Semi-natural Habitats (semi-natural + habitat)

Distribution by Scientific Domains


Selected Abstracts


Oilseed rape crops distort plant,pollinator interactions

JOURNAL OF APPLIED ECOLOGY, Issue 1 2010
Tim Diekötter
Summary 1. New incentives at the national and international level frequently lead to substantial structural changes in agricultural landscapes. Subsidizing energy crops, for example, recently fostered a strong increase in the area cultivated with oilseed rape Brassica napus across the EU. These changes in landscape structure affect biodiversity and associated ecosystem services. 2. Mass-flowering oilseed rape has been shown to positively affect colony growth and densities of bumblebees, which may enhance pollination services in agroecosystems. Not considered, however, have been species-specific traits of pollinators resulting in disproportionate benefits from these recurrent resource pulses. A subsequent community shift towards the subsidized species potentially distorts plant,pollinator interactions in the surrounding landscape. 3. We analysed the effects of mass-flowering crops on the abundance of legitimate long-tongued bumblebee pollinators, nectar robbing by illegitimate short-tongued bumblebees and seed set in the long-tubed flowers of red clover Trifolium pratense in 12 landscape sectors with differing amounts of oilseed rape. 4. Densities of long-tongued bumblebees visiting long-tubed plants decreased with increasing amounts of oilseed rape. The simultaneous increase of nectar robbing suggests that resource depletion is a likely explanation for this decline which may lead to a distortion in plant,pollinator interactions. The decline in long-tongued bumblebees, however, did not result in an immediate effect on seed set. In contrast, seed set increased with increasing amounts of semi-natural habitats, indicating the positive effects of these habitats on the legitimate long-tongued pollinators. 5.Synthesis and applications. Accounting for species-specific traits is essential in evaluating the ecological impacts of land-use change. The disproportional trait-specific benefits of increasing oilseed rape to short-tongued bumblebees may abet an increasingly pollinator-dependent agriculture but simultaneously threaten the more specialized and rare long-tongued species and their functions. Semi-natural habitats were found to positively affect seed set in long-tubed plants indicating that they can counteract the potentially distorting effects of transient mass-flowering crops on plant,pollinator interactions in agroecosystems. Future agri-environmental schemes should aim to provide diverse and continuous resources matching trait-specific requirements of various pollinators in order to avoid resource competition. Thereby they harmonize the economic interest in abundant pollinators and the conservation interest in protecting rare species. [source]


Indicators for biodiversity in agricultural landscapes: a pan-European study

JOURNAL OF APPLIED ECOLOGY, Issue 1 2008
R. Billeter
Summary 1In many European agricultural landscapes, species richness is declining considerably. Studies performed at a very large spatial scale are helpful in understanding the reasons for this decline and as a basis for guiding policy. In a unique, large-scale study of 25 agricultural landscapes in seven European countries, we investigated relationships between species richness in several taxa, and the links between biodiversity and landscape structure and management. 2We estimated the total species richness of vascular plants, birds and five arthropod groups in each 16-km2 landscape, and recorded various measures of both landscape structure and intensity of agricultural land use. We studied correlations between taxonomic groups and the effects of landscape and land-use parameters on the number of species in different taxonomic groups. Our statistical approach also accounted for regional variation in species richness unrelated to landscape or land-use factors. 3The results reveal strong geographical trends in species richness in all taxonomic groups. No single species group emerged as a good predictor of all other species groups. Species richness of all groups increased with the area of semi-natural habitats in the landscape. Species richness of birds and vascular plants was negatively associated with fertilizer use. 4Synthesis and applications. We conclude that indicator taxa are unlikely to provide an effective means of predicting biodiversity at a large spatial scale, especially where there is large biogeographical variation in species richness. However, a small list of landscape and land-use parameters can be used in agricultural landscapes to infer large-scale patterns of species richness. Our results suggest that to halt the loss of biodiversity in these landscapes, it is important to preserve and, if possible, increase the area of semi-natural habitat. [source]


Plant diversity and land use under organic and conventional agriculture: a whole-farm approach

