共查询到20条相似文献，搜索用时 11 毫秒
1.
Elisabet Safont Valentí Rull Teresa Vegas-vilarrúbia Bruce k. Holst Otto Huber Shingo Nozawa 《分类学与生物多样性》2013,11(3):292-314
Climate change is forcing many plant species to shift their range in search of adequate environmental conditions, being localized endemic species particularly at risk on mountain summits. The Pantepui biogeographic province, a set of flat-topped mountain summits (called tepuis) of northern South America, contains both high plant diversity and a high degree of endemism. Previous studies based on warming projections for the area suggested that half of the Pantepui endemic flora would disappear due to habitat loss by 2100. In this study, we selected one of the best-explored tepuis, Roraima-tepui, to establish the baseline of diversity and endemism for comparisons with historical data and future monitoring surveys, aimed at testing the hypothesis of upward migration of plants in response to global warming. We also analysed floristic and physiognomic features of the Eastern Tepui Chain (ETC, the mountain range where Roraima is located), and the phytogeographic patterns of both the ETC and Pantepui. The Roraima summit contains 227 species, including 44 new records, 13 exotic species (some of them with high invasive potential), and at least one species new to science. At the ETC level, Roraima is the tepui with highest species richness and degree of endemism, and shows a relatively high floristic similarity with Kukenán and Ilú. Herbaceous species dominate over shrubs on these tepuis, Tramen and Maringma, whereas on Yuruaní, Karaurín and Uei, they reach similar abundances. At the Pantepui level, endemic species have highly localized distribution patterns (17% local endemics). Conservation opportunities are evaluated in light of these results. 相似文献
2.
Valentí Rull 《Global Ecology and Biogeography》2004,13(2):141-148
Aim To document the occurrence of vertical displacements of vegetation in the high plateaus of the Venezuelan Guayana (tepuis) over the last c. 6000 years, and to discuss their significance for the origin of their flora, especially the endemism patterns observed in their flat summits. Two hypotheses have been proposed for the origin of the summit flora. One (the Lost World hypothesis) proposes a long history of evolution in isolation from the surrounding plains, while the other (the Vertical Displacement hypothesis) suggests that vertical movements of vegetation during the Pleistocene glacial‐interglacial cycles would have resulted in floristic mixing within the lowlands, and genetic interchange among plateau summits. Location This work has been conducted on the flat summit of the Churí‐tepui, in the Chimantá massif, at 5°15′ Lat. N and 62°01′ Long. W, around 2250 m altitude. Methods Pollen analysis and radiocarbon dating of two peat outcrops, using modern analogue technique and numerical methods for palaeoecological interpretation were used. Results The replacement of a high‐altitude plant community (a paramoid Chimantaea shrubland) by a lower elevation (< 2300 m) Stegolepis meadow, occurred about 2500 years before present (yr bp ). This vegetation change is inferred to have resulted from a regional climatic shift to higher temperature and moisture. A subsequent decrease in temperature and moisture led to the establishment of present conditions after about 1450 yr bp . Main conclusions The highland vegetation of the tepuis responded to climate shifts with vertical displacements, supporting the hypothesis of vertical mixing. However, a physiographical analysis shows that around half of the tepuis would never have been connected by lowlands. Therefore, both hypotheses are needed to explain the origins of the summit flora in the tepuis. 相似文献
3.
董劭琼;侯东杰;曲孝云;郭柯 《植物生态学报》2024,48(4):534-540
柴达木盆地地处青藏高原东北部, 为高原型巨大封闭盆地, 植被以荒漠为主, 兼具沼泽湿地、盐生草甸和山地草原等。为更精细地展示柴达木盆地地区植被的物种组成、群落特征及其分布格局, 该研究利用2022年夏季第二次青藏高原综合科学考察及2014年青藏高原资料匮乏区综合科学考察的野外数据, 共157个样地, 458个样方, 整合为柴达木盆地植物群落样方数据集。通过数据的整理与汇编, 共得到185条物种信息, 其中物种数最多的科依次为菊科(39种)、禾本科(33种)、豆科(17种)、苋科(16种)及十字花科(10种), 包含物种数最多的属依次为针茅属(Stipa)、蒿属(Artemisia)、黄耆属(Astragalus)、棘豆属(Oxytropis)和风毛菊属(Saussurea)等。植物生活型组成以草本居多, 占78.37%; 区系地理成分以亚洲中部种占优势, 占41.62%。基于群落学-生态学分类原则, 157个样地可以归为4个植被型组, 7个植被型, 11个植被亚型, 40个群系。该数据集可为深入研究柴达木盆地植被特征、《中国植被志》编研、青藏高原及全国植被图绘制提供最原始的基础数据。 相似文献
4.
