Éditeur(s) : HAL CCSD
Résumé :  
The spatial genetic differentiation among European beech stands in western Germany was analysed by a new method. The genetic structure at 8 enzyme gene loci of 100 sampled populations was used as data base. The data represent authors' own results and published data from 8 different studies. For 10 geographic distance classes [h] from 0 to 500 km, the average genetic distance between the populations for each single gene locus, a gene-pool distance and the semivariances of genetic diversity gam were computed. Significant deviation from random spatial genetic structure was tested by permutation analysis. In many cases (Lap-B, Mdh-B, Mdh-C and 6Pgdh-C) the mean genetic distance between stands with spatial distance up to 200 km was significantly smaller and the genetic distance between stands with geographic distances of 200 and 400 km was significantly greater than expected for random spatial genetic structure. Similar tendencies were found for the gene-pool distance and the semivariances of diversity. Kriging, as a method for spatial interpolation, was used to draw synthetic maps of the spatial patterns of allelic frequencies and genetic diversity. The influence of postglacial recolonisation and regeneration with foreign seed material on the spatial genetic patterns are discussed
Forest genetics

hal-01032093
https://hal.archives-ouvertes.fr/hal-01032093

Éditeur(s) : HAL CCSD
Résumé : International audience
Here, we synthesize conceptual frameworks, applied modeling approaches, and as case studies to highlight complex social-ecological system (SES) dynamics that inform environmental policy, conservation and management. Although a set of “good practices” about what constitutes a good SES study are emerging, there is still a disconnection between generating SES scientific studies and providing decision-relevant information to policy makers. Classical single variable/hypothesis studies rooted in one or two disciplines are still most common, leading to incremental growth in knowledge about the natural or social system, but rarely both. The recognition of human dimensions is a key aspect of successful planning and implementation in natural resource management, ecosystem-based management, fisheries management, and marine conservation. The lack of social data relating to human-nature interactions in this particular context is now seen as an omission, which can often erode the efficacy of any resource management or conservation action. There have been repeated calls for a transdisciplinary approach to complex SESs that incorporates resilience, complexity science characterized by intricate feedback interactions, emergent processes, non-linear dynamics and uncertainty. To achieve this vision, we need to embrace diverse research methodologies that incorporate ecology, sociology, anthropology, political science, economics and other disciplines that are anchored in empirical data. We conclude that to make SES research most useful in adding practical value to conservation planning, marine resource management planning processes and implementation, and the integration of resilience thinking into adaptation strategies, more research is needed on (1) understanding social-ecological landscapes and seascapes and patterns that would ensure planning process legitimacy, (2) costs of transformation (financial, social, environmental) to a stable resilient social-ecological system, (3) overcoming place-based data collection challenges as well as modeling challenges.
Ocean and Coastal Management

Droits : http://creativecommons.org/licenses/by-nc-nd/
hal-01224152
https://hal-univ-perp.archives-ouvertes.fr/hal-01224152
https://hal-univ-perp.archives-ouvertes.fr/hal-01224152/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01224152/file/1-s2.0-S096456911500126X-main.pdf
DOI : 10.1016/j.ocecoaman.2015.04.018

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Tarim and Junggar basins in central Asia are capped by a thick pile of conglomerates, called the Xiyu Formation, that are commonly linked to a change in climate and/or accelerated uplift near the Plio-Pleistocene boundary. In order to better understand their origin and significance, we carried out a combined structural and magnetostratigraphic study in the Quilitage syncline (southern Tianshan), where the base of the Xiyu conglomerates is observed at both sides of the syncline. A balanced cross-section shows that, even at a local-scale, the base of the Xiyu conglomerates cannot be regarded as a single continuous stratigraphic layer. On the southern flank of the Quilitage syncline, we collected 172 samples collected for magnetostratigraphic dating identify 17 polarity chrons that date the new section from 5.2 to ~ 1.7 Ma and constrain the base of the Xiyu conglomerate here at ~ 1.7 Ma. This is 4.2 Ma younger than the age of the Xiyu previously found on the northern limb of the same syncline. Together with other magnetostratigraphic studies carried out around the Tianshan, our study unambiguously demonstrates that the onset of deposition of the Xiyu conglomerates is diachronous, and that the conglomerates are systematically younger toward the basin. Consequently, the Xiyu Formation should not be considered as a chronostratigraphic marker related to any particular tectonic or climatic event, but is instead a prograding gravel wedge that has prograded over the underthrusting forelands. A synthesis of chronologic and structural results yields progradation rates over the last 10 Ma on the order of ~ 2.0 mm/yr and ~ 3.9 mm/yr south and north of the Tianshan Mountains respectively. These rates are comparable to the shortening rate across the Tianshan range, suggesting that underthrusting is the main factor governing the progradation rate of the Xiyu Formation.
ISSN: 0012-821X

insu-00414151
https://hal-insu.archives-ouvertes.fr/insu-00414151
https://hal-insu.archives-ouvertes.fr/insu-00414151/document
https://hal-insu.archives-ouvertes.fr/insu-00414151/file/Charreau-EPSL-2009.pdf
DOI : 10.1016/j.epsl.2009.07.035