JOURNAL OF APPLIED ECOLOGY, Issue 4 2007
R. H. GIBSON
Summary 1Organic farming is thought to lead to increased biodiversity and greater sustainability than higher-yielding conventional farming systems. It is usually assumed that organic farms have both larger and higher quality areas of semi-natural habitats, although this assumption has not been unequivocally tested. 2Here we test the hypothesis that in comparison to conventional farms, organic farms have larger areas of semi-natural and boundary vegetation, and organic farms support higher levels of plant abundance, richness and diversity within cropped and semi-natural areas. 3Our study compared whole-farms: 10 organic farms were paired with 10 conventional farms in a complex landscape in the south-west of England. On average, organic farms were 7·3 years post conversion. Plant abundance, species richness and diversity were measured in all crop and non-crop landscape elements on each farm. 4Organic farms had greater total areas of semi-natural habitat (woodland, field margins and hedgerows combined). Woodland area on it's own was also significantly greater. Organic farms had more continuous blocks of woodland (with simpler perimeters than similarly sized patches on conventional farms), whereas woodland on conventional farms often consisted of more linear patches. 5Semi-natural habitats on organic farms did not have higher plant abundance, richness or diversity than their conventional counterparts. The only landscape element that showed a significant increase in plant abundance, richness or diversity was arable fields. 6Synthesis and applications. Even within a complex agricultural landscape differences do exist between organic and conventional farms, these differences being larger areas of semi-natural habitats on organic farms. However, with the exception of arable fields, no habitats on organic farms were yet of a better quality than their conventional counterparts in terms of plant abundance and diversity. Conventional farmers may be able to achieve an increase in plant diversity within arable fields by adopting some organic management practices at the field scale (e.g. exclusion of synthetic herbicides), and whole-farm conversion to organic practice might not be required. However, further work is needed to determine any biodiversity benefits of larger areas of semi-natural habitat on conventional farmland. [source]


Could we live with reintroduced large carnivores in the UK?

MAMMAL REVIEW, Issue 3 2004
CHARLES J. WILSON
ABSTRACT 1.,Literature on the wolf Canis lupus, brown bear Ursus arctos and lynx Lynx lynx is reviewed to determine if sufficient semi-natural habitat exists in the UK for a viable population of any of these species and to assess the potential risks to human safety, livestock and economically valuable wildlife. Public attitudes to the recovery and reintroduction of some other mammals are also briefly reviewed. 2.,The large home range sizes and low population densities of large carnivores mean that the Scottish Highlands is the only UK region with the potential to support a viable population. Human population density is also lower in the Highlands and the density of wild ungulate prey higher than in many parts of Europe where large carnivores survive. 3.,Attacks on people have been recorded in Europe for healthy bears and for rabid bears and wolves but there are no reports of attacks by lynx. Bears are more carnivorous in the north of their range than in the south and although wild mammals seldom appear to be important prey serious predation of livestock can occur. Livestock predation is also reported for the wolf and the lynx but they appear to prefer wild prey if available. However, mass kills of up to 100 or more sheep are occasionally recorded for wolves. 4.,Attitudes to reintroductions and carnivores generally tend to be favourable amongst the general public, but negative amongst those most likely to be adversely affected. Fears for human safety and significant livestock predation with bears and wolves, respectively, suggest that reintroduction of these species is unlikely to be acceptable in the foreseeable future. Reintroduction of the lynx may be feasible but habitat suitability and potential impact on vulnerable native wildlife need to be assessed. Socio-economic and legal issues also need to be addressed before such a reintroduction is considered. [source]


Genetic and phenotypic differences between thistle populations in response to habitat and weed management practices