Hussein M. Sulieman 《African Journal of Ecology》2014,52(2):217-227
The present study seeks to provide a contribution to the understanding of vegetation regrowth on abandoned agricultural land by investigating the impacts of the previous cultivation period and the duration of the fallow on the subsequent natural regeneration in terms of vegetation composition, structure and diversity. The results of the study show that both factors have significant effects on the subsequent regeneration of plant species and thus the vegetation development in the southern Gadarif Region, Sudan. The oldest abandoned farmlands were recolonized by tree/shrub species, whereas recently abandoned ones are covered with herbaceous vegetation. There is a general tendency regarding the number of species to decrease with an increase in the period of cultivation. The plant species diversity pattern shows domination of herbaceous species with some scattered woody species. Vegetation changes due to land abandonment may have implications for the conservation of plant species diversity and composition of fauna harboured in the region. Although natural regeneration could be recommended as means of restoring natural vegetation that previously dominated that region, the current regeneration capacity might not be sufficient to reach the climax vegetation except for some pockets, which received more regenerative resources. 相似文献
5.
对山西五台山林区4种典型人工林群落物种多样性特征进行了定量研究,结果表明: 1 4种人工林群落灌木层和草本层的Simpson指数 D 和Shannon-Wienner指数 H′ 差异不显著,物种丰富度指数和均匀度指数 Jsw 差异显著,均匀度指数 Ea 差异极显著,草本层发育明显好于灌木层; 2 各人工群落尚处于演替初期阶段,林下植被发育常以禾本科阳生性植物为主; 3 对4种人工林群落灌草层物种多样性显著性检验结果显示,在灌草层物种多样性特征上,油松林与桦木林、山杨林多样性差异显著 P<0.05 ,其它群落差异不显著.山杨林物种多样性程度较高,油松林最差; 4 不同人工林群落物种总体多样性特征分析表明,桦木和山杨人工林群落总体α多样性与油松林差异显著,且多样性较大,阔叶林更有利于林下植被的发育和更新; 5 对人工生态系统物种多样性研究是退耕还林、天然林保护等生态环境工程的延伸,对于植被恢复后的生物学效果评价有重要意义. 相似文献
6.
James L. Tsakalos Michael Renton Mark P. Dobrowolski Erik J. Veneklaas Paul D. Macintyre Sarah J. Broomfield Ladislav Mucina 《Austral ecology》2019,44(5):906-916
The nature of community patterns and environmental drivers in kwongan mediterranean‐type shrubland on nutrient‐poor soils occurring in Western Australia remain poorly examined. We aimed to determine whether (i) classification of the kwongan vegetation of the northern Swan Coastal Plain would be ecologically informative and (ii) which environmental drivers underpin the plant community patterns. The study area was positioned on the northern Swan Coastal Plain, locality of Cooljarloo (30°39′ S, 115°22′ E), situated 170 km north of Perth, Western Australia. Compositional (518 species × 337 relevés) and environmental data set (29 variables × 87 relevés) describing time since last fire, soil chemical and physical properties, and terrain characteristics were analysed using classification and ordination techniques. OptimClass assisted in the selection of a robust data transformation, resemblance function and clustering algorithm to identify the vegetation patterns. Major ecological drivers of the vegetation patterns were detected using distance‐based redundancy analysis (db‐RDA). Classification revealed major groupings of Wet Heath and Banksia Woodland distinguishable by the high prevalence of myrtyoid and proteoid taxa, respectively. On floristic‐sociological grounds, we recognised four Wet Heath and two Banksia Woodland communities. The Wet Heath was constrained to areas of higher litter depth (db‐RDA axis 1: 9%). Soil chemical and physical properties explained the highest proportion (17%) of the compositional variance, while the terrain‐ and fire‐related variables explained 2% and <0.001%, respectively. While fire explained little compositional variance overall, a separate db‐RDA analysis found that it may play an important pattern‐structuring role within Banksia Woodlands. Fine‐scale compositional patterns correspond only to a small extent to environmental data; the substantial unexplained variance may be due to slow‐acting neutral and stochastic processes. 相似文献
7.
