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1.
Lately there has been a shift in Sweden from grazing species‐rich semi‐natural grasslands towards grazing ex‐arable fields in the modern agricultural landscape. Grazing ex‐arable fields contain a fraction of the plant species richness confined to semi‐natural grasslands. Still, they have been suggested as potential target sites for re‐creation of semi‐natural grasslands. We asked to what extent does fine‐scale variation in soil conditions, management history and site location effect local plant diversity in grazed ex‐arable fields. We examined local soil conditions such as texture, pH, organic carbon, nitrogen (N) and extractable phosphate (P) and effects on plant richness in ten pairs of grazed ex‐fields and neighbouring semi‐natural grasslands in different rural landscapes. Each grassland pair where in the same paddock. A multivariate test showed that site location and land use history explained more of differences in species richness than local soil property variables. Plant species richness was positively associated to grazed ex‐fields with low pH, low N and P levels. Sites with high plant richness in semi‐natural grasslands also had more species in the adjacent grazed ex‐fields, compared to sites neighbouring less species‐rich semi‐natural grasslands. Although both soil properties and species richness were different in grazed ex‐fields compared to semi‐natural grassland, the site location within a landscape, and vicinity to species‐rich grasslands, can override effects of soil properties. In conclusion, if properly located, ex‐arable fields may be an important habitat to maintain plant diversity at larger spatio‐temporal scales and should considered as potential sites for grassland restoration.  相似文献   

2.
Local species richness of butterflies can be expected to benefit from both local habitat properties as well as the availability of suitable habitats and source populations in the surrounding landscape. Whether local species richness is dependent on local or landscape factors can be assessed by examining the relationship between local and landscape species richness. Here we studied how local species richness is related to landscape‐level species richness in landscapes differing in agricultural intensity. The relationship was linear for field boundaries in intensively cultivated landscapes and non‐linear in less‐intensively cultivated landscapes. In landscapes containing semi‐natural grasslands (on average 4% of overall land‐use), the relationship was non‐linear for field boundaries, but linear when considering local species richness of the grasslands themselves. These results show that local factors are more important than landscape factors in determining local species richness in landscapes which contained semi‐natural grasslands. Local species richness was limited by landscape factors in intensively cultivated landscapes. This interpretation was supported by the relationship between local species richness and landscape‐scale average mobility and generalist percentage of butterfly assemblages. We conclude that the management of field boundary habitat quality for butterflies is expected to be most effective in landscapes with semi‐natural grasslands, the species composition of which in turn is dependent on the regional occurrence of grasslands. Based on our results, managing non‐crop habitats for the conservation of habitat specialists and species with poor mobility will be most efficient in regions where patches of semi‐natural grasslands occur.  相似文献   

3.
Question: What are the consequences of grazing abandonment on the Stipa lessingiana dominated steppe‐like grasslands? What is the relative importance of management and environmental factors in causing variation in species composition and abundance in the continuously grazed and abandoned grassland stands? Location: Transylvanian Lowland, Romania. Methods: Repeated vegetation mapping of a grassland stand, where grazing was abandoned 35 years ago; re‐sampling six grassland stands surveyed 29–57 years ago. For revealing long‐term changes in species composition and rank abundance PCoA ordination was applied. The relative importance of management and environmental factors in structuring vegetation were explored by CCA ordination. Diversity, evenness and the relative number and abundance of red‐listed species were compared between managed and abandoned stands. Results: Our results pointed out that grasslands which were formerly grazed and dominated by S. lessingiana, in the long‐term absence of grazing, have been transformed into a S. pulcherrima dominated type. Management, probably by creating bare surfaces and preventing litter accumulation, had the strongest effect on the species composition and abundance in the grasslands. Abandoned grassland stands had lower diversity and evenness compared to continuously grazed stands. While at the same time, the relative number of threatened, rare species did not differ between managed and abandoned sites. Conclusion: Maintaining extensively grazed, as well as un‐managed, Stipa dominated grasslands would be important in order to create various habitat conditions for plant species, especially threatened and rare species, and promote diversity on the landscape scale.  相似文献   