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010
RICCARDO BOMMARCO
Rapid evolutionary change is increasingly being recognized as commonplace, but the evolutionary consequences for species and ecosystems under human-induced selection regimes have not been explored in detail, although many species occur in such environments. In a common garden experiment and with amplified fragment length polymorphism markers, we examined whether genetic differentiation has taken place between spatially intermixed populations of creeping thistles Cirsium arvense (Asteraceae) collected from a natural habitat (maritime shores), a semi-natural habitat (road verges) and arable fields under two management regimes: conventional and organic farming. Populations of C. arvense have altered genetically and locally adapted their growth patterns with changed land use. Although plants from different habitats showed similar total biomass production, shoot and root production was higher for maritime populations, suggesting selection for increased competitive ability. Competitive ability then declined in the order semi-natural, conventional farms and organic farms. Thistles in arable fields may be more selected for tolerance against disturbances from herbicides and mechanical weed control. In addition, early shoot sprouting and genetic analysis showed differentiation between plants originating from conventional farms and farms that were converted to organic 9,30 years ago, suggesting some adaptation to altered crop cultivation practices. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 797,807. [source]


Mass flowering crops enhance pollinator densities at a landscape scale

ECOLOGY LETTERS, Issue 11 2003
Catrin Westphal
Abstract To 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. [source]


Oilseed rape crops distort plant,pollinator interactions

JOURNAL OF APPLIED ECOLOGY, Issue 1 2010
Tim Diekötter
Summary 1. New incentives at the national and international level frequently lead to substantial structural changes in agricultural landscapes. Subsidizing energy crops, for example, recently fostered a strong increase in the area cultivated with oilseed rape Brassica napus across the EU. These changes in landscape structure affect biodiversity and associated ecosystem services. 2. Mass-flowering oilseed rape has been shown to positively affect colony growth and densities of bumblebees, which may enhance pollination services in agroecosystems. Not considered, however, have been species-specific traits of pollinators resulting in disproportionate benefits from these recurrent resource pulses. A subsequent community shift towards the subsidized species potentially distorts plant,pollinator interactions in the surrounding landscape. 3. We analysed the effects of mass-flowering crops on the abundance of legitimate long-tongued bumblebee pollinators, nectar robbing by illegitimate short-tongued bumblebees and seed set in the long-tubed flowers of red clover Trifolium pratense in 12 landscape sectors with differing amounts of oilseed rape. 4. Densities of long-tongued bumblebees visiting long-tubed plants decreased with increasing amounts of oilseed rape. The simultaneous increase of nectar robbing suggests that resource depletion is a likely explanation for this decline which may lead to a distortion in plant,pollinator interactions. The decline in long-tongued bumblebees, however, did not result in an immediate effect on seed set. In contrast, seed set increased with increasing amounts of semi-natural habitats, indicating the positive effects of these habitats on the legitimate long-tongued pollinators. 5.Synthesis and applications. Accounting for species-specific traits is essential in evaluating the ecological impacts of land-use change. The disproportional trait-specific benefits of increasing oilseed rape to short-tongued bumblebees may abet an increasingly pollinator-dependent agriculture but simultaneously threaten the more specialized and rare long-tongued species and their functions. Semi-natural habitats were found to positively affect seed set in long-tubed plants indicating that they can counteract the potentially distorting effects of transient mass-flowering crops on plant,pollinator interactions in agroecosystems. Future agri-environmental schemes should aim to provide diverse and continuous resources matching trait-specific requirements of various pollinators in order to avoid resource competition. Thereby they harmonize the economic interest in abundant pollinators and the conservation interest in protecting rare species. [source]


Indicators for biodiversity in agricultural landscapes: a pan-European study

JOURNAL OF APPLIED ECOLOGY, Issue 1 2008
R. Billeter
Summary 1In many European agricultural landscapes, species richness is declining considerably. Studies performed at a very large spatial scale are helpful in understanding the reasons for this decline and as a basis for guiding policy. In a unique, large-scale study of 25 agricultural landscapes in seven European countries, we investigated relationships between species richness in several taxa, and the links between biodiversity and landscape structure and management. 2We estimated the total species richness of vascular plants, birds and five arthropod groups in each 16-km2 landscape, and recorded various measures of both landscape structure and intensity of agricultural land use. We studied correlations between taxonomic groups and the effects of landscape and land-use parameters on the number of species in different taxonomic groups. Our statistical approach also accounted for regional variation in species richness unrelated to landscape or land-use factors. 3The results reveal strong geographical trends in species richness in all taxonomic groups. No single species group emerged as a good predictor of all other species groups. Species richness of all groups increased with the area of semi-natural habitats in the landscape. Species richness of birds and vascular plants was negatively associated with fertilizer use. 4Synthesis and applications. We conclude that indicator taxa are unlikely to provide an effective means of predicting biodiversity at a large spatial scale, especially where there is large biogeographical variation in species richness. However, a small list of landscape and land-use parameters can be used in agricultural landscapes to infer large-scale patterns of species richness. Our results suggest that to halt the loss of biodiversity in these landscapes, it is important to preserve and, if possible, increase the area of semi-natural habitat. [source]