We evaluated effects of atmospheric deposition of nitrogen on the composition of forest understorey vegetation both in space and time, using repeated data from the European wide monitoring program ICP‐Forests, which focuses on normally managed forest. Our aim was to assess whether both spatial and temporal effects of deposition can be detected by a multiple regression approach using data from managed forests over a relatively short time interval, in which changes in the tree layer are limited. To characterize the vegetation, we used indicators derived from cover percentages per species using multivariate statistics and indicators derived from the presence/absence, that is, species numbers and Ellenberg's indicator values. As explanatory variables, we used climate, altitude, tree species, stand age, and soil chemistry, besides deposition of nitrate, ammonia and sulfate. We analyzed the effects of abiotic conditions at a single point in time by canonical correspondence analysis and multiple regression. The relation between the change in vegetation and abiotic conditions was analyzed using redundancy analysis and multiple regression, for a subset of the plots that had both abiotic data and enough species to compute a mean Ellenberg N value per plot using a minimum of three species. Results showed that the spatial variation in the vegetation is mainly due to “traditional” factors such as soil type and climate, but a statistically significant part of the variation could be ascribed to atmospheric deposition of nitrate. The change in the vegetation over the past c. 10 years was also significantly correlated to nitrate deposition. Although the effect of deposition on the individual species could not be clearly defined, the effect on the vegetation as a whole was a shift toward nitrophytic species as witnessed by an increase in mean Ellenberg's indicator value. 相似文献
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Summary
Neblinaria celiae (Theaceae), a rosette shrub endemic to the exceedingly rainy summit of remote Cerro de la Neblina in southern Venezuela, has a previously undescribed set of adaptations to fire. Its growth form entails sparse branching, massive terminal leaf rosettes, and thick bark. It is highly fire-tolerant, with a survival rate of 93% in a stand recently ignited by lightning, vs. 0% in seven co-occurring woody species. Survival increases sharply with rosette height, favoring a sparsely branched habit that would maximize the rate of upward growth through the sparse fuel layer supported by a sterile substrate. Thick bark and massive rosettes help protect cambial and foliar meristems from brief exposure to high temperatures. Rosettes on shorter plants are exposed to greater damage from fire near the ground and, as expected, are bigger and impound more rainwater; the greater number of leaves nearly balances the greater leaf mortality caused by fire. We relate Neblinaria's growth form to its dominance atop Neblina, to a general model for the evolution of sparse branching, and to the evolution of growth form in other tepui plants. 相似文献
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Jacob Nabe‐Nielsen Signe Normand Francis K. C. Hui Lærke Stewart Christian Bay Louise I. Nabe‐Nielsen Niels Martin Schmidt 《Ecology and evolution》2017,7(23):10233-10242
Arctic plant communities are altered by climate changes. The magnitude of these alterations depends on whether species distributions are determined by macroclimatic conditions, by factors related to local topography, or by biotic interactions. Our current understanding of the relative importance of these conditions is limited due to the scarcity of studies, especially in the High Arctic. We investigated variations in vascular plant community composition and species richness based on 288 plots distributed on three sites along a coast‐inland gradient in Northeast Greenland using a stratified random design. We used an information theoretic approach to determine whether variations in species richness were best explained by macroclimate, by factors related to local topography (including soil water) or by plant‐plant interactions. Latent variable models were used to explain patterns in plant community composition. Species richness was mainly determined by variations in soil water content, which explained 35% of the variation, and to a minor degree by other variables related to topography. Species richness was not directly related to macroclimate. Latent variable models showed that 23.0% of the variation in community composition was explained by variables related to topography, while distance to the inland ice explained an additional 6.4 %. This indicates that some species are associated with environmental conditions found in only some parts of the coast–inland gradient. Inclusion of macroclimatic variation increased the model's explanatory power by 4.2%. Our results suggest that the main impact of climate changes in the High Arctic will be mediated by their influence on local soil water conditions. Increasing temperatures are likely to cause higher evaporation rates and alter the distribution of late‐melting snow patches. This will have little impact on landscape‐scale diversity if plants are able to redistribute locally to remain in areas with sufficient soil water. 相似文献
12.