4.
Across Western Siberia, land use has changed substantially since the collapse of the Soviet Union in 1991: large cropland areas were abandoned and livestock numbers declined. In recent years these trends have partly been reversed, and an intensification of agricultural management has been observed that is still ongoing. We evaluated the impact of land use, as well as effects of landscape patterns and vegetation structure on Orthoptera communities and discuss them as drivers of community composition, species richness and abundance. We sampled Orthoptera using a box-quadrat on ancient grassland, ex-arable grassland (both including different management types: unmanaged, grazed and mown) and cereal fields. Landscape heterogeneity and composition strongly affected species richness and abundance of Orthoptera. Both were higher in grassland than in cropland, but did not differ significantly between ex-arable and ancient grasslands or different management practices. An Indicator Species Analysis revealed differentiation of Orthoptera communities between all management types. On croplands, the number of adult individuals and nymphs was influenced by the proportion of grassland in the surrounding landscape and tillage practices. Conservation tillage is most likely the key factor allowing Orthoptera to reproduce on croplands. After up to 24 years of succession, Orthoptera communities of ex-arable grasslands can be considered as completely recovered, as differences to ancient grasslands were minimal. Besides the continuation of low-intensity management, conservation strategies for this region should consider landscape composition and support habitat heterogeneity like ecotones with hemi-boreal forests in grassland-dominated landscapes.  相似文献   

5.
Question: Is plant diversity in fragmented semi‐natural grasslands related to present and historical landscape context? Location: Southern Sweden. Methods: Plant diversity was described at 30 semi‐natural grassland sites in terms of total and specialist plant species richness at the site and species density at different scales (0.5–10 m2). These measures are commonly used to assess conservation value of semi‐natural grasslands. Landscape context was measured as contemporary connectivity to other semi‐natural grasslands, historical connectivity 50 years ago, amount of linear elements potentially suitable for dispersal (road verges, power line clearings), and amount of forest (inverse of the openness of the landscape). Results: The diversity measures were generally correlated with each other, implying that species richness in a subset of the grassland can predict the total richness. Plant species density at three scales (0.5 m2, 10 m2 and total) was related to the landscape context using an information theoretic approach. Results showed that total species richness increased with increased size of grasslands, contrary to earlier diversity studies in semi‐natural grasslands. Larger grasslands were more heterogeneous than smaller grasslands, and this is a likely reason for the species‐area relationship. Heterogeneity was also of high importance at the smaller scales (0.5 m2, 10 m2). With increased amount of forest, total species richness increased but species density on 10 m2 decreased. There was no influence of connectivity in either the contemporary or the historical landscape, contrary to previous studies. Conclusions: Grassland size and heterogeneity are of greater importance for plant diversity in semi‐natural grassland, than grassland connectivity in the landscape.  相似文献   

6.
During recent decades, concern about the loss of biodiversity on agricultural land has increased, and semi‐natural grasslands have been highlighted as critical habitats. Temperate European agricultural landscapes require distinct and appropriate management to prevent further impoverishment of the flora and fauna. This is especially urgent for pollinating insects that provide important ecosystem services. Our aim was to examine how species richness of three important groups of pollinating insects; solitary bees, butterflies and burnet moths are related to different farm characteristics, and if there are any differences between these three groups. A further aim was to test if red‐listed species are related to any farm characteristics. Species richness of solitary bees, butterflies and burnets was measured on all semi‐natural grasslands at 16 farms in a forest‐dominated area of 50 km2 in southern Sweden, using systematic transect walks in April to September 2003 (only butterflies and burnets) and 2005. Species richness of solitary bees and butterflies was intercorrelated, both before and after controlling for the area of semi‐natural grassland. Species richness of solitary bees increased with the area of semi‐natural grassland. After controlling for the effect of the area of semi‐natural grassland species richness was strongly positively related with the density of the plant Knautia arvensis and negatively related with the proportion of grazed grassland. The results were similar for solitary bees and butterflies. The number of red‐listed solitary bees was positively related to the proportion of meadows with late harvest (after mid‐July) and decreased with increased farm isolation. The number of burnet species (all red‐listed) was positively related to vegetation height, flower density and the proportion of meadows with late harvest on a farm. Areas with a high density of K. arvensis and with traditional hay‐meadow with late harvest present, harbour most species. Promoting traditional hay‐meadows, late extensive grazing and the herb K. arvensis, people managing agricultural biodiversity can encompass high species richness of pollinating insects and support red‐listed species. Further, we suggest that the density of K. arvensis at a farm can be used as a biodiversity indicator, at least for pollinating insects.  相似文献   

