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1.
Effects of habitat area, isolation, and landscape diversity on plant species richness of calcareous grasslands 总被引:14,自引:1,他引:14
Jochen Krauss Alexandra-Maria Klein Ingolf Steffan-Dewenter Teja Tscharntke 《Biodiversity and Conservation》2004,13(8):1427-1439
Calcareous grasslands harbour a high biodiversity, but are highly fragmented and endangered in central Europe. We tested the relative importance of habitat area, habitat isolation, and landscape diversity for species richness of vascular plants. Plants were recorded on 31 calcareous grasslands in the vicinity of the city of Göttingen (Germany) and were divided into habitat specialist and generalist species. We expected that habitat specialists were more affected by area and isolation, and habitat generalists more by landscape diversity. In multiple regression analysis, the species richness of habitat specialists (n = 66 species) and habitat generalists (n = 242) increased with habitat area, while habitat isolation or landscape diversity did not have significant effects. Contrary to predictions, habitat specialists were not more affected by reduced habitat area than generalists. This may have been caused by delayed extinction of long-living plant specialists in small grasslands. Additionally, non-specialists may profit more from high habitat heterogeneity in large grasslands compared to habitat specialists. Although habitat isolation and landscape diversity revealed no significant effect on local plant diversity, only an average of 54% of habitat specialists of the total species pool were found within one study site. In conclusion, habitat area was important for plant species conservation, but regional variation between habitats contributed also an important 46% of total species richness. 相似文献
2.
Katja M. Raatikainen Risto K. Heikkinen Miska Luoto 《Biodiversity and Conservation》2009,18(4):1067-1085
Using species and environmental data from an extensive grassland area in south-western Finland, we investigated the effect
of patch area and connectivity, management and local habitat variables on the occurrence of spring-flowering vascular plants
and their richness in boreal agricultural landscapes. Generalized linear models (GLM) and variation partitioning were used
to study the explanatory power of the three groups of variables and their combined contributions on the richness and occurrence
of six spring-flowering plant species. Generalized additive models (GAMs) and associated cross-validation tests were used
to evaluate the predictability of the species occurrence and richness patterns. Present-day grassland patch area and connectivity
were important predictors for occurrence and richness of the studied plant species. In addition, local habitat factors, especially
radiation, accounted for major fractions of occurrence patterns of the studied species. Hybrid models including variables
from all three variable groups had higher explanatory power and predictive capability than partial models. However, performance
of the separate single-species models varied considerably between the six study species. Exclusion of radiation or connectivity
from the hybrid models decreased their predictive performance, suggesting that these factors are of particular importance
for grassland plant species at their northern range margins. When developing conservation and management planning for grassland
plant species in Northern Europe, attention should be paid to well-connected networks of grassland patches including large,
steeply-sloped patches with a favorable microclimate. 相似文献
3.
Tracking the effects of one century of habitat loss
and fragmentation on calcareous grassland
butterfly communities 总被引:1,自引:0,他引:1
Emmanuelle Polus Sofie Vandewoestijne Julie Choutt Michel Baguette 《Biodiversity and Conservation》2007,16(12):3423-3436
Habitat loss and fragmentation are known to reduce patch sizes and increase their isolation, consequently leading to modifications
in species richness and community structure. Calcareous grasslands are among the richest ecosystems in Europe for insect species.
About 10% (1,150 ha) of the total area of a calcareous ridge region (Calestienne, Belgium) and its butterfly community was
analysed over a timeframe of about 100 years. Since 1905 to present day (2005), the Calestienne region has undergone both
calcareous grassland loss and fragmentation: not only did calcareous grassland size decrease and isolation increase, but also,
the number of calcareous grassland patches within the landscape increased until 1965, and subsequently decreased, clearly
reflecting the effects of fragmentation. These processes have had a profound effect on the butterfly community: extinction
and rarefaction affected significantly more often specialist species, which means that generalist species are more and more
overrepresented. This ecological drift, i.e. the replacement of specialists by generalists in species assemblages is likely
to be a general effect of habitat loss and fragmentation on natural communities. 相似文献
4.
