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1.
While the increasing vehicular traffic is widely suspected to play a role in the worldwide amphibian population decline, the research of amphibian road mortality is scarce, fragmented, fraught with methodological problems, and largely inconclusive. As the first attempt at a synthesis, we analyzed all available data on amphibian mortality in Europe and combined them with four previously unpublished surveys conducted by us. Based on our recalculation of road-kill counts in terms of species-specific road-kill recordability, we conclude that, in lowland Central Europe, the common toads, Bufo bufo, are the most common victims of vehicular traffic in suburban landscapes, while the common frogs, Rana temporaria and Triturus newts, prevail in rural landscapes. The green frogs also tend to be more frequent in rural areas. Common tree frogs, Hyla arborea, are unexpectedly rare in the road-kill record despite their terrestrial and migratory habits. In consideration of problems with obtaining accurate amphibian population estimates, we further propose the road kills-to-spawners ratio (R/S) as a working measure of the impact of road mortality on a local population. While the R/S ratio may not reflect the losses to an entire local amphibian population, it is free of the errors of whole-population estimates, which are notoriously difficult for amphibians. When corrected for species-specific road-kill recordability, most results suggest that the impact of roads on newts may have been underestimated and that the impact on common frog populations may be higher than on those of common toads. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Communicated by H. Kierdorf  相似文献   

2.
We contrasted traditionally used indicators of service provision quality, such as overall species richness and growth form composition, to three more specific functional properties: functional diversity, functional intensity, and functional stability. We defined flower colour as a functional trait perceived differently by humans and insect pollinators, and used user specific colour richness, flower size, and species richness within colour group as indicators of these three properties. We asked (1) do field margins and road verges provide flower-based ecosystem services with the quality of permanent grasslands; and (2) do traditional and detailed functional indicators of service provision quality agree on the service quality ranking of habitats?In an agricultural landscape of central and south-eastern Estonia (115 ÿ 95 km area, centroid 26°49⿲43⿳ and 58°54⿲49⿳) we sampled 87 field margins and 111 road verges as linear grassland-substitution habitats, and 84 permanent grasslands to scale their service quality.Linear habitats generally provided service of lower quality than permanent grasslands, but detailed indicators showed less evident contrast among habitat types than the overall species richness and stronger contrast than the proportion of forbs. Detailed indices, however, had strong seasonal dynamics to take into account. Vegetation in the first year field margins had greater colour richness (functional diversity) and species richness within colour groups (functional stability), but the smallest flower size (functional intensity), in contrast to road verges. By the third year of succession, field margins had become more similar to road verges. Indication of service provision quality differed between humans and pollinators, but their estimates were correlated across habitats.We showed that (1) combinations of specific service quality indicators provide more adequate information than generalized richness or growth form system, and (2) single grassland surrogate habitat type is an insufficient service providing substitute for permanent grasslands, although a mosaic of these habitats might be more efficient. Therefore, remnant fragments of semi-natural grasslands should receive top priority attention for conservation and restoration, particularly in agriculture dominated landscapes.  相似文献   

3.
Aim This study tests the hypothesis that linear, woody habitat patches surrounding small, sunken rural roads not only function as an unstable sink but also as a true, sustainable habitat for forest plants. Furthermore, factors affecting the presence of forest plant species in sunken roads are determined. Finally, the implications of these findings for the overall metapopulation dynamics of forest plant species in fragmented agricultural landscapes are assessed. Location The study area, c. 155 km2 in size, is situated in a fragmented agricultural landscape within the loamy region of central Belgium. Methods Forest species presence–absence data were collected for 389 sunken roads. The effect of area, depth, age and isolation on sunken road species richness was assessed using linear regression and analysis of variance (anova ). Analysis of covariance was employed to study the interaction between age and isolation. Differences in plant community dispersal spectra in relation to sunken road age and isolation were analysed by means of linear regression and anova . Results Sunken roads proved to function as an important habitat for forest plants. The sink‐hypothesis was falsified by a clear species accumulation in time: sunken road species richness significantly increased with the age of the elements. Sunken road age mainly affected species richness through effects on both area and depth, affecting habitat quality and diversity. Furthermore, sunken road isolation had a significant impact on species richness as well, with the number of forest species decreasing with increasing isolation of the elements, indicating dispersal limitation in sunken road habitats. Moreover, a significant age × isolation interaction effect was demonstrated. Differences in regression slopes for isolation between age classes revealed that the effect of isolation intensified with increasing age of the elements. Differential colonization in relation to forest species dispersal capacities probably account for this, as confirmed by the analysis of sunken road plant community dispersal spectra, with the fraction of species with low dispersal capacities increasing with increasing age and decreasing isolation of the elements. Main conclusions During sunken road development, area and depth increase and, gradually, suitable habitat conditions for forest plant species arise. Depending on their ecological requirements and dispersal capacities, forest species progressively colonize these habitats as a function of the element's isolation. The functioning of sunken roads as a sustainable habitat for forest species enhances the metapopulation viability of forest plants in agricultural landscapes and has important consequences for forest restoration practices. Moreover, the results of this work call for integrating the presence of forest species in small‐scaled linear habitat patches in forest fragmentation studies.  相似文献   

