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Clinal variation along precipitation gradients in Patagonian temperate forests: unravelling demographic and selection signatures in three Nothofagus spp. / Carolina Soliani in Annals of Forest Science, Vol 77 n° 1 (March 2020)  

Public [article]  inAnnals of Forest Science > Vol 77 n° 1 (March 2020) . - 17 p. Titre : Clinal variation along precipitation gradients in Patagonian temperate forests: unravelling demographic and selection signatures in three Nothofagus spp. Type de document : Article/Communication Auteurs : Carolina Soliani, Auteur ; Maria Marta Azpilicueta, Auteur ; Maria Veronica Arana, Auteur ; Paula Marchelli, Auteur Année de publication : 2020 Article en page(s) : 17 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse diachronique [Termes IGN] forêt tempérée [Termes IGN] génétique forestière [Termes IGN] Nothofagus (genre) [Termes IGN] nothofagus pumilio [Termes IGN] Patagonie [Termes IGN] Pléistocène [Termes IGN] précipitation [Termes IGN] prévision [Termes IGN] sécheresse [Termes IGN] stress hydrique [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) Key message: Past demographic changes and current selection pressures determine the genetic variation displayed by Nothofagus species along rainfall gradients. Based on the diversity trends observed at candidate genes associated to drought stress, we inferred a differential species’ adaptive potential. Context: Clinal genetic variation in natural populations could reflect either recent demographic history or the evolution of adapted genotypes along heterogeneous environments. Aims: We describe genetic variation patterns in three Nothofagus species of South American temperate forests, growing along steep rainfall gradients. Our hypothesis is that the selection pressure along this gradient reinforces the genetic structure previously shaped by Pleistocene climate oscillations. Methods: We screened variation along gradients at putative adaptive markers: candidate genes involved in response to drought, and EST-SSRs linked to drought stress genes. Genomic SSRs (gSSRs) were used to decouple the incidence of demographic events in the genetic structure. Results: Genetic diversity at SSRs agreed with the putative location of cryptic Pleistocene refugia in Nothofagus. In addition, each species showed different trends for nucleotide diversity at candidate genes. Unbiased heterozygosity significantly correlated with precipitation at EST-SSRs in Nothofagus nervosa. We found evidences of balancing selection and several SNPs departed from neutral expectations. Conclusions: Nothofagus genetic variability shows a strong imprint of demographic changes that reveals refugia location for the species during Pleistocene. This variability is modelled by environmental conditions across natural gradients, which impose selection pressure at genome regions related to stress response, providing clues about inter-specific differences in adaptive potential to water deficit. Numéro de notice : A2020-032 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-019-0908-x Date de publication en ligne : 10/01/2020 En ligne : https://doi.org/10.1007/s13595-019-0908-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94489 [article]

Determining forest degradation, ecosystem state and resilience using a standard stand stocking measurement diagram: theory into practice / Carlos Bahamondez in Forestry, an international journal of forest research, vol 89 n° 3 (July 2016)  

Public [article]  inForestry, an international journal of forest research > vol 89 n° 3 (July 2016) . - pp 290 - 300 Titre : Determining forest degradation, ecosystem state and resilience using a standard stand stocking measurement diagram: theory into practice Type de document : Article/Communication Auteurs : Carlos Bahamondez, Auteur ; Ian D. Thompson, Auteur Année de publication : 2016 Article en page(s) : pp 290 - 300 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Chili [Termes IGN] dégradation de la flore [Termes IGN] écosystème forestier [Termes IGN] forêt de production [Termes IGN] Nothofagus (genre) [Termes IGN] productivité [Vedettes matières IGN] Ecologie forestière Résumé : (auteur) Forest degradation is a major issue for policy-makers that is exacerbated by no clear and globally accepted definition of the term. For forest managers, a loss of forest productive capacity is one form of forest degradation. We present a quantitative method to assess forest degradation from a productivity perspective. Our method uses a standard stocking chart and calculation methods based on standard forest inventory data, to derive a clear threshold value for stocking, below which a forest should be considered degraded. The method is illustrated using the example of a self-regenerating Nothofagus production forest type from Chile. For that forest type, we determined that harvesting trees to below a specific basal area relative to site type, resulted in a loss of resilience, an unpredictable shift in ecosystem state, and a degraded condition. Our method illustrates how over-harvesting can degrade the long-term productivity of a stand and forest resilience. Nevertheless, it is important to consider that forests can also be degraded from other perspectives, such as loss of biodiversity, carbon, or protective functions as a result of excessive disturbances. Ecosystem management requires that managers consider degradation from a range of perspectives. We see the quantified approach used here as a way to provide practitioners with, in part, a transition from sustained yield to ecosystem management with an ultimate objective of providing a pathway towards adaptive management of complex systems and avoiding degradation. Numéro de notice : A2016--136 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1093/forestry/cpv052 Date de publication en ligne : 12/01/2016 En ligne : https://doi.org/10.1093/forestry/cpv052 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85779 [article]