Stephanie S. Bauerfeind Anett Theisen Klaus Fischer 《Journal of Insect Conservation》2009,13(3):271-277
While there is agreement that both habitat quality and habitat network characteristics (such as patch size and isolation)
contribute to the occupancy of patches by any given species, the relative importance of these factors is under debate. This
issue is of fundamental ecological importance, and moreover of special concern for conservation biologists aiming at preserving
endangered species. Against this background we investigated patch occupancy in the violet copper Lycaena helle, one of the rarest butterfly species in Central Europe, in the Westerwald area (Rhineland-Palatinate, Western Germany). Occupied
(n = 102) differed from vacant (n = 128) patches in altitude, size, connectivity, availability of wind shelter, in the abundance of the larval host-plant,
in the abundance of a grass species indicating favorable habitat conditions and in the abundance of nitrophilous plants. Overall,
patch occupancy was primarily determined by patch size, connectivity and the abundance of the larval host plant, while all
other parameters of habitat quality were of subordinate importance. Therefore, our findings suggest that even for extremely
sedentary species such as L. helle habitat networks are decisive and—next to the preservation of habitat quality—need to be an integral part of any conservation
management for this species. 相似文献
5.
Peat bogs are valuable ecosystems because they support regional and local hydrological conditions, and store carbon and other greenhouse gases. Nevertheless, their area in Europe is extremely reduced due to human activities. As a result, the number of studies on biodiversity and the environmental factors affecting the distribution of insects, including butterflies, in large intact peatlands is limited. Such studies provide an important baseline for the subsequent analysis of changes during climate warming and for the assessment of succession in degraded peatlands. The results of such research have shown how butterfly assemblages react to local peat bog habitat conditions and contribute new information on the relations of consumers and the very specific environment of peat bogs. The presented research targets the relationship between characteristics of butterfly assemblages and key environmental variables in intact peat bog habitats. A total of 1427 individuals belonging to 23 butterfly species were recorded. In this study, I found that butterfly abundance, diversity and species composition varied significantly among three main habitat types, namely lagg zones, pine bogs and open bogs, although these habitats did not differ in species richness. The highest abundance was in the pine bogs which are characterized by higher plant community structural complexity and, as a result, higher butterfly food resources. The results confirmed positive responses of species richness and abundance of butterflies to nectariferous flower cover. On the other hand, open, sunny, but windy sites on the peat bogs contribute to a decrease of abundance. 相似文献
6.
We examined nestedness and potential mechanisms causing that distributional pattern in resident butterfly communities of
the Toiyabe Range, a mountain range in the central Great Basin of western North America. We tested whether life history characteristics,
including habitat use and vagility, affected the relative degree of nestedness or mean species incidence. We also tested whether
nestedness at the level of individual species was independent of life history. Relationships between distributional patterns
and habitat use, particularly in ecologically sensitive riparian areas, are relevant to ongoing conservation planning in the
Great Basin. The distributional pattern of the 68 resident butterfly species in 19 Toiyabe Range canyons was significantly
nested, as was the distribution of all functional subgroups that we tested. Life history affected neither relative nestedness
of species groups nor mean species incidence. More than 80% of the individual butterfly species that inhabit the Toiyabe Range
had distributions that were more nested than expected. Colonization does not appear to have played an important role in determining
the composition of butterfly communities in Toiyabe Range canyons. Likewise, selective dispersal has probably played a minor
role in producing nested distributions of Toiyabe Range butterflies. Our results suggest either that impacts to riparian areas
are not jeopardizing species viability, or that highly sensitive butterfly species have already been extirpated from the Toiyabe
Range.
Received: 15 February 1998 / Accepted: 19 December 1998 相似文献
7.
The effects of grassland management using fire on habitat occupancy and conservation of birds in a mosaic landscape 总被引:3,自引:0,他引:3
Pere Pons Bernard Lambert Eric Rigolot Roger Prodon 《Biodiversity and Conservation》2003,12(9):1843-1860
Prescribed burning is routinely used to improve grazing in Pyrenean rangelands affected by an overall trend of land abandonment. This study considers the environmental variables influencing habitat occupancy by birds and the consequences of the use of fire in range management for bird conservation. Bird use and habitat structure of 11 cover types, the result of specific management regimes, were monitored for two breeding seasons in a mosaic landscape. Three main gradients of avian composition, corresponding to tree cover, shrub volume and grazing intensity, were identified from canonical correspondence analysis. The structure of the bird community seemed more intensely affected by species-specific selection of cover types than by the birds' use of multiple patches. Out of a total of 10 bird species analysed by a simultaneous confidence intervals procedure, four species with an unfavourable conservation status in Europe (Emberiza cia, Lullula arborea, Saxicola torquata and Lanius collurio) preferred managed grassland. Three types of grassland with shrubs (derived from single or repeated burning) had the highest bird conservation index (taking into account specific status and abundance of the bird assemblage), whereas forests showed middle or low values. The relation (P = 0.054) of this index to the logarithm of the pastoral value (which includes density and grazing quality of grasses) in currently managed cover types suggests that the objectives of grassland recovery by appropriate management practices and those of bird conservation coincide in our study area. 相似文献
8.
