The effects of two operational nursery fertilization regimes on the growth and nutrient dynamics of Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) seedlings after planting were compared. Seedlings were grown in a nursery with nutrients added at a constant rate (conventional fertilization) or at a rate that increased exponentially by 2%Áday -1 (exponential fertilization) and planted near Barriere and Victoria, British Columbia. At the time of planting, half of the conventionally fertilized seedlings were planted with slow-release fertilizer packets. Growth and nutrient allocation was observed for 2 years following planting. Although the exponential fertilization regime provided 25% more N in the nursery compared with the conventional fertilization regime, exponentially fertilized seedlings were smaller at the time of planting, did not differ significantly in foliar N concentration, and showed no lasting benefits in growth or nutrient allocation. Two years after planting, there were no significant differences between the conventional and exponential fertilization regimes in seedling height, root collar diameter, total dry mass, or whole-plant N concentration. Seedlings fertilized at the time of planting had greater height and dry mass on the Barriere site but not on the dry Victoria site and whole-plant N concentrations did not differ 2 years after planting.Résumé : Deux régimes opérationnels de fertilisation en pépinière pour les semis de douglas de Menzies (Pseudotsuga menziesii var. glauca (Beissn.) Franco) ont été comparés quant à leurs effets sur la dynamique de la croissance et des nutriments après la plantation. Les semis ont été cultivés en pépinière où des nutriments ont été ajoutés à un taux constant (fertilisation conventionnelle) ou à un taux qui augmentait de façon exponentielle à raison de 2 % par jour (fertilisation exponentielle) et ils ont été plantés près de Barriere et de Victoria, en Colombie-Britannique. Au moment de la plantation, la moitié des semis fertilisés de façon conventionnelle ont été plantés avec des sachets de fertilisant à libération lente. La croissance et l'allocation des nutriments ont été observées pendant deux ans après la plantation. Bien que la fertilisation exponentielle eusse fourni 25 % plus de N en pépinière comparativement à la fertilisation conventionnelle, les semis fertilisés de façon exponentielle étaient plus petits au moment de la plantation, leur concentration en N foliaire n'était pas significativement différente et aucun bénéfice durable tant du point de vue de la croissance que de l'allocation des nutriments n'a été observé. Deux ans après la plantation, il n'y avait aucune différence significative entre les deux traitements de fertilisation appliqués en pépinière du point de vue de la hauteur des semis, du diamètre au collet, de la masse anhydre totale et de la concentration de N dans l'ensemble de la plante. La taille et la masse anhydre des semis fertilisés au moment de la plantation étaient plus grandes sur le site de Barriere mais pas su...

Everett, Kim T., and Ken A. Otter. 2004. Presence of cavities in snags retained in forest cutblocks: do management policies promote species retention? Canadian Field-Naturalist 118(3): 354-359.Tree cavities, which are frequently excavated by primary cavity nesters, are typically used by a number of avian and non-avian species and are thus important components in maintaining biodiversity in forest ecosystems. One way to provide these habitat opportunities in harvested areas is through the retention of snags. In this study, we assessed the habitat and snag characteristics that promote cavity excavation, using the presence of cavities to infer activity of primary cavity excavators. Snags retained closer to the forest/cutblock edge contained a greater density of cavities than trees further from edge. However, the proportion of cavities found within cutblocks declined at a more rapid rate with distance from edge than did those in adjacent forested stands. There was also a tendency for cavities to occur more frequently in trees that were at the advanced stages of decay. The results of our study suggest management for snags in harvest areas should include the retention of snags closer to the forest edge combined with incorporating trees showing signs of advanced decay.

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