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Universidad de Buenos Aires (2008)

Efectos de la fragmentación del bosque de caldén sobre las comunidades de aves en el centro-este de La Pampa

Sosa, Ramón Alberto

Titre : Efectos de la fragmentación del bosque de caldén sobre las comunidades de aves en el centro-este de La Pampa

Effects of caldenal forest fragmentation on birds assemblage in central-eastern of La Pampa

Auteur : Sosa, Ramón Alberto

Université de soutenance : Universidad de Buenos Aires

Grade : Doctor de la Universidad de Buenos Aires en el área de Ciencias Biológicas 2008

Résumé
The study of the bird assemblage organization in the fragmented calden forest was carried out at La Primavera Ranch, located in central-eastern La Pampa province between August 2000 and February 2005. The general objectives of this study were : 1) to analyze the changes in the bird assemblage after forest fragmentation ; 2) to determine the edge effects in their abiotic and biotic aspects. With this purpose in mind, six calden fragments of mature forest sizing 2.1, 10.4, 13.6 ; 26.3 ; 27.9 ; and 117.6 ha were studied. First, the study area was described and the possible causes of the caldenal fragmentation were analyzed. Second, the specific riches and abundance of birds were evaluated as a function of the fragments size and the vegetation structure. The bird assemblage showed seasonal changes, due to the ocurrence of summer migratory species. The density and species riches were affected by the fragments size. On the other hand the vegetation structure was an important factor influencing species distribution in forest fragments. The microenvironmental changes, bird assemblage and artificial nest predation were the edge effects considered. The microenvironmental changes included the air and the soil temperatures, the air and the litter humidity, the photosyntetic active radiation and the rain, variables which changed according to the distance from the edge. No edge effects were found on the bird assemblage. The artificial nests experiment showed a stronger edge effect only for the ground nests, while those placed on trees had nearly 100% predation. The obtained results suggest that birds inhabiting the caldenal would be more affected by microenvironmental variables, vegetation structure and nests predation. However, indirect biological effects caused by the microenvironmental changes, brood parasitism and natural nests predation, need to be evaluated in future studies.

Mots clés : ENSAMBLES DE AVES ; FRAGMENTACION ; ECOLOGIA DE COMUNIDADES ; ESPINAL DISTRITO DEL CALDENAL ; EFECTO DE BORDE ; MICROAMBIENTE ; NIDOS ARTIFICIALES ; BIRDS ASSEMBLAGE ; FOREST FRAGMENTATION ; COMMUNITY ECOLOGY ; SPINAL DISTRICT OF THE CALDENAL ; EDGE EFFECT ; MICROENVIRONMENTAL ANALYSIS ; ARTIFICIAL NESTS

Présentation (Biblioteca Digital)

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