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Canada’s urban forests play a critical role in local environmental systems and conditions, and will likely be the most influential forest of the 21st century (Nowak et al. 2001; Dwyer et al. 2003). Winnipeg is home to the largest remaining elm forest in North America and has a long and unique history with its residents. While a great deal of research has examined the many urban forest benefits, there was opportunity to further develop an understanding of residents expressed values and preferences in relation to Winnipeg’s urban forest ecosystems. The study adopted a qualitative research approach, collecting data through multiple methods including site tours, participant journals, photo elicitation, and follow-up semi-structured interviews. The results indicate that Winnipeggers have deeply held urban forest values, particularly in relation to aesthetics, naturalness and biodiversity, and social values such as recreation and alternative uses. Personal development of the values held began early in life, has occurred over time, and is continually reassessed through critical reflection.

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A description of the development and subsequent use of an integrated and semi-stochastic computer simulation model, <I>GHAFORGROM</I> (Ghana Forest Growth and Yield Simulation Program), designed to investigate forest tree dynamics and also predict growth and yield of timber in the tropical forests of Ghana is presented. This simulator considers many aspects of natural forest growth including species-group-specific individual tree diameter growth based on competition, mortality and recruitment. The 687 tree species used in these studies have been aggregated into 13 species groups. The simulator is based on a new individual tree-based distance-dependent diameter increment model. Diameter increment of a tree is predicted by a multiplicative composite function of initial diameter, relative tree dominance index, and (or) categorical site index. The based function of diameter increment on diameter is an extension of a power-exponential growth function. The relative tree dominance index of a subject tree is defined in terms of a new competition index. This index is the sum of the ratios of volume of overtopping competing trees to the volume of the subject tree, where the competitor trees are within a radius of 20 m of the subject tree for large-sized trees and 1.5 m of the subject tree for medium- and small-sized trees. The probability of mortality of a tree is defined in the form of a logistic function based on the explanatory variables of functions of diameter and stand density, including basal area per hectare and volume per hectare for each species group. The total amount of recruitment at 10 cm diameter is predicted as a linear function of stand basal area, stand volume and categorical site variables. It is hoped that the model will provide practical steps to improved natural tropical forest management in Ghana, leading to higher sustainable timber yields.

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Fire suppression has resulted in dramatic changes to species composition and structural diversity in the Sierra Nevada mixed-conifer forests of California. Advancing the ecological understanding and management of these forests requires a better understanding of changes that occurred during the fire suppression era, but empirical historical datasets are rare and methodologies for developing new historical reference information are subject to many limitations. I sought to develop historical reference information for the Yosemite Forest Dynamics Plot (YFDP), a research plot located in an old-growth mixed-conifer stand in Yosemite National Park. I performed a dendrochronological fire history analysis to characterize the historical fire regime of the YFDP (pre-1900 fire return interval: 29.5 years). I then developed two different forest reconstruction models to estimate pre-suppression forest conditions. Two alternative tree growth models, one regionally-parameterized and one locally-parameterized, and a decay model based on published estimates of tree decay rates were evaluated. Limited tree decay data available in the literature is a source of uncertainty in forest reconstructions, both for this study and other studies in the Sierra Nevada. Model analysis demonstrated that the regionally-parameterized growth model resulted in unreasonably fast tree growth rates. The site-specific growth model produced results similar to empirical historical datasets (84.5 trees ha-1 and 25.7 m2 ha-1 in 1900) I utilized these results to investigate patterns of tree establishment during the fire suppression era. I found evidence for spatial attraction between early ingrowth (trees that established between 1930 and 1970) sugar pine and legacy trees (trees established before 1930) and spatial repulsion between late ingrowth (trees that established after 1970) sugar pine and legacy trees. This indicates that fire suppression is driving changes to intertree relationships, causing current tree spatial patterns to be outside of their historical range and variability. These results highlight the need for a substantial increase in research efforts regarding tree decay data for Sierra Nevada mixed-conifer forests. When developing restoration targets, managers should avoid a one size fits all approach and consider site-specific factors, such as parent material and the historical fire regime, which have influenced changes to forest conditions during the fire suppression era.

Carbon dioxide is one of the major greenhouse gases being cycled by forests. Mature boreal forests are often carbon sinks, however, following disturbance, forests can become carbon sources. Three forest sites in central Saskatchewan burned in 1977 (F77 site), 1989 (F89 site), and 1998 (F98 site) were studied using eddy covariance to obtain measurements of the energy, carbon, and water budgets. Latent heat flux density increased gradually over time at F98 but remained lower than F77 and F89. Weekly net ecosystem production was lower at F98 than at F77 and F89. F77 lost 40 g C m-2 and 79 g C m-2 in 2004 and 2005, respectively. F89 gained 177 g C m-2, 113 g C m-2, and 88 g C m-2 in 2003, 2004, and 2005, respectively. F98 lost 5 g C m-2, 17 g C m-2, and 52 g C m-2 during these three years, respectively.

Canada’s urban forests play a critical role in local environmental systems and conditions, and will likely be the most influential forest of the 21st century (Nowak et al. 2001; Dwyer et al. 2003). Winnipeg is home to the largest remaining elm forest in North America and has a long and unique history with its residents. While a great deal of research has examined the many urban forest benefits, there was opportunity to further develop an understanding of residents expressed values and preferences in relation to Winnipeg’s urban forest ecosystems. The study adopted a qualitative research approach, collecting data through multiple methods including site tours, participant journals, photo elicitation, and follow-up semi-structured interviews. The results indicate that Winnipeggers have deeply held urban forest values, particularly in relation to aesthetics, naturalness and biodiversity, and social values such as recreation and alternative uses. Personal development of the values held began early in life, has occurred over time, and is continually reassessed through critical reflection.

No description available.