Aims: The aim of this work was to investigate the effects of dispersal limitation and environmental filtering on tree recruitment. To accomplish this, we employed the unified neutral theory of biodiversity and biogeography to examine migration within the metacommunity, defined as a set of interacting local communities linked by the dispersal of multiple potentially interacting species.
Methods: We sampled 12,975 individuals with dbh ≥ 1 cm in 26 1-ha permanent plots, including habitats of terra firme, transitional forests, várzea and campinarana, on the upper Madeira River, Brazilian Amazon.
Results: Campinarana drew individuals from outside the metacommunity species pool at a mean probability of recruitment of 0.06, a much lower probability than terra firme (0.31), transitional (0.21) and várzea forests (0.22). Environmental variables, such as water table depth, soil texture and fertility, were related to differences in community assembly.
Conclusions: Species abundance distribution and diversity patterns of plant assemblages in a large river landscape in the Amazon highlight the importance of environmental heterogeneity that conditions beta-diversity. The high variation in recruitment probabilities from the metacommunity species pool to local communities suggests high habitat variability in the process of maintaining patterns of local diversity. 相似文献
Aim: We related pathway width as a proxy for edge effects to fruit production. Our underlying hypothesis was that pathway width would be positively related to fruit production.
Methods: We observed fruit production along three pathways of different widths – 2, 10 and 20 m wide – and in a control area of undisturbed forest in an Atlantic rain forest stand monthly over a 2-year period.
Results: The number of species and individuals-bearing fruit was higher along the wider pathways than along the narrowest pathway and in the control area. The amount of zoochorous fruits was higher in the control area than along pathways, and the widest pathway had higher non-zoochorous fruits production. Fruiting peaks occurred along pathways, while fruiting in the control area was aseasonal.
Conclusions: Pathway width is related to fruit type and its quantity and temporal availability. These effects extend towards the forest interior beyond 35 m. The presence of paths affects food resources for frugivores and thus can contribute to reconfiguring the spatio-temporal distribution of the fauna. 相似文献
Aims: To determine how litter and standing vegetation affected seedling recruitment in plant communities in Tibetan alpine grasslands.
Methods: Seedling recruitment was quantified in response to experimental treatments: (1) removal of standing vegetation and litter; (2) removal of standing vegetation with litter intact; (3) intact standing vegetation and removal of litter and (4) control: intact standing vegetation and litter.
Results: Litter removal increased seedling numbers, while standing vegetation removal had no effect. An interaction between litter and standing vegetation removal marginally increased seedling number. Species richness of seedlings was not related to either litter removal or standing vegetation removal. Species composition of seedling differed significantly between removal of both litter and standing vegetation and control.
Conclusions: Litter and its interaction with standing vegetation has an important role in affecting plant species recruitment in this alpine plant community. In contrast, biotic interactions, such as competition or facilitation from standing vegetation, appear to have only minor effects on recruitment. 相似文献
Methods: We measured understorey plant cover and biomass five years after excluding deer from mature forests of three ecological regions in Mississippi, USA. We extended the significance of P values to 0.10 to detect developing impacts.
Results: Deer impacts were limited and varied by ecological region. We recorded 151 species in cover transects. Consistent exclosure treatment effects were detected in two regions where there was greater cover of two deer forages and less cover of three non-forages. Species richness was greater in exclosures in one region, but otherwise species richness and diversity indices did not differ. We recorded 127 species in biomass quadrats. Exclosure treatment effects on biomass were inconsistent. Out of five species with significant differences, three had more biomass in controls, including two deer forages. Except for greater total biomass in controls of one region, there were no differences by growth form or total vegetation for canopy coverage or biomass. Ordination of community canopy cover demonstrated similarity of paired exclosure and controls.
Conclusions: Exclosure treatment effects on canopy cover and species richness in two regions indicated limited negative impacts from deer foraging. A time frame of more than five years may be required for exclusion to allow recovery of vegetation, even with relatively open canopies and a long growing season. 相似文献
Aims: To investigate effects of Eucalyptus saligna leaf litter on the colonisation and development of the ground layer by grassland species and if these effects were related to allelopathy.
Methods: We assessed the effects of Eucalyptus litter on the establishment of species of the native grassland community and on seeded test species (Paspalum notatum and Lotus corniculatus – introduced). We tested the impact of the addition of E. saligna leaf litter, artificial leaves (shading and mechanical impediment) and shading. We also tested the phytotoxicity of the soil from E. saligna plantations.
Results: Species richness, diversity, plant height, cover and biomass were lower in E. saligna leaves and artificial leaves treatments than in the control (absence of litter). The test species showed lower biomass and higher mortality in treatment plots with E. saligna leaves, artificial leaves and shading treatments than in the control. Allelochemicals did not accumulate in soil at phytotoxic levels.
Conclusions: Eucalyptus saligna leaf litter suppresses the establishment of grassland vegetation, but the effects are mainly physical. Field evaluations with appropriate controls should be more extensively used in allelopathy investigations. 相似文献
Aims To investigate the morphological variation in A. f. islandica among different periods of the year and its morphological differentiation from the other subspecies A. f. flammea and A. f. rostrata, and also from the redpoll species, A. cabaret and the two subspecies of A. hornemanni, exilipes and hornemanni.