Plant diversity and land use under organic and conventional agriculture: a whole-farm approach

JOURNAL OF APPLIED ECOLOGY, Issue 4 2007
R. H. GIBSON
Summary 1Organic farming is thought to lead to increased biodiversity and greater sustainability than higher-yielding conventional farming systems. It is usually assumed that organic farms have both larger and higher quality areas of semi-natural habitats, although this assumption has not been unequivocally tested. 2Here we test the hypothesis that in comparison to conventional farms, organic farms have larger areas of semi-natural and boundary vegetation, and organic farms support higher levels of plant abundance, richness and diversity within cropped and semi-natural areas. 3Our study compared whole-farms: 10 organic farms were paired with 10 conventional farms in a complex landscape in the south-west of England. On average, organic farms were 7·3 years post conversion. Plant abundance, species richness and diversity were measured in all crop and non-crop landscape elements on each farm. 4Organic farms had greater total areas of semi-natural habitat (woodland, field margins and hedgerows combined). Woodland area on it's own was also significantly greater. Organic farms had more continuous blocks of woodland (with simpler perimeters than similarly sized patches on conventional farms), whereas woodland on conventional farms often consisted of more linear patches. 5Semi-natural habitats on organic farms did not have higher plant abundance, richness or diversity than their conventional counterparts. The only landscape element that showed a significant increase in plant abundance, richness or diversity was arable fields. 6Synthesis and applications. Even within a complex agricultural landscape differences do exist between organic and conventional farms, these differences being larger areas of semi-natural habitats on organic farms. However, with the exception of arable fields, no habitats on organic farms were yet of a better quality than their conventional counterparts in terms of plant abundance and diversity. Conventional farmers may be able to achieve an increase in plant diversity within arable fields by adopting some organic management practices at the field scale (e.g. exclusion of synthetic herbicides), and whole-farm conversion to organic practice might not be required. However, further work is needed to determine any biodiversity benefits of larger areas of semi-natural habitat on conventional farmland. [source]


Assemblages of soil macrofauna across a Scottish land-use intensification gradient: influences of habitat quality, heterogeneity and area

JOURNAL OF APPLIED ECOLOGY, Issue 6 2005
PAUL EGGLETON
Summary 1Land-use intensification strongly influences biodiversity by altering habitat heterogeneity, the distribution of habitat types and their extent. This study explores these effects within mixed semi-natural/agricultural mosaic habitats in Scotland, examining the effect of land-use intensification on the soil macrofauna at point (m2), landscape (km2) and regional (> 1 km2) scales. 2The soil macrofauna in six 1-km2 sampling areas (land-use units; LUU) were sampled using a combined hand-sorting and Winkler bag extraction technique. Within each LUU, 16 1-m2 samples were taken in each of 2 successive years. Each LUU had a mixture of land-use types, representing an agricultural intensification gradient. 3The following hypotheses were tested: (i) the study area sustains a number of distinct habitats as defined by soil macrofaunal composition; (ii) a greater number of restricted range species are found in semi-natural habitats; (iii) local (point) species density is related to habitat type; (iv) overall levels of species richness per habitat at regional scales are related to species-area effects; and (v) landscape-level species density is correlated with habitat heterogeneity. 4Initial analysis revealed five distinct habitat types: Caledonian forest (semi-natural pine forest), closed canopy woodland (pine plantation and broadleaved woodland), riparian habitats (wet woodland and grassland), pasture (improved grassland) and arable (crop fields). 5As hypothesized, the Caledonian habitat contained a greater number of restricted-range species than the other habitats. However, conifer plantations contained more restricted range species than expected, given their anthropogenic origin. Species density per m2 was most strongly affected by habitat type. At the regional level, the size of the species pool was correlated with the size of habitat areas. There were more species overall in LUU with greater habitat heterogeneity. 6Synthesis and applications. Caledonian pine forests have high species densities and contain species of conservation value. Mixed conifer plantations also appear to have a surprisingly high invertebrate conservation value. In contrast, intensively managed agricultural habitats have low species densities and conservation value. Generally, mixed land-use areas have higher species densities than single land-use areas. This emphasizes the need for careful management of forest systems within the matrix of agricultural habitats to maximize landscape diversity. [source]


