The effects of sewage sludge application and the additional effects of clearfelling on nutrient cycling have been assessed in a mature Scots pine stand, north-east Scotland. The forest site was situated in a low rainfall area with high evapotranspiration and low leaching losses. The ground vegetation formed an important sink for N and P following sludge addition and clearfelling. Sludge application caused a foliar N response, increased foliar needle weight, and litterfall showed a significant and rapid potential to immobilize NH₄-N and PO₄-P added in sludge. The soil availability of NH₄-N and PO₄-P together with rates of mineralization of N and P and nitrification in sludge-treated areas were significantly increased compared with that of the control. Concentrations of NH₄-N, NO₃-N, PO₄-P and organic P were increased significantly following sludge addition and fluxes were an order of magnitude greater than that of the control. Peaks in concentrations of NH₃-N in sludge-treated areas exceeded the EC limit of 11.3 mg 1^-1 on several occasions. Of the total N and P applied to the sludge, throughfall and litterfall over a 17 month period, 2.4 % and 0.72 % were measured in the B_s soil horizon flux. After clearfelling, initial increases in soil availability of NH₄-N, NO₃-N andPO₄-P were measured. Felling increased nitrification rates, although increases were significant only in areas previously treated with sludge. Fluxes of NO₃-N, NH₄-N and PO₄-P and organic P were increased at least an order of magnitude greater in felled areas than those of the control. Immobilization of N and P was greater in green and abscised litters placed in previously sludge-treated areas than compared with those placed in control areas.

Loblolly pine (Pinus taeda L.) is an ecologically and economically important southern pine, distributed across the southeastern United States. Its genetic improvement for breeding and deployment is a major goal of the Western Gulf Forest Tree Improvement Program (WGFTIP) hosted by the Texas A&M Forest Service. Rapid advances in genomics and molecular marker technology have created potential for application of Marker Assisted Selection (MAS) and Genomic Selection (GS) for accelerated breeding in forest trees. First-generation selection (FGS) and second- generation selection (SGS) breeding populations of loblolly pine from east Texas were studied to estimate the genetic diversity, population structure, linkage disequilibrium (LD), signatures of selection and association of breeding traits with genetic markers using a genome-wide panel of 4264 single nucleotide polymorphisms (SNPs). Under- standing the genetic basis of local adaptation is crucial to disentangle the dynamics of gene flow, drift and selection and to address climate change. Bayesian mixed linear models and logistic regression were used to associate SNP variation with geography, climate, aridity and growth season length and markers with strong correlations were investigated for biological functions. Relatively high levels of observed (Ho = 0.178–0.198) and expected (He = 0.180-0.198) heterozygosities were found in all populations. The amount of inbreeding was very low, and many populations exhibited a slight excess of heterozygotes. The population substructure was weak, but FST indicated more pronounced differentiation in the SGS populations. As expected for outcrossing natural populations, the genome-wide LD was low, but marker density was insufficient to deduce the decay rate. Numerous associations were found between various phenotypes and SNPs, but few remained significant after false positive correction. Signatures of diversifying and balancing selection were found in markers representing important biological functions. Strong correlations supported by Bayes factors were found between various environmental variables and several SNPs. Logistic regression found hundreds of significant marker-environment associations, but none remained significant after false-positive correction, which was likely too stringent and will require further investigation. Annotations of significant markers implicated them in crucial biological functions. These results present the first step in the application of MAS to the WGFTIP for loblolly pine genetic improvement and will contribute to the knowledgebase necessary for genomic selection technology. Results from environmental association study provide important information for designing breeding strategies to address climate change and for genetic conservation purposes.

Whitebark pine (Pinus albicaulis) is declining across its range due to disturbances such as mountain pine beetle and white pine blister rust. In this thesis, I assess the response and vulnerability of whitebark pine ecosystems to multiple stressors and disturbances at the northern edge of P.albicaulis range in the Coastal Mountains of British Columbia, Canada. Both the compositional change over time of overstory and understory communities as well as vegetation spatial patterns suggest that different sites or ecosystem types housing whitebark pine may differ in their response to disturbance and stress. Surveys conducted ~ 20 years apart indicate that overstory community change differed between site types following the decline of P. albicaulis over time, while the understory did not change significantly. The spatial pattern of overstory species and understory communities also indicates that site type may be important in determining forest change under ongoing disturbance to whitebark pine. / Forest Biology and Management

Thesis (M.S. - Watershed Management)--University of Arizona. / Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 210-228). Also available on the World Wide Web.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "August, 2007." Includes bibliographical references. Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2007]. 1 microfilm reel ; 35 mm.

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thesis (M.S.)--Oregon State College, 1958. / Typescript. Includes bibliographical references (leaves 91-95). Also available on the World Wide Web.

Thesis(M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographic references (p.64-82).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 60-64). Also available via the Internet.