共查询到20条相似文献，搜索用时 15 毫秒
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The colonization patterns of larval chironomid midges were studied on clean sieved sediments (range 0.25-4.0 mm; pure and mixed) placed in a third order stream in NW Pennsylvania, USA. Chironomid abundance and species richness were significantly different among four sites for homogeneous and mixed sediments. Species richness increased with sediment particle size. Fourteen of the 18 most common species had significant substrate preferences. The interpretation of two cluster analyses of sediment samples indicated two assemblages of chironomid species, each of which appeared to correlate with particular sediments, indicating some assemblage level sediment preference. Sediment size, but not heterogeneity, appears to be a strong factor in the species richness pattern of the community, and in the microhabitat choices of individual chironomid species, in this sandy environment. 相似文献
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Mervin E. Pérez Inés Sastre‐De Jesús Ariel E. Lugo Oscar J. Abelleira Martínez 《Biotropica》2012,44(6):763-770
The introduced tree species Spathodea campanulata (Bignoniaceae) forms novel forests in Puerto Rico, these having emerged after the abandonment of fields in the mid‐20th century and resulting in forests with a new species composition. We assessed bryophyte species richness in these novel forests and sought correlations with geological substrate, past land use, forest edge and patch area, forest structure, elevation, microhabitat diversity, tree species richness, and microclimatic conditions. Transects were established (edge and forest interior) in nine moist forest patches dominated by Spathodea in north‐central Puerto Rico. These Spathodea forest patches ranged from 0.6 to 9 ha. ANOVA, Chi‐square, correlation, and cluster analyses were used in data analyses. We found 57 bryophyte species. There was a significant difference in bryophyte richness among patches. Those on karst exhibited highest bryophyte richness due to microhabitat diversity, past land use, and shorter hydroperiods. Alluvial sites scored lowest in bryophyte species richness, and forest structure was important for bryophyte communities on these sites. Significant differences in temperature, relative humidity, and light intensity were observed between edge and forest interior. These appeared important for establishing bryophyte species cover but not richness and composition. Microhabitat diversity, patch area, and forest age were more related to bryophyte species richness than elevation, exposed edge, and tree species richness, regardless of geologic substrate. Collectively, Spathodea patches were similar to mature forests on the Island with respect to bryophyte species richness and composition. Novel Spathodea forests have conservation value due to their habitat suitability for bryophyte communities. 相似文献
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Species richness, diversity and composition of butterflies in two Kenya coastal forest remnants, Muhaka and Mrima hill, were investigated. Sixty‐three species were recorded from each forest remnant from a total of 1329 individuals. Species accumulation curves for both forests did not reach an asymptote. High species similarity was recorded between the forest interior and the surrounding matrix, primarily due to invasion of the forest interior clearings by the savanna species. Despite their small sizes, these forest remnants were found to maintain viable populations of true forest butterflies. However, the number of species was less than half that recorded from the larger forest reserve of Arabuko‐Sokoke, located in the same geographical area. Records from Muhaka forest show species unique to it, not found in the larger forest reserves, underscoring the importance of small remnants in the preservation of forest biodiversity. The high species similarity between the forest remnants implied that if habitat corridors were created, gene flow between these remnants and other larger forest reserves would be possible. This would reduce the isolation of true forest butterfly populations within the remnants and potential local extinction. 相似文献
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M. Anjum‐Zubair Martin H. Schmidt‐Entling Pascal Querner Thomas Frank 《Agricultural and Forest Entomology》2010,12(3):301-306
- 1 The influence of within‐field position and adjoining habitat on carabid beetles was studied in 20 winter wheat fields in ten different Swiss agricultural landscapes. In each landscape, two winter wheat fields (one with adjoining sown wildflower area and one with adjoining grassy margin) were investigated.
- 2 Carabid beetles were caught in pitfall traps 3 and 30 m from the edge in each of the 20 wheat fields. Significantly more individuals were found in the centres (30‐m position) than at the edges (3‐m position). Conversely, species richness was significantly higher at the field edges than in the centres.
- 3 Of the ten most abundant species, Poecilus cupreus, Agonum muelleri and Pterostichus melanarius were significantly more abundant in the field centres than at the edges. Harpalus rufipes was significantly more abundant in the fields adjoining sown wildflower areas than in the fields adjoining grassy margins.
- 4 In conclusion, the response of carabid beetles to within‐field position and adjoining habitats was species specific. This needs to be taken into account in habitat management for biodiversity conservation and pest control.
