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 31 毫秒
1.
European agricultural landscapes are mosaics of intensively cultivated areas and semi-natural elements. Although comprising only a small fraction of the total area, semi-natural elements provide habitat for most of the landscape biodiversity. Agricultural intensification has increasingly fragmented semi-natural elements and species numbers are in decline. Insights into the effects of landscape structure on species’ distributions within and among semi-natural habitats are needed to conserve biodiversity in agricultural landscapes more effectively. We investigated the landscape- and habitat-specific diversity partitions of wild bees, true bugs, and carabid beetles in two differently structured agricultural landscapes in Switzerland. In each landscape, we partitioned the total species diversity (γ) into its additive components within (P) and among patches (βP) and among habitats (βH). In the landscape characterized by a patchy, isolated distribution of habitat elements, among-patch diversity (βP) explained 44% of the total species richness (γ) and was significantly higher than expected under a random distribution of samples among habitat patches; in the landscape with higher habitat connectivity, among-patch diversity (βP) comprised 32% of the total species richness (γ) and did not differ from the random expectation. Habitat-specific within-patch contributions to species richness were similarly low across habitat types (P=23–24%) in the patchy landscape, whereas in the more connected landscape within-patch partitions tended to be higher and differed among habitat types (P=22–38%). Functionally different groups of bees, true bugs, and carabids also responded differently to landscape structure in a manner that was consistent with known differences in resource specialization and dispersal ability. Differences in diversity partitions among landscapes and taxa indicate the need for flexible conservation strategies. Conservation of habitat-specific diversity may require more habitat patches in landscapes that have lower habitat connectivity and low within-patch diversity (P) than in landscapes with higher within-patch diversity (P).  相似文献   

2.
Landscape context and habitat quality may have pronounced effects on the diversity of flower visiting insects. We investigated whether the effects of landscape context and habitat quality on flower visiting insects interact in agricultural landscapes in the Netherlands. Landscape context was expressed as the area of semi-natural habitats or the density of linear landscape features, and was quantified at spatial scales ranging from 250 to 2000 m. Habitat quality was determined as flower abundance. Species richness and abundance of hoverflies and bees were determined along 16 stream banks experiencing similar environmental conditions but situated in areas with contrasting landscape context. Only flower abundance and the area of semi-natural habitats within 500–1000 m were significantly related to species richness of hoverflies and bees and these factors had interacting effects on both species groups. Our results suggest that the regional area of semi-natural habitats had a positive effect on hoverfly species richness when flower abundance was relatively high, but not when flower abundance was low. Moreover, flower abundance had positive effects on hoverfly species richness only in areas with relatively many semi-natural habitats. Contrastingly, flower abundance had a more positive effect on bee species richness in landscapes with few semi-natural habitats compared to landscapes with more semi-natural habitats. Our results suggest that the importance of landscape context for the species richness of flower visiting insects depends upon the quality of the habitat patches.  相似文献   

3.
Agriculture and development transform forest ecosystems to human‐modified landscapes. Decades of research in ecology have generated myriad concepts for the appropriate management of these landscapes. Yet, these concepts are often contradictory and apply at different spatial scales, making the design of biodiversity‐friendly landscapes challenging. Here, we combine concepts with empirical support to design optimal landscape scenarios for forest‐dwelling species. The supported concepts indicate that appropriately sized landscapes should contain ≥ 40% forest cover, although higher percentages are likely needed in the tropics. Forest cover should be configured with c. 10% in a very large forest patch, and the remaining 30% in many evenly dispersed smaller patches and semi‐natural treed elements (e.g. vegetation corridors). Importantly, the patches should be embedded in a high‐quality matrix. The proposed landscape scenarios represent an optimal compromise between delivery of goods and services to humans and preserving most forest wildlife, and can therefore guide forest preservation and restoration strategies.  相似文献   

