<p> Butternut (<i>Juglans cinerea</i> L.), or white walnut, has suffered large population declines in the past half-century due to poor regeneration and mortality caused by an introduced fungus, <i>Ophiognomonia clavigignenti-juglandacearum </i> (Nair, Kostichka &amp; Kuntz) Broders &amp; Boland. This fungus causes branch and trunk cankers that can coalesce to girdle adult trees. Chapter 1 provides background information on butternut and butternut canker. We used next-generation sequencing to identify new nuclear DNA markers for butternut and Japanese walnut, a congener with which butternut readily hybridizes. We also examined the alignment of SSR repeat sequences in butternut and Japanese walnut with similar sequences from other angiosperms in public sequence databases. The methods used and results obtained in this process are detailed in Chapter 2. Chapter 3 summarizes an investigation of the environmental and genetic factors contributing to canker disease incidence, severity, and mortality in a large (n=113) population of butternut in southern Wisconsin and two other populations of butternut, one near the main study site in southern Wisconsin and another in the Great Smoky Mountains National Park. We present evidence for weak correlations of genetic similarity and phenotypic similarity for several disease traits, parentage analysis of regeneration in the smaller Wisconsin population, and evidence for significant microsite influences on butternut mortality over an 11-year period in the large Slocum's Woods butternut population.</p>

Snowshoe hares (Lepus americanus) are a critically important prey species for Canada lynx (Lynx canadensis). Determination of snowshoe hare distribution and abundance is needed in western Wyoming for lynx conservation. We used linear regression to examine the correlations between snowshoe hare density, as determined by mark-recapture estimates, and fecal pellet plot counts on both uncleared and annually cleared plots on the Bridger-Teton National Forest, western Wyoming. We found significant correlations between hare density estimates and fecal pellet counts for both uncleared and annually cleared pellet counts; however the relationship was much stronger for annually cleared pellet counts. Adjusting the buffer size by omitting hard habitat edges (not used by hares) around the trapping grids improved correlations between hare density and fecal pellet counts further. We recommend pellet counts from annually cleared plots be used when precise estimates of snowshoe hare abundance are required. Though precision is sacrificed when using uncleared plots, they are useful as a coarse index of habitat use by hares. The derived regression equations should be used to identify foraging habitat for lynx in western Wyoming. In addition to snowshoe hares, in western Wyoming red squirrels (Tamiasciurus hudsonicus) and grouse (Bonasa umbellus and Dendragapus obscurus) are used by Canada lynx. Whether young forests or older multi-storied forests contain more snowshoe hares, red squirrels, and grouse in western Wyoming is currently unknown. We estimated snowshoe hare density, and indexed red squirrel and forest grouse abundance in 3 classes of 30-70-year-old lodgepole pine (Pinus contorta) and 4 classes of mature multi-storied forest with a spruce (Picea engelmannii)-fir (Abies lasiocarpa) component. We recorded landscape and forest structure characteristics to understand how these influence lynx prey abundance. Overall, snowshoe hares, red squirrels, and forest grouse were more abundant in multi-storied forests than young forests. Forest attributes that predicted prey abundance were often more prevalent in multi-storied forests. Results from this study suggest that multi-storied forests with a spruce-fir component were disproportionately important to snowshoe hares, red squirrels, and forest grouse in western Wyoming. Canada lynx conservation efforts should focus on maintaining, enhancing, and promoting multi-storied forests in this region.

L’utilisation de matières résiduelles fertilisantes (MRF) dans les plantations de peupliers hybrides (PEH) au Québec pourrait en maximiser la productivité et le volume marchand. Elle présenterait aussi l’avantage de minimiser l’enfouissement ou l’incinération des MRF. Cependant, le dosage des MRF doit être calibré en fonction de la réponse optimale des arbres. L’étude a été réalisée dans une plantation de PEH en Estrie. Un dispositif expérimental comprenant deux blocs (répétitions) de cinq parcelles - un témoin et quatre traitements de combinaisons de biosolides papetiers et de boue de chaux - y a été mis en place à l’automne 2012 et au printemps 2013, soit trois ans avant l’échantillonnage (été 2015). Les traitements représentaient les doses suivantes : 140 et 15 t ha-1 (humides), 140 et 30 t ha-1, 240 et 15 t ha-1 et 240 et 30 t ha-1 de biosolides et de boue de chaux, respectivement. Les propriétés physico-chimiques du sol et la morphologie et la nutrition des PEH ont été évaluées. Nous avons observé un effet très significatif des traitements de MRF sur la croissance des PEH par rapport aux parcelles non traitées. La hauteur des arbres a augmenté de 1,6 à 2 fois, le diamètre de 2,5 à 4 fois, la surface foliaire de 3 à 8 fois et le poids foliaire de 2,7 à 9 fois dans les parcelles traitées comparativement aux arbres des parcelles non traitées. Toutefois, aucune différence significative n’a pu être constatée entre les différents amendements. Les analyses de nutrition foliaire ont, quant à elles, démontré que la fertilisation avec les MRF permettait de pallier la faible disponibilité des nutriments dans le sol. Ainsi, avec l’ajout de MRF, les macronutriments N, P, K et Ca dans les feuilles se situaient à l’intérieur des plages de concentrations optimales, alors que sans MRF, les feuilles montraient des concentrations sous ces seuils. Malgré les faibles différences observées entre les quatre amendements, le traitement combinant 240 t ha-1 de biosolides et 15 t ha-1 de chaux est celui qui se rapprochait le plus d’une nutrition optimale pour le PEH. Les biosolides papetiers en combinaison avec la boue de chaux donnent des résultats très encourageants en ce qui a trait à la nutrition foliaire et le rendement des plantations du PEH lors des premières années d’établissement. / The use of fertilizing residual materials (FRM) in hybrid poplar (HP) plantations in Quebec could maximize yields and merchantable volumes. It would also have the advantage of minimizing the burial (landfill) or incineration of FRM. However, applications rates of FRM must be calibrated for an optimal response of the trees. The study was conducted in a PEH plantation in the Eastern Townships. An experimental design comprising two blocks (repetitions) of five plots - one control and four combinations of papermill biosolids and lime sludge - was established in fall 2012/spring 2013 and sampling was conducted three years later (summer 2015). The treatments represented the following application rates: 140 and 15 t ha-1 (wet), 140 and 30 t ha-1, 240 and 15 t ha-1 and 240 and 30 t ha-1 of biosolids and lime, respectively. Soil properties as well as morphology and nutrition of HP were evaluated. We observed a highly significant treatment effect on HP growth compared to untreated plots. The height of HP trees in the treated plots increased by 1.6 to 2 times, diameter by 2.5 to 4 times, leaf area by 3 to 8 times and the foliar weight by 2.7 to 9 times compared to the trees in the untreated plots. However, there was no significant difference among the various treatments. Foliar nutrition analyses showed that fertilization with FRM was sufficient to compensate for the low availability of nutrients in the soil. Thus, with FRM application, the macronutrients N, P, K and Ca in the leaves were within the optimal concentration ranges, whereas without FRM, the leaves showed concentrations below these thresholds. Despite the small differences observed among the four amendments, the treatment combining 240 t ha-1 of biosolids and 15 t ha-1 of lime was the one the closest to the optimal nutrition for HP. Papermill biosolids in combination with lime sludge provide very encouraging results in regard to foliar nutrition and yields of HP plantations.