下载免费PDF全文
 对天童常绿阔叶林地被层植物种类组成及群落学作用进行了初步研究。研究表明:组成地被层计有维管植物44科78属114种。蕨类植物优势度最大,里白占绝对优势。39种草木植物,以世界分布科和地面芽植物为主,常绿种类占84.6%,未见亚洲和北美洲间断分布的地理成分。乔灌木幼苗51种,80%的苗量集中于4~6个种中,优势种突出。藤本植物24种,草质藤本占25%,落叶种类42%。地面苔藓植物(22种)与枯枝落叶构成镶嵌分布,发育较成熟的群落中苔藓种类多,盖度大。里白及其枯死物形成层层交错重叠的地被层,阻碍凋落物进入地表,减弱光照,使近地表光照长期低于幼苗光补偿点,抑制了乔灌木优势种的更新。凋落物阻碍种子下移至半分解层,栲树种子下移率为17%至22.3%,冬季种子的动物损耗率平均为98.2%,凋落物中种子的平均腐烂率为28.2%,表层保存下来的栲树种子因缺水萌发速度慢且成活率低,下层萌发速度虽快,但腐烂率高,栲树天然更新幼苗主要来源于草窗。  相似文献   

5.
蔺菲  郝占庆  叶吉  姜萍 《应用生态学报》2006,17(8):1398-1402
研究了长白山暗针叶林两种主要地面苔藓植物——塔藓和拟垂枝藓对红松、红皮云杉和落叶松种子萌发及幼苗生长的影响.结果表明,在一定浓度下,塔藓浸提液抑制红松发芽,拟垂枝藓浸提液促进红松发芽;苔藓浸提液对红皮云杉和落叶松的发芽率没有显著影响,但不同程度地加快了种子日萌发高峰的出现.用苔藓植物体直接培养红皮云杉和落叶松种子,发现活植物体量大时对发芽率没有显著影响,但延迟了红皮云杉种子萌发高峰的出现,加速了落叶松种子萌发高峰的出现;杀青后的苔藓植物体则明显地抑制种子发芽.通过幼苗培养实验,发现苔藓植物浸提液抑制红皮云杉和红松幼苗生长,但促进了落叶松幼苗的生长;不同处理的苔藓植物体对幼苗生长的影响差异较大,活植物体量大时,两种苔藓均促进了红皮云杉和落叶松幼苗生长,而杀青后植物体则明显地抑制幼苗生长.  相似文献   

6.
俞英  郭水良  陈建华  方芳 《广西植物》2009,29(4):518-521
研究卵叶泥炭藓(Sphagnumovatum),卷叶凤尾藓(Fissidenscristatus),弯叶灰藓(Hypnumcallichroum)和大金发藓(Polytrichumcommune)的水粗提取液对维管植物虎杖和皱叶酸模种子萌发和幼苗生长的影响。结果显示:四种苔藓植物的粗提取液对两种植物的种子萌发率并没有显著影响。然而,弯叶灰藓,、卵叶泥炭藓和卷叶凤尾藓的提取液抑制了皱叶酸模种子的活力指数。除此之外,卷叶凤尾藓还显著地抑制了它幼苗的干重。四种藓类的提取液对虎杖的种子活力指数和干重,但是卷叶凤尾藓的提取液对幼苗的生长有显著的影响。苔藓植物粗提取液对种子萌发和幼苗生长的影响的机制并不清楚,有待进一步研究。  相似文献   

7.
植物病原菌在森林动态中的作用   总被引:4,自引:0,他引:4       下载免费PDF全文
付先惠  曹敏  唐勇 《生态学杂志》2003,22(3):59-64,69
植物病原菌作为森林生态系统的重要组成成分及调控因子之一,在森林动态中扮演着重要的角色。植物病原菌通过侵染过程导致寄主植物的幼苗及成熟个体死亡、成熟个体的种子量降低或不实,或造成植物个体或群落中不同物种不同程度的病害,影响它们之间的营养竞争,从而导致群落结构、物种及个体数量的变化。感染散布前、后的种子和土壤种子库中的种子,以及由种子萌发产生的幼苗,它们的存活率降低,进而影响森林中的种子散布、幼苗更新与增补格局。在天然林中,先锋树种比顶极树种对病原菌更敏感,群落演替的早期阶段对病原菌比较敏感。植物病原菌主要通过密度依赖机制造成森林树种不同的死亡格局,从而参与森林的动态过程。  相似文献   

