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Organic farming often counteracts the decline of various taxa owing to agricultural intensification, but little is known about the relative importance of local management and landscape context for small mammals. We examined the abundance, species richness and diversity of small mammal communities in 22 organically and conventionally managed winter wheat fields pairwise located along a gradient of landscape structural complexity (41–94% arable land). Complex landscapes significantly increased small mammal abundance and (with marginal significance) species richness and diversity, but only in conventional fields, whereas organic farming increased small mammals in simple landscapes. These results indicate the importance of landscape complexity for small mammal populations in an intensified agriculture. Analyses at multiple spatial scales (100 m, 250 m, 500 m radii around focal fields), showed opposing responses of the three most abundant species to landscape complexity. Apodemus agrarius PALLAS abundance increased with increasing landscape complexity at a spatial scale of 100 m, whereas Microtus arvalis PALLAS and Sorex araneus L. abundances decreased with increasing landscape complexity at spatial scales of 100 m and 500 m, respectively, suggesting species-specific ecological needs as well as functional spatial scales for conservation management. In conclusion, agri-environmental measures for small mammals such as organic farming are most effective in simple landscapes, while complex landscapes presumably function as source habitats and can compensate for local agricultural intensification in conventional fields. 相似文献
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Michiala E. Bowen Clive A. McAlpine Leonie M. Seabrook 《Biological conservation》2009,142(12):3051-3059
In highly-modified agricultural landscapes, regrowth (secondary) forest on abandoned farmland offers the potential for passive landscape restoration for biodiversity conservation. While numerous studies have investigated the ecological values of regrowth for fauna recovery at the local-level (1-10 ha), there is a dearth of studies quantifying the contribution of regrowth forest at the landscape-level (100-1000s ha). To address this critical knowledge gap we question how the age and amount of regrowth forest in the landscape influence species richness and abundance of mature forest dependent species? Using woodland dependent birds in fragmented sub-tropical brigalow landscapes in southern Queensland, Australia, we applied model averaging and hierarchical partitioning analyses to test and rank the relative importance of the amount of regrowth forest in the landscape in three age classes (<15, 15-30, and >30 years) compared to local (grazing disturbance, abundance of aggressive miners, mistletoe abundance and patch age) and landscape measures of habitat (amount of mature forest and number of mature forest patches). Response variables included the species richness of woodland dependent birds and sub-groupings of foraging guilds, and the abundance of selected individual species. The importance of explanatory variables differed considerably among response groups. Local attributes, such as patch age and the abundance of mistletoe plants, had the strongest influences on woodland dependent birds. However, we found that the amount of regrowth forest, particularly >30 years, also had a strong influence on both species richness and abundance. This study confirms that regrowth, especially older regrowth, can make an important contribution to landscape restoration in highly-modified agricultural landscapes. 相似文献
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A critical handicap to tropical biodiversity conservation efforts in agroecosystems is the unknowns regarding the influence of landscape-scale factors on the persistence of species. To address these uncertainties, we explored two essential landscape-scale questions, within India’s biologically-rich Western Ghats, examining two nearby human-dominated landscapes that dramatically differed in their pattern of land cover. First, how does the proximity of intact forest patches affect bird community composition within agricultural landscapes? Second, can simple remote sensing-derived measures (brightness, wetness, and NDVI) be used to estimate native bird species composition within those landscapes? In both landscapes, as distance to intact forest decreased, the similarity in bird community composition between agricultural areas and intact forest increased. This suggests that the retention of tropical forest bird communities within human-dominated landscapes critically depends on the maintenance of nearby intact forest. In an answer to the second question, the remote sensing measures correlated with forest-affiliated avian species richness in only one of the two landscapes, reflecting an ecological difference between the two in the response of forest bird species to local agricultural conditions. In the landscape where a correlation was found, there was high variation in vegetative structure, which strongly impacted both the remote sensing measures and forest bird species richness. In the other landscape, forest species richness strongly correlated with changes in tree species composition in the agriculture, a factor that could not be detected by the remote sensing metrics. In order to successfully conserve biodiversity in tropical agricultural landscapes, our findings show that it is essential to conserve intact forest within those landscapes and to understand the effect of local agricultural practices on species. 相似文献
