Habitats In Agricultural Landscapes Research Articles

Vineyard and riparian habitat, not nest box presence, alter avian community composition

In California, oak woodlands are being converted into vineyards, resulting in a loss of songbird nesting sites. Although many vineyards contain wooded riparian habitat, no previous research has examined the avian species composition in oak-vineyard landscapes. We compared the avian communities associated with vineyard, edge, and riparian habitats and examined to what degree the riparian habitat in vineyard landscapes continues to support birds associated with native oak woodland habitat that spanned the region before agricultural intensification. We further tested whether the presence of nest boxes in vineyard and riparian areas altered avian species composition in the landscape. Mist nets were used to survey the avian community in vineyard, edge, and riparian habitat at four sites during the breeding season. Permutational ANOVAs, using presence-absence data from captures, identified habitat, study sites, and time over the breeding season as highly significant main effects that explained differences in species composition. Establishment of songbird nest boxes did not alter the species composition. Two-thirds of the birds identified as woodland species in prior studies were found in riparian areas adjacent to vineyards, including five watch-list species. Overall the species composition of birds using riparian habitat was greater and significantly different from those found in the vineyard. This highlights the importance of maintaining natural areas like riparian habitat in agricultural landscapes.

Disentangling multiple drivers of pollination in a landscape-scale experiment

Animal pollination is essential for the reproductive success of many wild and crop plants. Loss and isolation of (semi-)natural habitats in agricultural landscapes can cause declines of plants and pollinators and endanger pollination services. We investigated the independent effects of these drivers on pollination of young cherry trees in a landscape-scale experiment. We included (i) isolation of study trees from other cherry trees (up to 350 m), (ii) the amount of cherry trees in the landscape, (iii) the isolation from other woody habitats (up to 200 m) and (iv) the amount of woody habitats providing nesting and floral resources for pollinators. At the local scale, we considered effects of (v) cherry flower density and (vi) heterospecific flower density. Pollinators visited flowers more often in landscapes with high amount of woody habitat and at sites with lower isolation from the next cherry tree. Fruit set was reduced by isolation from the next cherry tree and by a high local density of heterospecific flowers but did not directly depend on pollinator visitation. These results reveal the importance of considering the plant's need for conspecific pollen and its pollen competition with co-flowering species rather than focusing only on pollinators' habitat requirements and flower visitation. It proved to be important to disentangle habitat isolation from habitat loss, local from landscape-scale effects, and direct effects of pollen availability on fruit set from indirect effects via pollinator visitation to understand the delivery of an agriculturally important ecosystem service.

Herbicide drift can affect plant and arthropod communities

Field edges, old fields, and other semi-natural habitats in agricultural landscapes support diverse plant communities that help sustain pollinators, predators, and other beneficial arthropods. These plant and arthropod communities may be at significant ecotoxicological risk from herbicides applied to nearby crop fields. Recent innovations in herbicide-resistant crop biotechnology may lead to major increases in the use of the herbicides dicamba and 2,4-D. These herbicides selectively affect broadleaf plants, and non-target exposures may therefore lead to a net reduction in the functional diversity and floral resources provided by semi-natural habitats. In multi-year experiments at two sites (a field edge and an old field), we exposed replicated plots to low doses of dicamba designed to simulate herbicide drift and monitored changes in plant and arthropod communities. At the field edge site, we observed a significant decline in forb cover (but not floral resources) in plots treated at doses (∼1% of the field application rate) that are substantially lower than those that have been documented to affect plant communities in previous research. We also observed declines in three herbivorous pest species (pea aphids, spotted alfalfa aphid, and potato leaf hopper), increases in one pest species (clover root curculio), and increases in beneficial seed predators (crickets) associated with dicamba exposure. In contrast, at the old field site, drift-level doses did not affect plant community structure but reduced flowering of a key species (Monarda fistulosa). Variability across sites and taxonomic groups makes it difficult to offer general conclusions about the risks of dicamba drift to plant and arthropod biodiversity. Factors including the successional age of the plant community and water stress at the time of herbicide exposure likely explain the differing responses at the two sites to simulated drift.