8.
不同演替阶段的群落中植物幼苗建植特性以及幼苗建植时所处的环境都会有所不同.这些差异可能会导致种子萌发率与物种多度之间的关系随着群落的演替阶段而发生改变.目前关于不同类型群落中以及同一类型群落的不同演替阶段物种多度和种子萌发能力之间的关系的研究较少.本研究以全面收集的青藏高原东缘3种常见次生植被(鼢鼠土丘群落、人工草地群落和弃耕地群落)中植物种子为基础,沿着群落演替梯度来探明种子萌发和物种多度之间的关系.通过对结果的线性回归分析发现:在鼢鼠土丘群落和人工草地群落中,种子萌发率和物种多度之间无显著相关性;而在弃耕地群落中,种子萌发率和物种多度之间的关系有随着群落的演替呈现由正相关向负相关转变的趋势.  相似文献   

9.
植物激素是由植物自身代谢产生的一类从产生部位移动到作用部位发挥调控功能的微量小分子有机物质,在植物生长发育、响应环境胁迫过程中起到关键作用。苔藓植物作为早期登陆的非维管植物,处于陆生植物进化早期的阶段,具有许多不同于维管植物的形态和生理特征。大部分苔藓中普遍存在8种主要的植物激素及其衍生物(包括ABA、JA、ET、SA、Auxin、CK、GAs和BRs),并且在合成代谢以及信号转导通路上存在相关同源基因,但苔藓植物中某些植物激素在存在形式及功能上与维管植物传统认知有所不同,说明苔藓植物激素的合成代谢、信号转导过程在进化上既具有保守性也具有特殊性。目前苔藓植物激素研究较少,且多集中在ABA等少数激素的功能研究上,缺乏调控机制研究。该文梳理了苔藓植物激素在合成代谢与信号转导通路中关键基因组分及其与维管植物的异同,系统综述了植物激素在苔藓生长发育、非生物与生物胁迫过程中所起到的作用以及调控机制,旨在对今后苔藓植物激素调控机制的研究提供一定的研究思路和理论参考。  相似文献   

10.
植物天然更新过程中种子和幼苗死亡的影响因素   总被引:46,自引:0,他引:46  
植物天然更新包括有种子搬运、种子库动态、种子萌发和幼苗定居等过程。从种子生产到幼苗定居的更新是植物生活史中最为敏感的阶段之一 ,多种因素的影响种子和幼苗的命运。其中包括 :( 1 )动物取食或病原体侵袭。种子在扩散和搬运过程中 ,易被小哺乳动物或无脊椎动物取食。蛀虫也可以使种子失去萌芽能力。病原体感染种子和幼苗 ,容易引起种子和幼苗的死亡。 ( 2 )异质生境的影响。在不同生境中 ,光照条件、土壤水分和化学成分等因子的组合严重影响种子和幼苗的命运。 ( 3 )干扰的影响。小尺度和大尺度的干扰都可以影响到植物更新时种子和幼苗的命运。林窗作为特殊的干扰体系 ,为不同种类植物提供了更新的机会。 ( 4 )繁殖体特征。种子大小、质量和保护色等特征影响种子和幼苗在更新过程中的生存。种子休眠期间 ,由于生理衰老和腐烂的原因使种子失去活力而不能萌发。 ( 5 )密度和距离制约。母株附近由于密度竞争的影响 ,种子和幼苗死亡率都较高。  相似文献   