4.
Questions: Can patterns of species similarity on ditch banks be explained by environmental and dispersal factors and, if so, to what extent? Does the pattern of distance decay differ among different species groups (all species versus target species of conservation interest; species of different dispersal type)? Location: Krimpenerwaard, the Netherlands. Methods: In 2006‐2007, ditch bank vegetation data on 130 terrestrial herbaceous species were collected on 72 plots. Species similarity was measured and related to environmental distance (soil type and nutrient level) and dispersal distance (geographic distance and limitation of dispersal by water, wind and agricultural activities) as explanatory factors using multiple regression on distance matrices (MRM). Differences in rates of distance decay in species similarity among different subsets of data (species groups) were investigated using randomization tests. Results: In all species, patterns of similarity of composition are influenced mainly by variations in dispersal, while for target species these are due to combined effects of environmental and dispersal variation. Compared with species using other dispersal mechanisms, water‐dispersed species had half the rate of distance decay. Conclusions: For all species considered here, dispersal limitation seems more responsible for the spatial variation in species composition than environmental determinism. Conservation management focused on plant species diversity would be more successful in areas adjacent to those where a similar management regime is already in force. For target species of conservation interest, besides dispersal limitation, environmental determinants like nutrient level are also important. As a means of conserving such target species, therefore, focusing on reducing nutrient levels and facilitating species dispersal will be more effective than current management practices, which mainly focus on reducing fertilizer inputs.  相似文献   

5.
Many studies have investigated the possible impact of climate change on the distributions of plant species. In the present study, we test whether the concept of potential distribution is able to effectively predict the impact of climate warming on plant species.Using spatial simulation models, we related the actual (current species distribution), potential (modelled distribution assuming unlimited dispersal) and predicted (modelled distribution accounting for wind-limited seed dispersal) distributions of two plant species under several warming scenarios in the Sagarmatha National Park (Nepal). We found that the two predicted distributions were, respectively, seven and nine times smaller than the potential ones. Under a +3 °C scenario, both species would likely lose their actual and predicted distributions, while their potential distributions would remain partially safe. Our results emphasize that the predicted distributions of plant species may diverge to a great extent from their potential distributions, particularly in mountain areas, and predictions of species preservation in the face of climate warming based on the potential distributions of plant species are at risk of producing overoptimistic projections.We conclude that the concept of potential distribution is likely to lead to limited or inefficacious conservation of plant species due to its excessively optimistic projections of species preservation. More robust strategies should utilize concepts such as “optimal reintroduction”, which maximizes the benefit–cost ratio of conservation activities by limiting reintroduction efforts to suitable areas that could not otherwise be reached by a species; moreover, such strategies maximize the probability of species establishment by excluding areas that will be endangered under future climate scenarios.  相似文献   

6.
Abstract. 315 isolated semi-natural and natural stands in NW Germany were investigated floristically, 285 stands of ancient woodlands and 30 recent ones. In the study area nearly all semi-natural and natural ancient woodlands are found on mesotrophic or eutrophic sites and can be assigned to the Fagetalia. 54 selected herbaceous and five woody Fagetalia-species have been tested in their association to ancient woodlands. 21 of the 59 selected plant species show a highly significant association to ancient woodlands and seven species show a weak significance. 31 plant species are not significantly correlated with ancient woodland sites, but 25 of them have a low frequency. The result shows that investigations of the historical ecology can help to understand floristic composition of present-day woodlands. Restriction of many woodland species to ancient woodlands, especially rare species, emphasizes the importance of woodlands with a long continuous history for the preservation of endangered species. Irrespective of ecological conditions, the restriction of plant species to ancient woodlands seems to be mainly caused by their low ability to colonize recent woodlands, especially isolated stands. Differences in the association to ancient woodlands between European countries are assumed to be a function of both time and degree of isolation of woodlands, of the dispersal mode of the plant species and of the availability of suitable habitats.  相似文献   