Stefan Meyer Erwin Bergmeier Thomas Becker Karsten Wesche Benjamin Krause Christoph Leuschner 《应用植被学》2015,18(3):432-442
13.
当前,西双版纳地区大面积橡胶单一种植林已引发了诸多的生态环境问题,为解决这些问题同时协调当地的经济发展,农林复合系统被生态学者们认为是最好的解决办法。然而目前关于不同间作模式下橡胶树水分利用效率研究还很少。因此,于2013－2014年的雨季中期(8月)和末期(11月)、雾凉季(1月)、干热季(3月),分别测定了中国科学院西双版纳热带植物园内四种不同胶农(林)复合系统(橡胶—叶茶、橡胶—咖啡、橡胶—大叶千斤拔、橡胶—可可复合系统)及单层橡胶林的土壤含水量、橡胶树及其林下间作植物的枝条凌晨水势和正午水势,以及它们植物叶片的δ13 C值,分析了各胶农(林)复合系统内橡胶树的水分利用效率,以期遴选出水分关系配置合理的复合橡胶林栽培模式,为环境友好型橡胶种植林的建设和推广提供相关的参考依据和理论支持。结果表明：除橡胶—可可复合系统以外,其余胶农(林)复合系统内的橡胶树水分利用效率值均高于单层橡胶林;橡胶—大叶千斤拔复合系统的土壤含水量显著高于其它复合系统;橡胶—叶茶复合系统的土壤含水量虽然低于橡胶—大叶千斤拔复合系统,但其最为稳定、季节变化小;橡胶—咖啡复合系统的水分利用效率最高最稳定,即使受到寒害也没有引起明显变化;而橡胶—可可复合系统的作用不明显,所有特征都与单层橡胶林相似。这表明除了橡胶—可可复合系统外,其他3种胶农(林)复合系统都显著地缓解了橡胶树在旱季所遭受的水分胁迫,同时也能有效地抵御突发性天气灾害。 相似文献
14.
Negative species co‐occurrence patterns have long intrigued ecologists because of their potential link to competition. Although manipulative field experiments have consistently revealed evidence of competition in natural communities, there is little evidence that this competition produces negative co‐occurrence patterns. Evidence does suggest that abiotic variation, dispersal limitation and herbivory can contribute to patterns of negative co‐occurrence among species; it is possible these influences have obscured a link with competition. Here, we test for a connection between negative co‐occurrence and competition by examining a small‐scale, relatively homogeneous old‐field plant community where the influence of abiotic variation was likely to be minimal and we accounted for the impact of herbivory with an herbivore exclosure treatment. Using three years of data (two biennial periods), we tested whether negatively co‐occurring pairs of species, when occasionally found together, experienced asymmetric abundance decline more frequently than positively co‐occurring pairs, for which there is no such expectation. We found no evidence that negatively co‐occurring pairs consistently suffered asymmetric abundance decline more frequently than positively co‐occurring pairs, providing no evidence that competition is a primary driver of negative co‐occurrence patterns in this community. Our results were consistent across control and herbivore exclosure treatments, suggesting that herbivores are not driving patterns of negative species co‐occurrence in this community. Any influence of competition or herbivory on co‐occurrence patterns is small enough that it is obscured by other factors such as substrate heterogeneity, dispersal and differential species responses to climatic variation through time. We interpret our results as providing evidence that competition is not responsible for producing negative co‐occurrence patterns in our study community and suggest that this may be the case more broadly. 相似文献
15.