4.
陈思淇  张玉钧 《生物多样性》2021,29(10):1411-92
乡村景观是一种人文和自然共生的复合生态系统, 为生物多样性的维持提供了支持。目前, 中国传统乡村地区生物多样性的维持正面临着农业集约化、人工林树种单一化、非农业用地急剧扩张及生态传承机制解体等复杂多样的威胁, 亟待展开深入研究。本文在总结乡村景观生物多样性相关概念及特征的基础上, 通过文献分析概括了国际乡村景观生物多样性的热点研究方向, 包括农业集约化下的生物多样性管理、区域尺度乡村景观与生物多样性的协同关系、局地尺度不同乡村景观类型的物种多样性及乡村景观中的生物文化多样性, 进一步梳理了国内在相关研究方向上的主要进展并指出研究不足。在此基础上提出未来研究展望, 包括突出生物文化多样性特征、加强多时空尺度分析、深化动态维持机制研究、推进生物多样性研究在乡村生态景观规划中的全过程应用等建议。  相似文献   

5.
Anna Jakobsson  Jon Ågren 《Oecologia》2014,175(1):199-208
Marginal grassland fragments, such as road verges and field margins, may act as important supplemental habitats for grassland plants in the modern agricultural landscape. However, abundance of pollinators in such fragments has been found to decline with distance to larger natural and semi-natural habitats, and this could have corresponding effects on plant pollination. In this study, we performed a field experiment on road verges with three insect-pollinated grassland herbs to examine the relationship between distance to semi-natural grassland and plant reproductive success in two landscapes with contrasting farming intensities. In Lychnis viscaria and Lotus corniculatus, seed production tended to decrease with increasing distance to semi-natural grassland, but only in the landscape with high farming intensity. Seed production in Armeria maritima spp. maritima decreased with distance in both landscapes. Although many studies have investigated effects of natural habitat on crop pollination, little is known about the impact on pollination in native plants. The results from this study indicate that management of semi-natural grasslands improves not only biodiversity within the actual grassland but also pollination of native plants in the surrounding agricultural landscape.  相似文献   

6.
Understanding how forest cover is related to patch attributes such as size, shape, and isolation, and how this influences the occurrence of a species in fragmented landscapes is an important question in landscape ecology and conservation biology. To study the effects of fragmentation on patch occupancy by the critically endangered Mexican mantled howler monkey (Alouatta palliata mexicana) in the Los Tuxtlas region of Mexico, we selected three landscapes of ca. 5,000 ha, which differed in their remaining forest cover (24, 11, and 4%). For each landscape, we related patch occupancy to forest cover, patch size and shape, and four isolation parameters. Landscape attributes varied according to forest cover, and the percentage of occupation was greater in landscapes with more forest cover. The attributes affecting the probability of occupancy differed among landscapes. Occupancy was positively related to patch size in all landscapes, but in the northernmost landscape, shape irregularity had a negative effect on occupancy, whereas in the southernmost landscape, occupancy was favored by greater distances to the nearest village. The results show that not only the total amount of forest cover but also patch configuration need to be taken into consideration when designing management strategies for the conservation of the Mexican mantled howler monkey.  相似文献   

7.
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   

8.
Landscape and local‐scale influences are important drivers of plant community structure. However, their relative contribution and the degree to which they interact remain unclear. We quantified the extent to which landscape structure, within‐patch habitat and their confounding effects determine post‐clearing tree densities and composition in agricultural landscapes in eastern subtropical Australia. Landscape structure (incorporating habitat fragmentation and loss) and within‐patch (site) features were quantified for 60 remnant patches of Eucalyptus populnea (Myrtaceae) woodland. Tree density and species for three ecological maturity classes (regeneration, early maturity, late maturity) and local site features were assessed in one 100 × 10 m plot per patch. All but one landscape characteristic was determined within a 1.3‐km radius of plots; Euclidean nearest neighbour distance was measured inside a 5‐km radius. Variation in tree density and composition for each maturity class was partitioned into independent landscape, independent site and joint effects of landscape and site features using redundancy analysis. Independent site effects explained more variation in regeneration density and composition than pure landscape effects; significant predictors were the proportion of early and late maturity trees at a site, rainfall and the associated interaction. Conversely, landscape structure explained greater variation in early and late maturity tree density and composition than site predictors. Area of remnant native vegetation within a landscape and patch characteristics (area, shape, edge contrast) were significant predictors of early maturity tree density. However, 31% of the explained variation in early mature tree differences represented confounding influences of landscape and local variables. We suggest that within‐patch characteristics are important in influencing semi‐arid woodland tree regeneration. However, independent and confounding effects of landscape structure resulting from previous vegetation clearing may have exerted a greater historical influence on older cohorts and should be accounted for when examining woodland dynamics across a broader range of environments.  相似文献   

