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1.
Responses of carabid beetles (Coleoptera: Carabidae) to urbanisation were studied along an urban-suburban-rural gradient representing decreasing intensities of humandisturbance. Carabids were collected by pitfall trapping during their activity period in lowland oak forest patches in the city of Debrecen, Eastern Hungary. The average number of carabid species was significantly higher in the rural and urban areas compared to the suburban one. The high overall species richness in the urban area was due to the presence of species preferring open habitats. The species richness of forest specialist carabids significantly increased along the urban-rural gradient. The overall carabid abundance was significantly higher in the rural than the other two areas. The results did not support the hypothesis that overall diversity should decrease in response to habitat disturbance. They also contradicted the intermediate disturbance hypothesis: species richness was not the highest in the moderately disturbed suburban area. In the urban area, opportunistic species dominated. The average carabid body size was significantly larger in the rural and suburban areas than in the more disturbed urban area. Multivariate methods detected changes in species composition and abundance structure along the urban-rural gradient. Significant proportion of the variation in abundance and species richness was explained by the heterogeneity of environmental variables (ground temperature, surface temperature, humidity, cover of decaying wood material, herbs, canopy layer, and by the amount of prey).  相似文献   

2.
We conducted two studies on how highways affect their adjacent habitats by sampling carabid beetles (Coleoptera, Carabidae) in patches of formerly continuous forest next to highways. (1) We sampled carabids at 14 highway intersections near Helsinki, Finland. Each intersection (constructed 2–40 years ago) had two forested patches to study: a remnant (0.5–37.4 ha) and, isolated from the remnant by an intersection lane, an islet (size 0.2–1.8 ha). Pitfall trap catch data (2301 carabids, 25 species) showed that remnants hosted higher catches of three carabid species, and slightly higher species richness, than islets (patch-size effect). Time since intersection construction had no apparent effect on carabids. Traffic volume along the intersection lane determined the assemblage structure of carabids in dry patches, and the abundance of a forest carabid Calathus micropterus. Compared to moist patches, drier patches hosted lower catches of four generalist species; they also had different assemblages of carabids (habitat-type effect). An interaction between patch size and habitat type for a forest generalist Pterostichus oblongopunctatus indicated that the patch-size effect was dependent on habitat type. (2) We examined possible dispersal of carabids among forested patches that were separated by highway lanes in Drenthe, the Netherlands. We released 2696 marked individuals of 10 species, and recaptured 376 using dry pitfall traps. We found no evidence for inter-patch movement for nine forest species, but 22 of 225 recaptured individuals of Poecilus versicolor, an eurytopic open-habitat species, had crossed the highway. Catches of seven forest species were also significantly lower in the road verges, compared to the adjacent forests. These two studies suggest that (i) decreasing patch size negatively affects forest-carabid catch and overall species richness, (ii) habitat type can affect the intensity of the patch-size effect, (iii) carabid assemblages of forest fragments vary with traffic volume (which may be linked with urbanization), (iv) forest carabids rarely cross highways, and (v) open habitats associated with road margins are dispersal barriers for forest carabids.  相似文献   

3.
To evaluate the importance of urban woodlands to serve as potential sites for biodiversity conservation, we analysed bird, carabid beetle and small mammal community responses to urbanisation at different spatial scales. We analysed the relationships between the variations of the structure (species richness S, diversity H′ and dominance D) of animal communities of woodlands distributed along a rural–urban gradient, and the variations along this same gradient of (1) the vegetation within woodlands, (2) the landscape at 100 m and (3) 600 m around the woodlands. We identified the spatial scales whose variations along the gradient most affected each animal community structure, and characterised community responses to these variations. Our results showed that urbanisation affected taxa differently according to their dispersal ability. Carabid beetles, less mobile, seem to be sensitive to increasing fragmentation and built surfaces from periurban to town centre which could make their movement within the urban landscape difficult. Birds, mobile species, seem to be more sensitive to variations of the vegetation structure within woodlands from periurban to town centre that could affect their capacity to maintain in habitat patches. Although our study did not allow relating the small mammal community structure to urbanisation, it suggests that this taxa is sensitive to urban local disturbances. A relevant management scale of woodlands can be specified for each taxa conservation. Urban woodlands accommodate over 50% of the species present in periurban woodlands, and effective management could enhance this number. Woodlands seem to be a good choice for promoting biodiversity conservation in towns.  相似文献   