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Bettina Ohse Carolin Seele Frédéric Holzwarth Christian Wirth 《Ecology and evolution》2017,7(17):6779-6789
Browsing of tree saplings by deer hampers forest regeneration in mixed forests across Europe and North America. It is well known that tree species are differentially affected by deer browsing, but little is known about how different facets of diversity, such as species richness, identity, and composition, affect browsing intensity at different spatial scales. Using forest inventory data from the Hainich National Park, a mixed deciduous forest in central Germany, we applied a hierarchical approach to model the browsing probability of patches (regional scale) as well as the species‐specific proportion of saplings browsed within patches (patch scale). We found that, at the regional scale, the probability that a patch was browsed increased with certain species composition, namely with low abundance of European beech (Fagus sylvatica L.) and high abundance of European ash (Fraxinus excelsior L.), whereas at the patch scale, the proportion of saplings browsed per species was mainly determined by the species’ identity, providing a “preference ranking” of the 11 tree species under study. Interestingly, at the regional scale, species‐rich patches were more likely to be browsed; however, at the patch scale, species‐rich patches showed a lower proportion of saplings per species browsed. Presumably, diverse patches attract deer, but satisfy nutritional needs faster, such that fewer saplings need to be browsed. Some forest stand parameters, such as more open canopies, increased the browsing intensity at either scale. By showing the effects that various facets of diversity, as well as environmental parameters, exerted on browsing intensity at the regional as well as patch scale, our study advances the understanding of mammalian herbivore–plant interactions across scales. Our results also indicate which regeneration patches and species are (least) prone to browsing and show the importance of different facets of diversity for the prediction and management of browsing intensity and regeneration dynamics. 相似文献
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《Plant Ecology & Diversity》2013,6(4):483-492
Background: Habitat loss and fragmentation have been argued to drastically alter the composition of tree assemblages inhabiting small forest fragments but the successional trajectory experienced by such edge-affected habitats remains controversial.Aims: Here we examine whether small fragments (3.4–91.2 ha) support seedling assemblages more similar to those in 10–70-year-old secondary forests than to those in mature forests, in order to infer to what extent fragments move toward early successional systems.Methods: Using 59 0.1-ha plots distributed in a fragmented landscape of Brazilian Atlantic forest, we evaluated species richness and functional and taxonomic composition of seedling assemblages in 20 small forest fragments, 19 stands of secondary forest and 20 stands of mature forests in the interior of an exceptionally large fragment (ca. 3500 ha).Results: Small fragments presented the least species-rich seedling assemblages (17.2 ± 5.7 species), followed by secondary (22.5 ± 5.3), and mature forest (28.4 ± 5.3). Small fragments had seedling assemblages with functional and taxonomic composition more similar to those in secondary than in mature forest. Small fragments had a greater relative richness and abundance of pioneer trees (ca. 40% more), vertebrate-dispersed (6–25%), and those bearing medium-sized seeds (30–70%), while large-seeded species and individuals were reduced (>50% decrement) in comparison to seedling assemblages in mature forest.Conclusions: By comparing seedlings across a wide range of successional habitats we offer evidence that small forest fragments are experiencing an alternative successional pathway towards an early-successional system with reduced plant diversity. 相似文献
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Abstract: Little quantitative information exists about the survey effort necessary to inventory temperate bat species assemblages. We used a bootstrap resampling algorithm to estimate the number of mist net surveys required to capture individuals from 9 species at both study area and site levels using data collected in a forested watershed in northwestern California, USA, during 1996–2000. The mean number of simulated surveys required to capture individual species varied with species' rarity and ranged from 1.5 to 44.9. We retrospectively evaluated strategies to reduce required survey effort by subsampling data from 1996 to 1998 and tested the strategies in the field during 1999 and 2000. Using data from 1996 to 1998, the mean number of simulated surveys required to capture 8 out of 9 species was 26.3, but a 95% probability of capture required >61 surveys. Inventory efficiency, defined as the cumulative proportion of species detected per survey effort, improved for both the study area and individual sites by conducting surveys later in summer. We realized further improvements in study area inventory efficiency by focusing on productive sites. We found that 3 surveys conducted between 1 July and 10 September at each of 4 productive sites in this 10-km2 study area resulted in the capture of 8 species annually. Quantitative estimation of the survey effort required to assess bat species occurrence improves the ability to plan and execute reliable, efficient inventories. Results from our study should be useful for planning inventories in nearby geographical areas and similar habitat types; further, the analytical methods we used to assess effort are broadly applicable to other survey methods and taxa. 相似文献
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LUCY HAYES DARREN J. MANN ALEXANDER L. MONASTYRSKII OWEN T. LEWIS 《Insect Conservation and Diversity》2009,2(3):194-203
