首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
During 2002–2009, we surveyed butterflies at 73 bogs, 20 adjacent lowland roadsides, and 5 nearby upland roadsides in northern Wisconsin and three bogs in central Wisconsin, with additional observations from 1986 to 2001. Especially in northern Wisconsin, bogs are relatively unaffected by humans, but naturally comprise <1% of the landscape. Bog specialist species composition varied by bog type (muskeg, kettlehole, coastal peatland). Specialist abundance also varied significantly both among bog types and within type among sites. A number of bog specialists frequently occurred in numerous examples of bogs, including all three types. But virtually no specialist individuals occurred in nearby upland roadsides. Northern Wisconsin bogs had similar specialist species richness compared to large barrens and heaths in the same region. Specialist species comprised a small proportion (10%) of all butterfly species recorded in bogs, similar to proportions reported for specialists in tallgrass prairie and barrens. However, specialists accounted for nearly half the total individuals recorded in bogs, comparable to proportions of specialists found in less fragmented vegetation (barrens) and larger patches of favorably managed prairie, but far exceeding proportions observed in other highly fragmented prairie patches. A fundamental lesson may be that aiming to conserve typical ecosystems, even if native, and their average processes, leads to average (generalist) butterflies. Bogs have different vegetation types superimposed on each other, including bog, heath, forest, sedge meadow, and wet meadow associates in the same spots. Conservation management needs to avoid simplifying the vegetation to one layer, reducing specialist fauna. Long-term vegetative consistency, as in bogs, is advised for conservation management of specialist butterflies in other fragmented vegetations.  相似文献   

2.
Obligate myrmecophilic butterfly species, such as Phengaris (Maculinea) teleius and P. nausithous, have narrow habitat requirements. Living as a caterpillar in the nests of the ant species Myrmica scabrinodis and M. rubra, respectively, they can only survive on sites with both host ants and the host plant Great Burnet Sanguisorba officinalis. After having been reintroduced into a nature reserve in the Netherlands in 1990, both butterfly species expanded their distribution to linear landscape elements such as road verges and ditch edges outside this reserve. As additional habitat of both butterfly species, vegetation management of these landscape elements became important. Our results show that a management beneficial for Phengaris butterflies should aim to increase the nest density of Myrmica species, at the same time reducing the density of nests of the competitor Lasius niger or at least keeping them at a low density. Unfavourable grassland management under which L. niger thrives, includes not mowing or flail-cutting the grass, or depositing dredgings along the side of the ditch. Management favourable for the two Myrmica species differs, demanding some flexibility if both species are to benefit. M. scabrinodis is best supported with early mowing of the road verge vegetation or late mowing in the nature reserve, both of which result in an open vegetation and warm microclimate. In contrast, the nest sites of M. rubra should be left undisturbed during the summer, and mown in late autumn. Mowing of butterfly habitat should be avoided between mid-June and mid-September as this would remove the flowerheads of the Sanguisorba plants, on which the butterflies lay their eggs.  相似文献   

3.
Many grassland ecosystems are disturbance-dependent, having evolved under the pressures of fire and grazing. Restoring these disturbances can be controversial, particularly when valued resources are thought to be disturbance-sensitive. We tested the effects of fire and grazing on butterfly species richness and population density in an economically productive grassland landscape of the central U.S. Three management treatments were applied: (1) patch-burn graze—rotational burning of three spatially distinct patches within a pasture, and moderately-stocked cattle grazing (N?=?5); (2) graze-and-burn—burning entire pasture every 3?years, and moderately-stocked cattle grazing (N?=?4); and (3) burn-only—burning entire pasture every 3?years, but no cattle grazing (N?=?4). Butterfly abundance was sampled using line transect distance sampling in 2008 and 2009, with six 100-m transects per pasture. Butterfly species richness did not respond to management treatment, but was positively associated with pre-treatment proportion of native plant cover. Population density of two prairie specialists (Cercyonis pegala and Speyeria idalia) and one habitat generalist (Danaus plexippus) was highest in the burn-only treatment, whereas density of one habitat generalist (Cupido comyntas) was highest in the patch-burn graze treatment. Treatment application affected habitat structural characteristics including vegetation height and cover of bare ground. Historic land uses have reduced native plant cover and permitted exotic plant invasion; for some butterfly species, these legacies had a greater influence than management treatments on butterfly density. Conservation of native insect communities in altered grasslands might require native plant restoration in addition to restoration of disturbance processes.  相似文献   

