Carleton University

About: Carleton University is a education organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 15852 authors who have published 39650 publications receiving 1106610 citations.

Fire Interval Effects on Successional Trajectory in Boreal Forests of Northwest Canada

Abstract: Although succession may follow multiple pathways in a given environment, the causes of such variation are often elusive. This paper describes how changes in fire interval mediate successional trajectory in conifer-dominated boreal forests of northwestern Canada. Tree densities were measured 5 and 19 years after fire in permanent plots and related to pre-fire vegetation, site and fire characteristics. In stands that were greater than 75 years of age when they burned, recruitment density of conifers was significantly correlated with pre-fire species basal area, supporting the expectation of stand self-replacement as the most common successional pathway in these forests. In contrast, stands that were under 25 years of age at the time of burning had significantly reduced conifer recruitment, but showed no change in recruitment of trembling aspen (Populus tremuloides). As a result, young-burned stands had a much higher probability of regenerating to deciduous dominance than mature-burned stands, despite the dominance of both groups by spruce (Picea mariana and Picea glauca) and pine (Pinus contorta) before the fire. Once initiated, deciduous-dominated stands may be maintained across subsequent fire cycles through mechanisms such as low on-site availability of conifer seed, competition with the aspen canopy, and rapid asexual regeneration of aspen after fire. We suggest that climate-related increases in fire frequency could trigger more frequent shifts from conifer to deciduous-dominated successional trajectories in the future, with consequent effects on multiple ecosystem processes.

Current-Use Flame Retardants in the Eggs of Herring Gulls (Larus argentatus) from the Laurentian Great Lakes

Abstract: Of the 13, current-use, non-polybrominated diphenyl ether (PBDE) flame retardants (FRs) monitored, hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and α- and γ-isomers of hexabromocyclododecane (HBCD), and the syn- and anti-isomers of the chlorinated Dechlorane Plus (DP) were quantified in egg pools of herring gulls (Larus argentatus) collected in 2004 from six sites in all five of the Laurentian Great Lakes of North America. α-HBCD concentrations ranged from 2.1 to 20 ng/g (wet weight (ww)). Other “new” FR levels ranged from 0.004 to 1.4 ng/g ww and were much lower than those of the major BDE congeners that are in technical mixtures (namely BDE-47, -99, -100), where Σ3PBDE ranged from 186 to 498 ng/g ww. Nineteen hepta-BDEs (Σhepta = 4.9−11 ng/g ww), octa-BDEs (Σocta = 2.6−9.1 ng/g ww), and nona-BDEs (Σnona = 0.12−5.6 ng/g ww) were detectible at all six colonies, while BDE-209 was low but quantifiable (<0.1−0.21 ng/g ww) at two ...

Relations Among the Frequency of Shared Reading and 4-Year-Old Children's Vocabulary, Morphological and Syntax Comprehension, and Narrative Skills

Abstract: Books can be a rich source of learning for children and adults alike. In the present study, the contribution of shared reading and parent literacy to a variety of child outcomes was tested. Child outcomes included measures of expressive vocabulary, morphological and syntax comprehension, and narrative ability (story grammar, cohesion, and language complexity) for book stories as well as personal stories. A total of 106 English-speaking 4-year-old children and their parents participated. As predicted, shared reading accounted for unique variance in children's expressive vocabulary and morphological knowledge after controlling for child nonverbal intelligence, parent education, and parent literacy (i.e., book exposure). Although shared reading predicted syntax comprehension, the effect was mediated by parents' own level of literacy. Contrary to expectation, shared reading was not correlated with any of the narrative measures. Interestingly, the narrative measures for telling stories from a book and telling ...

Gender, Structural Factors, and Credit Terms between Canadian Small Businesses and Financial Institutions

Abstract: This paper reports on an analysis of whether or not the terms of bank credit differ between men and women business owners. Based on a large sample of borrowing experiences, it is found that men and...