Abstract. 1. We carried out rapid assessments of the richness and diversity of fruit‐feeding butterflies (sampled with baited traps) and dung beetles (sampled with buffalo dung‐baited pitfall traps) at 20 sites across an anthropogenic forest disturbance gradient in Ba Be National Park, Vietnam. 2. We investigated measures of diversity, richness, and functional composition for individual taxa in relation to the degree of disturbance, and verified whether dung beetles and butterflies showed congruent trends. 3. For butterflies, overall species richness increased with forest disturbance, but the richness of rare species decreased. Species diversity was uncorrelated with disturbance. 4. In dung beetles, species richness was unrelated to forest disturbance, but species diversity increased with forest disturbance. The richness of dung beetles in the telecoprid (roller) guild declined with forest disturbance. 5. There was no significant correlation between dung beetles and butterflies across sites for either species richness or species diversity. 6. Apparent effects of disturbance were thus sensitive to the particular metric used (species richness or diversity), the taxonomic group studied (butterflies or dung beetles), and the functional group investigated (different guilds of dung beetle). 相似文献
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In north Khorasan province, Iran, we compared the effectiveness of two types of traps for collecting reptiles: funnel traps and pitfall traps. Three stations were monitored over three 10-day periods and in total 544 individuals (including 200 recaptures) belonging to 5 species and 4 families of lizards (Lacertidae) were collected. Funnel traps with 280 captures were more efficient than pitfall traps with 264 captures, but the differences between the two traps are not significant. Three species were captured most often in the three different stations respectively: station 1, Bunopus crassicauda (22% relative frequency); station 2, Eremias fasciata (29% relative frequency); and station 3, Trapelus agilis (32% relative frequency). Shannon species richness indices were higher for pitfall than funnel traps (i.e., 1.45 vs. 1.40), but the difference was not significant. Pitfall traps were better for capturing species that search widely for food, while the funnel traps preferentially captured species that climb plants, such as Trapelus agilis. We recommend using both types of trap to capture the various types of species in any one region. 相似文献
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Detailed information on the ground-dwelling ant diversity and distribution in the rainforests of the Congo Basin is lacking
so far. A new ant species list from a continuous mixed secondary lowland rainforest on the northern periphery of the Dja Biosphere
Reserve in southeast Cameroon is presented. We investigated the effect of vegetation type on ant species density, activity
and composition. Ants were collected by pitfall trapping in seven vegetation types in each of three seasons during 12 months
in 2003 and 2004–2005. Our site in Cameroon had a total observed ant diversity of 145 species. Vegetation type significantly
influenced the ground-dwelling and -foraging (arboreal) ant assemblages. Differences in species density, activity and composition
between vegetation types were explained not only by soil type (hydromorphous – terra firme), but also by developmental stage
of vegetation types. The highly inundated Raphia-swamp had the lowest ant species density and activity. Older secondary forests still had a different species composition
than near primary forest even after 25 years of recovery after anthropogenic disturbance. Finally, the high ant species number
captured by our pitfalls, the absence of the invasive exotic ant Wasmannia auropunctata and the high Dorylus (Anomma) army ant diversity confirm the importance of the Cameroonian rainforest for biodiversity conservation programs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 4 October 2006; revised 4 June 2007; accepted 2 July 2007. 相似文献
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Richard G. Davies Paul Eggleton David T. Jones Freddy J. Gathorne-Hardy Luis M. Hernández 《Journal of Biogeography》2003,30(6):847-877
Aim To (1) describe termite functional diversity patterns across five tropical regions using local species richness sampling of standardized areas of habitat; (2) assess the relative importance of environmental factors operating at different spatial and temporal scales in influencing variation in species representation within feeding groups and functional taxonomic groups across the tropics; (3) achieve a synthesis to explain the observed patterns of convergence and divergence in termite functional diversity that draws on termite ecological and biogeographical evidence to‐date, as well as the latest evidence for the evolutionary and distributional history of tropical rain forests. Location Pantropical. Methods A pantropical termite species richness data set was obtained through sampling of eighty‐seven standardized local termite diversity transects from twenty‐nine locations across five tropical regions. Local‐scale, intermediate‐scale and large‐scale environmental data were collected for each transect. Standardized termite assemblage and environmental data were analysed at the levels of whole assemblages and feeding groups (using components of variance analysis) and at the level of functional taxonomic groups (using correspondence analysis and canonical correspondence analysis). Results Overall species richness of local assemblages showed a greater component of variation attributable to local habitat disturbance level than to region. However, an analysis accounting for species richness across termite feeding groups indicated a much larger component of variation attributable