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Oregon State University (2008)

Mapping mortality following a long-term drought in a pinyon-juniper ecosystem in Arizona and New Mexico using Landsat data

Kirschbaum, Alan A.

Titre : Mapping mortality following a long-term drought in a pinyon-juniper ecosystem in Arizona and New Mexico using Landsat data

Auteur : Kirschbaum, Alan A.

Université de soutenance : Oregon State University

Grade : Master of Science in Forest Science 2008

Résumé
Protracted drought in the southwest U.S. has had significant impacts on the region’s keystone ecosystem, the pinyon-juniper (PJ) woodlands. Drought conditions in 9 of the last 10 years, exacerbated by extreme drought in one year, stressed the pinyon pine (Pinus edulis) trees, making them highly vulnerable to native ips beetles (Ips confusus). Current global climate predictions include further increases in temperatures and more extreme climatic events such as drought which will likely cause even more large-scale disturbances such as shifts in ecotones and increased insect outbreaks. This study investigated the utility of the Landsat satellite sensor for predicting percent dead tree cover in the PJ ecosystem in Arizona and New Mexico by relating field measurements of percent tree cover with Landsat spectral data. Direct change modeling and state model differencing (Healey et al. 2006)were compared in the two study areas in terms of RMSE for predicting percent dead cover. Direct change modeling outperformed state model differencing in both AZ and NM, with RMSEs of 4.2% and 7.3%, respectively. Landscape patterns were investigated in maps of dead cover made from the models. Consistent with expectations of the mechanism of the mortality, percent mortality on southwest aspects was higher than on northeast aspects. Percent dead cover model predictions were also validated with an independent data source (Forest Health Monitoring overflight data) in AZ and NM with overall agreement of 80 and 76%, respectively.

Mots-clés : pinyon ; Landsat ; mortality ; drought ; Arizona ; New Mexico

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Page publiée le 9 mai 2011, mise à jour le 7 mars 2019