4.
Northern Wisconsin bogs provide a natural experiment on butterfly population occurrence in a naturally highly fragmented vegetation type, which may provide insight on conserving butterflies in anthropogenically fragmented and degraded landscapes. We surveyed butterflies in bogs (about as unaffected by humans as possible, but naturally occurring over <1% of northern Wisconsin) primarily during 2002?C2009, with additional observations from 1986 to 2001. Different bog types had different bog-specialist butterfly faunas, but bog butterfly abundance also differed in similar vegetations among subregions. Some small isolated bogs held very high densities of specialist butterflies. Summer but not spring specialists frequented adjacent lowland roadsides and utilized a variety of non-native as well as native nectar sources. Paleo-entomology indicates that insects don??t evolve out of trouble; instead they move out of trouble. Given the low dispersal apparent today for species restricted to bogs, ??move?? might be better understood as ??hunkering?? within their vegetation as it expands and shrinks and moves around the landscape. Although bogs appeared to have more intact specialist butterfly faunas than tallgrass prairies (99.9% destroyed by human activities), bog butterflies do not live in average sites even in a relatively natural landscape. Just as bog butterflies are ??sunk and dunked?? in isolation, specialist butterflies elsewhere may have been left ??high and dry?? naturally, or are now due to human activities. Numerous studies have demonstrated that presence and abundance of specialist butterflies increase with increasing size and connectedness of habitat patches. But with long-term consistent vegetation, populations with high abundances in small isolated sites and with low numbers thinly occurring in large sites can be secure, as shown by bog butterflies.  相似文献   

5.
Satoyama, the traditional agricultural landscape in Japan, has drawn much attention from the viewpoint of biodiversity conservation. It is composed of diverse vegetation types, including secondary forests, paddy fields and cultivated fields in a narrow area (ca. 1 km2). To clarify the characteristics of butterfly assemblage and the relative contribution of each vegetation type to butterfly diversity and endemism in satoyama, we conducted a line-transect survey along a 1.1-km route with five sections (two forest interior, one interior-edge, one edge-openland and one openland). Life history features (voltinism, host plant range and host plant type) and endemism of butterflies were discussed in relation to their abundance and vegetation association. Fifty-one species and 856 individuals were recorded. Species richness was highest in the two sections with edges, 32 and 36 species, respectively. Analysis of vegetation association of each butterfly species showed that 16 species were forest interior species, 24 forest edge species and 11 openland species, indicating that vegetation diversity enhanced butterfly diversity. However, the point is that forest interior and edge species contained many specialists sensitive to human impact (univoltine and/or oligophagous species) and many species within temperate East Asia including all endemic species. In contrast, most openland species were generalists (multivoltine and/or polyphagous species) feeding on herbs/grasses with the widest geographic range. Since secondary forests kept more butterfly diversity and specialists than openlands, and had all endemic species, they must be maintained without over fragmentation in order to avoid loss of specialists and endemics in satoyama.  相似文献   

6.
A high level of plant and insect diversity, and more specifically high butterfly diversity characterizes the Mediterranean Basin. However, alarming negative trends have been reported for butterfly populations in that region emphasizing the urgent need to better understand the drivers of their population declines. Habitat specialists of grasslands are strongly affected, mainly by land use change and climate change. Thorough assessments of habitat requirements and dispersal abilities are crucial to establish appropriate conservation measures to counter these threats. Here, we investigate the ecological requirements and dispersal ability of Euphydryas desfontainii, one of Portugal’s rarest butterflies, to develop targeted conservation strategies. The assessment of habitat requirements showed differences between occupied and unoccupied patches in terms of host plant abundance and area. Mark–release–recapture data were used to model demographic parameters: survival rates decreased linearly over the flight period and recruitment followed a parabolic curve with separate peaks for males and females. The movement data were fitted to an inverse power function and used to predict the probability of long-distance dispersal. The obtained probabilities were compared to related checkerspot butterflies and interpreted regarding the structural connectivity of the investigated habitat network. We suggest focusing on the preservation of remaining habitat patches, whilst monitoring and safeguarding that their vegetation structure does provide sufficiently diversified microclimates in order to best conserve E. desfontainii populations.  相似文献   