不同干扰背景下景观指数与物种多样性的多尺度效应——以巩义市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 不同干扰背景下景观指数与物种多样性的多尺度效应——以巩义市为例 DOI: 10.5846/stxb201310302618 作者: 作者单位: 教育部黄河中下游数字地理技术重点实验室,教育部黄河中下游数字地理技术重点实验室,教育部黄河中下游数字地理技术重点实验室;河南大学环境与规划学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（41371195，41071118） Multi-scale effects for landscape metrics and species diversity under the different disturbance：a case study of Gongyi City Author: Affiliation: Key Laboratory of Geospatial Technology For the Middle and Lower Yellow River Regions,Ministry of Education,Key Laboratory of Geospatial Technology For the Middle and Lower Yellow River Regions,Ministry of Education,Key Laboratory of Geospatial Technology For the Middle and Lower Yellow River Regions,Ministry of Education;China;College of Environment and Planning,Henan University;China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以黄河中下游山地丘陵区的巩义市为研究区，采用典型样地法对灌草丛、人工林和农田边缘3种不同干扰背景下的自然、半自然生境内的植物进行调查。基于景观生态学原理，在地理信息系统技术支持下，借助于Fragstatta3.3软件，以调查样地为中心，计算了150、250、500、750、1000、1250、1500m不同半径缓冲区内表征景观形状（Edge and patch shape）、边缘对照（Edge contrast）、相似度和邻近度（Proximity and similarity）、景观多样性（Diversity）、基质（Texture）、斑块大小和密度（Patch size and patch density）共6类52个指数，运用冗余分析（RDA）筛选出不同尺度下对该区农业景观中植物多样性有显著影响的景观指数。结果表明：不同尺度，景观指数对物种多样性的影响变化显著。灌草丛生境，在500-750m范围内，SHAPE_AM指数和PARA_AM指数能够很好的解释物种多样性，解释量为33.6%；人工林生境，SHAPE_AM指数、AREA_CV指数、SIMI指数和PAFRAC指数在1000-1250m范围内对物种多样性的解释量达到48.1%；农田边缘生境，GYRATE_CV指数、ENN_CV指数、PARA_MN指数和FRAC_AM指数在 750-1250m范围内对物种多样性影响显著，解释量为32%。其中，辛普森多样性指数（SIDI）与灌草丛物种多样性在750-1250m范围内作用显著，ENN_CV指数仅对农田边缘物种多样性影响较大。景观指数对物种多样性的影响具有尺度依赖性，未来应全面综合探讨这些指数的尺度效应及在景观生态学中的应用。 Abstract:Heterogeneity and stability of the agricultural landscape is the premise to maintain the stable and high efficient agricultural ecosystem. Currently, habitat loss and the changes of landscape structure caused by human activities have become the important reason for the loss of biodiversity of the agricultural landscape. Although there are numerous metrics available to investigate the spatial structure of landscape, only little empirical research has examined these metrics to indicate the plant species diversity at several scales. The study area is in Gongyi city which is distributed in the mountainous and hilly areas of Middle-Lower Yellow River. We select three types of habitat, such as shrub, plantation and farmland edge to investigate plant species by the typical sample method. These three types of habitat also represent three different disturbance levels. Shrub corresponds to the natural habitat, plantation is under semi-Natural habitat, and the farmland edge habitat is under the strongest human disturbance level. Natural and semi-Natural habitats in agricultural landscapes are of vital importance for preserving biodiversity in agro-ecosystems. Based on the principles of Landscape Ecology, under the technical support of Geographic Information System (GIS), each sample plot is considered as the center to set different radius (150, 250, 500, 750, 1000, 1250, 1500m) of buffers. In each buffer, we extract six classes of landscape metrics, which include patch shape, edge contrast, similarity and proximity, landscape diversity, texture, patch size and patch density, a total of 52 landscape metrics. By applying the redundancy analysis (RDA), the landscape metrics that affect plant species diversity significantly in agriculture landscape are extracted from different scales. Through the analysis of the RDA, the result shows that different extent, the relationship between landscape metrics and species diversity changes significantly. In terms of shrub habitat, the landscape metrics of SHAPE_AM and PARA_AM can well support the species diversity at the extent of 500-750m, and the cumulative percentage variance can get to 33.6%. For plantation habitat, the landscape metrics of SHAPE_AM, AREA_CV, SIMI and PAFRAC can well explain the species diversity at the extent of 1000-1250m, and the cumulative percentage variance is 48.1%. For farmland edge habitat, the GYRATE_CV, ENN_CV, PARA_AM and FRAC_AM are major metrics have strong relationship with species diversity, and the cumulative percentage variance is 32%. At the extent of 750-1250m, Simpson's diversity index (SIDI) shows significant relation with shrub plants; while the metric of ENN_CV only has correlation with farmland plants at the extent of 1000-1250m. This study indicates that the effects of landscape metrics on plant species diversity are strongly depended on the spatial scales, since no metric has constant relation with plant diversity across all extents. This study implies that some landscape metrics can be good indicators for revealing diversity characteristics of different habitats. To get a better relationship of the landscape heterogeneity and species diversity, we recommend further research about scale effects of the landscape metrics and much more application studies of these metrics in Landscape Ecology. 参考文献 相似文献 引证文献