4.
Analysis of carabids spatial distribution in a hedgerow network landscape in western France, pinpoints the role of the landscape among other levels of ecological organization.Dispersion of forest species differs among core forest species, peninsula forest species and corridor forest species. Abundance of forest carabid species in a particular hedgerow is related to the positive effect of a dense herbaceous layer and the presence of a tree layer which is enhanced by the presence of two parallel hedgerows, especially along lanes.At the landscape level distance from the largest forest determines abundance of forest species within the first kilometer out of it. Beyond that, abundance is independent of distance from the source forest and the discriminant ecological factors are: hedgerow structure, presence of lanes bordered by two hedgerows.  相似文献   

5.
Weeds constitute major constraints for farmers by reducing crop yield and quality. However, weeds are managed effectively using herbicides, but this may cause harmful effects on human health and the environment. In an experiment on weed seed predation, we tested the biological control potential of carabid beetles to combat weeds in the absence of herbicides. Seeds from three common weed species were placed in cereal fields on conventional and organic farms located along a landscape complexity gradient (area annual crops within 1 km) in two distinct regions in Sweden. Carabid beetles were sampled in the same fields using pitfall traps. Neither carabid species richness nor seed removal was related to organic farming. Seed removal was significantly related to carabid species richness and both carabid species richness and seed removal was higher in landscapes with large total area of annual crops, although the evenness of the carabid communities was lower. The carabid genera with strongest positive relationship to seed removal differed between regions (Trechus in Uppland and Pterostichus in Scania), as did the preference for the different weed seed species. This study concludes that carabid species richness contributes to weed seed predation and that large scale landscape context explains more variation in the carabids’ responses than local farming practices.  相似文献   

6.
Impact of agricultural subsidies on biodiversity at the landscape level   总被引:1,自引:0,他引:1  
Agricultural management is a major factor driving the change of faunal richness in anthropogenic landscapes. Thus, there is an urgent need to develop tools that allow decision-makers to understand better intended and unintended effects of agricultural policy measures on biodiversity. Here we demonstrate the potential of such a tool by combining a socio-economic model with the biodiversity model GEPARD to forecast the response of bird and carabid species richness to two scenarios of agricultural subsidies: (1) subsidies based on production levels and prices and (2) direct income support that is independent of production levels. We focussed on farmland of the Lahn-Dill area, Germany, as an example of European regions with low intensity farming. GEPARD predicts faunal richness and is based on multi-scaled resource-selection functions. Under both scenarios the area of predicted losses in species richness of birds and carabids was larger than the area of predicted gains in species richness. However, the area with predicted losses of avian richness was smaller under the direct income support scenario than under the production-based subsidy scenario, whereas the area with predicted losses of carabid species richness was smaller under the production-based subsidy scenario than under the direct income support. Yet locally, richness gains of up to four species were predicted for carabids under both scenarios. We conclude that the sometimes contrasting and heterogeneous responses of birds and carabids at different localities suggest the need for spatially targeted subsidy schemes. With the help of the GIS-based approach presented in this study, prediction maps on potential changes in local and regional species richness can be easily generated.  相似文献   

7.
The influence of urbanisation on diversity and trait composition of birds   总被引:1,自引:0,他引:1  
We analysed the effect of the urban matrix, the urban space surrounding distinct habitat patches, on bird communities. In doing so we assessed the impact of urbanisation beyond the effect of habitat loss. We used a set of 54 wasteland sites of early successional stages that were scattered over the entire urban area of Berlin, Germany. Sites were similar to each other in habitat structure but differed in their surroundings, the urban matrix. Thus, our study design allows to investigate associations between birds and the urban matrix. Our measures for urbanisation are human population density and degree of sealing within 50 to 2,000 m buffer zones surrounding each wasteland site. Along the urbanisation gradients we calculated three measures of bird communities: alpha diversity, beta diversity, and trait profile of the entire bird community regarding food, life-history, and behavioural traits. Alpha diversity did not change significantly along the gradients of urbanisation. However, beta diversity increased along the urbanisation gradients with urbanisation at the local scale (50 m) but decreased at the landscape scale (200 and 2,000 m). Fourth-corner analysis of relationships between urbanisation and species traits showed trait shifts: adult survival rate increased with human population density and densities of birds that are more often reported to show innovative behaviour increased with both human population density and degree of sealing. We conclude that the influence of the urban matrix contributes to the homogenisation of the avifauna by filtering certain species traits and promoting others.  相似文献   