to region. Mean local assemblage body size also showed the greater overall significance of region compared with habitat type in influencing variation. Ordination of functional taxonomic group data revealed a primary gradient of variation corresponding to rank order of species richness within sites and to mean local species richness within regions. The latter was in the order: Africa > south America > south‐east Asia > Madagascar > Australia. This primary gradient of species richness decrease can be explained by a decrease in species richness of less dispersive functional taxonomic groups feeding on more humified food substrates such as soil. Hence, the transects from more depauperate sites/regions were dominated by more dispersive functional taxonomic groups feeding on less humified food substrates such as dead wood. Direct gradient analysis indicated that ‘region’ and other large‐scale factors were the most important in explaining patterns of local termite functional diversity followed by intermediate‐scale geographical and site variables and, finally, local‐scale ecological variables. Synthesis and main conclusions Within regions, centres of termite functional diversity lie in lowland equatorial closed canopy tropical forests. Soil feeding termite evolution further down food substrate humification gradients is therefore more likely to have depended on the long‐term presence of this habitat. Known ecological and energetic constraints upon contemporary soil feeders lend support for this hypothesis. We propose further that the anomalous distribution of termite soil feeder species richness is partly explained by their generally very poor dispersal abilities across oceans. Evolution, radiation and dispersal of soil feeder diversity appears to have been largely restricted to what are now the African and south American regions. The inter‐regional differences in contemporary local patterns of termite species richness revealed by the global data set point to the possibility of large differences in consequent ecosystem processes in apparently similar habitats on different continents. 相似文献
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PEDRO CARDOSO NIKOLAJ SCHARFF CLARA GASPAR SRGIO S. HENRIQUES RUI CARVALHO PEDRO H. CASTRO JESPER B. SCHMIDT ISRAEL SILVA TAMS SZÜTS ALBERTO DE CASTRO LUIS C. CRESPO 《Insect Conservation and Diversity》2008,1(2):71-84
Abstract.
- 1 A thorough inventory of a Mediterranean oak forest spider fauna carried out during 2 weeks is presented. It used a semi‐quantitative sampling protocol to collect comparable data in a rigorous, rapid and efficient way. Four hundred and eighty samples of one person‐hour of work each were collected, mostly inside a delimited 1‐ha plot.
- 2 Sampling yielded 10 808 adult spiders representing 204 species. The number of species present at the site was estimated using five different richness estimators (Chao1, Chao2, Jackknife1, Jackknife2 and Michaelis–Menten). The estimates ranged from 232 to 260. The most reliable estimates were provided by the Chao estimators and the least reliable was obtained with the Michaelis–Menten. However, the behavior of the Michaelis–Menten accumulation curves supports the use of this estimator as a stopping or reliability rule.
- 3 Nineteen per cent of the species were represented by a single specimen (singletons) and 12% by just two specimens (doubletons). The presence of locally rare species in this exhaustive inventory is discussed.
- 4 The effects of day, time of day, collector experience and sampling method on the number of adults, number of species and taxonomic composition of the samples are assessed. Sampling method is the single most important factor influencing the results and all methods generate unique species. Time of day is also important, in such way that each combination of method and time of day may be considered as a different method in itself. There are insignificant differences between the collectors in terms of species and number of adult spiders collected. Despite the high collecting effort, the species richness and abundance of spiders remained constant throughout the sampling period.
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Questions
What are the most important drivers of plant species richness (gamma‐diversity) and species turnover (beta‐diversity) in the field layer of a forest edge? Does the tree and shrub species richness structure and complexity affect the richness of forest and grassland specialist species?Location
Southeast Sweden.Methods
We sampled 50 forest edges with different levels of structural complexity in agricultural landscapes. In each border we recorded trees, shrubs and herb layer species in a 50‐m transect parallel with the forest. We investigated species composition and species turnover in relation to the proportions of gaps in the border and the diversity of trees and shrubs.Results
Total plant species richness in the field layer was mainly explained by the proportion of gaps to areas with full canopy cover and tree diversity. Increasing number of gaps promoted higher diversity of grassland specialist species within the field layer, resulting in open forest borders with the highest overall species richness. Gaps did however have a negative impact on forest species richness. Conversely, increasing forest species richness was positively related to tree diversity, but the number of grassland specialist species was negatively affected by tree diversity.Conclusions
Managing forest borders, and therefore increasing the area of semi‐open habitats in fragmented agricultural landscapes, provides future opportunities to create a network of suitable habitats for both grassland and deciduous forest specialist species. Such measures therefore have the potential to increase functional connectivity and support dispersal of species in homogeneous forest/agricultural landscapes. 相似文献18.