7.
Landscape changes and resource exploitation have driven global biodiversity declines and reduced provision of ecological functions and services. In grassland working landscapes managed for ecological services and livestock production, it is essential to understand the influence of grazing practices on biodiversity to guide conservation. We used grassland butterflies to investigate the effects of four grazing management practices on biodiversity and pollination services from 2015 to 2016. We hypothesized grazing management practices would generate differing floristic resources that would thereby influence grassland butterfly community composition. To address our hypothesis, we sampled floral resources using belt transects and butterfly community and species level dynamics using line-transect distance sampling. We detected 2578 butterflies representing 34 species. Management practice was not a significant predictor of floral (p?=?0.319) or butterfly community composition (p?=?0.604), and sites under the same management showed dissimilarity in ordination space, indicating differences that may not be associated with grazing practices. At the species level, management explained density for six of nine butterfly species, but no individual management practice was optimal for a majority of detected species. Thus, over the timeframe of this study, grazing management practices did not generate differences in floristic community composition to drive community-level responses in grassland butterflies. Rather, management drove differences in individual species’ abundance within the butterfly community, likely contributing to the butterfly diversity observed at a broader scale.  相似文献   

8.
Transect surveys of adult butterflies were conducted along fixed routes at 27 study sites grouped into three subregions of tallgrass prairie and one subregion of pine-oak barrens in the midwestern USA. Within subregion, each site was visited the same number of times over 5–7 years on similar dates with similar weather. For each site, five indices of species richness and/or abundance were calculated both for total butterflies and for specialist species primarily restricted to native herbaceous vegetation. These indices were then analysed as to how much they agreed or conflicted in site ranking and how site rankings based on total butterflies compared to those based on specialists. Variation in site ranking by different indices was relatively low. Mean site rank by specialist indices covaried significantly with mean site rank by indices for total butterflies. Numerous studies have shown that on a regional scale, areas of higher richness for all species in a taxonomic group are different habitat types (based on amount of canopy or degree of degradation) from hotspots for that taxon's subset of species of conservation concern (endemics or specialists). But in this study, within a habitat type, site rankings based on total butterflies significantly tended to agree with site rankings based on specialist butterflies. This suggests that site prioritization and management favouring specialist butterflies would also favour the overall butterfly fauna possible in the same habitat.  相似文献   

9.
Comparisons of related species differing in conservation status may offer insights into causes of species declines. We studied egg-laying patterns and landscape occupancy of two sympatric lycaenidae butterflies inhabiting xeric grasslands, vulnerable Polyommatus thersites and critically endangered Polyommatus [Agrodiaetus] damon, both developing on sainfoin, Onobrychis spp. Females of bivoltine P. thersites oviposit on host plant leaves at a relatively low height (??20 cm), in both spring (May?CJune) and summer (July?CAugust) generations. Females of univoltine P. damon (July?CSeptember) oviposit to senescing inflorescences, in significantly higher heights (>30 cm), and the species is hence vulnerable to summer mowing or grazing. On a landscape scale, both species tended to occur at sites with diverse sward management, including temporarily unmanaged patches. In addition, P. damon occurred only in the proximity of other occupied sites. The study documents that grassland management must respect the needs of the most vulnerable species, and because these needs are seldom known, it must maintain a high diversity of conditions within individual sites.  相似文献   

10.
Habitat restoration is critical to the conservation of rare species. However, restoration efforts often proceed without knowledge of their effects on these species. We investigated the reproductive response of federally endangered Fender’s blue butterfly (Plebejus icarioides fenderi) to prairie restoration in Willamette Valley, Oregon, USA. In 2009 and 2010, we quantified availability of larval host plant, Kincaid’s lupine (Lupinus oreganus), and butterfly oviposition in three restored areas (1–10 years old) and adjacent intact habitat. Oviposition measures in restored areas reached or exceeded intact habitat (0.1 eggs/leaf of host plant and 12 % of time ovipositing) within five years post-restoration. However, none of the restorations provided an equivalent host plant density to intact areas (55 leaves/m2). The different response time of host plants and butterflies to restoration highlights the importance of monitoring both vegetation and oviposition over an ecologically relevant timescale (at least 10 years). For imperiled species, quantifying reproductive response to restoration is critical for adaptive management and successful conservation of the species which restoration efforts are intended to benefit.  相似文献   

11.
Pollinators provide an important class of ecological services for crop plants and native species in many ecosystems, including the tallgrass prairie, and their conservation is essential to sustaining prairie remnants. In Iowa these remnants are typically either block-shaped or long, linear strips along transportation routes. In this study we examined differences in the butterfly, bee, and forb community composition in linear and block prairie remnants, determined correlations between species diversity among butterflies, bees and forbs in the 20 prairie remnants sampled, and examined correlations of community similarity among butterflies, bees and forbs. Correspondence analysis showed that distinct communities exist for butterflies and forbs in block versus linear sites and discriminant analysis showed that the bee and forb communities in block and linear sites can be distinguished on the basis of a few species. Diversity of one group was a poor predictor of diversity in another, except for a significant inverse relationship between bees and butterflies. These two pollinator taxa may be responding very differently to microhabitat components within fragmented ecosystems. Our studies show that there need to be differences in conservation strategies for bees and butterflies to maintain both pollinator communities.  相似文献   