8.
通过建立城市森林群落密度梯度,对沈阳市森林群落进行抽样调查,应用spss分析各密度梯度下物种群落及群落中不同层次物种的丰富度指数(Ma)、优势度指数(C)、Simpson指数(D)、Shannon-Wiener指数(H)及Pielou指数(Jh,Jd)等响应关系。结果表明:群落的Ma指数与群落密度变化响应关系显著,群落密度对物种多样性、物种均匀度均不具有显著相关关系。  相似文献   

9.

Context

Landscape heterogeneity (the composition and configuration of matrix habitats) plays a major role in shaping species communities in wooded-agricultural landscapes. However, few studies consider the influence of different types of semi-natural and linear habitats in the matrix, despite their known ecological value for biodiversity.

Objective

To investigate the importance of the composition and configuration of matrix habitats for woodland carabid communities and identify whether specific landscape features can help to maintain long-term populations in wooded-agricultural environments.

Methods

Carabids were sampled from woodlands in 36 tetrads of 4 km2 across southern Britain. Landscape heterogeneity including an innovative representation of linear habitats was quantified for each tetrad. Carabid community response was analysed using ordination methods combined with variation partitioning and additional response trait analyses.

Results

Woodland carabid community response was trait-specific and better explained by simultaneously considering the composition and configuration of matrix habitats. Semi-natural and linear features provided significant refuge habitat and functional connectivity. Mature hedgerows were essential for slow-dispersing carabids in fragmented landscapes. Species commonly associated with heathland were correlated with inland water and woodland patches despite widespread heathland conversion to agricultural land, suggesting that species may persist for some decades when elements representative of the original habitat are retained following landscape modification.

Conclusions

Semi-natural and linear habitats have high biodiversity value. Landowners should identify features that can provide additional resources or functional connectivity for species relative to other habitat types in the landscape matrix. Agri-environment options should consider landscape heterogeneity to identify the most efficacious changes for biodiversity.
  相似文献   

10.
Maintaining connectivity among local populations in a fragmented landscape is crucial for the survival of many species. For isolated habitat patches, stochastic fluctuations and reduced gene flow can lead to high risk of extinction. The connectivity of the landscape is especially crucial for the carabid species living in the fragmented forests of the Bereg plain (NE Hungary and W Ukraine) because a highway will be constructed through the plain. Our purpose is to (1) evaluate the impacts of three possible highway tracks, (2) suggest a solution that is realistic with less impact on connectivity than other plans and (3) discuss how to decrease the disadvantageous effects of each track. Our results, based on a network analysis of landscape graph of patches and ecological corridors, indicate that the intended highway could have deleterious consequences on forest-living carabids. Relatively simple actions, like the establishment of stepping stones, could compensate for the loss of habitat connectivity and promote the survival of carabids, or minor modifications in one possible track could diminish its adverse effects. While many other studies would be needed for a comprehensive assessment of the biotic impact of the highway, we provide an example on the usefulness of network analysis for land use management. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

11.
Hollow-bearing trees provide habitat for diverse taxonomic groups and as such they are recognised for their importance globally. There is, however scant reference to this resource relative within urban forest patches. The functional ecology of habitat remnants along an urbanisation gradient plays an important ecological, social and economic role within urban landscapes. Here we quantify the impacts of urbanisation, landscape, environmental, disturbance (past and present) and stand variables on hollow-bearing tree density within urban forest patches. This was undertaken by surveying 45 forest patches on the Gold Coast, south-east Queensland, Australia. Sites were categorised as; urban, peri-urban or rural along an urbanisation gradient, with an additional five control sites. Historical logging practices were found to be the driving factor influencing hollow-bearing tree density along the urbanisation gradient; while the impacts of urbanisation itself are not as yet discernible. These findings highlight the significance of incorporating historical land use practise into current and future urban planning, as these will have continuing impacts on remaining urban biodiversity values. These findings, will benefit natural resource managers and urban planners when making decisions about where and how best to manage for hollow-bearing trees along urbanisation gradients.  相似文献   

12.

