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Auteur Kevin John Walker |
Documents disponibles écrits par cet auteur (4)
Affiner la rechercheEnhancing 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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Article (2007)URL
Titre : No saturation in the accumulation of alien species worldwide Type de document : Électronique Auteurs : Hanno Seebens ; Tim M. Blackburn ; Ellie E. Dyer ; Piero Genovesi (1960-) ; Philip Eric Hulme ; Michael Jeschke ; Shyama Pagad ; Petr Pyšek ; Marten Winter ; Margarita Arianoutsou ; Sven Bacher ; Bernd Blasius ; Giuseppe Brundu ; César Capinha ; Laura Celesti-Grapow ; Wayne Dawson ; Stefan Dullinger ; Nicol Fuentes ; Heinke Jäger ; John Kartesz ; Marc Kenis ; Holger Kreft ; Ingolf Kühn ; Bernd Lenzner ; Andrew Liebhold ; Alexander Mosena ; Dietmar Moser ; Misako Nishino ; David A. Pearman (1943-) ; Jan Pergl (1977-) ; Wolfgang Rabitsch (1968-) ; Julissa Rojas-Sandoval ; Alain Roques (1951-) ; Sephanie L. Rorke ; Silvia Rossinelli ; Helen E. Roy ; Riccardo Scalera ; Stefan Schindler ; Kateřina Štajerová ; Barbara Tokarska-Guzik ; Mark van Kleunen (1973-) ; Kevin John Walker ; Patrick Weigelt ; Takehiko Yamanaka ; Franz Essl (1973-) Année de publication : 2017 Article en page(s) : 9 p. Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Plantes subspontanées, naturalisées, envahissantes Résumé : Although research on human-mediated exchanges of species has substantially intensified during the last centuries, we know surprisingly little about temporal dynamics of alien species accumulations across regions and taxa. Using a novel database of 45,813 first records of 16,926 established alien species, we show that the annual rate of first records worldwide has increased during the last 200 years, with 37% of all first records reported most recently (1970–2014). Inter-continental and inter-taxonomic variation can be largely attributed to the diaspora of European settlers in the nineteenth century and to the acceleration in trade in the twentieth century. For all taxonomic groups, the increase in numbers of alien species does not show any sign of saturation and most taxa even show increases in the rate of first records over time. This highlights that past efforts to mitigate invasions have not been effective enough to keep up with increasing globalization. Lien pérenne : DOI : 10.1038/ncomms14435 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=143199
in Nature communications > 8 (2017) . - 9 p.Seebens, Hanno, Blackburn, Tim M., Dyer, Ellie E., Genovesi, Piero (1960-), Hulme, Philip Eric, Jeschke, Michael, Pagad, Shyama, Pyšek, Petr, Winter, Marten, Arianoutsou, Margarita, Bacher, Sven, Blasius, Bernd, Brundu, Giuseppe, Capinha, César, Celesti-Grapow, Laura, Dawson, Wayne, Dullinger, Stefan, Fuentes, Nicol, Jäger, Heinke, Kartesz, John, Kenis, Marc, Kreft, Holger, Kühn, Ingolf, Lenzner, Bernd, Liebhold, Andrew, Mosena, Alexander, Moser, Dietmar, Nishino, Misako, Pearman, David A. (1943-), Pergl, Jan (1977-), Rabitsch, Wolfgang (1968-), Rojas-Sandoval, Julissa, Roques, Alain (1951-), Rorke, Sephanie L., Rossinelli, Silvia, Roy, Helen E., Scalera, Riccardo, Schindler, Stefan, Štajerová, Kateřina, Tokarska-Guzik, Barbara, Kleunen, Mark van (1973-), Walker, Kevin John, Weigelt, Patrick, Yamanaka, Takehiko, Essl, Franz (1973-) 2017 No saturation in the accumulation of alien species worldwide. Nature communications, 8: 9 p..Documents numériques
Article (2017)URLNon-native species in Great Britain : establishment, detection and reporting to inform effective decision making / Helen E. Roy (2012)
Titre : Non-native species in Great Britain : establishment, detection and reporting to inform effective decision making Type de document : Électronique Auteurs : Helen E. Roy ; Jim Bacon ; Bjorn Beckmann ; Colin A. Harrower ; Mark O. Hill (1945-) ; Nick J. B. Isaac ; Christopher David Preston (1955-) ; Biren Rathod ; Sephanie L. Rorke ; John H. Marchant ; Andy Musgrove ; David Noble ; Jack Sewell ; Becky Seeley ; Natalie Sweet ; Léoni Adams ; John D. D. Bishop ; Alison R. Jukes ; Kevin John Walker ; David A. Pearman (1943-) Editeur : Botanical Society of Britain and Ireland, British Trust for Ornithology Année de publication : 2012 Importance : 110 p. Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Plantes subspontanées, naturalisées, envahissantes Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=82537 Roy, Helen E., Bacon, Jim, Beckmann, Bjorn, Harrower, Colin A., Hill, Mark O. (1945-), Isaac, Nick J. B., Preston, Christopher David (1955-), Rathod, Biren, Rorke, Sephanie L., Marchant, John H., Musgrove, Andy, Noble, David, Sewell, Jack, Seeley, Becky, Sweet, Natalie, Adams, Léoni, Bishop, John D. D., Jukes, Alison R., Walker, Kevin John, Pearman, David A. (1943-) , 2012. Non-native species in Great Britain : establishment, detection and reporting to inform effective decision making. Botanical Society of Britain and Ireland, British Trust for Ornithology, [S.l.]. 110 pp.Documents numériques