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Ondine Filippi-Codaccioni Vincent Devictor Jean Clobert 《Biological conservation》2010,143(4):883-890
Increases in farming practice intensity and landscape simplification are two well-known threats for many farmland bird species. Nevertheless, the effects of these two factors may differ strongly among species. Here, we propose to use the specialist-generalist concept to assess which bird species are most affected by these two factors. Bird density and intensity of farming practices were assessed within a sample of 58 farms across the Seine-et-Marne region in France, using point counts and a standardised farmer survey. The local abundance of 41 farmland and non-farmland species was related to farming intensity (pesticide applications) and landscape simplification (proportion of arable land), which was quantified using generalised least square models to account for spatial autocorrelation. The more specialised the farmland and non-farmland birds were, the more negatively affected they were by the intensity of farming practices, relative to the generalist bird species. Local habitat simplification had a more positive effect on abundance of the most specialist farmland bird species. This latter relationship was not significant when tested at a landscape scale, which strongly suggests that the sensitivity of farmland specialists to landscape simplification is scale-dependent. Some non-farmland species’ abundance was also reduced by farming intensity and local landscape simplification suggesting that low-input agri-environmental measures could benefit both farmland and non-farmland specialists, regardless of local and landscape habitat context. However, if diversity-enhancing measures should benefit non-farmland populations, it is likely that they do not favour farmland specialist species which are more at risk. We suggest designing of priority areas for farmland specialist birds, and landscape managing accordingly. 相似文献
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为满足日益增长的粮食需求,丘陵地区的农业发展已受到越来越多的重视,而农业集约化生产是导致生物多样性丧失的主要原因之一。为了解地形区域、生产管理模式及边界树篱带对农田地表天敌多样性的影响,在我国华北典型农区,选取5种农田,包括丘陵地区的常规管理无植物篱玉米地(CM)、常规管理有植物篱玉米地(CMH)、有机管理无植物篱玉米地(OM)、有机管理有植物篱玉米地(OMH)和平原地区常规管理无植物篱玉米地(PCM),于2019年8—9月采用陷阱法展开蜘蛛多样性调查。结果表明:处于丘陵地区的玉米地蜘蛛的香农多样性和物种稀疏指数显著高于平原地区,有机管理下的玉米地蜘蛛物种稀疏指数显著高于常规管理下的玉米地,有植物篱的玉米地蜘蛛的物种稀疏指数高于无植物篱的玉米地;且丘陵与平原、有植物篱与无植物篱、有机和常规管理下蜘蛛群落结构显著不同。基于上述研究结果,研究建议农业发展和生物多样性保护应当加强区域土地利用规划和分区管理;丘陵地区因受人类干扰较小,维持了较平原地区更高的蜘蛛物种库,可以作为集约化农区生物多样性保护的热点区,农业发展应优先规划发展低集约化的生产模式(如有机农业等),并加强景观多样性建设。而平原地区也应合理保留农田半自然边界带和降低集约化管理强度以推动生态环境改善和绿色发展。 相似文献
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Agricultural landscapes with spatial and temporal variations interact with each other to affect the existing biodiversity. Though rice fields provide important habitats for birds all over the world, studies so far have rarely explored the effects of landscape heterogeneity on bird species in rice paddy areas. This study investigated the effects of habitat cover and landscape variables on the species richness and the abundance of birds in rice paddy areas in Japan. Data on bird occurrence and the environment were collected at 32 grid squares (1 × 1 km) in the Tone River basin. The richness and the abundance of agricultural wetland species were particularly high in landscapes with large areas of rice fields in summer, when rice fields were irrigated, but in those with large areas of open water in winter, when rice fields were drained. It is important to maintain a combination of rice fields and open water to satisfy multiple habitat requirements by agricultural wetland species throughout the year. Grassland species were positively associated with a rich diversity of land cover including fallow fields and open water, indicating the importance of a simultaneous existence of multiple landscape elements. Forest cover in landscapes positively affected edge species and woodland species. Since forest cover had a relatively strong correlation with edge density, the responses of bird species to changes in forest cover and edge density need to be explored further. This study illustrates the importance of spatial and temporal landscape complementation for bird species in rice paddy areas. 相似文献
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It has been suggested that an increase in the area of low-intensity land-use on arable land (e.g. set-aside fields and short-rotation coppice), and high or increased farmland habitat heterogeneity, may halt or reverse the observed population decline of farmland birds. We tested these hypotheses by undertaking farmland bird censuses during two contrasting periods of agricultural policies and land-use (i.e. 1994 and 2004) in a farmland region covering a gradient of forest- to farmland-dominated landscapes in Sweden. Local species richness (i.e. at 3 hectare sites) declined significantly between 1994 and 2004. Local species richness was positively related to habitat heterogeneity in both years of study whereas temporal change in species richness was not. Local