Management defines species turnover of bees and flowering plants in vineyards

Effects of land use and management on plant and pollinator diversity at the local scale have been reported. However, there is little information available on the spatial and temporal aspects of plant-pollinator mutualist diversity relative to farm management. Information on these aspects will provide a better understanding of agri-environment schemes in a conservation context. 2 In the present study, we use additive partitioning (sum of within and among community diversity) to determine local (alpha) diversity and spatial and temporal (beta) diversity of bees and flowering plants in differently managed vineyards and adjacent natural vegetation in the Cape Floristic Region biodiversity hotspot. 3 Alpha, spatial beta and temporal beta diversities accounted for 18-61%, 19-72% and 7-36% of total bee diversity, respectively. Local diversity and spatial turnover of flowering plant diversity were significantly higher in the natural vegetation compared with organic and conventional vineyards. Spatial turnover of bees varied significantly with longitudinal coordinates of study sites. 4 We show that wildlife-friendly management practices ensure species-rich plant communities that promote pollinator diversity. We demonstrate the necessity to conserve mosaics of natural and semi-natural habitats in agricultural landscapes to conserve plant and bees. Our findings demonstrate the need to include spatial factors of habitats for effective conservation in this region.

Are degraded habitats from agricultural crops associated with elevated faecal glucocorticoids in a wild population of common vole (Microtus arvalis)?

The severe impact of agriculture on species’ abundance and diversity is widely recognized. However, its effects on the physiology of wild animal populations are poorly known. We analyzed faecal glucocorticoids levels in wild common voles (Microtus arvalis) living in a farmland landscape to test whether living in degraded habitats, such as crops, is correlated with increased glucocorticoids. Other factors such as sex, reproductive status, and population density were also considered. We captured voles with Sherman traps in crops and in their field margins which were comprised of semi-natural vegetation. We collected fresh faecal samples from captured individuals and quantified their levels of faecal corticosterone metabolites (FCM) in the laboratory. The quantification of FCM concentrations was performed by competitive enzyme immunoassay. Individuals captured within the crops had higher levels of FCM than those in field margins; females and breeding individuals exhibited higher FCM levels. In addition, FCM concentrations positively correlated with abundance of voles. Our results suggest that degraded habitats in agricultural landscapes are associated with increased glucocorticoid levels on common voles likely caused by a higher disturbance from agricultural practices and a lesser vegetation cover in crops compared with field margins.

Conservation of species occupying ephemeral and patchy habitats in agricultural landscapes: The case of the Eurasian reed warbler