7.
Fragmentation of grasslands and forests is considered a major threat to biodiversity. In the case of plants, the effect of fragmentation or landscape context is still unclear and published results are divergent. One explanation for this divergence is the slow response of long‐lived plants, creating an extinction debt. However, this has not been empirically confirmed. In this study, data were compiled from broad‐scale studies of grasslands from throughout the world that relate plant diversity to fragmentation effects. Only seven studies from northern Europe, out of a total 61, gave any information on actual habitat fragmentation in time and space. In landscapes with >10% grassland remaining, present‐day species richness was related to past landscape or habitat pattern. In landscapes with <10% grassland remaining, in contrast, plant species richness was more related to contemporary landscape or habitat pattern. Studies from landscapes with >10% grassland remaining supported the concept of an extinction debt, while studies from more fragmented landscapes did not provide any evidence of an extinction debt. In order to make generalisations about historical legacies on species diversity in grasslands it is important to consider a range of highly transformed landscapes, and not only landscapes with a high amount of grassland remaining.  相似文献   

8.
Abstract. Plants associated with traditional agricultural landscapes in northern Europe and Scandinavia are subjected to drastic habitat fragmentation. In this paper we discuss species response to fragmentation, against a background of vegetation and land‐use history. Recent evidence suggests that grassland‐forest mosaics have been prevalent long before the onset of human agriculture. We suggest that the creation of infield meadows and outland grazing (during the Iron Age) increased the amount and spatial predictability of grasslands, resulting in plant communities with exceptionally high species densities. Thus, distribution of plant species in the present‐day landscape reflects historical land‐use. This holds also when traditional management has ceased, due to a slow response by many species to abandonment and fragmentation. The distribution patterns are thus not in equilibrium with the present habitat distribution. Fragmentation influences remaining semi‐natural grasslands such that species density is likely to decline as a result of local extinctions and invasion by habitat generalists. However, species that for a long time have been subjected to changing mosaic landscapes may be more resistant to fragmentation than is usually believed. Conservation should focus not only on ‘hot‐spots’ with high species richness, but also consider species dynamics in a landscape context.  相似文献   

9.
10.
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   

11.
Question: Which are the plant functional groups responding most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricultural landscapes? Location: 25 agricultural landscape areas in seven European countries. Methods: We examined the plant species richness and abundance in 4 km × 4 km landscape study sites. The plant functional group classification was derived from the BIOLFLOR database. Factorial decomposition of functional groups was applied. Results: Natural habitat availability and low land use intensity supported the abundance and richness of perennials, sedges, pteridophytes and high nature quality indicator species. The abundance of clonal species, C and S strategists was also correlated with habitat area. An increasing density of field edges explained a decrease in richness of high nature quality species and an increase in richness of annual graminoids. Intensive agriculture enhanced the richness of annuals and low nature quality species. Conclusions: Habitat patch availability and habitat quality are the main drivers of functional group composition and plant species richness in European agricultural landscapes. Linear elements do not compensate for the loss of habitats, as they mostly support disturbance tolerant generalist species. In order to conserve vascular plant species diversity in agricultural landscapes, the protection and enlargement of existing patches of (semi‐) natural habitats appears to be more effective than relying on the rescue effect of linear elements. This should be done in combination with appropriate agricultural management techniques to limit the effect of agrochemicals to the fields.  相似文献   