9.
Human‐induced alteration of habitat is a major threat to biodiversity worldwide, especially in areas of high biological diversity and endemism. Polylepis (Rosaceae) forest, a unique forest habitat in the high Andes of South America, presently occurs as small and isolated patches in grassland dominated landscapes. We examine how the avian community is likely influenced by patch characteristics (i.e., area, plant species composition) and connectivity in a landscape composed of patches of Polylepis forest surrounded by páramo grasslands in Cajas National Park in the Andes of southern Ecuador. We used generalized linear mixed models and an information‐theoretic approach to identify the most important variables probably influencing birds inhabiting 26 forest patches. Our results indicated that species richness was associated with area of a patch and floristic composition, particularly the presence of Gynoxys (Asteraceae). However, connectivity of patches probably influenced the abundance of forest and generalists species. Elsewhere, it has been proposed that effective management plans for birds using Polylepis should promote the conservation of mature Polylepis patches. Our results not only suggest this but also show that there are additional factors, such as the presence of Gynoxys plants, which will probably play a role in conservation of birds. More generally, these findings show that while easily measured attributes of the patch and landscape may provide some insights into what influences patch use by birds, knowledge of other factors, such as plant species composition, is essential for better understanding the distribution of birds in fragmented landscapes.  相似文献   

10.
Having historically been abundant throughout Europe, the house sparrow (Passer domesticus) has in recent decades suffered severe population declines in many urban and rural areas. The decline in rural environments is believed to be caused by agricultural intensification, which has resulted in landscape simplification. We used giving-up densities (GUDs) of house sparrows feeding in artificial food patches placed in farmlands of southern Sweden to determine habitat quality during the breeding season at two different spatial scales: the landscape and the patch scale. At the landscape scale, GUDs were lower on farms in homogeneous landscapes dominated by crop production compared to more heterogeneous landscapes with mixed farming or animal husbandry. At the patch level, feeding patches with a higher predation risk (caused by fitting a wall to the patch to obstruct vigilance) had higher GUDs. In addition, GUDs were positively related to population size, which strongly implies that GUDs reflect habitat quality. However, the increase followed different patterns in homogeneous and heterogeneous landscapes, indicating differing population limiting mechanisms in these two environments. We found no effect of the interaction between patch type and landscape type, suggesting that predation risk was similar in both landscape types. Thus, our study suggests that simplified landscapes constitute a poorer feeding environment for house sparrows during breeding, that the population-regulating mechanisms in the landscapes differ, but that predation risk is the same across the landscape types.  相似文献   

11.
The landscape matrix is increasingly being recognized as important to biodiversity conservation. The nature of the matrix impacts the persistence of species in human‐modified landscapes through its pervasive influence on adjacent habitat and through the habitat value of the matrix itself. However, previous studies have not isolated the effects of the matrix from the effects of other aspects of landscape modification, such as habitat loss and fragmentation, and much remains to be understood about the independent impact of the matrix on wildlife. We investigated the effects of the matrix on mammal abundance and landscape use in south‐east Queensland, Australia. Mammals were surveyed in patch ‘core’, patch ‘edge’ and ‘matrix’ landscape elements along a rural–suburban gradient of matrix development intensity quantified by a weighted road‐length metric, which was significantly correlated with housing density, while controlling for potentially confounding patch and landscape attributes. Response to increasing matrix development intensity was highly species‐specific. Several native species declined in abundance; however, others were more resilient to moderate levels of matrix intensity, one species increased in abundance, and at least one species appeared unaffected by matrix intensity. Native species richness peaked at moderate levels of matrix development intensity. Exotic species richness and feral predators increased with matrix intensity and were negatively correlated with native species. Species response to matrix intensity appeared related to their use of edge or matrix habitat. An ability to use the matrix per se, however, may not translate into an ability to persist in a landscape where development substantially reduces the habitat or movement value of the matrix.  相似文献   