7.
8.
Rivers provide an excellent system to study interactions between patterns of biodiversity structure and ecological processes. In these environments, gene flow is restricted by the spatial hierarchy and temporal variation of connectivity within the drainage network. In the Australian arid zone, this variability is high and rivers often exist as isolated waterholes connected during unpredictable floods. These conditions cause boom/bust cycles in the population dynamics of taxa, but their influence on spatial genetic diversity is largely unknown. We used a landscape genetics approach to assess the effect of hydrological variability on gene flow, spatial population structure and genetic diversity in an Australian freshwater fish, Macquaria ambigua. Our analysis is based on microsatellite data of 590 samples from 26 locations across the species range. Despite temporal isolation of populations, the species showed surprisingly high rates of dispersal, with population genetic structure only evident among major drainage basins. Within drainages, hydrological variability was a strong predictor of genetic diversity, being positively correlated with spring-time flow volume. We propose that increases in flow volume during spring stimulate recruitment booms and dispersal, boosting population size and genetic diversity. Although it is uncertain how the hydrological regime in arid Australia may change under future climate scenarios, management strategies for arid-zone fishes should mitigate barriers to dispersal and alterations to the natural flow regime to maintain connectivity and the species' evolutionary potential. This study contributes to our understanding of the influence of spatial and temporal heterogeneity on population and landscape processes.  相似文献   

9.
Astha Varma 《Plant biosystems》2018,152(5):1088-1100
Systematic analysis of germplasm diversity and genetic relationship among cultivars is critical for development of appropriate conservation and breeding strategies. This approach has been applied to gain an insight about the molecular variance that exists in wild population of two important medicinal plant species of India that have a long history of therapeutic usage in herbal medicine. Adhatoda vasica and Andrographis paniculata, members of the family Acanthaceae, have wide geographical and climatic distribution across India suggesting a large amount of genetic diversity available for resource management and breeding programs. In this study we have assessed the genetic diversity of both these species distributed in five varied geo-environmental regions, using Amplified Fragment Length Polymorphism (AFLP) fingerprinting with selected primer combinations and statistical analysis. Cluster analysis and analysis of molecular variance also suggested a very high genetic variation. Detailed analyses of the results predict that the genetic variation found in A. vasica was more discrete that reflected strongly in the populations studied, whereas the genetic variation in A. paniculata was relatively uniform. Considering significantly large sample size and distinctive characteristics of the selected populations, this work contributes valuable insights that can be used to engineer conservation and utilization strategies for these species.  相似文献   

10.
We monitored the concentration of 21 trace elements in zooplankton samples collected in a Northwestern Mediterranean coastal ecosystem (Italy). In the last 20 years, this area has been the target of important anthropogenic impacts including maritime traffic and substantial industrial activities. Zooplankton contributes to the transfer of trace metals to higher trophic levels and constitute one of the recommended groups for the baseline studies of metals in the marine environment. The essential trace elements (As, Cu, Mn, Zn, Fe, Mo, Co, Cr, Se, Ni) and the nonessential trace elements (Al, Be, Cd, Pb, Sb, Sn, V) were generally found at concentrations of no concern in the analyzed zooplankton samples, but showed important variations between seasons and different water depths. The zooplankton was found to be a significant accumulator of metals, and bioaccumulation factors were in the range of 28 (Co) to 10,9015 (Fe) in marine surficial waters, with increasing values at increasing water depth. Zooplankton is a useful bioindicator to assess metal contamination and its impact in the marine environment.  相似文献   

11.
The aim of this study was to detect suites of traits related to whole plant and seed morphology, phenology and resource use – including water – in species differing in successional status. Twenty traits were measured on 55 species representative of 5 successional stages in Mediterranean southern France, including eight pertaining to phenology and five to water economy. Suites of traits that changed along succession in agreement with the acquisition/conservation trade-off were completed by continuous changes in phenology. Early successional species had leaves with a high specific leaf area that were produced and lost continuously through the growing season. Late-successional species were taller with long-lived, high δ13C leaves produced during short periods, most of them persisting during summer, and produced large seeds requiring a long ripening period. Replacement of species occurred with change in strategies of drought survival: early successional species escaped drought by dying before summer; later herbaceous species maintained favourable water status in relation to leaf shedding during summer; late successional trees with a large body allowing access to a large pool of resources, produced dense leaves that could tolerate desiccation. These changes occurred concomitantly with a shift in CSR strategies, using traits related to resource use, plant size and flowering phenology: ruderal herbs were replaced by more stress-tolerant herbs and shrubs throughout the succession, with competitive trees dominating the latest successional stage. These results suggest that the breadth of functional variability found in natura is not predicted by the CSR framework, and calls for a more integrated view of whole plant functioning.  相似文献   