采用样地样方调查法,通过Margalef指数、Shannon-weiner指数和Pielou指数综合分析了北京市3条主要河流(潮白河、拒马河、清水河)的滨岸带植被物种丰富度、多样性及均匀度。结果表明:在11个样地中共记录植物74科248种,其中蕨类植物3科7种,双子叶植物56科166种,单子叶植物15科75种。清水河滨岸带的植物Mar-galef指数、Shannon-weiner指数和Pielou指数均高于潮白河与拒马河,植被状况保持较好。 相似文献
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To investigate the dynamic changes in the artificial vegetation in an abandoned mining site,we analyzed the relationships among community types,environmental variables and community structure in the process of vegetation restoration in the Antaibao mining site,China by survey of the communities and use of biological dating methods.By means of the quantitative classification method (two-way indicator-species analysis,TWINSPAN) and the ordination technique (de-trended correspondence analysis,DCA; and de-trended canonical correspondence analysis,DCCA),the plant communities were classified into seven groups:community Ⅰ,Robinia pseudoacacia + Pinus tabulaeformis-Caragana korshinskii-Agropyron cristatum; community Ⅱ,Robinia pseudoacacia-Hippophae rhamnoides-Artemisia capillaries; community Ⅲ,Ulmus pumila-Elaeagnus angustifolia-Artemisia capillaries;community Ⅳ,Caragana korshinskii-Agropyron cristatum+Artemisia capillaries;community Ⅴ,Hippophae rhamnoides-Elymus dahuricus;cornrnunity Ⅵ,Elaeagnus angustifolia+Hippophae rhamnoides-Brassica jucea;community Ⅶ,Hippophae rhamnoides+Elaeagnus angustifolia-Salsola collina.We conclude that the community types and diversity are mainly influenced by the succession time and the soil organic matter content.The forest community is more adaptable to the special inhabitation than the shrub community. 相似文献
17.
《应用生态学报》2024,35(1)
荒漠化区植物群落研究是评价区域生态环境质量和开展荒漠化防治的科学基础,本研究按经度将辽西北荒漠化区划分为东部(122°50′37″—123°49′40″ E)、中部(121°16′41″ —122°35′00″ E)和西部(119°20′03″ —120°02′41″ E)3个区域,对植物群落进行调查。结果表明: 乔木林所占比例及郁闭度自西向东增加;东部区域多为樟子松林和杨树林,中部区域多为油松林和杨树林,西部区域则多为油松林和西伯利亚杏林。灌丛在东部、中部和西部区域占比分别为0、22.2%和28.0%。东部和中部区域的草地多由人为扰动后形成。物种数量为中部区域(110种)＞西部区域(88种)＞东部区域(75种)。东部和中部区域都以一年生植物占比最高,分别为68.2%和66.7%,西部区域则以地面芽植物最占优势(36.3%);小高位芽植物、矮高位芽植物、地上芽植物和地下芽植物的比例从东向西逐渐升高。物种数量、Shannon指数和Simpson指数均以中部区域最高,Pielou均匀度指数则从东向西逐渐升高。β多样性指数显示,东部与西部区域之间的群落相似性最小,中部与西部区域的群落相似性较高。中部区域的群落类型、物种数量、物种构成特征及物种多样性均呈现出了生态过渡带的特征。总体上,辽西北荒漠化区植被状况良好,但存在乔木林垂直结构简单、树种组成单一、人为干扰较为严重等问题。 相似文献