12.
  1. Increasing landscape heterogeneity, both in terms of composition and configuration, can promote natural enemies and biological control in agricultural landscapes. However, relatively poor information exists about the effects of landscape heterogeneity on lacewings, which are a major group of predators. Furthermore, temporal changes of landscape effects on natural enemy dynamics remain largely unexplored.
  2. Here, we investigated how landscape composition and configuration affect lacewings and their biological control potential on leafhoppers. Lacewings and leafhoppers were sampled from April to July in 10 vineyards located in southwestern France. The vineyards were selected along a gradient of a proportion of semi‐natural habitats in the landscape.
  3. The proportion of semi‐natural habitats positively affected the abundance of adults and eggs, as well as species richness, of lacewings, alone or in interaction with the sampling month. Landscape configuration was never found to enhance abundance or species richness of lacewings. Finally, the predator–prey ratio increased through time but did not respond to landscape composition or configuration.
  4. Our study highlights that the proportion of semi‐natural habitats increases both abundance and diversity of lacewings in vineyard landscapes but that this effect varies over time. This result indicates the need to assess the variability of landscape effects over time to maximize biological pest control services in agricultural landscapes.
  相似文献   

13.
In addition to habitat loss and fragmentation, agricultural change has led to a change in seed dispersal processes in the rural landscape through a loss of structural and functional connectivity. Here, human‐mediated dispersal vectors are prevalent, and we explored whether the loss of connectivity via free‐ranging livestock could be mitigated by the increase in roads and motor vehicles. We found that structurally, 39% of all valuable semi‐natural grassland habitats in southern Sweden are adjacent to public road verges, which in the rural landscape are often considered to be suitable habitat for grassland species. Additionally, by collecting mud attached to cars and farming machinery and manure from livestock (cattle, horse, sheep) grazing semi‐natural grassland pasture, we found that motor vehicles are also capable seed dispersers. A similar number of species were dispersed by both vectors, although the composition of samples was quite different. Motor vehicles dispersed more grassland specialists than invasive species, although in much lower abundances than did grazing livestock. Despite these differences, motor vehicles were found to be able to disperse species with the same kinds of dispersal traits as livestock. A high number of seeds, species and specialists in manure samples means that greater movement of livestock is desirable to increase functional grassland connectivity. However, effective management could improve the suitability of roadsides as grassland corridors and increase the availability of seeds for long‐distance human‐mediated dispersal via cars and tractors. Our results suggest that in many rural landscapes, connectivity by road networks could help mediate habitat loss and fragmentation of grasslands. However, such effects can be context dependent, and the connectivity provided by roads could have serious negative consequences in other regions.  相似文献   

14.
Agriculture intensification has drastically altered farmland mosaics, while semi-natural grasslands have been considerably reduced and fragmented. Bird declines in northern temperate latitudes are attributed to habitat loss and degradation in farmed landscapes. Conversely, landscape-modification effects on grassland/farmland bird communities are less studied in the South American temperate grasslands. We investigated how bird communities were influenced by landscape characteristics in the Rolling Pampa (Argentina). We sampled bird communities in 356 landscapes of 1-km radius that varied in cover and configuration of pastureland, flooding grassland and cropland. Using generalized linear models, we explored the relationship between both bird species richness and abundance, and landscape structure. Analyses were carried out for all species, and open-habitat, grassland and aquatic species. Pasture area was far the most important factor, followed by landscape composition, in predicting species richness and abundance, irrespective of specific habitat preferences, followed by partially-flooded grassland cover and its mean shape index. Grassland fragmentation did not affect species richness or abundance. When comparing the effects of landscape variables on bird richness and abundance (using mean model coefficients), pasture and grassland area effects were on average more than four times greater than those of compositional heterogeneity, and about ten times greater than shape effects. To conserve species-rich bird communities persisting in Rolling Pampa farmland, we recommend the preservation of pasture and grassland habitats, irrespective of their fragmentation level, in intensively managed farmland mosaics.  相似文献   