change in species richness was positively associated with a change in the proportion of non-rotational set aside and short-rotation coppice (i.e. low-intensity land-use forms), but also to changes in the amount of spring-sown crops. However, the effect of low-intensity land-use was significantly dependent on the amount of forest in the surrounding landscape. An increase in low-intensity land-use was linked to an increase (or less marked decrease) in species richness at sites located in open farmland surroundings but to a decrease in richness at sites located in forest surroundings. This interaction between amount of forest and low-intensity land-use could be interpreted as a “rare habitat effect”, where an increase in a farmland habitat only positively affects biodiversity when it was originally uncommon (i.e. open farmland areas). Our results suggest that conservation measures of farmland biodiversity have to be put in a landscape context. 相似文献
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This study examines bird occurrence on 20 green lanes (farmland tracks with un-sealed surfaces, bordered on each side by hedgerows) and on 20 paired single hedgerows during the 2002 breeding season in Cheshire, UK. Measures of bird abundance, territories and species richness were all found to be significantly greater on green lanes than on single hedgerows. Significantly more birds were also found to occur on the inside rather than on the outside of green lanes in terms of abundance and species richness. All measures of bird occurrence on green lanes were influenced by hedge width and surrounding land use. Bird abundance on single hedgerows was influenced by the number of trees and amount of hawthorn in the hedge. Seventeen of the 18 most abundant bird species recorded in this study were found to occur in greater numbers on green lanes rather than in single hedgerows; for half of these species the difference was significant. The importance of green lanes for birds, and other wildlife is discussed, as well as their possible future within the UK landscape. 相似文献
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Olivier Duriez Yves Ferrand Françoise Binet François Gossmann 《Biological conservation》2005,122(3):479-490
The Eurasian woodcock (Scolopax rusticola) is a game species experiencing high hunting pressure, long-term modifications of its habitats, and with questions regarding its current conservation status. Winter is a season of highest concentration of birds and hunting pressure but woodcock precise habitat requirements are poorly known. It is crucial to assess threats and to develop sustainable management options for the conservation of woodcock populations. During three consecutive winters, we monitored 65 individual woodcocks fitted with radio-tags in Brittany, France. Habitat selection was analysed using GIS and compositional analysis, in relation to vegetation types, soil variables (humus types) and the abundance of their main prey (earthworms). Woodcocks used different habitats diurnally and nocturnally, generally preferring areas with high earthworm biomass. Diurnal habitat selection in forests was associated with humus type (preference for mulls, rich in earthworms) and dense shrub strata (better protection). Hedges with a high density of trees and shrub were also important habitat. At night, grazed meadows were the preferred habitat, containing five times higher biomass of earthworms compared to cultivated fields. Sustainable management of populations requires protection and management of habitats that incorporates food and cover. Forestry practices should preserve rich humus types and coppices by choosing tree species that ameliorate the soil and soil tilling. Changes in landscapes and intensive agricultural practices are current threats to woodcock populations: destruction of hedges, decrease of permanent grazed meadows, impoverishment of soils fauna biomasses from ploughing and chemical applications. However, woodcocks may benefit from the recent development of set-asides, grass field-borders and simplified farm practices (no-tillage and direct sowing). 相似文献
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Since 1992 the European Union helps member states to reverse the loss of biodiversity in agricultural landscapes by the financial support of agri-environment schemes. Long-term studies investigating the effects of these schemes are an essential prerequisite for the development of an effective policy to restore biodiversity on farmland. In Dutch meadow landscapes almost all agri-environment schemes focus on the restoration of meadow bird populations by postponement of the mowing date. Between 1990 and 2002 we measured long-term changes in meadow bird densities in areas with and without agri-environment schemes in the Netherlands, both before and after the start of the contract. During these years bird territories were surveyed during five field visits between 15 March and 15 June. Densities of black-tailed godwit (Limosa limosa), and redshank (Tringa totanus) were higher in the areas with management agreements, but these differences were already present before the start of the contracts. After the start of the management contracts densities of black-tailed godwit and oystercatcher (Haematopus ostralegus) did not increase, while those of lapwing (Vanellus vanellus) and redshank even declined relative to the control areas. It is concluded that the current agri-environment schemes are not sufficient to restore meadow bird populations in Dutch agricultural landscapes. In addition to the prescribed postponement of the mowing date, it is probably necessary to raise groundwater levels and to reduce fertilization to allow for the development of an open vegetation structure that will increase chick survival to sufficiently high levels. 相似文献