11.
Interactions between vascular plants and bryophytes determine plant community composition in many ecosystems. Yet, little is known about the importance of interspecific differences between bryophytes with respect to their effects on vascular plants. We compared the extent to which species-specific bryophyte effects on vascular plant generative recruitment depend on the following underlying mechanisms: allelopathy, mechanical obstruction, soil moisture and temperature control. We sowed 10 vascular plant species into monospecific mats of six chemically and structurally diverse bryophytes, and examined 1-yr seedling recruitment. Allelopathic effects were also assessed in a laboratory phyto-assay. Although all bryophytes suppressed vascular plant regeneration, there were significant differences between the bryophyte species. The lack of interactions indicated the absence of species-specific adaptations of vascular plants for recruitment in bryophyte mats. Differences between bryophyte species were best explained by alterations in temperature regime under bryophyte mats, mostly by reduced temperature amplitudes during germination. The temperature regime under bryophyte mats was well predicted by species-specific bryophyte cushion thickness. The fitness of established seedlings was not affected by the presence of bryophytes. Our results suggest that climatically or anthropogenically driven changes in the species' composition of bryophyte communities have knock-on effects on vascular plant populations via generative reproduction.  相似文献   

12.
Herbivory can affect plant community composition and diversity by removing biomass and reducing light competition. Herbivory may particularly benefit low growing species such as bryophytes, which are frequently limited by light competition. Gastropods are important herbivores of seed plants and cryptogams, furthermore, they can disperse propagules such as seeds and spores via endozoochory. However, whether gastropod herbivory can reduce the dominance of vascular plants and thereby promote the germination and establishment of endozoochorously dispersed bryophyte spores has never been tested experimentally. Moreover, it is unclear whether these possible interacting effects can influence bryophyte species richness. Here, we tested for endozoochorous spore dispersal by slugs, in combination with sowing of vascular plants, in a fully factorial common garden experiment. Enclosures contained either slugs previously fed with bryophyte sporophytes, control slugs, or no slugs. After 21 days the bryophyte cover was on average 2.8 times higher (3.9% versus 1.4%) and after eight months the bryophyte species richness 2.6 times higher (5.8 versus 2.2) in enclosures containing slugs previously fed with bryophyte sporophytes than in the other treatments. Furthermore, after eight months high vascular plant cover reduced bryophyte diversity. On average enclosures without seed sowing harboured 1.6 times more bryophyte species than the ones with seed sowing (4.2 versus 2.6), indicating competitive effects of vascular plants on bryophytes. Our findings suggest that slugs are important dispersal vectors for bryophytes and that they can increase bryophyte populations and maintain bryophyte diversity by reducing the dominance of vascular plants.  相似文献   

13.
Fungal communities associated with plant tissues were compared between two bryophyte species dominating decaying logs (Scapania bolanderi and Pleurozium schreberi), and roots of spruce seedlings growing on the bryophytes and in the ground soil, to evaluate the contribution of fungal communities to seedling regeneration. Using high-throughput DNA sequencing, a total of 1233 fungal operational taxonomic units (OTUs) were detected. Saprotrophic Ascomycota were dominant in bryophytes, whereas ectomycorrhizal (ECM) Basidiomycota were dominant in spruce roots. Fungal communities were significantly different between the two bryophyte species. In addition, fungal communities of spruce seedlings were significantly affected by the substrates on which they were growing. Some ECM fungi were detected from both of the bryophytes and the spruce seedlings growing on them; however, the dominant OTU identities differed between the two bryophyte systems. The possible effects of functional differences between dominant fungal OTUs on spruce seedling regeneration are discussed.  相似文献   