Context

Intensive agricultural management practices and landscape homogenisation are the main drivers of biodiversity loss in agricultural landscapes. Agricultural fields are regularly disturbed and provide unstable habitats due to crop management regimes. This may lead to movement of arthropods into neighbouring non-arable habitats, as natural and semi-natural habitats provide suitable overwintering sites.

Objectives

Here we assessed the effect of landscape composition and configuration on the overwintering spider and carabid fauna of grassy field margins and hedgerows.

Methods

We sampled ground-dwelling arthropods at field edges of different types (grassy field margin and hedgerows), landscape composition (diverse and simple) and configuration (mosaic and large-scale agricultural landscapes).

Results

We detected larger spiders in hedgerows than in grassy field margins and in complex landscapes rather than in simple landscapes. We found a significant effect of interaction between landscape composition and edge type on ballooning propensity of spiders. Agrobiont carabids were more abundant in field edges of compositionally simple and large-scale agricultural landscapes. Furthermore, we showed an effect of interaction between landscape composition and edge type on agrobiont spiders. We collected larger carabids in grassy field margins than in hedgerows and carabids were smaller in simple landscapes than in diverse landscapes. The spider community was affected by edge type, and landscape composition had a significant effect on the carabid community.

Conclusions

Small-scale agricultural landscapes may have higher overall densities of ground-dwelling spiders and carabids than large scale landscapes due to the relatively high edge density and the higher quantity of available overwintering sites.
  相似文献   

13.
Avian response to landscape pattern: The role of species' life histories   总被引:3,自引:0,他引:3  
We suggest that the life histories of species within communities may differ among geographic locations and that communities from distinct biomes may respond uniquely to a given trajectory of landscape change. This paper presents initial tests relevant to these hypotheses. First, the representation of various life-history guilds in avifaunas from the Eastern Deciduous (EDF) and Pacific Northwest (PNW) forests were compared. Three guilds contained more species in the EDF community (large patch and/or habitat interior guild, small patch and/or edge guild, and fragmentation-sensitive guild). The guild of predators requiring large forest tracts was better represented in the PNW. Next, the relative sensitivity of each community to habitat change was ranked based on the life-history traits of their species. The EDF avifauna had a significantly higher index of sensitivity to both forest fragmentation and to landscape change in general. Among the birds with high scores for sensitivity to landscape change were several species that have received little conservation attention thus far including some associated with open-canopy habitats. Lastly, the validity of using life histories to predict community response to landscape change was supported by the fact that the sensitivity scores for PNW species correlated significantly with independent data on species population trends. While more rigorous analyses are suggested, we conclude that knowledge of life histories is useful for predicting community response to landscape change and that conservation strategies should be uniquely tailored to local communities.  相似文献   

14.
Studies dealing with community similarity are necessary to understand large scale ecological processes causing biodiversity loss and to improve landscape and regional planning. Here, we study landscape variables influencing patterns of community similarity in fragmented and continuous forest landscapes in the Atlantic forest of South America, isolating the effects of forest loss, fragmentation and patterns of land use. Using a grid design, we surveyed birds in 41 square cells of 100 km2 using the point count method. We used multivariate, regression analyses and lagged predictor autoregressive models to examine the relative influence of landscape variables on community similarity. Forest cover was the primary variable explaining patterns of bird community similarity. Similarity showed a sudden decline between 20 and 40% of forest cover. Patterns of land use had a second order effect; native bird communities were less affected by forest loss in landscapes dominated by tree plantations (the most suitable habitat for native species) than in landscapes dominated by annual crops or cattle pastures. The effects of fragmentation were inconclusive. The trade-off between local extinctions and the invasion of extra-regional species using recently created habitats is probably the mechanism generating the observed patterns of community similarity. Limiting forest loss to 30–40% of the landscape cover and improving the suitability of human-modified habitats will contribute to maintain the structure and composition of the native forest bird community in the Atlantic forest.  相似文献   

15.

