The urban Influence on diversity of avifauna in the Edwards Plateau ecoregion and surrounding area was studied using spatial analysis. Indices and metrics of urban influence, ownership property sizes, landscape structure, and avian diversity were calculated for 31 North American Breeding Bird Survey (BBS) transects, 12 located within the Edwards Plateau ecoregion and 18 in contiguous ecoregions. Spatial correlations were calculated between each pair of these indices. The spatial analysis identified an emergent property at the landscape level: A “threshold of habitat fragmentation” at an ownership property size of 500 acres, which is reached when urban influence increases to an intermediate level. Highly significant spatial correlations among variables showed that property sizes lower than 500 acres produce habitat fragmentation represented by a decrease in mean patch size (MN) and proximity among habitat patches (Index PROX). Consequently, avian α-diversity (richness) decreases because both MN and Index PROX are landscape metrics related to availability of suitable habitat for avian populations. The spatial analysis also made possible the prioritization of ecological subregions of the Edwards Plateau for conservation or restoration with respect to the threshold of habitat fragmentation and avian α and β-diversity. Balcones Canyon Lands showed a high percentage of land covered by farms smaller than 500 acres (64%), an ownership property average size above the threshold of fragmentation (1440 acres) and the highest avian α- diversity; so, management policies should focus on habitat conservation. In contrast, Lampasas Cut Plains showed the highest percentage of land covered by farms smaller than 500 acres (71%), and ownership property average size was very close to the threshold of fragmentation (625 acres); there, urban bird species are dominant and avian α-diversity is low because of the loss of native bird species. Management in this ecoregion should focus on habitat restoration. Finally, the Live Oak-Mesquite Savannah subregion showed the highest average ownership property size (7305 acres), and the highest values of patch richness and β-diversity. Management in this ecoregion should focus on conservation of land mosaic diversity to assure native avian species turnover.

Cette thèse se situe dans le prolongement direct des travaux de recherche de l'« Observatoire de l'école rurale », dont l'auteur est membre depuis 2002, qui a étudié la scolarité de près de 2400 élèves du rural français depuis l'année 1999/2000 correspondant à la classe de CM2 pour tous jusqu'à l'année 2006/ 2007 correspondant à la classe de terminale pour ceux qui n'ont jamais pris de retard. Elle aborde une thématique jusque là peu traitée par les membres de l'OER : une approche croisant genre et typologie des territoires au niveau des trajectoires scolaires des jeunes ruraux. L'objectif est de déterminer s'il existe des « effets de territoire » qui impactent de façon distincte la scolarité des filles et celle des garçons et de mesurer leur incidence sur celle-ci. Pour y parvenir, deux types de milieux ruraux ont été étudiés : le « rural isolé » et le « rural sous faible influence urbaine ». L'étude s'est appuyée sur six variables de la scolarité des élèves ruraux : les résultats scolaires ; le goût pour les études ; les ambitions scolaires ; l'opinion des élèves sur leur propre niveau scolaire ; les pratiques culturelles ; le potentiel de mobilité. Cette recherche a l'ambition d'ouvrir de nouvelles pistes de recherches prenant en compte l'évolution d'un milieu en perpétuelle mutation et l'espoir de contribuer à nourrir les débats éducatifs autour de « l'école rurale » au sens générique du terme. / This thesis is situated in the direct continuation of the research works of the Monitoring Observatory of the rural school the author of which is member and which studied the schooling of about 2400 pupils of the French countryman for the year 1999/2000 corresponding to the 5th year of primary school for all until year 2006/2007 corresponding to the final year of high school for those who have never taken delay. It approaches a theme to there little treated by the members of the OER: an approach by kind(genre) and typology of the school trajectories of the young countrymen. The objective to determine if there are « effects of territory «which impact in a different way on the schooling of the girls and on that of the boys and to measure their incidence on this one. To reach there, two types of rural circles were studied: the isolated countryman and the countryman under low urban influence and the study leaned on six variables of the schooling of the rural pupils: The school results; the motivation for the studies; the school ambitions; the opinion of the pupils on their own school level; the cultural practices; the potential of mobility. This research has also the ambition to open new avenues of research in connection with the evolution of an environment in perpetual transformation and the hope to contribute to feed the educational debates around «the rural school" in the generic sense of the term.