14.
Bryophytes, which include mosses, liverworts and hornworts, indeed play a significant role in the natural dynamics of native forests. They contribute to fundamental ecological processes such as tree regeneration. In this context, the objective was to analyse the association of bryophytes with Nothofagus seedlings, as well as whether the substrates where bryophytes grew influenced bryophyte-tree seedling association, in sub-Antarctic forests at two contrasting landscapes (coastal and mountain) of Tierra del Fuego (Argentina), to better understand their impacts on the natural regeneration processes. We hypothesized that bryophytes act as a substrate for seed germination and initial regeneration growth in pure and mixed forests of N. pumilio and N. betuloides, resulting in widespread tree seedlings–bryophyte associations in all landscapes. In each forest and landscape location, 60 transects were established (10 m in length) to evaluate bryophyte cover (by point intercept method) and substrate type (bare soil, decaying wood and litter cover) where they were growing. An adaptation of the relative interaction index (RII) based on tree seedling cover associated with bryophyte species (%) and tree seedling cover in the absence of bryophytes (%) was calculated and analysed to assess competition or facilitation between bryophytes and tree seedlings. Nothofagus pumilio seedlings were less abundant in bryophytes compared to other substrates, suggesting an inhibitory effect on the germination and/or survival of N. pumilio. In contrast, the seedlings of N. betuloides, in both pure and mixed forests, exhibited higher abundance on bryophyte substrates, particularly in mosses at mountain landscape (RII = 0.83 ± 0.08 in litter and 0.62 ± 0.11 in decaying wood). These findings suggest that bryophytes play a facilitating role for N. betuloides seedlings during germination and initial phases of growth, mainly in the mountain. Therefore, their conservation promotes N. betuloides forest continuity, both in pure and mixed structures.  相似文献   

15.
Bryophytes are widespread in terrestrial ecosystems but little is known about their influence on vascular species. Water‐soluble leachates (0%, 1%, 5%, 10% concentration) derived from 18 species of bryophytes (mosses 11 species; liverworts 7 species) were tested on the germination and seedling growth of Lactuca sativa and two common trees Melicytus ramiflorus (Violaceae) and Fuchsia excorticata (Onagraceae) in southern New Zealand forests. Bryophyte water soluble extracts (BWSE) have minor impact on seed germination of Lactuca, stimulatory effects on radical growth at low (1%) concentrations and inhibitory effects at higher concentrations (5–10%). For Melicytus the BWSE had variable effects, with evidence of strong stimulatory (Dendrohypopterygium filiculiforme) and inhibitory (Lepidozia concinna) effects on germination, but generally inhibited radical growth. BWSE at all test concentrations consistently inhibit both germination and seedling radicle growth in Fuchsia. The toxicity effect of water‐soluble leachates varies significantly between bryophyte species but not consistently between mosses and liverworts. Bryophyte species exhibiting strongest inhibition effects under control conditions were associated with significantly reduced densities of broadleaved tree seedlings in forest ecosystems. Our results demonstrate that some bryophyte species via allelopathic interactions can inhibit seedling establishment and growth of forest trees. This mechanism provides an additional factor constraining the spatial distribution of the regeneration niche in forest communities.  相似文献   

16.
In grassland communities vascular plants and bryophytes form two distinct layers. In order to understand the factors responsible for plant community structure, more information about interactions between these plant groups is needed. Often negative correlations between vascular plant and bryophyte covers have been reported, suggesting competition. Here we tested experimentally whether different grassland vascular plant species (Trifolium pratense, Festuca pratensis, Prunella vulgaris) had different influences on the cover of two bryophyte species (Rhytidiadelphus squarrosus, Brachythecium rutabulum). In a two-year garden pot experiment one bryophyte species and one vascular plant species were planted per pot. Bryophytes were planted at a constant density, vascular plants in four densities. The cover of both bryophyte species increased with increasing vascular plant cover, showing the facilitative effect of vascular plants through creating better microclimate, e.g., optimising temperature. Bryophyte responses to vascular plant species were species-specific. Festuca had significantly positive effects on both bryophyte species in the second year, and Trifolium on Brachythecium in both years, whereas Prunella had no significant effect on bryophytes. The facilitative effect of vascular plants was stronger at the second experimental year. In summary, the biotic effects between bryophytes and grassland vascular plants are species-specific and positive interactions are prevailing at low vascular plant densities.  相似文献   