Context

In heterogeneous landscapes, habitat complementation is a key process underlying the distribution of mobile species able to exploit non-substitutable resources over large home ranges. For instance, insectivorous bats need to forage in a diversity of habitat patches offering varied compositions and structures within forest landscape mosaics to fulfill their life cycle requirements.

Objectives

We aimed at analyzing the effects of forest structure and composition measured at the stand and landscape scales on bat species richness, abundance and community composition in pine plantation forests of south-western France.

Methods

We sampled bat communities at different periods of the summer season using automatic ultrasound recorders along a tree composition gradient from pine monocultures to pure oak stands. We analyzed bat species activity (as a proxy for bat abundance) and species richness with linear mixed models. Distance-based constrained ordinations were used to partition the spatio-temporal variation in bat communities.

Results

Deciduous tree cover increased bat activity and modified community composition at both stand and landscape scales. Changes in bat communities were mostly driven by landscape-scale variables while bat activity responded more to stand-scale predictors.

Conclusions

The maintenance of deciduous trees at both stand and landscape scales is likely critical for bat communities living in fast-growing conifer plantations, by increasing the availability and diversity of prey and roosting sites. Our study suggests that bats respond to forest composition at both stand and landscape scales in mosaic plantation landscapes, mainly through a resource complementation process.
  相似文献   

16.
Human trampling destroys seedlings and saplings without regard to species in urban park forests and the addition of deer browsing compounds the losses. The unexamined research question is: what is the effect of white deer browsing in the absence of human trampling? Radnor Lake State Natural Area, Nashville, TN, USA has been protected from off-pathway human transit since 1973 and white-tailed deer (Odocoileus virginianus Zimmerman) were restored to the Natural Area in 1980. From 1976 to 2007, a plot with tagged trees in the mesic slope forest showed the tree population for 16 species decreased, two remained stable, and one increased. The pattern of increase for sugar maple (Acer saccharum Marsh) was 57 new trees added but 46 trees were lost, which appears as a population increase from 1976 to 1996 and a decrease in 2007. In all five forest communities, the total tree stems per ha declined from 1974 to 2008. During the period 1994–2008, O. virginianus over browsing decimated the seedling population of all species and caused the total for stems per ha for saplings to become smaller than the total stems per ha for trees in each community except the ravine forest, which had the greatest loss of trees. The only consistent change in trees across the five communities when comparing 1974–2008 was the significant tree importance value increase for A. saccharum. The conflicting significant changes for major species, other than A. saccharum, across the Natural Area forest communities informs management for other urban park forests—browsing by O. virginianus results in increased numbers for trees and saplings in the communities the species are well adapted to grow and reproduce in and fewer trees and saplings in the communities with environmental conditions that are not well suited to the species.  相似文献   

17.
Spatial and temporal changes in community structure of soil organisms may result from a myriad of processes operating at a hierarchy of spatial scales, from small-scale habitat conditions to species movements among patches and large-sale landscape features. To disentangle the relative importance of spatial and environmental factors at different scales (plot, patch and landscape), we analyzed changes in Collembola community structure along a gradient of forest fragmentation, testing predictions of the Hierarchical Patch Dynamics Paradigm (HPDP) in different European biogeographic regions (Boreal, Continental, Atlantic, Mediterranean, Alpine). Using variance partitioning methods, based on partial CCAs, we observed that the independent effect of environmental processes was significantly explaining Collembola community variance in all regions, while the relative effect of spatial variables was not significant, due to the observed high levels of landscape heterogeneity along the gradient. Environmental factors at the patch and plot scales were generally significant and explained the larger part of community changes. Landscape variables were not significant across all study sites. Yet, at the landscape level, an increase in forest habitat and proximity of forest patches were showed to have an indirect influence on local community changes, by influencing microhabitat heterogeneity at lower spatial scales in all studied regions. In line with HPDP, large-scale landscape features influenced spatio-temporal changes in soil fauna communities by constraining small-scale environmental processes. In turn, these provided mechanistic understanding for diversity patterns operating at the patch scale, via shifts in community weighted mean of Collembola life-forms occurring in local communities along the fragmentation gradient.  相似文献   