Habitat loss and fragmentation are amongst the main threats for animal populations. These two processes are mainly due to the conversion of natural habitats to agroecosystems and have effects at different spatial scales. The identification of their landscape-scale effects is the first step to target habitat management toward specific actions. At the same time the role of single habitat patches should not be overlooked, since some processes, like habitat degradation, occur at the patch scale. Multi-scale studies allow evaluating the relative role of patch-scale versus landscape-scale factors on species distribution allowing the identification of the spatial scale toward which conservation and management actions should be targeted.We studied the distribution of the Eurasian reed warbler (Acrocephalus scirpaceus) in ephemeral reed beds embedded in an agricultural landscape. After separating the independent, landscape-scale effects of habitat loss and fragmentation per se, we evaluated the role of patch-scale characteristics.Our multi-scale analysis showed that landscape characteristics are the most important features, while the role of patch is weaker and varies depending on the landscape context. We found no effects of fragmentation per se and of habitat structure in single patches.Our results suggest that for some species adapted to live in naturally ephemeral and patchy habitats, landscape context could be more important than patch-scale factors. From a conservation point of view, for such species the management actions should be prioritized toward increasing landscape suitability rather than that of single habitat fragments.

Effects of management intensity and orchard features on bird communities in winter

AbstractThe knowledge and conservation of diminishing valuable habitats in agricultural landscapes are of key importance in saving declining farmland biodiversity. One of these habitats is the traditional orchard whose role in supporting birds is still poorly known, especially in winter. We counted birds in 106 orchards differing in management intensity (abandoned, traditional, and intensive) during December 2009 and January 2010 in Wielkopolska, western Poland and measured site characteristics and composition of surrounding landscapes for every orchard. Old abandoned and traditionally managed orchards had significantly higher bird species richness than intensive ones. Irrespective of orchard type, bird species richness as well as density were positively influenced by the cover of unmown herb layer in orchards and tree diversity. Tree and fruit densities positively affected bird species richness and density mainly in abandoned orchards while in other orchard types the effect of these variables was less pronounced. Land cover diversity in a landscape had a positive effect on species richness and density mostly in abandoned orchards and we believe that this effect reflects the elevated utilization of such orchards by birds from the surrounding landscape. Thus, abandoned, as well as traditionally managed orchards seems to be especially important habitats that offer food source and refuge for wintering birds and should be protected. We propose to diversify fruit production by planting various tree species, leaving part of the herb layer unmown and several trees unharvested in intensive orchards in order to improve suitability of modern orchards for birds.

Effects of managing semi-natural grassland buffers on butterflies

Butterflies are important components of biodiversity in grassland ecosystems and provide ecosystem services such as pollination. Although agricultural intensification has led to a scarcity of native grassland habitats within most agricultural landscapes of North America, fragmented remnants and semi-natural habitats may support diverse communities, including butterflies, as long as vital resources such as host plants are available. The United States Department of Agriculture’s (USDA) Conservation Reserve Program practice CP33 Habitat Buffers for Upland Birds (USDA 2004) provides semi-natural grassland habitat in agricultural landscapes, but a knowledge gap exists about impacts of prescribed disturbance (e.g. burning or disking) on butterflies. We monitored butterfly habitat and butterfly communities on experimentally manipulated CP33 grassland buffers in Clay County, Mississippi from 2007 to 2009. Disturbance guild butterfly species richness did not differ among treatments. However, disturbance guild abundance was positively affected by disking in both the first and second growing seasons following disking, and the magnitude of this response varied between years. Effects of burning on disturbance guild abundance did not differ from the control treatment. There were no treatment differences for grassland guild butterfly abundance and species richness suggesting that periodic disturbance does not unduly impact grassland-associated butterflies in the southeastern US. Our results support current USDA practice standards that require periodic disturbance during the 10-year contract, but restrict the disturbance to 1/3 or 1/4 of grassland buffer area in a given year.

Impacts of edge density of field patches on plant species richness and community turnover among margin habitats in agricultural landscapes

In intensive agricultural environments, arable field margins are important habitats as reservoirs of various beneficial wild species. Many studies of species diversity in field margins have focused on the local habitat level. However, relationships between the network of the margin habitats and species diversity are less studied.Edge density index of field patches is a class-level landscape metric used as one measure of habitat network. This study focused on edge density index and its impacts on plant species richness and community turnover among the margins in agricultural landscapes. We examined how effectively the index of edge density can be used as a class-level indicator for species diversity in margins. This study introduces a method for indicating plant species diversity of the margin habitats by using an easily measured spatial indicator without comprehensive analysis of land use/land cover.A total of 29 landscape-square pairs, each consisting of two 25ha squares, were sampled across southern Finland. Vascular plant species were sampled in each square. In GIS, field patch edges were divided into two types: those within crop fields, referred to as within-field edges, and those between crop fields and non-crop lands, referred to as non-crop field edges.By comparing the roles of three landscape groups (the two different edge types as well as all edges grouped together) in explaining plant species richness (at alpha and gamma level) and community turnover (at beta level) in the sampled landscape squares, we found that density index of non-crop field edges surrounded by contrast land use is an effective indicator of species diversity at beta and gamma level. This study suggested that field margins surrounded by contrast land use shall be considered as a priority landscape element in agricultural edge network design, whereas simply using the density of all field edges to indicate species diversity without separating the different effects of various edge types shall not be recommended.