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The switch from spring-sown to autumn-sown cereals and the loss of habitat heterogeneity are often suggested to be key drivers of breeding bird decline on arable farmland. Yet, both factors are interlinked and it remains uncertain whether autumn-sown cereals reduce breeding bird numbers also in the structurally complex arable farmland of northern Europe. We tested whether autumn-sowing of cereals at both local and landscape scales affected the breeding bird community in a heterogeneous agricultural landscape of south-central Sweden. Rotation between sowing types was used as a semi-experiment based on 34 spring- vs. 41 autumn-sown cereal plots centred on infield non-crop islands of similar structure, size and surroundings. Species richness and territory abundance of ground-foraging species were significantly lower in autumn- than in spring-sown cereal plots both in the crop fields and the infield non-crop islands during the breeding season. No such effect was observed among foliage gleaning birds. Species richness in spring-sown cereal plots was less the more autumn-sown crops in the surrounding landscape within a 500 m radius. Average skylark densities did not differ between autumn- and spring-sown cereal plots because habitat preferences changed; densities declined in autumn-sown cereals during the growing season whereas they increased on spring-sown fields which had shorter swards throughout the breeding season. Our results indicate that negative effects of autumn-sown crops on breeding bird numbers spill over into both neighbouring non-crop and crop habitats. We conclude that agri-environmental schemes should place more emphasis on facilitating the value of the cropped area of fields as a foraging and nesting habitat. The retention of various non-crop habitats alone may not provide sufficient food close to nest sites for farmland birds that rely on crop fields for foraging. 相似文献
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Ondine Filippi-Codaccioni Vincent Devictor Romain Julliard 《Biological conservation》2008,141(11):2698-2707
Urban sprawl is now occurring worldwide and considered as a major large-scale perturbation on ecosystems. Consequently, urban territory is replacing other habitats such as agricultural areas. As farmland biotic communities are already reported to be declining, it seems necessary to assess the urbanization impact on them. We conducted a bird survey on 92 plots of 1 × 1 km chosen after stratification on the proportion of urban area and farmland habitat (either 0%, 25%, 50%, 75%), focusing on farmland habitat. Two aspects of urbanization were studied: its intensity and its age. We found that farmland bird species richness did not vary with increasing proportion of urbanized habitat. Non-farmland bird species richness increased from 0% to 25% classes and was constant for other classes. No effect of the urbanization age on farmland bird species richness was found, whereas a positive one was found on the non-farmland birds’ species richness. Abundance of the most specialized farmland birds decreases with urbanization intensity and age. We also found that, the more urbanized and the more recently urbanized the plots, the more similar bird communities. A strong difference in farmland bird’s communities’ compositions was found between 0% and 25% of urbanization, whereas no distinction was found between 50% and 75%. Altogether, our results suggest that to maintain for farmland birds, it is better to add new urban habitat in place where it already exist, rather than to spread it in small lots throughout the landscape. 相似文献
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While it is widely understood that local abundance of benthic invertebrates can greatly influence the distribution and abundance of wetland birds, no studies have examined if wetland landscape context can mediate this relationship. We studied the influence of wetland food abundance and landscape context on use of agricultural wetlands by wintering dunlin (Calidris alpina) and killdeer (Charadrius vociferus) in the Willamette Valley of Oregon, USA, over two winters (1999-2000, 2000-2001) of differing rainfall and subsequent habitat distribution. We monitored bird use (frequency of occurrence and abundance) at a sample of wetlands differing in local food abundance (density and biomass) and landscape context [adjacent shorebird habitat (defined as ha of wet habitat with less than 50% vegetative cover and within a 2-km radius) and nearest neighbor distance]. We evaluated predictive models for bird use using linear regression and the Cp criterion to select the most parsimonious model. During the dry winter (2000-2001), dunlin exhibited greater use of sites with higher invertebrate density and biomass but also with more adjacent shorebird habitat and closest to a wetland neighbor. However, neither landscape context nor food abundance were important predictors of dunlin use during the wet winter (1999-2000). Use of sites by killdeer was unrelated to either local food abundance or landscape context measures during both winters. Our findings contribute to a growing recognition of the importance of landscape structure to wetland birds and highlight a number of implications for the spatial planning and enhancement of wetlands using a landscape approach. 相似文献