15.
Recent loss of plant species richness in Swedish semi-natural grasslands has led to an increase in grassland recreation and restoration. To increase the establishment of declining species favoured by grazing and to re-establish original species richness, seed sowing has been discussed as a conservation tool. In this study, I examined to what extent seed sowing in former arable fields increases species richness and generates a species composition typical of semi-natural grasslands. Six grassland species favoured by grazing (target species) and six generalist species favoured by ceased grazing, were studied in a seed-addition experiment. Four different seed densities were used on four different grassland categories, two grazed former arable fields, one continuously grazed grassland and one abandoned grassland. Target and generalist species emerged in all grassland categories, but seedling emergence was higher in the grazed than in the abandoned grassland. Target species had higher emergence in the two grasslands with the longest grazing continuity. Seedling emergence and frequency of established plants of each target species were positively associated. The largest fraction of seeds germinated at an intermediate sowing density, 20–50 seeds/dm2, suggesting that aggregation of seeds positively affects emergence up to a certain threshold. In conclusion, artificial seed sowing may induce the recreation of typical grassland communities on former arable fields, which may be an important contribution to increase the total grassland area and species richness in the landscape.  相似文献   

16.
Increasing landscape complexity can mitigate negative effects of agricultural intensification on biodiversity by offering resources complementary to those provided in arable fields. In particular, grazed semi-natural grasslands and woody elements support farmland birds, but little is known about their relative effects on bird diversity and community composition. In addition, the relative importance of local habitat versus landscape composition remains unclear. We investigated how the presence of semi-natural grasslands, the number of woody elements and the composition of the wider agricultural landscape affect bird species richness, true diversity (exponential Shannon diversity) and species composition. Bird communities were surveyed four times on 16 paired transects of 250 m each with 8 transects placed between a crop field and a semi-natural grassland and 8 transects between two crop fields with no semi-natural grasslands in the vicinity. The number of woody elements around transects was selected as an important predictor in all models, having a positive effect on species richness and true diversity, while the local presence of semi-natural grasslands was not selected in the best models. However, species richness and true diversity increased with increasing cover of ley and semi-natural grasslands, whereas species composition was modified by the coverage of winter wheat at the landscape scale. Furthermore, bird species richness, true diversity and species composition differed between sampling dates. As bird diversity benefited from woody elements, rather than from the local presence of semi-natural grasslands as such, it is important to maintain woody structures in farmland. However, the positive effect of grassland at the landscape scale highlights the importance of habitat variability at multiple scales. Because species richness and true diversity were affected by different landscape components compared to species composition, a mosaic of land-use types is needed to achieve multiple conservation goals across agricultural landscapes.  相似文献   

17.
Plant species richness in rural landscapes of northern Europe has been positively influenced by traditional management for millennia. Owing to abandonment of these practices, the number of species‐rich semi‐natural grasslands has decreased, and remaining habitats suffer from deterioration, fragmentation, and plant species decline. To prevent further extinctions, restoration efforts have increased during the last decades, by reintroducing grazing in former semi‐natural grasslands. To assess the ecological factors that might influence the outcome of such restorations, we made a survey of semi‐natural grasslands in Sweden that have been restored during the last decade. We investigated how plant species richness, species density, species composition, and abundance of 10 species that are indicators of grazing are affected by (1) the size of the restored site, (2) the time between abandonment of grazing and restoration, (3) the time elapsed since restoration, and (4) the abundance of trees and shrubs at the restored site. Only two factors, abundance of trees and shrubs and time since restoration, were positively associated with total species richness and species density per meter square at restored sites. Variation in species composition among restored sites was not related to any of the investigated factors. Species composition was relatively similar among sites, except in mesic/wet grasslands. The investigated factors had small effects on the abundance of the grazing‐indicator species. Only Campanula rotundifolia responded to restoration with increasing abundance and may thus be a suitable indicator of improved habitat quality. In conclusion, positive effects on species richness may appear relatively soon after restoration, but rare, short‐lived species are still absent. Therefore, remnant populations in surrounding areas may be important in fully recreating former species richness and composition.  相似文献   

