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Ajouter le résultat dans votre panierTrait interactions help explain plant invasion in the German flora / Eva C Küster in Journal of ecology, 96 (2008)
Titre : Trait interactions help explain plant invasion in the German flora Type de document : Numérique Auteurs : Eva C Küster ; Ingolf Kühn ; Helge Bruelheide ; Stefan Klotz Année de publication : 2008 Article en page(s) : 860-868 Langues : Anglais (eng) Catégories : [CBNPMP-Géographique] Allemagne
[CBNPMP-Thématique] Plantes subspontanées, naturalisées, envahissantesIdentifiant : DOI : 10.1111/j.1365-2745.2008.01406.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=141869
in Journal of ecology > 96 (2008) . - 860-868Küster, Eva C, Kühn, Ingolf, Bruelheide, Helge, Klotz, Stefan 2008 Trait interactions help explain plant invasion in the German flora. Journal of ecology, 96: 860-868.Documents numériques
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Titre : Regional tree line dynamics in response to global change in the Pyrenees Type de document : Imprimé Auteurs : Enric Batllori ; Emilia Gutiérrez Année de publication : 2008 Article en page(s) : 1275-1288 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Dendrométrie (mesure le diamètre des arbres)
[CBNPMP-Thématique] Changement climatique
[CBNPMP-Géographique] PyrénéesMots-clés : Pinus uncinata Note de contenu : 1 Many studies in northern Europe, North and South America, describe regional trends of population densification at altitudinal and polar tree lines during the 20th century. The purpose of this study was (1) to ascertain if this regeneration enhancement is present across the alpine ecotones of the Pyrenees, (2) if synchronous recruitment trends are common among the studied populations and (3) to determine the tree limit stability during recent decades.
2 Twelve Pinus uncinata tree line populations were studied on the Iberian eastern range of the Pyrenees. Rectangular plots ranging from 940 to 7600 m2 were set along the forest-alpine grassland transition; more than 3600 P. uncinata individuals were mapped. Tree size and age were used to establish the demographic structure at each stand, and to characterize abrupt or smooth transition patterns along the tree line ecotone. A new procedure for estimating missing rings in off-centre cores was developed to ensure a correct interval for the age-classes distribution analysis.
3 Past and recent synchronous recruitment trends (mid 19th century, second half of the 20th century) were apparent at the tree line over the studied area of the Pyrenean range. The ecotone densification since the 1950s occurred in the context of climatic warming and substantial land use abandonment. Both gradual and step-like transition patterns in tree age and size along the ecotone were observed.
4 Regeneration enhancement in the last approximately 30 years appears as an abrupt change in population age structures, which could indicate the importance of feedback mechanisms for tree line recruitment dynamics. In 50% of the surveyed tree lines ecotone densification has been coupled to tree limit shifts in the recent past. This indicates both great tree limit sensitivity to short-term climatic changes and the presence of differential tree line dynamics at a regional scale.
5 Synthesis. The observed past and recent synchronous recruitment trends suggest the presence of regional climatic factors modulating tree line structure and dynamics. However, tree line dynamics in the Pyrenees have been widely affected by local anthropogenic activities. We suggest that the presence of step-like tree line transitions in tree age can be considered an evidence of recent human-induced disturbances when no other major natural disturbances affect the tree line dynamics.
Identifiant : DOI : 10.1111/j.1365-2745.2008.01429.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=148045
in Journal of ecology > 96 (2008) . - 1275-1288Batllori, Enric, Gutiérrez, Emilia 2008 Regional tree line dynamics in response to global change in the Pyrenees. Journal of ecology, 96: 1275-1288.Documents numériques
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Titre : Neighbourhood analyses of the allelopathic effects of the invasive tree Ailanthus altissima in temperate forests Type de document : Imprimé Auteurs : Lorena Gómez-Aparicio Année de publication : 2008 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Plantes subspontanées, naturalisées, envahissantes Mots-clés : Ailanthus altissima (Mill.) Swingle Résumé : 1 Allelopathic interactions between invasive and native species have been suggested to be an important mechanism for the success of some of the most aggressive plant invaders. However, field experiments that test the effects of natural levels of allelopathic compounds on coexisting native species are exceptionally rare.
2 In this study, we analyzed the allelopathic effects of the invasive tree Ailanthus altissima on seedling emergence, survival and growth of three native tree species (Acer rubrum, A. saccharum and Quercus rubra) in temperate forests of the northeastern United States. We used activated carbon (AC) to reduce potential allelopathic interference, and developed neighbourhood models that explain the observed spatial variation in the effects of the AC treatments on seedling performance as a function of the size, abundance and distribution of Ailanthus trees in the neighbourhood.
3 Our results showed that the addition of AC to the soil did not affect seedling emergence or survival, but caused a significant increase in seedling growth of all three species. Moreover, the AC shifted the overall interaction between Ailanthus and maple seedlings from neutral or slightly positive to very positive for A. rubrum, and from negative to positive for A. saccharum, whereas the net interaction between Ailanthus and Q. rubra was always negative. As Ailanthus has the ability to increase soil fertility, these species-specific responses are presumably influenced by among-species differences in the net effects of both allelopathy and changes in resource availability caused by the presence of Ailanthus.
4 The cumulative allelopathic effects of Ailanthus were proportional to the density of Ailanthus in the neighbourhood, regardless of their size. In contrast, Ailanthus effects were strongly influenced by distance from a tree, generally dropping to zero within 5 m from the trunk.
5 Synthesis. Taken together, our results indicate that allelopathy is an important mechanism to take into account when trying to understand the causes and consequences of plant invasions. However, this study also strongly suggests that the real significance of the allelopathic effects of an invasive species cannot be assessed independently of its target community, or in isolation of other resource interactions involving the invader and the native community.Identifiant : DOI : 10.1111/j.1365-2745.2007.01352.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=155362
in Journal of ecology > 96 (2008)Gómez-Aparicio, Lorena 2008 Neighbourhood analyses of the allelopathic effects of the invasive tree Ailanthus altissima in temperate forests. Journal of ecology, 96.Documents numériques
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