12.
Distributions were predicted for 1430 native plant species as part of a biodiversity assessment in the forests of south‐west Western Australia. From these predicted distributions, an index of plant species richness was generated for the forest area. The most common predictors for distribution were found to be climatic surfaces incorporating some aspect of seasonality in temperature and precipitation. Although coarse, the index confirmed existing knowledge of areas of high biodiversity within the study area and introduced a new area, the Blackwood Plateau, for consideration as a conservation reserve with high species richness. An additional survey was conducted to sample actual species richness in 11 test sites. When actual richness was regressed against predicted richness, a significant correlation was obtained if both annuals and geophytes were excluded from the analysis. With refinement of the model and further data collection targeted at areas of low effort, the species richness index is proposed as a useful tool for conservation planning.  相似文献   

13.
Aim Using a large database that has been created over the past 5 years with the RECORDER package, presence/absence data for 829 species of vascular plants in the 103 1-km2 squares that cover the city of Plymouth (pop. 243,373) have been analysed by two-way indicator species analysis (TWINSPAN ) and canonical correspondence analysis (CCA) to establish the major species assemblages and to examine their spatial distribution across the city in relation to variation in land use. Location The City of Plymouth. Methods Nine groupings of squares emerged and their distribution was mapped across the city. Interpretation of those groups and their variation in relation to the land use ordination axes showed that TWINSPAN groups lying along the first axis of variation correlated floristic variation with the process of urban development and the historical evolution of urban structure. The second axis appeared to be related to particular remnant semi-natural habitats within the city that could be regarded as ‘hot-spots’ for survival of many plant species. Species were categorized into four types on the basis of their recency and mode of arrival in the city and by using the historical flora of Plymouth produced by T. R. Archer-Briggs in 1880. Variations in the sources of species in relation to the TWINSPAN classification groups were then examined. A second ordination was also computed; this time with geological, altitudinal and distance variables. TWINSPAN groups were then superimposed on the ordinations using polygons to assist with biogeographical interpretation. Results and conclusions The results of both the multivariate analyses and distribution of species by source are then discussed in the context of previous research into urban plant ecology, particularly in Central Europe. The problems of inferring process from pattern in this meso-scale study are reviewed and suggestions are made for further research into urban ecology and biogeography in the city.  相似文献   

14.
15.
Populations of a threatened aquatic plant, Nymphoides peltata, have rapidly degenerated under the influence of recent artificial changes in Lake Kasumigaura of Japan. To estimate the potential of soil seed banks for genetic restoration of the species, we used 10 microsatellite markers to analyze the genetic variation in adults and in seedlings that emerged from soil seed banks. About 187 leaf samples from the cultured stocks that were collected in 17 adult subpopulations in 1995 and 2000 and from three subpopulations that were newly discovered in 2002 were analyzed. As a result, only 18 genets could be identified, suggesting that clonal diversity of the adult population had already become extremely low. Genetic tests were performed on 430 seedlings from seed banks at six locations of natural lakeshores and three of the restoration sites that were artificially constructed in an attempt to assign them to the remnant adult population; many of the seedlings showed genetic variation different from the adults. Furthermore, the seedlings preserved seven alleles that had been lost from remnant adults. However, they had lower average numbers of alleles and heterozygosity levels (NA = 1.5–3.1, H E = 0.146–0.487) than the remnant adults (NA = 3.5, H E = 0.539) and showed high inbreeding coefficients, suggesting that the seed banks were produced by inbreeding. Thus, although the seed banks had a certain potential to restore genetic diversity, the fitness reduction in seed banks caused by inbreeding could affect the success of restoration based on seed banks.  相似文献   

16.
中华菊头蝠(Rhinolophus sinicus)主要分布于我国境内,属于典型的洞栖食虫性蝙蝠,具有重要的研究意义与保护价值。近年,在湘西州境内的16个溶洞中对其栖息生态特征进行了观察,共记录到其个体12942只次,数据分析结果显示:该蝠是该区域溶洞中的居留型优势蝠种,具有集群冬眠的习性。每年的9月中下旬开始逐步聚群冬眠,翌年的3月底开始苏醒,其夏季的繁育场所非常隐蔽,通常位于人无法进入的洞段或人迹罕至的洞穴。总体上,其栖点主要集中于距洞口150—200 m(91.60%)的洞段,离地高度6—10 m(91.75%),多以“双足悬挂”的栖姿将身体悬空倒挂于洞道的顶壁。其体温与栖点温度之间不存在显著性差异(P>0.05),但具有明显的线性正相关关系(R~2=0.8886)。其栖点安全性春夏季高,秋冬季中等偏低。中华菊头蝠作为该区域洞栖性蝙蝠的优势种,在维持洞穴生态系统的稳定中发挥着至关重要的作用,加强对洞穴生态系统中蝙蝠伞护性的研究有助于洞穴生态保护教育及对蝙蝠种群的保护实践。  相似文献   