Sown grass strip—A stable habitat for grasshoppers (Orthoptera: Acrididae) in dynamic agricultural landscapes

This study assessed the benefits of sown grass strips on grasshopper communities in intensive farmland, and the effects of farming practices and landscape context. Results showed that sown grass strips were high quality habitats for grasshoppers compared to grasslands. Farming practices influenced grasshopper densities in sown grass strips while landscape context affected more the species richness of grasshoppers. Sown mixture and cutting export option were the main factors driving grasshopper density. Mixtures composed of grasses without legumes were the best, as well as hay export compared to no export. Increased grasshopper species richness occurred in sown grass strips located in landscapes with low grassland field availability and high connectivity. Enhanced use of sown grass strips by grasshoppers can be seen as a direct effect of establishment and management options, but also as an effect of the rarity and instability of other grassland habitats in agricultural landscapes.

Invertebrates in field margins: taxonomic group diversity and functional group abundance in relation to age

Sown, temporary field margins are a common agri-environment scheme (AES) in the Netherlands. Despite their wide application, though, there has been scarcely any long-term monitoring of the succession of invertebrates. In the field margins of 40 farms, invertebrate diversity and the abundance of three functional groups were assessed in relation to age. The diversity in terms of number of species groups was found to increase with the age of the margins. The abundance of herbivores and detritivores also showed a positive correlation with the age of the margins. However, the abundance of predators decreased with increasing age. Older margins showed a higher total vegetation cover and fewer plant species, also resulting in lower plant species evenness. We suggest several changes to the current AES regulations. For the conservation of invertebrate diversity, longer-lasting field margins are desirable. In addition, old margins are favoured by detritivores, a group that has particular difficulty finding suitable habitats in agricultural landscapes. However, such margins are less favourable from an agricultural perspective, as they appear unsuitable for high abundances of potentially useful predators and the high vegetation cover attracts many potentially harmful herbivores. To circumvent this, the AES might be extended by incorporating hay-making, which would reduce standing biomass and might lead to more predators and fewer herbivores.

BIODIVERSITY RESEARCH: Diversity and distribution of macroinvertebrates in lentic habitats in massively altered landscapes in south‐eastern Australia

AbstractAim We investigated whether faunas of lentic macroinvertebrates differed among two landscape types: (1) those that are largely covered in forests (presumed to be in a more pre‐human‐impact condition) and (2) those that are completely cleared for agricultural exploitation (massively altered).Location Five pairs of landscapes (each pair referred to as a region) – one of each landscape type – across a 30,000 km2 region of north‐central Victoria, Australia.Methods Each individual waterbody was surveyed three times (austral spring 2006, autumn 2007, and spring 2007) for invertebrates. Waterbodies were characterized by measurements of static (e.g. abutting vegetation cover) and labile (e.g. pH) variables. Data were analysed using hierarchical Bayesian models of species richness, α‐ and β‐diversities and functional feeding groups. Assemblage composition was related to landscape and in‐waterbody characteristics.Results Neither measured, nor asymptotic estimates of, species richness differed among landscape types, notwithstanding consistent differences in in‐waterbody habitat characteristics among waterbodies in the two landscape types. There were no discernible differences in patterns of α‐ and β‐diversities at landscape scales relating to landscape type. Habitat diversity of waterbodies at the landscape scale did not affect β‐diversity, although distinct waterbodies within landscapes tended to have more distinct faunas.Main conclusions The lentic macroinvertebrate faunas are relatively homogeneous over the entire region, with little differentiation between wooded and cleared landscapes. The regional fauna may be a homogenized subset of native species, possibly arising from the huge numerical predominance of lentic habitats in agricultural landscapes producing ‘spill‐over’ effects into forested landscapes. Of taxa more frequently found in one or other landscape type, trophic group diversity was greater in forested landscapes.

