Treesearch

Ecology is defined as the science that studies relationships between organisms and their environments. There are many different perspectives through which these relationships can be viewed. As a natural science, ecology focuses on understanding the physical, chemical and biological interactions that take place between organisms and environments. When the organisms in question include human beings, however, there are many other kinds of interactions that must be considered as well.

In a 1993 article in Annals, Leu, Crompton, and Fesenmaier (LCF) presented a model of multi-destination pleasure trips. In the article, they question the practice of modeling pleasure trips as single destination trips, and put forward conceptual arguments suggesting that most trips "are not simple origin-destination trips: (1993:291) but instead involve visiting multiple destinations. LCF put forth their conceptual model as a tool for classifying trips for descriptive, modeling, and marketing purposes, but offered no empirical data to illustrate the model's use and applicability. The...

There is considerable interest in developing relaible methods for regenerating red oak (Quercus rubra) in Ontario. Traditional silviculture methods have not been successful in maintaining the curent levels of oak growing stock. In this paper, we review the ecology, physiology and reproductive biology of red oak. This discussion stresses the importance of seedling ecophysiology and regenerating ecology to the use and further development of the shelterwood method for regenerating red oak. Silviculture recommendations based on the best information currently available are presented.

This report is one of a series of site-specfic fire histories being developed for red oak (Quercus rubra L.)-pine ecosystems in central Ontario. Collectively, these studies documents the role of fire in upland oak forests. this information also provides an ecological basis for developing silviculture prescriptions that use prescribed burning to promote oak regeneration, and to maintain or estore fire dependent forests by emulating natural disturbance processes. A fire history from old white pine (Pinus strobus L.) stumps is presented for an aok-mixed hardwood-conifer stand near Seguin...

The individual-tree, distance-independent stand growth simulator NE-TWIGS has been tested for Ontario's tolerant hardwood stands using data from long-term permanent sample plots. NE-TWIGS provides reliable short-term (5-year) predictions of stand basal area (modelling efficiency from 77% to 99%), but in longer projections the efficiency of the model drops significantly. Basal area is underestimated an average of 2% to 5% for 5-year projections (with exception of the data set representing low-productivity sites). The error of basal area for individual stands ranges from -22% to 37%....

Research that defines the role of fire in upland red oak-pine ecosystems in central Ontario is being conducted by the Great Lakes-St. Lawrence Silviculture program. Site-specific fire histories are being developed that document fire frequency, fire behavior, fire effects on forest regeneration and grwoth, and the influnce of human activites on fire disturbances. This information will provide an ecological basis for developing silviculture prescriptions that use prescribed burning to promote oak regeneration, and to maintain or restore fire dependent forests by emulating natural disturbance...

Human beings are one of the most important agents of ecosystem disturbance and have been for millenia (Pyne 1982, 1995). Until recently, fire was the major tool peopel used to alter vegetation to their benefit. The variability in the occurrence and influnce of fire on forested ecosystems over long time periods is often the result of changes in human land use practices, population levels and migrations. For thousands of years, the St. lawrence and Ottawa rivers have served as a major travel route from the Atlantic coast into the upper Great Lakes. This route was well used by Native peoples...

Quantitative, spatial tools are needed to assess the long-term spatial consequences of alternative management strategies for land use planning and resource management. We constructed a timber harvest allocation model (HARVEST) that provides a visual and quantitative means to predict the spatial pattern of forest openings produced by alternative harvest strategies. HARVEST was used to investigate the effect on landscape structure of alternate management plans formulated for the Hoosier National Forest (HNF) in southern Indiana, U.S.A. The 1985 Forest Plan for the HNF specified primarily...

The Ohio Corridor Study (OCS) was designed to detect possible effects of acidic deposition on oak-hickory (Quercus-Carya) forests in the midwestem United States. There was one study site in Arkansas, and two each in Illinois, Indiana, and Ohio. Estimates of total sulfate deposition have generally increased about two-fold from west (Arkansas) to east (Ohio) during the 1900s. Sites were broadly analogous in forest cover type, stand age, slope, aspect, mean annual temperature and rainfall, soil type (mostly poorly buffered soils derived from sandstone and shale), and disturbance history. The...

Knowledge of rates of release of base cations from mineral dissolution (weathering) is essential to understand ecosystem elemental cycling. Although much studied, rates remain enigmatic. We compared the results of four methods to determine cation (Ca + Mg + K) release rates at five forested soils/sites in the northcentral U.S.A. Our premise was that multiple approaches, each With their own specific strengths and weaknesses, would yield a "best" overall estimate. We used (1) a cation input-output budget on a pedon scale; (2) trends in elemental and mineral depletion in silt-size particles;...