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Wang Zhijun 《Biological conservation》2003,110(2):231-243
This study took a comparative look at the relationship between human-altered landscapes and bird diversity in two mountainous swidden (slash and burn) agricultural sites in Xishuangbanna, Yunnan, China. Over the course of 3 years (1998-2000) the authors used line-transect identification surveys in the two regions, Mengsong and Jinuo, where four different habitats were surveyed: 6-year fallow fields; traditional economic forests; monsoon evergreen broadleaf forests; and montane rain forests. Data were analyzed for species diversity, richness (family, genera, species), co-occurrence (family, genera, species), characterization of migratory status and feeding habits. Both of these study areas are inhabited by minority groups (Hani and Jinuo) that employ swidden agriculture as their main form of economic activity. The forest landscape in the Jinuo ethnic region is quickly transforming due to changing agricultural practices, and as a result bird diversity and richness are declining, while the Hani ethnic region (Mengsong), with a stable form of traditional swidden agriculture, is maintaining a high diversity and richness of birds. The greatest differences in bird diversity between the two sites occurred in the traditional economic forests and the 6-year fallow fields where the Hani region had a much greater richness and diversity. The two natural forest types (monsoon evergreen broadleaf forests and montane rain forests) were more similar in richness and diversity and also maintained the greatest richness and diversity of the four forest types analyzed. The transformation of healthy forests into degraded landscapes is one of the major impacts of human activity on the natural environment, which is posing a great threat to biodiversity. This study looks at the bird diversity of the two regions and tries to take into account how humans can extract economic benefits while preserving ecological benefits, such as a landscape that allows biodiversity to thrive. 相似文献
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Organic farming has often been found to provide benefits for biodiversity, but the benefits can depend on the species considered and characteristics of the surrounding landscape. In an intensively farmed area of Northeast Italy we investigated whether isolated organic farms, in a conventionally farmed landscape, provided local benefits for insect pollinators and pollination services. We quantified the relative effects of local management (i.e. the farm system), landscape management (proportion of surrounding uncultivated land) and interactions between them. We compared six organic and six conventional vine fields. The proportion of surrounding uncultivated land was calculated for each site at radii of 200, 500, 1000 and 2000 m. The organic fields did not differ from the conventional in their floral resources or proportion of surrounding uncultivated land. Data were collected on pollinator abundance and species richness, visitation rates to, and pollination of experimental potted plants. None of these factors were significantly affected by the farming system. The abundance of visits to the potted plants in the conventional fields tended to be negatively affected by the proportion of surrounding uncultivated land. The proportion fruit set, weight of seeds per plant and seed weight in conventional and organic fields were all negatively affected by the proportion of surrounding uncultivated land. In vine fields the impact of the surrounding landscape was stronger than the local management. Enhancement of biodiversity through organic farming should not be assumed to be ubiquitous, as potential benefits may be offset by the crop type, organic-management practices and the specific habitat requirements in the surrounding landscape. 相似文献
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Small patches of natural or semi-natural habitat have an important role in the conservation of biodiversity in human-dominated environments. The values of such areas are determined by attributes of the patch as well as its context in the surrounding land mosaic. There is a need for better understanding of the ways in which assemblages are influenced by patch context and the scale over which this occurs. Here we examine the influence of regional environmental gradients on the richness, annual turnover and composition of breeding bird species in small woods in south-eastern England. Regional gradients were defined independently of woods by an ordination of attributes for 5 km × 5 km landscape units across a 2100 km2 region. Patch-level attributes, particularly area, were the most important predictors for most bird variables. For woodland migrants and woodland-dependent species, variables representing the context