17.
BACKGROUND AND AIMS: Natural regeneration of white spruce (Picea glauca) after disturbance has been reported to be very poor. Here a study was made to determine whether C compounds released from understorey species growing together with white spruce could be involved in this regeneration failure, either by (1) changing soil nutrient dynamics, (2) inhibiting germination, and/or (3) delaying seedling growth. METHODS: Foliage leachates were obtained from two shrubs (Ledum palustre and Empetrum hermaphroditum) and one bryophyte (Sphagnum sp.) with high phenolic compound concentrations that have been reported to depress growth of conifers in boreal forests, and, as a comparison, one bryophyte (Hylocomium splendens) with negligible phenolic compounds. Mineral soil from a white spruce forest was amended with plant leachates to examine the effect of each species on net N mineralization. Additionally, white spruce seeds and seedlings were watered with plant leachates to determine their effects on germination and growth. KEY RESULTS: Leachates from the shrubs L. palustre and E. hermaphroditum contained high phenolic compound concentrations and dissolved organic carbon (DOC), while no detectable levels of C compounds were released from the bryophytes Sphagnum sp. or H. splendens. A decrease in net N mineralization was determined in soils amended with L. palustre or E. hermaphroditum leachates, and this effect was inversely proportional to the phenolic concentrations, DOC and leachate C/N ratio. The total percentage of white spruce germination and the growth of white spruce seedlings were similar among treatments. CONCLUSIONS: These results suggest that the shrubs L. palustre and E. hermaphroditum could negatively affect the performance of white spruce due to a decrease in soil N availability, but not by direct effects on plant physiology.  相似文献   

18.
We compare species richness of bryophytes and vascular plants in Estonian moist forests and mires. The material was collected from two wetland nature reserves. Bryophyte and vascular plant species were recorded in 338 homogeneous stands of approximately 1 ha in nine forest and two mire types. Regional species pools for bryophytes and vascular plants were significantly correlated. The correlations between the species richnesses of bryophytes and vascular plants per stand were positive in all community types. The relative richnesses (local richness divided by the regional species pool size) were similar for bryophyte species and for vascular plant species. This shows that on larger scales, conservation of the communities rich in species of one taxonomic plant group, maintains also the species richness of the other. The minimum number of stands needed for the maintenance of the regional species pool of typical species for the every community type was calculated using the species richness accumulation curves. Less stands are needed to maintain the bryophyte species pools (300–5300 for bryophytes and 400–35 000 for vascular plants).  相似文献   

19.
Ingerpuu  Nele  Kull  Kalevi  Vellak  Kai 《Plant Ecology》1998,134(2):163-171
In the Laelatu wooded meadow in Estonia, famous for its phanerogam diversity, the bryophyte community has been investigated in order to compare its flora and diversity relationships with those of the vascular plant community. Ninety-six bryophyte species were found, 13 of them are hepatics; the majority of the bryophytes are epigeic species common to meadows and forests, including many calciphilous species. Vascular plants and bryophytes display opposite responses to fertilisation. For vascular plants, fertilisation increases the coverage and diminishes the number of species, while for bryophytes it diminishes coverage and increases the number of species. The relationship between the number of species in small plots and the total number of species in the area is similar for vascular plants and bryophytes. No significant changes in the bryophyte community in Laelatu wooded meadow has been detected during the last 30 years.  相似文献   

20.
 对壤塘县二林场4个不同时间皆伐和造林后形成的幼林地, 开展了苔藓植物和维管植物多样性调查, 采用方差分析法对苔藓植物特征进 行差异性检验, 对苔藓植物结构特征和环境因子作偏相关性分析。结果表明: 1)幼林地4个阶段的发展进程中苔藓物种组成变化显著。优势种相 似, 为喜光耐旱的侧蒴藓物种; 一些耐阴喜湿的种类种群扩大成为林下局部生境优势物种; 同时由于干扰造成地表裸露后产生耐旱土生或石生 性广泛分布的藓类。2)随着幼林地植被恢复进程, 苔藓物种丰富度(22~37)和多样性指数(0.37~1.08)呈增长趋势。结构特征在4个幼林地表现 出较强的差异性。3)乔木与灌木层盖度与苔藓植物的发育呈正相关, 灌木层盖度的发育明显促进了苔藓植物丰富度的增加, 而基于喜光先锋的 禾草为主的草本发育程度很高, 与凋落物生物量一起抑制了苔藓的发育。随幼林地发展, 乔、灌、凋落物发育性质及其相互作用发生动态变化 。因此加速幼林地乔、灌层片的发育对于促进地表苔藓植物多样性的恢复与层片发育具有重要作用。  相似文献   

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