18.
We tested the influence of grazing intensity and effect of landscape complexity on grassland specialist and generalist beetles of three beetle families, i.e. Carabidae, Chrysomelidae, and Curculionidae, on extensively and intensively grazed cattle pastures in three regions of the Hungarian Great Plain. In every region we investigated seven pairs of grazed grasslands. On each field, samples were taken along two 95-m-long transects; one transect at the edge and the other one 50 m away from the edge in the grassland interior (altogether 84 transects). Carabids (Carabidae) were sampled using funnel traps for three 2-week sampling periods during spring and early summer. Leaf-beetles (Chrysomelidae) and weevils (Curculionidae) were surveyed by sweep netting in May and June 2003. Analysing the grazing intensity and landscape complexity effects on generalist and specialist beetles with linear mixed models, grazing effect was detected only on specialist leaf-beetle species richness with more species in the extensively grazed sites. Landscape complexity had contrasting effects on specialist and generalist species. Habitat generalists were more and negatively affected by increasing grassland coverage (reduced heterogeneity) than specialists. At species level analyses on four species out of 21, landscape effects were shown, which suggested that landscape composition might have strong effects on the species composition of the beetle assemblages. Our results suggest that conservation of biodiversity in agricultural systems (such as in managed Central European grasslands) requires a landscape perspective besides investigating management effects.  相似文献   

19.
Pollination is a key ecosystem service, and appropriate management, particularly in agricultural systems, is essential to maintain a diversity of pollinator guilds. However, management recommendations frequently focus on maintaining plant communities, with the assumption that associated invertebrate populations will be sustained. We tested whether plant community, flower resources, and soil moisture would influence hoverfly (Syrphidae) abundance and species richness in floristically‐rich seminatural and floristically impoverished agricultural grassland communities in Wales (U.K.) and compared these to two Hymenoptera genera, Bombus, and Lasioglossum. Interactions between environmental variables were tested using generalized linear modeling, and hoverfly community composition examined using canonical correspondence analysis. There was no difference in hoverfly abundance, species richness, or bee abundance, between grassland types. There was a positive association between hoverfly abundance, species richness, and flower abundance in unimproved grasslands. However, this was not evident in agriculturally improved grassland, possibly reflecting intrinsically low flower resource in these habitats, or the presence of plant species with low or relatively inaccessible nectar resources. There was no association between soil moisture content and hoverfly abundance or species richness. Hoverfly community composition was influenced by agricultural improvement and the amount of flower resource. Hoverfly species with semiaquatic larvae were associated with both seminatural and agricultural wet grasslands, possibly because of localized larval habitat. Despite the absence of differences in hoverfly abundance and species richness, distinct hoverfly communities are associated with marshy grasslands, agriculturally improved marshy grasslands, and unimproved dry grasslands, but not with improved dry grasslands. Grassland plant community cannot be used as a proxy for pollinator community. Management of grasslands should aim to maximize the pollinator feeding resource, as well as maintain plant communities. Retaining waterlogged ground may enhance the number of hoverflies with semiaquatic larvae.  相似文献   

20.
Grasslands are often managed with different intensities in the European Alps. Studies have shown that a medium management can benefit plant and animal biodiversity in these ecosystems. However, in recent decades abandonment of extensively managed meadows is an ongoing global challenge. Syrphids (hoverflies) have been recognized as a threatened group due to environmental drivers, and these managed grasslands provide preferred habitats for them. Yet, at what extent syrphids respond to grassland management strategies is little known. We investigated whether abandonment of managed mountain meadows (mown once a year, no fertilizer use) affects syrphid abundance, richness and species assemblages. Moreover, the influence of plant richness, flower frequency and surrounding landscape on syrphids were assessed. Four managed meadows were compared with four abandoned meadows in a mountainous region in Austria. Adult syrphids were sampled over two consecutive years (June and August 2015–2016) by sweep netting using line transects and observation plots. Syrphid abundance was significantly higher in managed than abandoned meadows and increased with increasing plant richness and flower frequency across management types. Management and sampling time also significantly affected syrphid species assemblages. Syrphid richness and abundance were not influenced by surrounding landscape. We conclude that both abandoned and managed meadows provide important habitat types for syrphids. Therefore, efforts should be made to maintain both managed and abandoned meadows in order to protect syrphid species within mountainous landscapes.  相似文献   

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