9.
Biodiversity conservation requires strategies that encompass a variety of land uses and habitat diversity. In this study, we used sites of high ecological interest identified on the basis of the distribution of priority plant and vertebrate species to assess the implications of habitat diversity for conservation management in the Mediterranean mosaic landscape. 40% of the priority species occur in open habitats that depend on continued human presence and low-intensity land-use activities. Furthermore, 70% of the sites have more than one species habitat and 15% of sites contain more than four different species habitats. By explicitly integrating localized habitat variation, conservation planning can address the multiple conservation issues at stake in regions of high landscape diversity to provide clear and effective management objectives. 相似文献
10.
Persistence of species in a fragmented urban landscape: the importance of dispersal ability and habitat availability for grassland butterflies 总被引:13,自引:0,他引:13
Some species cope with, and survive in, urban areas better than others.From a conservation viewpoint it is important to understand why some species arerare or are excluded in the urban landscape, in order that we might take actionto conserve and restore species. Two ecological factors that might explain thedistribution and abundance of butterfly species in the urban landscape aredispersal ability and the availability of suitable habitat. The influence ofthese factors was assessed by examining the distribution and genetic structureof four grassland butterfly species in the West Midlands conurbation, UK. Thefour species differ in their distribution and abundance, mobility and habitatspecificity. No significant fit to the isolation-by-distance model was found forany of the study species at this spatial scale. MeanF
ST values revealed a non-significant level ofpopulation structuring for two species, Pieris napi (L.)and Maniola jurtina (L.), but moderate and significantpopulation differentiation for Pyronia tithonus (L.) andCoenonympha pamphilus (L.). Results suggest that thesespecies are limited more by the availability of suitable habitat than by theirability to move among habitat patches. Conservation strategies for thesegrassland species should initially focus on the creation and appropriatemanagement of suitable habitat. More sedentary species that have already beenexcluded from the conurbation may require a more complex strategy for theirsuccessful restoration. 相似文献
11.
Inge van Halder Luc Barbaro Emmanuel Corcket Hervé Jactel 《Biodiversity and Conservation》2008,17(5):1149-1169
While the area of plantation forests continues to increase worldwide, their contribution to the conservation of biodiversity
is still controversial. There is a particular concern on the central role played by natural habitat remnants embedded within
the plantation matrix in conserving species-rich insect communities. We surveyed butterflies in maritime pine plantation landscapes
in south-western France in 83 plots belonging to seven habitat types (five successional stages of pine stands, native deciduous
woodlands and herbaceous firebreaks). The effect of plot, habitat and landscape attributes on butterfly species richness,
community composition and individual species were analysed with a General Linear Model (GLM), partial Canonical Correspondence
Analysis (CCA) and the IndVal method. The most important factors determining butterfly diversity and community composition
were the presence of semi-natural habitats (deciduous woodlands and firebreaks) at the landscape scale and the composition
of understorey vegetation at the plot scale. Pure effects of plot variables explained the largest part of community variation
(12.8%), but landscape factors explained an additional, independent part (6.7%). Firebreaks were characterized by a higher
species richness and both firebreaks and deciduous woodlands harboured species not or rarely found in pine stands. Despite
the forest-dominated landscape, typical forest butterflies were rare and mainly found in the deciduous woodlands. Threatened
species, such as Coenonympha oedippus and Euphydryas aurinia, were found in pine stands and in firebreaks, but were more abundant in the latter. In the studied plantation forest, the
conservation of butterflies depends mainly on the preservation of semi-natural habitats, an adequate understorey management
and the maintenance of soil moisture levels. 相似文献
12.