12.
Landscape heterogeneity is a major driver of biodiversity in agricultural areas and represents an important parameter in conservation strategies. However, most landscape ecology studies measure gamma diversity of a single habitat type, despite the assessment of multiple habitats at a landscape scale being more appropriate. This study aimed to determine the effects of landscape composition and spatial configuration on life-history trait distribution in carabid beetle and herbaceous plant communities. Here, we assessed the gamma diversity of carabid beetles and plants by sampling three dominant habitats (woody habitats, grasslands and crops) across 20 landscapes in western France. RLQ and Fourth Corner three-table analyses were used to assess the association of dispersal, phenology, reproduction and trophic level traits with landscape characteristics. Landscape composition and configuration were both significant in explaining functional composition. Carabid beetles and plants showed similar response regarding phenology, i.e. open landscapes were associated with earlier breeding species. Carabid beetle dispersal traits exhibited the strongest relationship with landscape structure; for instance, large and apterous species preferentially inhabited woody landscapes, whereas small and macropterous species preferentially inhabited open landscapes. Heavy seeded plant species dominated in intensified agricultural landscapes (high % crops), possibly due to the removal of weeds (which are usually lightweight seeded species). The results of this study emphasise the roles of landscape composition and configuration as ecological filters and the importance of preserving a range of landscape types to maintain functional biodiversity at regional scales.  相似文献   

13.
14.
L Favre-Bac  C Mony  A Ernoult  F Burel  J-F Arnaud 《Heredity》2016,116(2):200-212
In intensive agricultural landscapes, plant species previously relying on semi-natural habitats may persist as metapopulations within landscape linear elements. Maintenance of populations'' connectivity through pollen and seed dispersal is a key factor in species persistence in the face of substantial habitat loss. The goals of this study were to investigate the potential corridor role of ditches and to identify the landscape components that significantly impact patterns of gene flow among remnant populations. Using microsatellite loci, we explored the spatial genetic structure of two hydrochorous wetland plants exhibiting contrasting local abundance and different habitat requirements: the rare and regionally protected Oenanthe aquatica and the more commonly distributed Lycopus europaeus, in an 83 km2 agricultural lowland located in northern France. Both species exhibited a significant spatial genetic structure, along with substantial levels of genetic differentiation, especially for L. europaeus, which also expressed high levels of inbreeding. Isolation-by-distance analysis revealed enhanced gene flow along ditches, indicating their key role in effective seed and pollen dispersal. Our data also suggested that the configuration of the ditch network and the landscape elements significantly affected population genetic structure, with (i) species-specific scale effects on the genetic neighborhood and (ii) detrimental impact of human ditch management on genetic diversity, especially for O. aquatica. Altogether, these findings highlighted the key role of ditches in the maintenance of plant biodiversity in intensive agricultural landscapes with few remnant wetland habitats.  相似文献   

