Our objective was to evaluate how different lake environments (Laurentian Great Lakes versus inland lakes) and hatchery rearing influence egg traits in lake trout Salvelinus namaycush. Lake trout eggs were collected from 11 hatchery populations and 15 wild populations in the vicinity of the Great Lakes. Average egg size (controlling for body size) differed among populations but not between hatchery and wild populations or Great Lakes and inland lake populations. However, within-female egg size variability was consistently higher in hatchery populations than in wild populations and, to a lesser extent, in Great Lakes populations than in inland populations. We hypothesize that these effects are due to confinement (hatchery)and habitat (lake environment)-mediated stress affecting oogenesis.

Much of the southern boreal forest is composed of second-growth stands that have been subjected to a variety of silvicultural treatments ranging from cut and leave to scarification, planting, and tending with herbicides. We have limited understanding of the effects that these treatments may have on wildlife species, as a result of changes to forest structures and species composition. Forest amphibians, generally, and the American marten (Martes americana) are species for which there has been long-standing concern about the effects of forest management. We examined the long-term effects at stand and landscape scales of a range of silviculture intensities on these species by comparing the relative abundances of some amphibians and habitat use by marten in forests that were about 32 to 50 years old. American toads (Bufo americanus) appeared to be unaffected by long-term changes in habitat structure and composition owing to silvicultural techniques. We observed lower relative abundance of wood frogs (Rana sylvatica) in treated stands 20 to 30 years old than in all other stands including uncut old forests. However, abundance in treated stands more than 32 years old did not differ from untreated or uncut stands. This effect may have resulted from lower moisture levels in treated young stands. Marten seemed to positively respond to post-harvest planting and tending treatments, suggesting that basic silviculture provided habitat attributes, notably a higher conifer content, which was favourable to marten.Key words: post-harvest silviculture, marten, wood frog, American toad, herbicide, boreal, woody debris, Ontario RÉSUMÉLa majeure partie du sud de la forêt boréale est composée de peuplements de seconde venue qui ont connu plusieurs traitements sylvicoles allant de la coupe à blanc au scarifiage, suivi de plantation et entretien au moyen d'herbicides. Nous comprenons en partie les effets que ces traitements pourraient entraîner sur les espèces fauniques, suite à des modifications de la structure et de la composition des peuplements. Les amphibiens du milieu forestier, de façon générale, et la martre d' Amérique (Martes americana) constituent des espèces pour lesquelles des études ont été entreprises depuis longtemps sur les effets de l'aménagement forestier. Nous avons étudié les effets à long terme au niveau du peuplement et de l' écosystème de l'intensité des travaux sylvicoles sur ces espèces en comparant l'abondance relative de certains amphibiens et de l'habitat utilisé par la martre dans des peuplements âgés de 32 à 50 ans. Le crapaud d' Amérique (Bufo americanus) a semblé ne pas être affecté par les changements à long terme de la structure et de la composition de l'habitat suite aux travaux sylvicoles. Nous avons observé une abondance relative plus faible chez la grenouille des bois dans les peuplements traités de 20 à 30 ans par rapport aux autres peuplements incluant les vieilles forêts non exploitées. Cependant, l'abondance dans les peuplements de plus de 32 ans n' était pas différente de celle des peu...

Two common methods of measuring forest stand woody stem attributes include prism plots for basal area and modified point-distance for stem density. The data from each method can be used for the other calculation; that is, prism data can provide stem density, and point-distance datacan provide estimated basal area. We examined data from the same 10 stands using the two techniques to determine whether the results for each calculation were comparable and/or consistent. There was a significant correlation between the estimated tree (defined as stems >10 cm) basal areas,and between tree stem densities, derived from the two methods (P < 0.01). Prism plots provided significantly higher estimated tree stem densities (+23.5%; P < 0.05) compared to estimates from the point-distance technique, but there was no difference between estimated treebasal area. For all stems, that is also including stems <10 cm dbh, there was no difference between the two methods for estimated basal area or stem density. There was no correlation between total stem densities derived from the two methods. This is likely because the prism plot method(two-factor metric prism) sampled relatively few trees with small diameters, whereas the point distance technique, as used, sampled small trees independently from trees using a diameter distinction. When we removed two young stands with <50 trees/ha, there was no difference in estimatesof stem density. We concluded that, for boreal forest stands with a normal density of trees (i.e., >10 cm dbh and 900 to 3,000 stems/ha), either method would provide comparable estimates of stem density and basal area. We found no time difference in conducting surveys using either method.