Spruce Forest Types Research Articles

Short-term use of different residual forest structures by three sciurid species in a clear-cut boreal landscape

We compared the abundance of red squirrel (Tamiasciurus hudsonicus Erxleben), northern flying squirrel (Glaucomys sabrinus Shaw), and eastern chipmunk (Tamias striatus L.) in three types of black spruce (Picea mariana (Mill.) BSP) residual forest 3 to 5 years after logging (upland strips, riparian strips, and forest blocks) in central Quebec, Canada. Controls consisted of mature forest undisturbed by forestry practices. Despite their sporadic occurrence, northern flying squirrels and eastern chipmunks were captured in the three residual forest types as well as in control sites. Red squirrels inhabited all types of residual forest and no differences in densities were found between residual forest treatments and controls. Juvenile recruitment, return rate (survival), and body mass were also similar for red squirrels in all treatments. However, midden abundance was higher in controls and blocks than in strips. In the short term, red squirrel populations maintain themselves in all types of residual black spruce forests after logging. The northern flying squirrel and the eastern chipmunk appear to tolerate the presence of logging disturbances and are present at low density in the different types of residual forests.

Classification of spruce beetle hazard in Lutz and Sitka spruce stands on the Kanai Peninsula, Alaska

Stand data from Lutz and Sitka spruce forest types occurring on the Kenai Peninsula were analyzed by tree-based classification and abductive inference to develop decision models for classifying spruce beetle hazard. Model development and validation data sets contained 286 and 88 stand observations, respectively. The final decision-tree structure yielded 13 possible hazard outcomes based on total stand basal area, percentage of total basal area composed of spruce, percentage of spruce basal area composed of trees with diameter > 25 cm, stand elevation, and stand aspect. Four paths in the decision tree led to low-hazard outcomes (spruce basal area loss ≤ 10%); two paths each led to low-medium, medium, and medium-high hazard outcomes (spruce basal area loss of ≤ 40%, 11–40%, and > 10%, respectively); and three led to high-hazard outcomes (spruce basal area loss > 40%). Results of model verification were considered very acceptable; in the worst case, predictions of high hazard were correct for 67% of the observations. Model validation results also were considered acceptable, but predictions of medium and high hazard showed a marked drop from verification results. For comparison, the same analysis was performed using abductive inference to test a modeling method better suited to automatic processing of numerous stands for landscape-level analysis. There was a high degree of correspondence between predictions of the two analytical methods.

Classification of spruce beetle hazard in Lutz spruce (Picea × lutzii) stands on the Kenai Peninsula, Alaska

Stand data from Lutz spruce (Picea × lutzii Little) forest types occurring on the Kenai Peninsula were analyzed by tree-based classification to develop a decision tree for classifying spruce beetle (Dendroctonusrufipennis Kby.) hazard. Model development and validation data sets contained 100 and 34 stand observations, respectively. The final decision-tree structure yielded seven possible hazard outcomes based on total stand basal area, percentage of total basal area composed of spruce, percentage of spruce basal area composed of trees with diameter >25 cm, stand elevation, and stand aspect. Three paths in the decision tree led to low-hazard outcomes (spruce basal area loss ≤10%); one path led to a high-hazard outcome (spruce basal area loss >40%). No paths through the decision tree led to a medium-hazard outcome (spruce basal area loss >10%, but ≤40%), but three less precise outcomes of low–medium and medium–high hazard were considered useful and retained in the final model. Results of model verification were considered very acceptable; in the worst case, predictions of high hazard were correct for 73% of the observations. Model validation results were also considered very acceptable considering the small number of observations available for this phase of analysis.

Effects of Species Mixtures and Inventory Zones on Net Yields of British Columbia Forests

A least squares procedure developed to determine statistical significance of both qualitative and quantitative data was applied to find proportions of plots and amounts of wood yield by species mixtures and inventory zones. For 9 781 plots in Douglas-fir, spruce, and lodgepole pine forest types, sample volumes were highest in mixtures of these species with other conifers. However, small differences in age, site index, and stand density could account for much of the variation. When stand volumes were brought to common levels of age, site and density the need to recognize species composition classes and forest inventory zones diminished.If indicated gains from mixtures were real, stand managers could easily improve density of pure stands to exceed the increased yields indicated for conifer mixtures with Interior Douglas-fir (20.4%) and with lodgepole pine (3.4%). Because our analyses of regional inventories could not provide conclusive results, well designed long-term field trials would be needed to evaluate effects of species mixtures under fully comparable conditions.When stand density is used with age and site index to estimate yields there should be no need to recognize inventory zones within Coast and Interior races of the species tested.

Some reproductive traits of four shrub species in the Black Spruce forest type of Alaska

Some reproductive traits of four shrub species in the Black Spruce forest type of Alaska

The Interrelationships of Logging, Birds, and Timber Regeneration in the Douglas-Fir Region of Northwestern California

tntensive logging of a virgin stand of Douglasfir (Pscidotsizga mnienziesii) began in 1950 in the inner cast ranges of northwestern California. Most timber is being clear cut in blocks of from 10 to 20 acres. Intervening blocks of roughly equal size are left for a later cutting and meanwhile serve as seed sources for the cutovers. Initial efforts to seed coniferous trees on these blocks by artificial or natural means have been discouraging. Rodents and other seed-eating animals flourishl after logging, and play a major role in retarding or preventing regeneration. The subject of animals as destroyers of conifer seed has been discussed l)y Smith and Aldous (1947), who reviewed the literature and listed all birds and mammals known to eat coniferous seed in the United States. Rodents, particularly mice of the genus Peroniivscits, have long been recognized as the chief consumers. Studies of the local distribution and food of two species of Pcronzysclus on timberland in California have beei7 made by J arneson (1951 and 1952). The responses of small mammal populations to logging of D)ouglas-fir were stuclied by Tevis (1956). Further information on animal factors that hinder reforestation is needed by the forester and an uinderstanding of how logging alters the fauna is of value to the ecologist and land manager. Toward these ends, tEis study of forest birds was made in cooperation \with the California Forest and Range Experiment Station on the Six Rivers National Forest near Salyer in Trinity and Humboldt Counties, California. The purpose of the investigation was to determinee changes in species composition, numbers, food habits, and activities of bird populatio1ls immediately after the forest is logged and during the first few years after logging when regeneration of timber is most en(langered by biological and physical adversity. The effect of environmental changes on populations of forest birds have been studied by Lack (1933, 1939, and 1951) in English pine plantations, and by Odum (1950) in successional stages towarcl climax hardwood and hemlock forest of the Highlands Plateau in North Carolina. Studies by Turcek (1952 and 1956) were concerned with bird populations of spruce and other forest types in Czechoslovakia. STUDY AREAS

Ecological Studies of the Vegetation of the Great Smoky Mountains. II. The Quadrat Method Applied to Sampling Spruce and Fir Forest Types

The purpose of this study is to examine the possibility of reducing the sampling of a forest community to the minimum consistent with the adequate representation of the arborescent stratum, that is, to approach reality as to the composition and structure of the tree stratum. The immediate goal is not that of crusing the association-individual, or stand, for its merchantable content in board feet or cordage, but the method, if valid, should yield such data with approximately the same limits of error as, for example, basal area, which is used here as the basis for comparison. The system, which is not at all new, is simply that of employing small sample areas (quadrats) on a basis of random sampling within the stand. The study differs from the usual in that an inspection of the influence of size and number of quadrats is made with the purpose of ascertaining the minimum quadrat area and the minimum number of such quadrats which will produce results within certain limits of error.