Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Master → Etats Unis → 2021 → Species Distribution Modeling of Desert Bighorn Sheep in the San Andres Mountains, New Mexico, U.S.A. : The Role of Piñon-Juniper Cover and Other Environmental Variables

New Mexico State University (2021)

Species Distribution Modeling of Desert Bighorn Sheep in the San Andres Mountains, New Mexico, U.S.A. : The Role of Piñon-Juniper Cover and Other Environmental Variables

Lopez-Brody, Nathan

Titre : Species Distribution Modeling of Desert Bighorn Sheep in the San Andres Mountains, New Mexico, U.S.A. : The Role of Piñon-Juniper Cover and Other Environmental Variables

Auteur : Lopez-Brody, Nathan

Université de soutenance : New Mexico State University

Grade : Master of Applied Geography (2021)

Résumé
As an area where desert bighorn sheep (Ovis canadensis mexicana) existed historically and have been successfully reintroduced, the San Andres National Wildlife Refuge in New Mexico is important for the conservation of this species. However, Refuge managers believe that the habitat of sheep has been negatively impacted by the encroachment of piñon (Pinus edulis) and juniper (Juniperus monosperma) trees in recent decades, as these trees can obstruct visibility. A quantitative understanding of the relationships between piñon-juniper population dynamics and bighorn sheep habitat is crucial for making sensible refuge management decisions. We aimed at creating this understanding by a) mapping piñon-juniper cover dynamics in the Refuge and b) modeling bighorn sheep habitat with piñon-juniper cover and other explanatory variables. To map changes in piñon-juniper cover, we applied multiple endmember spectral mixture analysis to Landsat 5 Thematic Mapper satellite imagery from 1985 and 2010. To model bighorn sheep habitat in 1985 and 2010, we used logistic regression with bighorn sheep radio collar locations, the piñon-juniper cover data, and various other explanatory data layers (e.g., slope and ruggedness). This study confirms that piñon-juniper cover has increased in the Refuge between 1985 and 2010 and suggests that this expansion in piñon-juniper cover has reduced the quantity of bighorn sheep habitat in the San Andres Mountains. Bighorn sheep appeared to avoid previously available habitat where piñon-juniper cover has expanded into steep rocky areas. Management efforts aimed at maintaining or reducing piñon-juniper cover may thus be effective at improving habitat for bighorn sheep.

Présentation

Aperçu du document (ProQuest)

Page publiée le 5 décembre 2021