This report analyzes urban tree canopy cover (UTC) in Austin, Texas in 2006 using a Geographic Information System (GIS) geoprocessing method developed by the U.S. Forest Service. Findings reveal where UTC exists, could exist, and where it could be prioritized (physically speaking) throughout the Austin region. Results are explained through the context of natural regions and land use to further characterize the urban forest distribution with the purpose of gaining valuable big-picture insights as to where environmental benefits have resulted from local land use planning decisions, development tendencies, and forestry management practices in Austin. / text

No description available.

Variation in snow albedo feedback (SAF) among CMIP5 climate models has been shown to explain much of the variation in projected 21st Century warming over Northern Hemisphere land. Prior studies using observations and models have demonstrated both considerable spread in the albedo, and a weak bias in the simulated strength of SAF, over snow-covered boreal forests. Boreal evergreen needleleaf forests are capable of intercepting snowfall throughout the snow season, which has a significant impact on seasonal albedo. Two satellite data products and tower-based observations of albedo are compared with simulations from multiple configurations of the Community Climate System Model (CCSM4) to investigate the causes of weak simulated SAF over the boreal forest. The largest bias occurs in April-May when simulated SAF is one-half the strength of SAF in observations. This is traced to two canopy snow parameterizations in the land model. First, there is no mechanism for the dynamic removal of snow from the canopy when temperatures are below freezing, which results in albedo values in midwinter that are biased high. Second, when temperatures do rise above freezing, all snow on the canopy is melted instantaneously, which results in an unrealistically early transition from a snow-covered to a snow-free canopy. These processes combine to produce large differences between simulated and observed monthly albedo, and are the sources of the weak bias in SAF. This analysis highlights the importance of canopy snow parameterizations for simulating the hemispheric scale climate response to surface albedo perturbations. A number of new experiments are described as recommendations for future work.

Pathogenic fungi, such as polypore fungi that infect live sapwood, decrease quality and value of wood; however their effects on canopy physiology and growth have been little examined. This study examines how Fomes fomentarius, a species of polypore fungus affects canopy physiology in Betula alleghaniensis. A mobile canopy lift enabled the collection of leaf physiology, morphology and chemistry data from canopies of infected, damaged, and control trees. A molecular protocol developed to detect and identify polypore fungi in live trees confirmed that F. fomentarius was the major species present in infected trees. Infected trees exhibited reductions in physiological performance and growth, along with higher leaf carbon and chlorosis. While some characteristics of fungal infection were consistent with a mechanism involving partial xylem occlusion, patterns did not resemble those of a simple drought response. Likely, other factors such as fungal toxins or host defense mechanisms also contribute to these patterns.

Pathogenic fungi, such as polypore fungi that infect live sapwood, decrease quality and value of wood; however their effects on canopy physiology and growth have been little examined. This study examines how Fomes fomentarius, a species of polypore fungus affects canopy physiology in Betula alleghaniensis. A mobile canopy lift enabled the collection of leaf physiology, morphology and chemistry data from canopies of infected, damaged, and control trees. A molecular protocol developed to detect and identify polypore fungi in live trees confirmed that F. fomentarius was the major species present in infected trees. Infected trees exhibited reductions in physiological performance and growth, along with higher leaf carbon and chlorosis. While some characteristics of fungal infection were consistent with a mechanism involving partial xylem occlusion, patterns did not resemble those of a simple drought response. Likely, other factors such as fungal toxins or host defense mechanisms also contribute to these patterns.

Methylmercury (MeHg) is a potent vertebrate neurotoxin and a contaminant of global concern. Increased anthropogenic emissions of mercury (Hg) to the atmosphere have led to increased bioaccumulation of MeHg in top predatory organisms such as fish, the consumption of which is the main exposure pathway of this toxin to humans and other animals. Forest canopies significantly increase the deposition of Hg in general to watersheds, but sources and fates of MeHg deposition in particular remain poorly understood. In this study, wet and dry loadings of MeHg to a watershed were quantified, and the retention and (photo)reduction of MeHg on foliage were measured using unique stable isotope experiments. We found that traditional methods of quantifying net deposition underestimate incoming sources of MeHg, and that retention of MeHg on forest canopies results in delayed transport of a significant portion of newly deposited MeHg from terrestrial catchments into adjacent lakes. / Ecology

主催：JST/CREST，Vrije University, ALTERRA, IBPC

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 45-51). Also available on the World Wide Web.

Thesis (M. Sc.)--Carleton University, 2003. / Includes bibliographical references (p. 28-34). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Tennessee, Knoxville, 2007. / Title from title page screen (viewed on June 10, 2008). Thesis advisor: Henri D. Grissino-Mayer. Vita. Includes bibliographical references.