Time filter

Source Type

Faber-Langendoen D.,NatureServe | Keeler-Wolf T.,Biogeographic Data Branch | Meidinger D.,British Columbia Ministry of forests | Tart D.,U.S. Department of Agriculture | And 7 more authors.
Ecological Monographs

A vegetation classification approach is needed that can describe the diversity of terrestrial ecosystems and their transformations over large time frames, span the full range of spatial and geographic scales across the globe, and provide knowledge of reference conditions and current states of ecosystems required to make decisions about conservation and resource management. We summarize the scientific basis for EcoVeg, a physiognomic-floristic-ecological classification approach that applies to existing vegetation, both cultural (planted and dominated by human processes) and natural (spontaneously formed and dominated by nonhuman ecological processes). The classification is based on a set of vegetation criteria, including physiognomy (growth forms, structure) and floristics (compositional similarity and characteristic species combinations), in conjunction with ecological characteristics, including site factors, disturbance, bioclimate, and biogeography. For natural vegetation, the rationale for the upper levels (formation types) is based on the relation between global-scale vegetation patterns and macroclimate, hydrology, and substrate. The rationale for the middle levels is based on scaling from regional formations (divisions) to regional floristic-physiognomic types (macrogroup and group) that respond to meso-scale biogeographic, climatic, disturbance, and site factors. Finally, the lower levels (alliance and association) are defined by detailed floristic composition that responds to local to regional topo-edaphic and disturbance gradients. For cultural vegetation, the rationale is similar, but types are based on distinctive vegetation physiognomy and floristics that reflect human activities. The hierarchy provides a structure that organizes regional/continental vegetation patterns in the context of global patterns. A formal nomenclature is provided, along with a descriptive template that provides the differentiating criteria for each type at all levels of the hierarchy. Formation types have been described for the globe; divisions and macrogroups for North America, Latin America and Africa; groups, alliances and associations for the United States, parts of Canada, Latin America and, in partnership with other classifications that share these levels, many other parts of the globe. © 2014 by the Ecological Society of America. Source

Paquette A.,University of Quebec at Montreal | Girard J.-P.,Ministere des Ressources naturelles | Walsh D.,University of Quebec at Chicoutimi
Northern Journal of Applied Forestry

Although studies in the past have reported that the deeper planting of conifers has no effect on seedling performance, most planting guidelines in use today still recommend that seedlings be planted to the rootcollar. Past studies were mostly observational, used bareroot seedlings, and often reported early results from just one or two depths of planting treatments. Most of the results available regarding planting depth for boreal species are anecdotal, although they are planted by the hundreds of millions every year. The present study reports no short-term (1 year) or long-term (15 to 19 years) negative effect of planting depth on the survival and height and diameter growth of black spruce, white spruce, and jack pine seedlings over three large, replicated experiments in the boreal forest of eastern and northern Quebec (eastern Canada). Four different depth treatments were compared, from manual planting at the rootcollar to the deepest mechanical planting treatment at 10 cm or more, making this the largest, longest-lasting study of its kind. Although, as expected, important differences in growth were present between species, all three commonly planted conifers reacted similarly to the planting depth treatments (no effect). This result can in part be attributed to an almost perfect control of frost heaving in the deepest two treatments. Planting depth effects were assessed using analysis of variance, multiple Tukey honestly significant difference, and uncorrected pairwise one-tailed t-tests to increase the probability of detecting a negative effect. Absolute differences and effect sizes (generally small and often positive with greater depths) were also analyzed. Copyright © 2011 by the Society of American Foresters. Source

Bose A.K.,University of Quebec | Harvey B.D.,University of Quebec | Brais S.,University of Quebec | Beaudet M.,Ministere des Ressources naturelles | Leduc A.,University of Quebec at Montreal