Methods The subspecies status of the Icelandic population was evaluated with Amadon's rule, by comparing its variation of traits to the distribution of the traits in different species/subspecies of the group.
Results A. f. islandica is characterized by intermediate wing, bill and tail lengths. Based on the 75% rule, wing length and bill depth can be used to discriminate A. f. islandica from both extreme morphs of redpolls (currently classified as different species); A. hornemanni and A. cabaret, and tail and wing length can distinguish A. f. islandica from its conspecifics A. f. flammea. The overall morphological divergence within the redpoll complex is not supported by association to the studied nuclear markers.
Conclusion The taxonomic status of the three redpoll species is supported by Amadon's rule, however the subspecies status of the Icelandic Redpoll remains unclear. 相似文献
Methods. A voucher of the Chinese specimen is deposited in IFP herbarium. This specimen was studied with the typical anatomical and morphological methods applied within Grimmia (Maier, 2010).
Key Results. The Chinese species represents G. exquisita. After examining the type specimens of G. exquisita, we confirmed that it should be recognised as a distinct species.
Conclusions. This study expands the distribution area of G. exquisita to East Asia. The Chinese specimen was discovered in a rather different habitat to its types and consequently, G. exquisita may be a more widely distributed species. Evaluation of the Grimmia specimens in many different herbaria is needed. 相似文献
Aims: This study had the aim of determining variation in liana diversity, structure and habitat associations across different topographic habitats, and the environmental factors influencing them, in the Penang Hill Forest Reserve, Malaysia.
Methods: Liana diversity, structure and habitat associations were examined in 30 plots, 40 m × 40 m, randomly demarcated within three topographic habitats (flatland, slope and valley). The physico-chemical properties of the soils in the plots were determined and the altitude and slope of the plots recorded.
Results: Liana species richness, diversity and structure varied significantly among the topographic habitats. Liana species richness, diversity and abundance variations were related to soil moisture, phosphorus content, pH and altitude, whereas liana diameter and basal area were associated with soil magnesium and slope. A total of eight species had a positive association with the habitat and a further six showed a negative association. Four species had a positive association with the flatland habitat, but only three and two species, respectively, with slope and valley habitats. The slope habitat gave the highest number of species that showed a negative association.
Conclusions: Liana diversity and structure varied between habitats. Some liana species showed different associations with specific habitats. Environmental variables were identified that influence liana diversity, structure and habitat associations. The study provides important information about the factors influencing liana success, and these will be of value in liana conservation and management in tropical forests. 相似文献
Methods. DNA sequences were extracted from recently collected material at two locations and compared with those for species in a published phylogeny of the genus to establish the position of C. morganii. Photographic images were obtained of key features of the species for the preparation of illustrations for publication.
Key results. Cheilolejeunea morganii does not match any species described for New Zealand or Australia. The sequencing results indicate its position in the phylogeny is close to Section Paroicae. A key to the New Zealand species of Cheilolejeunea is provided.
Conclusions. In the Australasian flora, C. morganii is distinguished from other species by its combination of monoicy, pycnolejeuneoid gynoecial innovations, lobule length less than 50% lobe length and a multicellular second lobule tooth with 3–4 cells uniseriate. A case is presented for the recognition of the species as a New Zealand endemic. 相似文献
http://www.zoobank.org/urn:lsid:zoobank.org:pub:38B210E3-610D-4BAB-91AC-A212A8054474 相似文献
Methods. Over 60 herbarium specimens, including types, of D. scottianum and putative allies were examined with the aim of outlining the diagnostic features of the taxon or taxa concerned, and establishing any necessary synonymy.
Key results. The true authorship of Dicranum scottianum by Turner is re-established, and the name is effectively lectotypified with extant original material from BM. The type specimen and some subsequent collections of the species are described and illustrated. New nomenclatural synonyms of D. scottianum (namely Dicranum canariense Hampe ex Müll.Hal., D. erythrodontium Hampe ex Müll.Hal. and Orthodicranum allorgei J.J.Amann & Loeske) are detailed.
Conclusions. Dicranum scottianum is characterised by its asymmetrical leaves with one side of the leaf wider than the other, the difference in the angle of insertion of the lamina with respect to the costa (one side of the leaf is inserted at a 45° angle and the other is plane but widely incurved), the laminal cells that are thick-walled with quadrate or rectangular lumina (seen in cross-section), and the wide and deep costa that has two bands of stereids. 相似文献
Aims: We evaluated differences in species richness, species diversity and species dominance patterns in 16 plant communities as well as the degree to which differences were driven by climatic conditions in sandy dunes in Yucatán. We evaluated the importance of invasive species in mediating patterns of species diversity and species dominance patterns.
Results: We found wide variation in plant species richness, species diversity and species dominance patterns among communities that stems from broad climatic differences along dune systems. Invasive plants represent almost one-third of total species richness and seem to be drastically changing the species dominance patterns in these communities.