12.
Selection of oviposition sites by female regal fritillary butterflies, Speyeria idalia (Drury), in relation to the location and abundance of their larval food plant, Viola pedatifida G. Don, was studied in Kansas tallgrass prairie. To identify potential cues that females use to select oviposition microsites, we compared plots in which eggs were laid with paired control plots in terms of violet abundance, distance from plot center to the nearest violet plant, plant species composition and relative abundance, plant diversity (Shannon's index), and average plant canopy height. No significant differences occurred between control and oviposition sites for any of these variables (P > 0.15). Violets were present in only 30% of the 1-m-diameter oviposition plots, compared with 24% of the corresponding controls. Furthermore, eggs were never laid directly on violets even when they were present nearby. These data imply that S. idalia females do not preferentially orient to or oviposit on their larval food plant. Nevertheless, female S. idalia did not oviposit randomly, for they invariably chose microsites near the ground that were shaded by the grass/forb overstory and usually deposited eggs on the underside of dead vegetation. We speculate that environmental stresses such as high temperatures and intense solar insolation during the egg stage or harsh overwintering conditions experienced by first-instar larvae impact survival and influence choice of oviposition sites. High fecundity (more than 2000 eggs in some individuals) may allow this species to use a conditional, sweepstakes strategy, i.e., producing and spreading many eggs over prairie that harbors host plants to compensate for low egg and larval survivorship.  相似文献   

13.
The selection of suitable ecological indicator groups is of great importance for environmental assessments. To test and compare two such groups, we performed transect walks of butterflies and light traps of moths at eight sample localities in the Carinthian Alps. All of them were conducted with identical methods in the years 2002 and 2004 allowing the evaluation of the response on the conservation measures performed on five of the eight sites in late 2002. We recorded a total of 2346 butterflies (including Zygaenidae and Sesiidae) representing 83 species and 7025 moths of 534 species. 150 of these species were listed in the Red Data Book of Carinthia. In general, butterflies increased from 2002 to 2004 while moths declined. The highest increase rates of butterflies were obtained for the numbers of individuals of calcareous grassland specialists at the conservation sites, while their numbers were unchanged at the control sites. Similar trend differences between conservation and control sites were obtained for the Red Data Book butterfly species. On the contrary, the development of moth individuals was more positive at the control than the conservation sites for calcareous grassland specialists (only macro-moths) and species of the Red Data Book. However, change rates of species numbers were positively correlated between butterflies and moths. Principal Component Analysis revealed strong differences between the different sites, but mostly consistent results for butterflies and moths; however, stronger differences between years were only detected for some of the conservation sites for the butterfly communities. Our results show that butterflies as well as moths are suitable ecological indicator groups, but they do not yield identical results. Thus, butterflies are more suitable for the analysis of open habitats, whereas moths are suitable for open and forested habitats as well. Furthermore, butterflies might be a more sensitive indicator group than moths for the short-term detection of conservation measures, especially for the restoration of open habitat types.  相似文献   

14.
Succession has a strong influence on species diversity and composition of semi-natural open terrestrial ecosystems. While several studies examined the effects of succession on butterflies in grassland and forest ecosystems, the response of heathland butterflies to succession had not been investigated so far. To address this issue we sampled butterfly abundance and environmental parameters on the Baltic island of Hiddensee (NE Germany) along a gradient of coastal heathland succession from grey dunes to birch forest. Our results provide evidence that succession of coastal heathland has a strong influence on butterfly diversity, abundance, and species composition. Thereby grass and tree encroachment present the main threats for heathland butterflies. Diversity and abundance of butterflies were highest in shrub-encroached heath directly followed by early stages of coastal heathland succession (dwarf-shrub heath, grey dune). Both observed threatened species (Hipparchia semele, Plebeius argus) were negatively affected by succession: abundance decreased with increasing vegetation density (both species) and grass cover (P. argus); consequently, the two later successional stages (shrub, birch forest) were not occupied. Our findings highlight the importance of the preservation of early stages of coastal heathland succession for endangered butterfly species. For coastal heathland management we therefore suggest to maintain early successional stages by sheep grazing, mowing or, in case of high nutrient contents, intensive techniques such as sod-cutting or choppering. To a lower extend shrub-encroached sites should also be present, which might be beneficial for overall species richness.  相似文献   