Nitrogen: the essential public enemy

JOURNAL OF APPLIED ECOLOGY, Issue 5 2003
Howard Dalton
Summary 1Increased demand for food and energy is leading to changes in the global nitrogen cycle. These changes are resulting in increasing levels of nitrogen in the environment in its pollutant forms with consequences for both biodiversity and human health. In this paper, we discuss the impacts in the UK and give examples of the steps that are being taken by the Department for Environment, Food and Rural Affairs (Defra) to tackle these problems. 2Over 70% of the UK land area is farmland. The farmed environment is composed of a wide range of semi-natural habitats including heather moorland, chalk downland, wet grasslands farm woodlands and hedgerows. As a result, much of the UK's cherished biodiversity is an integral part of agriculture and therefore vulnerable to changes in farming practices. 3Defra's overall goal is to build a sustainable future for the UK. With regard to nitrogen pollution, this involves finding ways of continuing to meet our food and energy requirements whilst causing little or no harm to the environment. 4Defra's science programme has a central role to play in the development of its nitrogen pollution policies. These pollution policies provide a key input to the Department's evidence base for policy formulation, and support international negotiations on pollution targets. 5The Department's science programme has addressed the major components of the nitrogen cycle associated with harmful impacts on the environment and human health. The main aims have been the understanding and quantification of impacts through monitoring and modelling and the development of abatement measures. 6Synthesis and application. It is becoming increasingly apparent that whilst advances can and have been made in the reduction of emissions from combustion processes, the problem of nitrogen pollution from agriculture is far more intractable. This scientific challenge, when taken together with emerging regulatory initiatives, will require imaginative solutions if the UK Government is to forge a sustainable way forward1, 2. [source]


Temporal changes in the island flora at different scales in the archipelago of SW Finland

APPLIED VEGETATION SCIENCE, Issue 4 2010
Jens-Johan Hannus
Abstract Question: How have species richness and vegetation patterns changed in a group of islands in the northern Baltic Sea over a 58-yr period of changing land use and increasing eutrophication? Location: A group of 116 islands, the Brunskär sub-archipelago, in SW Finland. Methods: A complete survey of vascular plant species performed in 1947,1949 by Skult was repeated by our group using the same methodology in 2005,2007 (historical versus contemporary, respectively). DCAs were performed and total number of species, extinction,colonization rates, species frequency changes and mean Ellenberg indicator values for light, moisture and nitrogen and Eklund indicator values for dependence of human cultural influence were obtained for each island and relevé. Results: Species richness has declined on large islands and increased on small islands. The increase in number of species on small islands is driven by a strong increase in frequency of shore species, which in turn is induced by more productive shores. The decrease in species richness on large islands is related to overgrowth of open semi-natural habitats after cessation of grazing and other agricultural practices. Conclusions: After the late 1940s, open habitats, which were created and maintained by cattle grazing and other traditional agricultural activities, have declined in favour of woody shrub and forest land. Shores have been stabilized and influenced by the eutrophication of the Baltic Sea, and the vegetation has become more homogeneous. This development, resulting in lower species diversity, poses a challenge for the preservation of biodiversity both on a local and on a landscape level. [source]