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In response to concerns that intensive logging of Alberta's boreal mixedwood forests may result in a change in forest structure and biota, this report describes forest structure and composition of plant and animal communities in young, mature, and old aspen mixedwood stands of fire origin in Alberta. The information in this report serves as a reference against which structure and biota in harvested forests can be compared. The report begins with a general overview of the flora and fauna of the aspen mixedwood forest, and an examination of the rationale and possible consequences of commercial aspen forestry. Subsequent chapters explore relationships between stand age and microclimate, forest structure and floristics, down woody material, understory vegetation, nonvascular species, birds, and mammals. Chapters addressing featured species cover ungulates, bats, and the flying squirrel. The final chapters discuss relationships between the vertebrate community and forest structure, and provide recommendations for aspen mixedwood forest management in Alberta.
Sixteen stands representing a range of structural variation in aspen, mixed aspen-conifer, and spruce-fir communities of the Wasatch Plateau, Utah, were censused by the sample count method. The stands were classified as eleven community types based on the understory dominants or indicator species and the cover types. Fifty bird species were recorded during the two seasons; thirty-two occurred in aspen cover, forty-four in mixed aspen-conifer cover, and twenty-two in spruce-fir. Comparisons of the composition and density of bird populations were made between uniform stands of a single life form and more structurally complex stands of either single or mixed life forms. Limiting factors in the structural characteristics of the stands were identified for birds restricted to particular stands. Low avian similarities between some aspen stands were attributed to the differences in structure between the stands. Bird species which favored the deciduous life form tended to decrease in abundance in the mixed stands as the canopy coverage of conifers increased, and they were absent in the spruce-fir stand. Coniferous forest bird species were more abundant in mixed stands with high coniferous coverage than in the aspen-dominated stands. Low individual bird numbers were found in the conifer stand of uniform small trees. Several vegetational characteristics of the stands were evaluated to determine if any was an index of forest heterogeneity predictive of bird species diversity. The habitat features of ecological relevance to most of the bird species were the size, spacing, and life form of the trees. The diversity of the distribution of diameter measurements at breast height for the tree species was predictive of bird species diversity. High diversity in the distribution of tree measurements at breast height was correlated with variation in tree height, tree canopy diameter, and the spacing of the life forms. It was therefore an index of three dimensional environmental patchiness, easily visualized by the variation in life forms and the number of stories within the stand.
Reports a two-year study initiated to examine the diversity of bird communities in different seral stages of the aspen ecosystem at the western end of the dry cool subzone of the sub-boreal spruce zone of the Prince Rupert Forest Region, British Columbia. Breeding birds were chosen for the study since they tend to stay within a relatively confined area once in their territories and are hence easier to count. The study also had the objective of identifying management indicator species that could represent the diversity of most birds likely to be affected by aspen management. Birds were counted by a modified point count method for clearcuts, sapling aspen stands, mature aspen stands, old aspen stands with century-old trees, and mixed aspen-conifer stands. Data were analyzed using a detrended correspondence analysis ordination procedure, and habitat relationships of the 16 most abundant species were analyzed by multiple regression.
This book is intended to provide information to those who wish to interact with the landbase in an ecologically sustainable manner. Practitioners charged with the administration of land-based programs in industry and government will find the information presented useful. It should also be a resource for many community groups involved in land-use decision-making. Humans continue to use forests and make decisions about land use without perfect information. Conservation Biology Principles for Forested Landscapes is intended to enable the improvement of planning and decison-making processes by providing ecological information on issues of forest use. Current approaches are not working. Where information exists on new, ecologically sustainable approaches, practitioners should switch. Where the information on a better approach is not yet available, practitioners should replace the current, inappropriate approach with a variety of flexible ones that offer the opportunity to change with new knowledge.