18.
Environmental changes associated with urbanisation can affect the functioning of ecosystem processes. In cities, forests are among the most frequent types of green areas and provide a wide range of ecosystem services including air cleaning, decomposition of leaf litter and recreation. The European beech (Fagus sylvatica) is a frequent and widespread deciduous tree in temperate forests in Central Europe. In this study, we examined the effects of urbanisation on decomposition processes of F. sylvatica leaves in different-sized forests in the urban region of Basel, Switzerland. We used standardised litterbags (mesh size: 2 mm) with F. sylvatica leaves to assess the impact of degree of urbanisation (indicated by the percentage cover of sealed area in the surroundings) and forest size on the early stage of leaf litter decomposition and seasonal microbial activity. We found combined effects of degree of urbanisation and forest size on the decomposition rate of leaf litter (klitter). Large forests showed the highest klitter in areas with sparse settlements and the lowest klitter in densely settled areas, whereas the opposite pattern was recorded for small and medium-sized forests. This indicates that abiotic and biotic forest characteristics of forests of similar size differently influenced klitter depending on the degree of urbanisation. Moisture content of litter was the best predictor of microbial activity, followed by forest size. We assume that factors acting at the landscape scale such as the degree of urbanisation might be too coarse to detect any differences in microbial activity. Our results revealed that even small urban forests contribute to this important ecosystem function. As decomposers are at the bottom of the food chain, management actions that support the biological activity in soil might be also beneficial for species at higher trophic ranks.  相似文献   

19.
We address effects of large-scale forestry on landscape structure and the structure and composition of boreal bird communities in North Sweden. Specifically, we ask: after controlling for the effect of patch size, forest age and tree species composition, is there any residual effect attributable to the reduction in area of old forest? Pairs of landscape blocks (25 by 25 km) were selected to maximize area difference in human-induced disturbance, clear-cut as opposed to semi-natural old forest. Median distance to natural edge (wetlands, open water) from randomly selected points in forest was 250 and 200 m in high and low impact landscapes, respectively, indicating a high degree of ‘natural’ fragmentation of the pristine boreal landscape in the area. By contrast, median distance to clear-cut in uncut forest was 750 and 100 m, respectively. Clear-cuts in high impact landscapes were disproportionally more common in areas with contiguous forest land than in areas with spatially disjunct forest, implicating that forestry increases natural fragmentation of the landscape by subdividing larger forest tracts. Point counts along forestry roads showed that species richness and relative abundance of forest birds were higher in landscapes with low forestry impact. These differences can partly be explained by differences in age composition of forest and composition of tree species. After controlling for patch size, forest age and tree species composition, a significant effect of forestry impact remained for Sibirian species and the Tree pipitAnthus trivialis. Our results thus imply that this group of species and the Tree pipit may be sensitive to forest fragmentation. In contrast to previous Finnish studies, we found relatively small negative effects on relative abundance of species hypothesized to be negatively affected by large-scale clear-cutting forestry. However, our picture of the present does not contradict results from Finnish long-term population studies. Five factors may account for this: 1) clear-cut areas are not permanently transformed into other land use types, 2) planted forests are not completely inhabitable for species preferring older forest, 3) the majority of species in the regional pool are habitat generalists, 4) the region studied is still extensively covered with semi-natural forest, and 5) our study area is relatively close to contiguous boreal forest in Russia, a potential source area for taiga species.  相似文献   

20.
Natural landscapes are increasingly subjected to anthropogenic pressure and fragmentation resulting in reduced ecological condition. In this study we examined the relationship between ecological condition and the soundscape in fragmented forest remnants of south-east Queensland, Australia. The region is noted for its high biodiversity value and increased pressure associated with habitat fragmentation and urbanisation. Ten sites defined by a distinct open eucalypt forest community dominated by spotted gum (Corymbia citriodora ssp. variegata) were stratified based on patch size and patch connectivity. Each site underwent a series of detailed vegetation condition and landscape assessments, together with bird surveys and acoustic analysis using relative soundscape power. Univariate and multivariate analyses indicated that the measurement of relative soundscape power reflects ecological condition and bird species richness, and is dependent on the extent of landscape fragmentation. We conclude that acoustic monitoring technologies provide a cost effective tool for measuring ecological condition, especially in conjunction with established field observations and recordings.  相似文献   

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