Over the last 25 years, greater understanding of natural dynamics in the boreal forest has led to the integration of forest ecosystem management principles into forest policy of several Canadian provinces and, in turn, to greater interest in developing silvicultural treatments that are grounded in natural stand-level dynamics - often referred to as natural disturbance-based silviculture. As a result, alternative silvicultural practices including variants of partial cutting are increasingly being applied in the boreal forest as an approach to balancing economic and ecological management objectives. While the numerous benefits of partial cutting reported in the literature are acknowledged, the objective of this paper is to provide an overview of factors or constraints that potentially limit the application of these practices in boreal Canada in the context of forest ecosystem management and natural disturbance-based silviculture. Among constraining factors, numerous studies have reported elevated mortality rates of residual stems following partial cutting, initial growth stagnation of residual trees, problems related to recruitment of desirable species and, on certain flat or lowland sites, risks of long-term decline in site and stand productivity. A number of operational challenges to partial cutting in the boreal forest are also presented and several avenues of research are proposed. © 2013 Institute of Chartered Foresters, All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com. Source

Grondin P.,Ministere des Ressources naturelles | Gauthier S.,Natural Resources Canada | Borcard D.,University of Montreal | Bergeron Y.,University of Quebec | Noel J.,Ministere des Ressources naturelles
Landscape Ecology

Traditional approaches to ecological land classification (ELC) can be enhanced by integrating, a priori, data describing disturbances (natural and human), in addition to the usual vegetation, climate, and physical environment data. To develop this new ELC model, we studied an area of about 175,000 km2 in the Abies balsamea-Betula papyrifera and Picea mariana-feathermoss bioclimatic domains of the boreal forest of Québec, in eastern Canada. Forest inventory plots and maps produced by the Ministère des Ressources naturelles du Québec from 1970 to 2000 were used to characterize 606 ecological districts (average area 200 km2) according to three vegetation themes (tree species, forest types, and potential vegetation-successional stages) and four sets of explanatory variables (climate, physical environment, natural and human disturbances). Redundancy, cluster (K-means) and variation partitioning analyses were used to delineate, describe, and compare homogeneous vegetation landscapes. The resulting ELC is hierarchical with three levels of observation. Among the 14 homogeneous landscapes composing the most detailed level, some are dominated by relatively young forests originating from fires dating back to the period centered on 1921. In others, forest stands are older (fires from the period centered on 1851), some are under the influence of insect outbreaks and fires (southern part), while the rest are strongly affected by human activities and Populus tremuloides expansion. For all the study area and for parts of it, partitioning reveals that natural disturbance is the dominant data set explaining spatial variation in vegetation. However, the combination of natural disturbances, climate, physical environment and human disturbances always explains a high proportion of variation. Our approach, called "ecological land classification of homogeneous vegetation landscapes", is more comprehensive than previous ELCs in that it combines the concepts and goals of both landscape ecology and ecosystem-based management. © 2013 Springer Science+Business Media Dordrecht. Source

Dumais D.,Ministere des Ressources naturelles | Prevost M.,Ministere des Ressources naturelles
Tree Physiology

We examined the ecophysiology and growth of 0.3-1.3 m tall advance red spruce (Picea rubens Sarg.) and balsam fir (Abies balsamea [L.] Mill.) regeneration during a 5-year period following the application of different harvest types producing three sizes of canopy openings: (i) small gaps (<100 m2 in area; SMA) created by partial uniform single-tree harvest; (ii) irregular gaps of intermediate size (100-300 m2; INT) created by group-selection harvest (removal of groups of trees, mainly balsam fir, with uniform partial removal between groups); and (iii) large circular gaps (700 m2; LAR) created by patch-selection harvest (removal of trees in 30-m diameter circular areas with uniform partial removal between gaps). An unharvested control (CON) was monitored for comparison. At the ecophysiological level, we mainly found differences in light-saturated photosynthesis of red spruce and specific leaf area of balsam fir among treatments. Consequently, we observed good height growth of both species in CON and INT, but fir surpassed spruce in SMA and LAR. Results suggest that intermediate 100-300 m2 irregular openings create microenvironmental conditions that may promote short-term ecophysiology and growth of red spruce, allowing the species to compete with balsam fir advance regeneration. Finally, results observed for spruce in large 700-m2 openings confirm its inability to grow as rapidly as fir in comparable open conditions. © 2014 The Author. Source

Discover hidden collaborations