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岷江干旱河谷生态环境脆弱,植被恢复困难,大规模的公路建设极易对当地生态环境造成破坏。筛选适宜的植被恢复措施对干旱地区道路边坡的乡土植被恢复重建和生态功能提升尤为重要。以岷江干旱河谷极端退化的土石混合的道路边坡为案例,选取乡土灌木和草本植物构建植物群落,进行裸地播种、播种后覆盖纤维毯和添加腐殖土后播种并地表覆盖纤维毯3种不同的种植处理,揭示了不同处理下群落结构、土壤改良以及水土保持效益的差异。发现,乡土灌草群落是干旱河谷适宜的道路边坡植被恢复模式,种植后第3年群落特征趋近于岷江干旱河谷区自然生态系统的多年生灌草植被。纤维毯覆盖+覆土处理在促进植物生长和群落构建,水土流失防治上效果最好,群落总盖度为74%,群落总生物量为506.35 g/m2;生长季内,与自然恢复相比小区径流量减少了87.8%,泥沙流失量降低了92.1%。土壤改良效应在3种处理之间差异不明显,但是与自然恢复样地相比,各处理均提升了边坡0—20 cm土层土壤养分。不同种植处理下植物群落结构差异是影响干旱河谷土石混合的道路边坡水土流失的关键因子。 相似文献
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网格化清查方法有助于准确诊断一个地区的植被性质,并为探索植被分类方法提供支持。该研究以上海大金山岛为对象,借助航拍影像等间距地将其划分为140个清查网格(40 m×40 m),按照统计样方法逐网格调查植物群落特征,综合运用列表法和双向指示种法,进行植被分类并绘制现状植被图。按照新修订的植被三级分类系统进行分类：一级单位根据植被型,大金山岛植被划分为落叶阔叶林、常绿落叶阔叶混交林、常绿阔叶林、落叶阔叶灌丛、常绿落叶阔叶混交灌丛、常绿阔叶灌丛和草丛;二级单位根据优势种和植物区系特征,可划分出15种群丛或群落类型;三级单位根据群落年龄和外貌可划分为22种群落类型。以上结果表明,大金山岛不仅是上海市物种多样性最高的区域,也拥有华东海岛最典型、最多样的自然半自然森林群落。就植被状态而言,地带性森林群落处于演替中后期,但少数次生植被处于演替前期,且面临着猴群干扰导致的植被发育停滞不前等生态问题。关于植被分类方法,网格化清查方法可充分揭示植物群丛连续性中包含间断性和过渡性群落的现象。 相似文献
20.
城市公共绿地常见木本植物组成对鸟类群落的影响 总被引：1，自引：0，他引：1
快速城市化背景下, 城市公共绿地已经成为重要的鸟类栖息地, 其中的木本植物群落构成对鸟类群落结构有显著影响, 研究木本植物配置与鸟类多样性的关系对提升城市公共绿地作为鸟类栖息地的生态服务功能有重要的理论和应用价值。我们于2009–2010年间在上海市滨江森林公园就木本植物和鸟类群落的相互关系展开研究。样线法结合样点调查共记录到鸟类10目25科64种5,368只(次), 鸟类多度全年变化显著, 峰值分别出现在4月和11月。丰富度全年也呈现双峰型变化, 峰值出现在4月和12月。全年鸟类多样性(Simpson指数)差异显著, 10月最高, 8月最低。样方调查共记录到77种木本植物, 其中有14种(乔木9种、灌木5种)出现率超过5个样方, 定义为常见种, 其果期主要集中在9月到翌年2月, 其上常见林业致病害虫的发生盛期集中在5–11月。主成分分析显示, 常见木本植物上观察到的鸟类可划分为8个鸟类集团, Spearman秩相关检验显示秋冬季常见木本植物果期与植食性、肉食性、食虫性、杂食性等多个鸟类集团的多度均呈显著正相关。说明在秋冬季鸟类迁徙高峰期不同鸟类集团均能获得丰富的食物资源。就常见木本植物对鸟类群落的重要值进行排序, 结果显示, 大叶杨(Populus lasiocarpa)、枫杨(Pterocarya stenoptera)、香樟(Cinnamomum camphora)等乔木对鸟类重要值较高, 而灌木层对鸟类的重要性整体偏低, 说明滨江森林公园的灌木层作为鸟类栖息地的功能建设尚需加强。根据以上研究结果, 我们提出了提高上海城市公园鸟类多样性的植被配置建议。 相似文献