Stefano Scalercio Roberto Pizzolotto Pietro Brandmayr 《Biodiversity and Conservation》2007,16(12):3463-3479
This paper is an attempt to outline a protocol for animal diversity census and evaluation aimed for areas in view of landscape
planning of territories of hundred square kilometres and more, that may work utilising different faunal groups and be anyway
useful at various scales. Many papers are addressed to elaborate tools for landscape planning starting from biodiversity evaluation
and butterflies are often utilised because of their sensitivity to landscape modifications. In this work, the biodiversity
evaluation has been performed using three hierarchically linked landscape units at micro-, meso- and macroscale. Being species
diversity values often inadequate to define the conservation interest of a landscape portion, more importance has been given
to which species compose the species assemblages. A community vulnerability Index was coded and used for evaluating potential
consequences of human disturbance on butterfly assemblages. Forty-four year samples were gained by visual census in the Sila
Greca, Southern Italy, on an area of approximately 520 square kilometres. During 5 years work, 2,535 specimens and 94 species
were recorded, equal to 75.8% of the whole Calabrian fauna. Four vulnerability levels have been established and used for mapping
butterfly assemblage vulnerability in the area, starting from a vegetation map. Species richness was found somewhat contradictory
at micro-scale, where the community vulnerability Index gives a sounder approach. S diversity gives a more reliable picture of naturalness at meso-scale, a level we identified with the “ecotope”. At this more
“geomorphic” scale level, biological functions reflected by butterfly assemblages revealed to be clearly linked to seral processes.
Similarity analysis results show that the ecotope species richness, here called “eta-diversity”, could be an useful measure
of zoological landscape (faunation) potentialities. 相似文献
13.
Samanta Iop Tiago Gomes dos Santos Sonia Zanini Cechin Eduardo Vélez-Martin Valério D. Pillar Paulo Inácio Prado 《Biotropica》2020,52(5):913-926
We investigated the role of local and landscape environmental variables on anurans density classified as habitat specialists and generalists in grassland landscapes, known as South Brazilian grasslands (SBG). In this region, we surveyed 187 ponds distributed over 40 landscape sampling units. For each pond, 31 local environmental variables were measured. Each landscape sampling unit was embedded within a larger regional sampling unit with different landscape properties. For each landscape and regional sampling units, 16 landscape metrics were extracted from a land cover and use map. We recorded 35 species, eleven of which are specialists in the SBG. The specialists were affected by 11 local and 2 landscape environmental variables, while generalists were affected by 14 local and one landscape environmental variable. Thus, specialists and generalists presented different relationships with local and landscape variables, but in general local variables had a greater influence on the density of anurans than the landscape variables. However, the landscape indirectly influenced local variables because higher quality ponds were in landscapes with higher percentages of natural habitat. In conclusion, reproductive sites with higher local quality and located within landscapes with higher percentages of natural grasslands are essential to conserve anurans in this habitat. Effective conservation of such sites would benefit from further studies that assess effects of land use and biotic integrity of ponds, which can help to determine (a) the relative effects of local habitat quality of ponds and (b) the effectiveness of protecting ponds and their local surroundings for anuran conservation in SBG. Abstract in Portuguese is available with online material. 相似文献
14.
Amy Pocewicz Penelope Morgan Sanford D. Eigenbrode 《Journal of Insect Conservation》2009,13(6):593-601
Understanding butterfly response to landscape context can inform conservation management and planning. We tested whether local-scale
resources (host and nectar plants, canopy cover) or landscape context, measured at two scales, better explained the densities
of four butterfly species. The density of Coenonympha tullia, which has host plants strongly associated with grassland habitats, was positively correlated with the amount of grassland
in 0.5- and 1-km radius landscapes and only occurred in forests when they bordered grasslands. For the other species, Celastrina ladon, Cupido amyntula, and Vanessa cardui, local-scale resources better explained butterfly densities, emphasizing the importance of local habitat quality for butterflies.
These three species also used host plants that were distributed more heterogeneously within and among habitat types. Our findings
demonstrate the importance of host plant spatial distributions when determining the scale at which butterfly density relates
to resources, and we recommend that both these distributions and landscape context be evaluated when developing butterfly
monitoring programs, managing for species of concern, or modeling potential habitat. 相似文献
15.
Rosamonde R. Cook 《Oecologia》1995,101(2):204-210
Biotic assemblages are said to be nested when the species making up relatively species-poor biotas comprise subsets of the species present at richer sites. Because species number and site area are often correlated, previous studies have suggested that nestedness may be relevant to questions of how habitat subdivision affects species diversity, particularly with respect to the question of whether a single large, contiguous patch of habitat will generally contain more species than collections of smaller patches having the same total combined area. However, inferences from analyses of nestedness are complicated by (1) variability in degrees of nestedness measured in natural communities, (2) variability in species-area relationships, and (3) the fact that nestedness statistics do not account for the size of habitat patches, only in the degree of overlap among sites with different numbers of species. By comparing various indices of nestedness with a saturation index that more directly measures the effect of habitat subdivision, it is shown that the first two of these factors are not as important as the third. Whether a single large site or several smaller ones having the same total combined area maximizes species diversity is dependent on (1) overlap in species composition among sites and (2) the number of species per unit area in the different sites. Because nestedness indices do not account for species number at a site, they cannot accurately predict how habitat subdivision affects species diversity patterns. Still, nestedness analyses are important in that they indicate the degree to which rare species tend to be found in the largest, or the most species-rich, sites, patterns not revealed by the saturation index. Both types of analysis are important in order to obtain a more complete picture of how species richness and compositional patterns are influenced by habitat subdivision. 相似文献
16.