17.
Anthropogenic global climate change is expected to cause severe range contractions among alpine plants. Alpine areas in the Mediterranean region are of special concern because of the high abundance of endemic species with narrow ranges. This study combined species distribution models, population structure analyses and Bayesian skyline plots to trace the past and future distribution and diversity of Linaria glacialis, an endangered narrow endemic species that inhabits summits of Sierra Nevada (Spain). The results showed that: (i) the habitat of this alpine‐Mediterranean species in Sierra Nevada suffered little changes during glacial and interglacial stages of late Quaternary; (ii) climatic oscillations in the last millennium (Medieval Warm Period and Little Ice Age) moderately affected the demographic trends of Lglacialis; (iii) future warming conditions will cause severe range contractions; and (iv) genetic diversity will not diminish at the same pace as the distribution range. As a consequence of the low population structure of this species, genetic impoverishment in the alpine zones of Sierra Nevada should be limited during range contraction. We conclude that maintenance of large effective population sizes via high mutation rates and high levels of gene flow may promote the resilience of alpine plant species when confronted with global warming.  相似文献   

18.
Carabidologists do it all’ (Niemelä 1996a) is a phrase with which most European carabidologists are familiar. Indeed, during the last half a century, professional and amateur entomologists have contributed enormously to our understanding of the basic biology of carabid beetles. The success of the field is in no small part due to regular European Carabidologists’ Meetings, which started in 1969 in Wijster, the Netherlands, with the 14th meeting again held in the Netherlands in 2009, celebrating the 40th anniversary of the first meeting and 50 years of long-term research in the Dwingelderveld. This paper offers a subjective summary of some of the major developments in carabidology since the 1960s. Taxonomy of the family Carabidae is now reasonably established, and the application of modern taxonomic tools has brought up several surprises like elsewhere in the animal kingdom. Progress has been made on the ultimate and proximate factors of seasonality and timing of reproduction, which only exceptionally show non-seasonality. Triggers can be linked to evolutionary events and plausibly explained by the “taxon cycle” theory. Fairly little is still known about certain feeding preferences, including granivory and ants, as well as unique life history strategies, such as ectoparasitism and predation on higher taxa. The study of carabids has been instrumental in developing metapopulation theory (even if it was termed differently). Dispersal is one of the areas intensively studied, and results show an intricate interaction between walking and flying as the major mechanisms. The ecological study of carabids is still hampered by some unresolved questions about sampling and data evaluation. It is recognised that knowledge is uneven, especially concerning larvae and species in tropical areas. By their abundance and wide distribution, carabid beetles can be useful in population studies, bioindication, conservation biology and landscape ecology. Indeed, 40 years of carabidological research have provided so much data and insights, that among insects - and arguably most other terrestrial organisms - carabid beetles are one of the most worthwhile model groups for biological studies.  相似文献   

19.
The Forest Stewardship Council developed the concept of High Conservation Values (HCVs) as a criteria in the forest certification process in order to promote sustainable forest management. It has six major components or values and component one and two of HCVs deal with the habitat for viable populations of “rare, endemic and threatened (RET) species” using the IUCN Red List category and other national / regional / local lists. But a consistent robust methodology for identification of these areas, does not exist. The present study tried to develop for the first time, a straight forward inclusive methodology for identification of HCVAs for the RET species on a spatio-temporal scale. A total of 50 RET and other significant species (32 flora, 10 fauna and 8 avifauna) were identified after a thorough literature review, field surveys and consultations with experts. Occurrence data of the selected species was collected from different secondary sources, field surveys, institutes and scientists who have worked on them. A 10 km grid-based approach and stratified random sampling was used for the primary GPS field surveys conducted during 2018–2019. MaxEnt species distribution model (SDM) software was used based on the occurrence data and environmental variables for identification of potential suitable habitats for the selected species. Linear support vector machine (LSVM) model was used for assessing the performance of the SDMs. The performance of each SDM has been validated through Cohen's Kappa (KAPPA), true skill statistic (TSS) and receiver operating characteristics (ROC) models. The proposed methodology addresses the urgent need for a holistic and robust set of techniques to apply the HCV toolkit. This is key to identify and map HCVAs for RET species at the landscape level and can be easily adapted to and adopted at the national, regional, state or local level in India. The methods offer an efficient, reliable approach for the application of the HCV concept, elsewhere in the world.  相似文献   

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