Spatially optimal habitat management for enhancing natural control of an invasive agricultural pest: Soybean aphid

By their direct effects on private profitability, invasive agricultural pests create special incentives for management that set them apart from other categories of invasive species. One attractive nonchemical management approach for agricultural pests relies upon biological control by natural enemies. By improving the habitat of natural enemies of invasive agricultural pests, biological pest control can become privately attractive. This study develops a spatial optimization model to explore economically optimal spatial configuration of natural enemy habitat in agricultural landscapes. The model is applied to the management of soybean aphid ( Aphis glycines), a recent invasive pest species of soybean production systems in the North Central region of the United States. Results indicate that non-crop habitat management can be a promising pest management option for organic cropping systems. Under current prices, however, habitat management tends to reduce net returns for conventional farms. Both area and configuration of non-crop habitats affect economic performance, with the greatest value coming from small, scattered areas of habitat.

The effects of habitat heterogeneity on avian density and richness in soybean fields in Entre Ríos, Argentina

Birds play several roles in agricultural lands and respond to habitat heterogeneity within the agricultural landscape. Agricultural intensification in Argentina has increased the sown area, mainly with soybean, fragmenting landscapes in the pampas and mesopotamic region. In Entre Ríos Province, the original Espinal forest has been fragmented, leaving remnant patches of natural vegetation, in cases modified by cattle grazing. These changes represent a potential threat for avian conservation. In Entre Ríos, terraces may be a useful habitat in maintaining avian diversity, similar to other non-cropped linear habitats in agricultural landscapes. We tested the hypothesis that habitat heterogeneity created by terraces would maintain higher species richness and densities of avian species that use original or modified forests within cropped areas compared to fields without terraces. The study was carried out in soybean fields with an adjacent forest and either herbaceous, shrub or no terraces in two periods (March-April 2004). Birds were surveyed using line transects in field interior and edge, and observations were carried out in one forest remnant adjoining each field. Most bird species recorded in soybean fields were insectivorous or consume invertebrates during the breeding season. Species richness, total bird density and the density of granivores, insectivores and omnivores were higher in fields with terraces than in fields without terraces. Moreover, shrub terraces had higher effect on species richness and bird density than herbaceous terraces. Our results suggest that terraces may serve as a possible tool for maintaining avian diversity in agroecosystems in Entre Ríos.

Winter Avian Community and Sparrow Response to Field Border Width

Abstract:Transformations of agricultural practices in the southeastern United States have drastically reduced preexisting quantities of strip‐cover habitat along field margins. The National Conservation Buffer Initiative has promoted the establishment of herbaceous field borders to restore wildlife benefits once provided by such habitat. We evaluated effects of native warm‐season grass field border establishment and width on winter bird response. Narrow (approx. 8‐m) field borders represented a marginal improvement to non‐bordered margins that were cropped ditch to ditch, whereas wide (approx. 30‐m) borders significantly enhanced total avian conservation value, abundance, species richness, and sparrow abundance compared to non‐ or narrow borders. Furthermore, presence of wide borders altered bird use of row‐crop fields. We observed increased sparrow (Emberizidae) abundances in agricultural fields adjacent to wide borders, which likely resulted from enhanced waste grain foraging opportunities. Given these benefits to wintering farmland birds, we advocate the integration of herbaceous field border habitat in agricultural landscapes, particularly borders of enhanced width.