Using data from 46 sites in southern Finland and ordination methods, we examined plant-environment relationships in boreal
mesic semi-natural grasslands at two spatial scales (grain sizes), using plots of 0.25 ha and 1 × 1 m. We applied the variation
partitioning approach to determine the pure fractions of environmental variable groups and their joint effects on plant species
compositional variation in the studied grasslands. The variables related to land-use intensity and high nutrient level (especially
phosphorus) had a major role in explaining the species composition at both scales, although soil heterogeneity and habitat
characteristics also accounted for a notable amount of the species compositional variation at the 0.25 ha grain size. At the
1 × 1 m grain size, the majority of the species compositional variation was related to the “pure” spatial differences between
the studied grasslands (i.e. the site identity (dummy 0/1) variable), whereas the impacts of within-site variation of local
environmental factors were considerably smaller. High nutrient levels and variables related to low land-use intensity, e.g.
litter accumulation, were also significantly correlated with floristic variation at the 1 × 1 m grain size. Rare and declining
grassland species are associated with low-nutrient grassland sites and patches. The main recommendation for the management
planning of boreal semi-natural grasslands is that the first restoration attempts should be targeted to areas where nutrient
levels, particularly that of phosphorus, are relatively low. Soil properties and plant species composition can provide useful
guidelines for defining the correct management procedures for different sites. 相似文献
17.
18.
19.
Metapopulation theory predicts that species richness and total population density of habitat specialists increase with increasing
area and regional connectivity of the habitat. To test these predictions, we examined the relative contributions of habitat
patch area, connectivity of the regional habitat network and local habitat quality to species richness and total density of
butterflies and day-active moths inhabiting semi-natural grasslands. We studied butterflies and moths in 48 replicate landscapes
situated in southwest Finland, including a focal patch and the surrounding network of other semi-natural grasslands within
a radius of 1.5 km from the focal patch. By applying the method of hierarchical partitioning, which can distinguish between
independent and joint contributions of individual explanatory variables, we observed that variables of the local habitat quality
(e.g. mean vegetation height and nectar plant abundance) generally showed the highest independent effect on species richness
and total density of butterflies and moths. Habitat area did not show a significant independent contribution to species richness
and total density of butterflies and moths. The effect of habitat connectivity was observed only for total density of the
declining butterflies and moths. These observations indicate that the local habitat quality is of foremost importance in explaining
variation in species richness and total density of butterflies and moths. In addition, declining butterflies and moths have
larger populations in well-connected networks of semi-natural grasslands. Our results suggest that, while it is crucial to
maintain high-quality habitats by management, with limited resources it would be appropriate to concentrate grassland management
and restoration to areas with well-connected grassland networks in which the declining species currently have their strongest
populations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
Declines of West European farmland birds have been associated with intensive agricultural practices, while in Central and
Eastern European countries grasslands still harbour a diverse and unique bird community. However, in these countries comparative
studies on the effects of agricultural intensity on biodiversity are virtually missing. We compared bird communities of paired
extensively and intensively grazed cattle pastures in three different regions of the Hungarian Great Plain. The influence
of grazing intensity, landscape and regional effects were tested on the abundance and species richness of two ecological groups
of bird species (grassland and non-grassland birds), as well as on the abundance of the three commonest grassland bird species
(Skylark, Yellow wagtail, Corn bunting) in linear mixed models. We found significant effects of grazing intensity on the abundance
of grassland birds, which were more abundant on the extensive sites, whereas no effects were found on non-grassland birds.
This could be explained by a closer dependence of grassland birds on grasslands for nesting and foraging, whereas non-grassland
birds only used grasslands opportunistically for foraging. Landscape effect was shown on grassland bird abundance, but not
on non-grassland birds. The regions did affect only the species richness of grassland birds. At species level, the effect
of management was significant for the three commonest grassland species, which were more abundant on the extensive fields
in all regions. Additionally, on Skylark abundance landscape and regional effects were also shown. These findings suggest
that conservation of biodiversity in agricultural systems requires the consideration of landscape perspective to apply the
most adequate management. 相似文献