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Rapport (2012)Adobe Acrobat PDF
Titre : Plant traits as predictors of performance in ecological restoration Type de document : Imprimé Auteurs : Richard F. Pywell ; James Bullock ; David Roy ; Liz Warman ; Kevin John Walker ; Peter Rothery Année de publication : 2003 Article en page(s) : 65-77 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Restauration des écosystèmes
[CBNPMP-Thématique] RevégétalisationRésumé : 1 There are few studies of the performance of species in restored vegetation communities. Here we report the results of a meta-analysis of 25 experiments concerned with species-rich grassland restoration on ex-arable land and agriculturally improved grasslands situated at a wide range of locations throughout lowland Britain. Differences in species’ performance were related to 38 physiological and morphological traits. 2 An experiment-adjusted performance index was calculated for each of the 58 species (13 grasses and 45 forbs). The performance index was calculated for the first 4 years after establishment together with a temporal trend. 3 Individual species showed large differences in performance indices. However, grasses consistently out-performed forbs. 4 We examined the linkage between species’ performance and traits according to four non-exclusive hypotheses. The ability to establish and persist in restored vegetation communities requires: (H1) good gap colonization ability; (H2) strong competitive capability; and (H3) ability to undergo vegetative regeneration. (H4) Successful species are generalists associated with fertile habitats. 5 Trait analyses supported all four hypotheses. Within the forbs, good establishment in the first year was linked to traits determining colonization ability: ruderality, percentage germination of seeds and autumn germination. However, traits linked to competitive ability, vegetative growth and seed bank persistence became increasingly important determinants of success with time. Species with generalist habitat requirements, and especially those associated with fertile soils, performed increasingly well with time. This reflects the development of a closed vegetation in which the ability to grow vigorously and out-compete other established plants is important. 6 Stress-tolerators, habitat specialists and species of infertile habitats performed badly. This may reflect high residual fertility in restored grasslands and particular niche requirements of these species. This may be a problem as grassland restoration often targets communities characterized by species with these traits and many are food plants of invertebrates of conservation value. 7 There were few significant correlations between the performance of the grasses and traits reflecting their overall good performance in comparison with the forbs. 8 This study has important implications for practical restoration programmes and policies. Efficiency might be increased by introducing only species with good performance, but this would lead to uniformity among restored grasslands and would diminish the benefits of habitat restoration for national and regional biodiversity. 9 Synthesis and applications. Future work should focus on practical methods to increase the successful establishment of the poor performing but desirable species, by (i) targeting restoration to low fertility soils, (ii) changing the abiotic environment or (iii) the ‘phased introduction’ of species several years after restoration, when both the plant community is more stable and the environmental conditions are more favourable for establishment. Note de contenu :
Lien pérenne : DOI : 10.1046/j.1365-2664.2003.00762.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=148808
in Journal of applied ecology > 40 [01/01/2003] . - 65-77Pywell, Richard F., Bullock, James, Roy, David, Warman, Liz, Walker, Kevin John, Rothery, Peter 2003 Plant traits as predictors of performance in ecological restoration. Journal of applied ecology, 40: 65-77.Documents numériques
Article (2003)URL