Conservation value of degraded habitats for forest birds in southern Peninsular Malaysia

ABSTRACTClearance of tropical forest for agricultural purposes is generally assumed to seriously threaten the survival of forest species. In this study, we quantified the conservation value, for forest bird species, of three degraded habitat types in Peninsular Malaysia, namely rubber tree plantations, oil palm plantations, and open areas. We surveyed these degraded habitats using point counts to estimate their forest bird species richness and abundance. We assessed whether richness, abundance, and activities of different avian dietary groups (i.e. insectivores and frugivores) varied among the habitats. We identified the critical habitat elements that accounted for the distribution of forest avifauna in these degraded habitats. Our results showed that these habitats harboured a moderate fraction of forest avifauna (approximately 46–76 species) and their functions were complementary (i.e. rubber tree plantations for moving; open habitats for perching; shrubs in oil palm plantations for foraging). In terms of species richness and abundance, rubber tree plantations were more important than oil palm plantations and open habitats. The relatively high species richness of this agricultural landscape was partly due to the contiguity of our study areas with extensive forest areas. Forecasts of forest‐species presence under various canopy cover scenarios suggest that leaving isolated trees among non‐arboreal crops could greatly attract relatively tolerant species that require tree canopy. The conservation value of degraded habitats in agricultural landscapes seems to depend on factors such as the type of crops planted and distance to primary forest remnants.

Stand characteristics of sericea lespedeza on the Louisiana Coastal Plain

Sericea lespedeza has been an important forage legume in portions of the USA for decades but has recently been recognized as invasive in some ecosystems. Stand characteristics potentially affecting usefulness and invasiveness were assessed on forested and open sites of a Louisiana Coastal Plain landscape. Typical heavy weed competition, which was not overcome by increased seeding rate or extent of seedbed preparation, occurred in full sunlight. An open longleaf pine canopy suppressed competitive herbaceous species and enhanced establishment compared to that in full sunlight. Shade of either longleaf pines or dense overstory of tall weeds reduced productivity but not stands. Sericea lespedeza spread was limited to a few meters during 7 years, apparently due to lack of an effective dispersal mechanism. Long stand life under mature longleaf pines and in the open field along with ability to re-colonize from soil seed reserves contribute to both usefulness of sericea lespedeza for conservation, forage, and wildlife habitat in agricultural landscapes and potential undesired persistence, especially with land-use changes to less intensive management, on Louisiana Coastal Plain landscapes.

Avian use of farm habitats, including windbreaks, on the New South Wales Tablelands

Many windbreaks are being planted on the Tablelands of New South Wales, Australia to provide shelter for stock and crops, but little is known of the effect of these linear plantations on the regional bird community. This paper compares the avian diversity, density and species composition in a range of habitats in agricultural landscapes, including farm windbreaks, and draws conclusions as to the benefits of windbreaks to bird conservation. The data were collected between 1993 and 1997 with 12 visits to each of 84 sites, placed a priori into seven habitat types on six grazing properties in the Tablelands of New South Wales, Australia and analysed using ANOVA and canonical variate analysis to identify bird-habitat relationships and patterns. Species diversity and density were found to be highest in remnant woodland and lowest in grassland, but differences between other habitats were less robust. Windbreaks >19 m wide were closer in diversity and species composition to remnant woodland than windbreaks =15 m wide. Of the 105 bird species observed, 17 were confined to remnant woodland and 67 native species were observed using planted sites. These species were not, as had been predicted, entirely composed of generalist-opportunistic species, but, particularly in the wider planted sites, included several woodland species identified as declining in this region. Although clearly not as important as remnant woodland, farm windbreaks, shelterbelts and woodlots of suitable size and composition appear to contribute significantly to avian diversity in agricultural areas and their planting should be encouraged and supported by the rural community and government.

Mass flowering crops enhance pollinator densities at a landscape scale

AbstractTo counteract the decline of pollinators in Europe, conservation strategies traditionally focus on enhancing the local availability of semi‐natural habitats, as supported by the European Union's Common Agriculture Policy. In contrast, we show that densities of bumblebees, an important pollinator group in agroecosystems, were not determined by the proportion of semi‐natural habitats in agricultural landscapes. Instead, bumblebee densities were positively related to the availability of highly rewarding mass flowering crops (i.e. oilseed rape) in the landscape. In addition, mass flowering crops were only effective determinants of bumblebee densities when grown extensively at the landscape scale, but not at smaller local scales. Therefore, future conservation measures should consider the importance of mass flowering crops and the need for management schemes at landscape level to sustain vital pollination services in agroecosystems.