Conclusions: Regional climatic differences along the Yucatán north coast seems to be a major driver of plant diversity and species composition. Our findings suggest that invasive plants have successfully colonised and spread along the coast over the past 30 years. Even though invasive species do not alter spatial patterns of species diversity, they are becoming more dominant with potential detrimental consequences for native plants. 相似文献
Areas covered: The traits that make A. fumigatus a successful colonizer and pathogen of humans are multi-factorial. Thus, a global investigative approach is required to elucidate the mechanisms utilized by the fungus to cause disease.
Expert commentary: In doing so, a better understanding of disease pathology can be achieved with improved therapeutic/diagnostic solutions, thereby improving patient outcome. Proteomic analysis permits such investigations and recent work has yielded insight into these mechanisms. 相似文献
Aim: To test whether revegetation of ski-pistes in open habitat areas results in bird community recovery.
Methods: The bird communities in two ski resorts in the Italian Maritime Alps were surveyed using a standardized area count method in three different plot types: non-restored ski-pistes (newly constructed), restored ski-pistes and control plots in grassland far from ski-pistes.
Results: In 49 independent plots, 32 species were recorded. Species richness and abundance of birds were significantly higher on restored than on non-restored ski-pistes, independently of the species group considered and the analyses carried out. Bird community parameters of restored ski-pistes were still lower than those of natural grassland, as shown by results of typical grassland species.
Conclusion: Our results suggest that an apparently successful restoration of ski-pistes may be not enough to promote a complete recovery of bird communities. The complete recovery of local bird communities may be promoted only if an integral recovery of the original vegetal communities is achieved. We suggest the best conservation option is to adopt techniques to maintain as far as possible original grassland if construction of new ski-pistes is unavoidable. 相似文献
Aims: Our aim was to quantify landscape (e.g. elevation, geographic location, and precipitation), site (e.g. overstorey cover and stoniness) and very fine scale factors (e.g. spatial associations in the understorey) that affect cover, height, and fruit production of V. myrtillus in subalpine forests in thePyrenees, with understorey usually dominated by Rhododendron ferrugineum.
Methods: We sampled 155 plots (0.5 m × 5 m) in six sites. For each plot, in the understorey layer, we assessed species cover, height for R. ferrugineum and V. myrtillus, number of total fruits in V. myrtillus, and spatial associations among V. myrtillus and the remaining cover types.
Results: Overstorey cover negatively influenced V. myrtillus cover, its height, and particularly, the number of fruits, which was also negatively influenced by R. ferrugineum cover. Associations between R. ferrugineum and V. myrtillus were site dependent, while V. myrtillus showed mostly positive associations with grasses and mosses.
Conclusions: Reducing overstorey and R. ferrugineum cover has the strongest positive effect on increasing V. myrtillus fruit production, but with additional positive effects on V. myrtillus cover and height. Increases in grass and moss coverage could favour V. myrtillus. 相似文献
Aim: To test the hypothesis that the epiphytic lichen diversity at the forest edges was reduced compared with that in the forest interior, and to analyse lichen diversity in comparison with the more highly elevated and more continental Mongolian Altai.
Methods: Six plots each in the interior and the edge with a total of 240 Larix sibirica trees were studied in the Katon-Karagai National Park, East Kazakhstan.
Results: Species richness and evenness at the tree level were higher in the interior than at the edge. The epiphytic lichen diversity in the forest interior was similar in the Kazakh and Mongolian Altai, whereas that at the forest edge was lower in the Mongolian Altai.
Conclusions: Strong degradation of the forest edges in the Kazakh Altai is the probable cause of the reduced epiphytic lichen diversity compared with the interior. The similar species richness in the forest interiors of the Kazakh and Mongolian Altai suggests that the differences at the forest edge are probably, at least partly, due to different land-use regimes and not to differences in macroclimate. 相似文献
Aims: In order to assess the effects of large herbivores on above-ground vegetation (AGV) and soil seed bank (SSB) characteristics, intensively sheep-grazed areas were compared to adjacent areas where grazing had been removed 10 years previously in a sub-alpine grassland of northern Iran.
Methods: A total of 40 4-m2 (2 m × 2 m) plots were established in each treatment, and soil samples were collected from each plot within a depth of 10 cm. Plant species composition was determined for each plot during the flowering stage of herbaceous species in June 2011. The seedling emergence method was used to estimate SSB composition.
Results: A total of 45 species (23 annuals and 22 perennials) emerged from the soil samples of the grazed area, while the number of species emerged from the soil samples of the previously grazing area was 76 (37 annuals and 39 perennials). The removal of grazing led to a significant increase in species richness and seed density in the SSB. Species turnover of AGV was higher, and that of the SSB was similar for grazed areas compared with areas that were formerly grazed. Detrended correspondence analysis ordination of AGV composition showed a clearly separate structure between grazed plots and plots where grazing has been removed, while the segregation was less clear for SSB composition.
Conclusions: We concluded that restoration of locally degraded sites cannot rely on the SSB when grazing is stopped simultaneously and unvegetated gaps are colonised by vegetative growth rather than by seed. 相似文献
http://www.zoobank.org/urn:lsid:zoobank.org:pub:77F54322-6CCA-46F1-A74B-B8A75E1F1F8D 相似文献