15.
Wildlife-friendly management practices promote pollinators and pollination services in agricultural landscapes. Wild bee densities are driven by landscape composition, as they benefit from an increased availability of nesting and foraging resources at landscape scale. However, effects of landscape composition on bee foraging decisions and consequences for crop pollination have rarely been studied. We investigated, how landscape composition affects bee densities and foraging behavior in faba bean (Vicia faba L.) fields and how this impacts faba bean yield. We recorded densities and nectar robbing behavior of honeybees, long- tongued and short-tongued bumblebees in faba bean fields in eleven landscapes with varying landscape composition (e.g. land cover of oilseed rape, faba bean and semi-natural habitats). Moreover, we assessed yield components of faba beans via pollinator exclusion experiments. Increasing covers of faba bean and semi-natural habitats positively influenced bumblebee densities, while high oilseed rape covers negatively affected short-tongued bumblebee densities in bean fields. Increased faba bean covers enhanced the proportion of nectar-robbing short-tongued bumblebees. The number of beans per pod was increased by insect pollination, while the number of pods was decreased; these effects however depended on variety. Landscape composition interacted with bee densities in shaping yield components in V. faba. Our study emphasizes the importance of considering landscape management to maximize crop yields, as shown for the case of faba beans. The composition of agricultural landscape can modulate bee densities in crop fields, bees foraging behavior and pollination services.  相似文献   

16.
Restoration of Biodiversity and Ecosystem Services on Agricultural Land   总被引:3,自引:0,他引:3  
Cultivation and cropping are major causes of destruction and degradation of natural ecosystems throughout the world. We face the challenge of maintaining provisioning services while conserving or enhancing other ecosystem services and biodiversity in agricultural landscapes. There is a range of possibilities within two types of intervention, namely “land sharing” and “land separation”; the former advocates the enhancement of the farmed environment, but the latter a separation between land designated for farming versus conservation. Land sharing may involve biodiversity-based agricultural practices, learning from traditional farming, changing from conventional to organic agriculture and from “simple” crops and pastures to agro-forestry systems, and restoring or creating specific elements to benefit wildlife and particular services without decreasing agricultural production. Land separation in the farmland context involves restoring or creating non-farmland habitat at the expense of field-level agricultural production—for example, woodland on arable land. Restoration by land sharing has the potential to enhance agricultural production, other ecosystem services and biodiversity at both the field and landscape scale; however, restoration by land separation would provide these benefits only at the landscape scale. Although recent debate has contrasted these approaches, we suggest they should be used in combination to maximize benefits. Furthermore, we suggest “woodland islets”, an intermediate approach between land abandonment and farmland afforestation, for ecological restoration in extensive agricultural landscapes. This approach allows reconciliation of farmland production, conservation of values linked to cultural landscapes, enhancement of biodiversity, and provision of a range of ecosystem services. Beyond academic research, restoration projects within agricultural landscapes are essential if we want to halt environmental degradation and biodiversity loss.  相似文献   

17.
Land-use change is one of the main drivers of biodiversity loss worldwide, but its negative effects can vary depending on the spatial scale analyzed. Considering the continuous expansion of agricultural demand for land, it is urgent to identify the drivers that shape biological communities in order to balance agricultural production and biodiversity conservation in human-modified landscapes. We used a patch-landscape design and a multimodel inference approach to assess the effects of landscape composition and configuration at two spatial scales (patch and landscape) on the structure of dung beetle assemblages. We performed our study in the Caatinga, the largest dry forest in South America. We sampled 3,526 dung beetles belonging to 19 species and 11 genera. At patch scale, our findings highlight the positive relationship of forest cover and landscape heterogeneity with dung beetle diversity, which are the major drivers of beetle assemblages. Edge density, in turn, is a major driver at the landscape scale and has a negative effect on beetle diversity. Our results support the hypothesis that landscapes combining natural vegetation remnants and heterogeneous agricultural landscapes are the most effective at conserving the biodiversity of dung beetles in the Caatinga landscapes. Directing efforts to better understand the dynamics of dung beetles in agricultural lands can be helpful for policymakers and scientists to design agri-environment schemes and apply conservation strategies in tropical dry forests.  相似文献   