of each wood, either at a local or regional scale, explained significant additional variance in species richness after accounting for wood area, but did not do so for species turnover. Significant context effects for woodland-dependent species related to the extent of hedges and woodland cover in the local vicinity (<1 km radius), whereas for woodland seasonal migrants the best predictors of richness after patch area were two regional environmental gradients. The initial cue to settlement for migrants may be at a coarse regional scale, with selection for suitable landscapes that have a greater extent of woodland cover. Edge species showed different responses: they were influenced by the diversity of structural features in woods, and were a more-dominant component of the avifauna in isolated woods in open fenland environments of the region. Significant relationships between coarse regional gradients (25 km2 units) and bird assemblages in small woods (0.5-30 ha) suggest that population and community processes in the avifauna operate across a broader scale than local patch neighbourhoods. They also highlight the importance of adopting a landscape or regional perspective on potential changes to land-use in rural environments, and on the conservation management of small reserves. 相似文献
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Luís Reino Pedro Beja Patrick E. Osborne António Fabião 《Biological conservation》2009,142(4):824-838
Afforestation often causes direct habitat losses for farmland birds of conservation concern, but it is uncertain whether negative effects also extend significantly into adjacent open land. Information is thus required on how these species react to wooded edges, and how their responses are affected by edge and landscape characteristics. These issues were examined in Mediterranean arable farmland, using bird counts at 0, 100, 200, 300 and >300 m from oak, pine and eucalyptus edges, embedded in landscapes with variable amounts and spatial configurations of forest plantations. Bird diversity declined away from edges, including that of woodland, farmland and ground-nesting birds. Positive edge responses were also found for overall and woodland bird abundances, and for five of the nine most widespread and abundant species (Galerida larks, stonechat, linnet, goldfinch and corn bunting). Strong negative edge effects were only recorded for steppe birds, with reduced abundances near edges of calandra larks and short-toed larks, but not of little bustards and tawny pipits. Edge contrast affected the magnitude of edge effects, with a tendency for stronger responses to old and tall eucalyptus plantations (hard edges) than to young and short oak plantations (soft edges). There were also species-specific interactions between edge and fragmentation effects, with positive edge responses tending to be strongest in less fragmented landscapes, whereas steppe birds tended to increase faster away from edges and to reach the highest species richness and abundances in large arable patches. Results suggest that forest plantations may increase overall bird diversity and abundance in adjacent farmland, at the expenses of steppe birds of conservation concern. Clustering forest plantations in a few large patches and thus reducing the density of wooded edges at the landscape-scale might reduce such negative impacts. 相似文献
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Long-term effects of fragmentation and fragment properties on bird species richness in Hawaiian forests 总被引：1，自引：0，他引：1
David J. Flaspohler Christian P. Giardina Patrick Hart Cassie Ka’apu Lyons 《Biological conservation》2010,143(2):280-288
Forest fragmentation is a common disturbance affecting biological diversity, yet the impacts of fragmentation on many forest processes remain poorly understood. Forest restoration is likely to be more successful when it proceeds with an understanding of how native and exotic vertebrates utilize forest patches of different size. We used a system of forest fragments isolated by volcanic activity 153 years ago in Hawaii to examine how long-term fragmentation, as well as fragment size and structural features affect the richness of native and exotic bird species. The total number of bird species increased rapidly with forest fragment size, with most of the native species pool found in patches <3 ha. Smaller fragments were dominated by native bird species with several exotic bird species found only in the largest fragments, suggesting that exotic bird species in this landscape show greater area-sensitivity than native species. We used airborne scanning light detection and ranging (LiDAR) to assess whether fragment area was correlated with estimates of fragment vegetation volume as well as measures of tree height. Fragment area was highly correlated with vegetation volume, maximum tree height, and canopy height heterogeneity, and these variables were strong predictors of bird richness, demonstrating that remote sensing can provide key insights into the relationship between fragment structural attributes and biodiversity indicators. Overall, this work demonstrates the value of conserving small remnant mid-elevation forest patches for native birds in Hawaii. This work also provides insight into how newly created forest patches might be used by native and exotic bird species in Hawaii. 相似文献