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Full-Text Articles in Biology

Conflicting Hydraulic Effects Of Xylem Pit Structure Relate To The Growth-Longevity Tradeoff In A Conifer Species, Beth Roskilly Jan 2018

Conflicting Hydraulic Effects Of Xylem Pit Structure Relate To The Growth-Longevity Tradeoff In A Conifer Species, Beth Roskilly

Graduate Student Theses, Dissertations, & Professional Papers

Consistent with a ubiquitous life history tradeoff, trees exhibit a negative relationship between growth and longevity among and within species. However, the mechanistic basis of this life history tradeoff is not well understood. In addition to tradeoffs among multiple traits based on resource allocation conflicts, life history tradeoffs may arise from tradeoffs based on single traits under opposing selection. While a myriad of factors likely contribute to the growth-longevity tradeoff in trees, we hypothesized that conflicting functional effects of xylem structural traits contribute to the growth-longevity tradeoff. We tested this hypothesis by examining the extent to which xylem morphological traits …


Molecular Diversity Of Foliar Fungal Endophytes In Relation To Defense Strategies And Disease In Whitebark Pine, Lorinda Bullington Jan 2017

Molecular Diversity Of Foliar Fungal Endophytes In Relation To Defense Strategies And Disease In Whitebark Pine, Lorinda Bullington

Graduate Student Theses, Dissertations, & Professional Papers

An invasive fungal pathogen, Cronartium ribicola (the causative agent of white pine blister rust) infects and kills whitebark pine (Pinus albicaulis) throughout the western US. Blister rust has decreased whitebark pine populations by over 90% in some areas. Whitebark pine, a keystone species, has been proposed for listing under the Endangered Species Act in the U.S., and the loss of this conifer is predicted to have severe impacts on forest composition and function in high elevations. Hundreds of asymptomatic fungal species live inside whitebark pine tissue, and recent studies suggest that these fungi can influence the frequency and …


Examining Historical And Current Mixed-Severity Fire Regimes In Ponderosa Pine And Mixed-Conifer Forests Of Western North America, Dennis C. Odion, Chad T. Hanson, Andre Arsenault, William L. Baker, Dominick A. Dellasala, Richard L. Hutto, Walt Klenner, Max A. Moritz, Rosemary L. Sherriff, Thomas T. Veblen, Mark A. Williams Feb 2014

Examining Historical And Current Mixed-Severity Fire Regimes In Ponderosa Pine And Mixed-Conifer Forests Of Western North America, Dennis C. Odion, Chad T. Hanson, Andre Arsenault, William L. Baker, Dominick A. Dellasala, Richard L. Hutto, Walt Klenner, Max A. Moritz, Rosemary L. Sherriff, Thomas T. Veblen, Mark A. Williams

Biological Sciences Faculty Publications

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of …


Invasive Plant Erodes Local Song Diversity In A Migratory Passerine, Yvette K. Ortega, Aubree Benson, Erick Greene Feb 2014

Invasive Plant Erodes Local Song Diversity In A Migratory Passerine, Yvette K. Ortega, Aubree Benson, Erick Greene

Biological Sciences Faculty Publications

Exotic plant invasions threaten ecosystems globally, but we still know little about the specific consequences for animals. Invasive plants can alter the quality of breeding habitat for songbirds, thereby impacting important demographic traits such as dispersal, philopatry, and age structure. These demographic effects may in turn alter song-learning conditions to affect song structure and diversity. We studied Chipping Sparrows (Spizella passerina) breeding in six savannas that were either dominated by native vegetation or invaded by spotted knapweed (Centaurea stoebe), an exotic forb known to diminish food resources and reproductive success. Here, we report that the prevalence of older birds was …