《生物多样性》2025,33(2)
在当前全球生物多样性面临严峻挑战的背景下, 深入探讨人为和自然干扰对森林群落物种多样性的影响显得尤为重要。本研究以中亚热带森林群落为研究对象, 选取钱江源-百山祖国家公园候选区钱江源园区内常绿阔叶老龄林、一次干扰次生林、两次干扰次生林和杉木(Cunninghamia lanceolata)人工林4种典型森林类型, 依托12个1 ha森林动态监测样地长期积累的数据, 采用物种丰富度、Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数, 系统分析了不同干扰程度下物种多样性的演替轨迹及演替速率的变化, 旨在为生物多样性保护和生态修复提供科学依据。研究结果表明, 常绿阔叶老龄林、一次干扰次生林和杉木人工林的物种丰富度、Shannon-Wiener多样性指数和Simpson多样性指数随演替进展而增加, 而两次干扰次生林则呈现下降趋势。在常绿阔叶老龄林和一次干扰次生林中, Pielou均匀度指数随演替进展呈现先增后减的变化趋势; 而在两次干扰次生林和杉木人工林中, Pielou均匀度指数则呈现逐渐增加之势。特别地, 当不考虑杉木时, 杉木人工林的Pielou均匀度指数随演替进展而下降。各物种多样性指数的演替速率总体上随时间呈下降趋势, 但物种丰富度和Pielou均匀度指数的演替速率多数情况下差异不显著。受冰雪灾害影响后, 常绿阔叶老龄林的演替轨迹偏离了其稳定状态, 其恢复初期物种丰富度的演替速率显著高于其他森林, 并随时间显著下降, 而Pielou均匀度指数演替速率较低, 随时间无显著变化。杉木人工林Pielou均匀度指数的演替速率显著高于其他森林, 且随时间显著降低, 而其物种丰富度的演替速率低, 与一次干扰次生林和两次干扰次生林无显著差异。综上所述, 本研究揭示了不同干扰对中亚热带森林物种多样性演替轨迹和速率的显著、差异性影响。建议在制定修复措施和评估修复成效时, 充分考虑森林的干扰历史和演替阶段, 以实现更有效的生物多样性保护和修复。 相似文献
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We tested if logging enhances the recruitment of tree species by comparing young tree density in areas disturbed by logging with areas unaffected by logging 6 mo after logging in two Forest Reserves in Ghana. Analysis of 46 commercial timber species showed significantly higher postlogging recruitment in felling gaps and skid trails than in areas unaffected by logging. New seedlings substantially exceeded those lost due to logging operations. Species richness was significantly greater in areas disturbed by logging. 相似文献
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Robert W. Johnson William J. McDonald Roderick J. Fensham Clive A. McAlpine Michael J. Lawes 《Austral ecology》2016,41(6):644-656
Plant succession theory underpins the development of strategies for the conservation and regeneration of native communities. Current theory has been based largely on space‐for‐time rather than long‐term monitoring data, which have known limitations. There is general consensus that more site‐specific studies are needed to corroborate existing hypotheses. The target vegetation is a brigalow (Acacia harpophylla, Mimosaceae) forest in one of Australia's most endangered ecosystems, which was cleared and burnt in 1963. Forty quadrats were placed systematically within each of six 20 m × 20 m permanent plots. Presence, density and per cent canopy cover data were recorded for each species at 18 times over 46 years. Brigalow dominated the original vegetation, assumed dominance soon after clearing through massive root suckering and remained dominant throughout the study. It achieved maximum density within two years when severe intraspecific competition led to self‐thinning. After approximately 30 years, vacant niches appeared. Woody understorey species were slow to recolonise. Species richness and other diversity indices increased rapidly to a maximum after 2–4 years, declined until the 30th year when they again increased. This was the pattern of the species‐rich herbaceous layer; woody species showed a steady monotonic increase. The ‘hump‐shaped’ relationship between cover (biomass) and species richness was confirmed. This example fits the inhibition model for which few examples have been described. While the long‐term successional pattern is slightly confounded by climatic variability preceding sample surveys, this space‐for‐time study not only supports a bimodal pattern of diversity over time but also indicates that the relative species richness of the herbaceous and woody layers may explain the extreme variability reported in the literature. 相似文献