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Ajouter le résultat dans votre panierEnhancing diversity of species-poor grasslands: an experimental assessment of multiple constraints / Richard F. Pywell in Journal of applied ecology, 44 (2007)
Titre : Enhancing diversity of species-poor grasslands: an experimental assessment of multiple constraints Type de document : Imprimé Auteurs : Richard F. Pywell ; James Bullock ; Jerry B. Tallowin ; Kevin John Walker ; Liz Warman ; Greg Masters Année de publication : 2007 Article en page(s) : 81-94 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Restauration des écosystèmes
[CBNPMP-Thématique] RevégétalisationMots-clés : Rhinanthus Résumé : 1 Many grasslands in north-west Europe are productive but species-poor communities resulting from intensive agriculture. Reducing the intensity of management under agri-environment schemes has often failed to increase botanical diversity. We investigated biotic and abiotic constraints on diversification by manipulating seed and microsite availability, soil fertility, resource competition, herbivory and deficiencies in the soil microbial community. 2 The effectiveness of 13 restoration treatments was investigated over 4 years in a randomized block experiment established in two productive grasslands in central-east and south-west England. 3 Severe disturbance involving turf removal followed by seed addition was the most effective and reliable means of increasing grassland diversity. Disturbance by multiple harrowing was moderately effective but was enhanced by molluscicide application to reduce seedling herbivory and by sowing the hemiparasite Rhinanthus to reduce competition from grasses. 4 Low-level disturbance by grazing or slot-seeding was ineffective in increasing diversity. Inoculation with soil microbial communities from species-rich grasslands had no effect on botanical diversity. Nitrogen and potassium fertilizer addition accelerated off-take of phosphorus in cut herbage but did not cause a reduction in soil phosphorus or increase botanical diversity. 5 Different grazing management regimes had little impact on diversity. This may reflect the constraining effect of the July hay cut on species dispersal and colonization. 6 Synthesis and applications. Three alternative approaches to grassland diversification, with different outcomes, are recommended. (i) High intervention deturfing, which would create patches with low competitive conditions for rapid and reliable establishment of the target community. For reasons of cost and practicality this can only be done over small areas but will form source populations for subsequent spread. (ii) Moderate intervention (harrowing or slot-seeding) over large areas, which would establish a limited number of desirable, generalist species that perform well in restoration. This method is low cost and rapid but the increases in biodiversity are less predictable. (iii) Phased restoration, which would complement the above approaches. Productivity and competition are reduced over 3–5 years using Rhinanthus or fertilizers to accelerate phosphorus off-take. After this time harrowing and seeding should allow a wide range of more specialist species to establish. However, further research is required to determine the long-term effectiveness of these approaches.
Lien pérenne : DOI : 10.1111/j.1365-2664.2006.01260.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=148809
in Journal of applied ecology > 44 (2007) . - 81-94Pywell, Richard F., Bullock, James, Tallowin, Jerry B., Walker, Kevin John, Warman, Liz, Masters, Greg 2007 Enhancing diversity of species-poor grasslands: an experimental assessment of multiple constraints. Journal of applied ecology, 44: 81-94.Documents numériques
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Titre : Plant diversity and land use under organic and conventional agriculture: a whole-farm approach Type de document : Imprimé Auteurs : Rachel H. Gibson ; S. Pearce ; R. J. Morris ; William O. C. Symondson ; Jane Memmott Année de publication : 2007 Article en page(s) : 792-803 Langues : Anglais (eng) Résumé : Organic 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. Here 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. Our 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. Organic 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. Semi-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. Synthesis 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.
Lien pérenne : DOI : 10.1111/j.1365-2664.2007.01292.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=148953
in Journal of applied ecology > 44 (2007) . - 792-803Gibson, Rachel H., Pearce, S., Morris, R. J., Symondson, William O. C., Memmott, Jane 2007 Plant diversity and land use under organic and conventional agriculture: a whole-farm approach. Journal of applied ecology, 44: 792-803.Documents numériques
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Titre : Comparing the efficacy of agri-environment schemes to enhance bumble bee abundance and diversity on arable field margins Type de document : Imprimé Auteurs : C. Carvell ; William R. Meek ; Richard F. Pywell ; Dave Goulson ; Marek Nowakowskic Année de publication : 2007 Article en page(s) : 29-40 Langues : Français (fre) Catégories : [CBNPMP-Thématique] Messicole Résumé : Declines in abundance and diversity of bumble bees (Bombus spp.) in Europe have been linked to agricultural intensification and the resulting loss of suitable foraging and nesting habitats. Environmental Stewardship (ES) is a new scheme in England offering the opportunity to restore habitats of value for these important pollinators to agricultural land. Scientific evaluation of the options prescribed within the scheme is essential to ensure that their objectives are met and that the benefits can be realized by the full bumble bee species assemblage. We compared the efficacy of different ES options for field margins on arable land in enhancing the abundance and diversity of flowering resources and foraging bumble bees. Our study was conducted over 3 years using a multisite experiment. Overall, uncropped margins sown with mixtures containing nectar and pollen-producing plants were more effective in providing bumble bee forage than margins sown with a grass mix, allowed to regenerate naturally or managed as conservation headlands. A mixture of agricultural legumes established quickly and attracted on average the highest total abundance and diversity of bumble bees, including the rare long-tongued species Bombus ruderatus and Bombus muscorum. However, marked differences were observed between species and sexes in their responses to field margin management over time. A diverse mixture of native wildflowers attracted more of the shorter-tongued Bombus spp. and provided greater continuity of forage resources, especially early in the season. Allowing Cirsium spp. to flower on such margins also increased their attractiveness to male bumble bees. Synthesis and applications. Our results suggest that the legume-based ‘pollen and nectar flower mix’, as prescribed under Entry Level Stewardship in England, can quickly provide a highly attractive forage resource for bumble bees, but that issues of seasonal flowering phenology and longevity of the mixture need to be addressed. Establishment of ‘floristically enhanced margins’ under Higher Level Stewardship will be important to provide diverse perennial communities of forage plants and to support a greater range of Bombus spp. and other pollinators. The population-level responses of bumble bees to introduced seed mixtures and other agri-environment options require further study in order to maximize the benefits of such schemes in intensively farmed landscapes.
Lien pérenne : DOI : 10.1111/j.1365-2664.2006.01249.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=149809
in Journal of applied ecology > 44 (2007) . - 29-40Carvell, C., Meek, William R., Pywell, Richard F., Goulson, Dave, Nowakowskic, Marek 2007 Comparing the efficacy of agri-environment schemes to enhance bumble bee abundance and diversity on arable field margins. Journal of applied ecology, 44: 29-40.Documents numériques
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