15.
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   

16.
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   

17.
During 1990–1997, we recorded 122 138 adult butterflies in transect surveys at 125 pine-oak barrens in northern Wisconsin and 106 tallgrass prairies in six midwestern states grouped into three prairie subregions. Before analysis, we classified the butterflies into three ecological subgroups: specialist of native herbaceous vegetation, grassland (widely occurring in native and degraded herbaceous vegetation), and generalist. We analyzed this dataset both by ecological subgroups and as total butterflies, and by relative density and species richness, to investigate how these different ways of ordinating the same dataset might affect the results. In multiple linear regressions, density and richness of total butterflies and the subgroups related significantly to many non-management factors. In comparisons of more vs. less recent burning, all significant results for most recent burning were negative. No significant negative relationships were attributed to the longest period since burning. In comparisons of burning vs. idling, all significant results in prairie favored idling, but in barrens favored burning. In comparisons of burning vs. mechanical cutting, all significant results in prairie favored cutting, but no significant differences occurred in barrens. In regressions including all management types, rotational burning (alone or combined with cutting) was significantly positive most often for generalists and never for specialists. Increasing years since last management was always negative in barrens and the southern prairie subregion but always positive in the two northern prairie subregions. Significant management patterns occurred more often in prairie than barrens, which were less fragmented. Specialists were favored by grazing in one northern prairie subregion (but disfavored in the other), haying, single wildfire (testable in barrens only), and increasing years since last treatment in one northern prairie subregion (but disfavored in barrens). Within subregion and subgroup, significant management results for density and richness never conflicted, but density had more significant results than richness. In no instances were the signs opposite when total butterflies and/or any subgroup(s) significantly related to the same management factor in the same type of regression. But what was significant for one sample was often not for another. Thus, management favorable for specialists and total butterflies did not conflict, but the subgroups had varying degrees of sensitivity, rather than opposite responses. Since the specialist (and total) butterflies did not consistently favor one management type over another among subregions, caution should be used in preserve management, to avoid overreliance on one management type over others.  相似文献   

18.
Butterflies (Insecta: Lepidoptera) contribute to the ecosystem services and thereby qualify as a group deserving conservation effort. Information on the butterfly-plant links is used as a foundation to sustain population and enhance conservation and management. Thus, in the present study, the structure of a butterfly-plant network in an urban landscape like Kolkata, India, was deciphered highlighting metrics like degree distribution, nestedness, and interaction strength and specialization index. A total of forty eight butterfly species associated with thirty different angiosperm plant species were observed during the study period of one year. While Lantana camara was observed to be the dominant plant species with 37 links to different butterflies, the Catopsilia pyranthe butterfly species was dominant in terms of the generalist pattern of links (21 links) with the plants. Differential ability of the shrubs and herbs in the sustenance of the butterflies was reflected in the network indices using the herbs and the shrubs, separately. In urban landscapes with restricted variety of flowering plants, an estimate of relative strength of interactions enables identification and further use of the concerned species in sustaining butterfly populations. In accordance with these propositions, the butterfly-plant network illustrated in the present instance may prove useful in selection of plant species required for the enhancement of population of desired butterfly species in urban areas like Kolkata, India.  相似文献   

19.
Private lands provide critical habitat for threatened and endangered species, but only recently have farm-based conservation programs focused on at-risk, invertebrate species. The USDA Conservation Reserve Program State Acres for Wildlife Enhancement (CRP-SAFE) is one of the first federal programs to do so with a Wisconsin-based initiative for the US federally endangered Karner blue butterfly (KBB). This study is the first to evaluate how well the KBB-SAFE provides suitable habitat for the Karner and other butterflies. It also provides a critical foundation for better understanding the potential of new USDA programs that create pollinator habitat including for declining species such as the Monarch butterfly. Here we compare data (2009–2014) on assemblages of grassland communities, blooming floral resource availability, and abundance and richness of butterflies, between KBB-SAFE and native prairie sites. We found that KBB-SAFE and native sites had distinctly different forb species assemblages, with SAFE sites having fewer native blooming species available during the first flight of the KBB yet similar availability during second flight. Butterfly abundance was ultimately greater on native sites compared to SAFE sites, but richness was comparable between sites. We conclude that KBB-SAFE can provide habitat for many grassland species, and serve as surrogate KBB habitat. We provide straightforward management recommendations designed to better meet the needs of the Karner blue and other sensitive butterfly species and we provide further evidence that increased abundance and richness of native forbs and grasses on land formerly used for agriculture can provide habitat for butterflies adapted to early successional habitats.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号