18.
Biomass for bioenergy is debated for its potential synergies or tradeoffs with other provisioning and regulating ecosystem services (ESS). This biomass may originate from different production systems and may be purposefully grown or obtained from residues. Increased concerns globally about the sustainable production of biomass for bioenergy has resulted in numerous certification schemes focusing on best management practices, mostly operating at the plot/field scale. In this study, we compare the ESS of two watersheds in the southeastern US. We show the ESS tradeoffs and synergies of plantation forestry, i.e., pine poles, and agricultural production, i.e., wheat straw and corn stover, with the counterfactual natural or semi-natural forest in both watersheds. The plantation forestry showed less distinct tradeoffs than did corn and wheat production, i.e., for carbon storage, P and sediment retention, groundwater recharge, and biodiversity. Using indicators of landscape composition and configuration, we showed that landscape planning can affect the overall ESS supply and can partly determine if locally set environmental thresholds are being met. Indicators on landscape composition, configuration and naturalness explained more than 30% of the variation in ESS supply. Landscape elements such as largely connected forest patches or more complex agricultural patches, e.g., mosaics with shrub and grassland patches, may enhance ESS supply in both of the bioenergy production systems. If tradeoffs between biomass production and other ESS are not addressed by landscape planning, it may be reasonable to include rules in certification schemes that require, e.g., the connectivity of natural or semi-natural forest patches in plantation forestry or semi-natural landscape elements in agricultural production systems. Integrating indicators on landscape configuration and composition into certification schemes is particularly relevant considering that certification schemes are governance tools used to ensure comparable sustainability standards for biomass produced in countries with variable or absent legal frameworks for landscape planning.  相似文献   

19.
关晓庆  刘军和  赵紫华 《生态学报》2013,33(14):4468-4477
农业景观格局与过程能够强烈影响寄生蜂对寄主的寻找及寄生作用,寄主密度亦是影响寄生蜂分布的重要因素,然而农业景观的格局和寄主密度对寄生蜂寄生率的相互影响是一项值得研究的工作.在简单与复杂2种麦田农业景观结构下,调查了麦蚜的分布格局与2种寄主密度下麦蚜的初寄生率与重寄生率,分析了景观结构对麦蚜密度的影响、景观格局与麦蚜密度对寄生蜂寄生率与重寄生率的影响及交互作用.结果表明:景观结构的复杂性对麦蚜分布和寄生蜂初寄生率与重寄生率的影响均不明显,但寄主密度与景观结构的复杂性对寄生蜂的影响存在着明显的交互作用,寄主密度与寄生率呈正相关,寄主密度较低时烟蚜茧蜂为优势种,寄主密度较高时燕麦蚜茧蜂为优势种.麦蚜初寄生蜂与重寄生蜂对寄主密度的反应与其形态学、体型大小以及生活史特征相关,初寄生蜂与重寄生蜂的群落组成显著影响其对麦蚜的寄生率,而与景观结构的复杂性关系不大.  相似文献   

20.
Landscape structure is known to critically affect biodiversity. However, although the multi-facetted character of biodiversity is widely recognized, few studies have linked landscape spatial pattern and history simultaneously to multiple facets (taxonomic, functional, and phylogenetic) and spatial components (α, β, and γ) of plant diversity. We set out to reveal whether landscape parameters have specific effects on the separate diversity facets and components of plant diversity at a patch scale on coastal dune landscapes of Central Italy. For each landscape patch, we computed a set of patch-based metrics relying on multi-temporal land-cover maps. Based on a database of plant community plots, on functional traits from field measurements and on a dated phylogenetic tree, we calculated taxonomic (TD), functional (FD), and phylogenetic diversity (PD) within each patch at α, β, and γ level. Diversity measures were then related to the landscape metrics via linear mixed-effect models. Landscape pattern and transformations affected TD only moderately in coastal dune ecosystems. We found much stronger and contrasted effects on FD and PD. FD increased in patches surrounded by human-dominated habitats; PD was higher in fragmented patches, particularly in the Mediterranean macchia. Moreover, landscape pattern affected differently the single communities, the turnover among communities and the pool of species within the patch (α, β, and γ components). Our results call for the combined inclusion of FD and PD and their partitions into ecological analyses, being TD too crude to capture the comprehensive and contrasted response of plant diversity to landscape spatial pattern.  相似文献   

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