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Stoffel M.,University of Bern | Stoffel M.,University of Geneva | Wilford D.J.,British Columbia Ministry of Natural Resource Operations
Earth Surface Processes and Landforms

Riparian vegetation and hydrogeomorphic processes are intimately connected parts of upland catchment and fan environments. Trees, shrubs and grasses and hydrogeomorphic processes interact and depend on each other in complex ways on the hillslopes, channels and cone-shaped fans of torrential watersheds. While the presence and density of vegetation have a profound influence on hydrogeomorphic processes, the occurrence of the latter will also exert control on the presence, vitality, species, and age distribution of vegetation. This contribution aims at providing a review of foundational and more recent work on the dependencies and interactions between hydrogeomorphic processes and vegetation. In particular, we address the role of vegetation in the initiation of hydrogeomorphic processes and its impact on stream morphology as well as immediate and long-term effects of hydrogeomorphic disturbance on vegetation. © 2011 John Wiley & Sons, Ltd. Source

White C.A.,Parks Canada Agency | Perrakis D.D.B.,British Columbia Ministry of Natural Resource Operations | Kafka V.G.,Parks Canada Agency | Ennis T.,Nature Conservancy of Canada
Fire Ecology

Currently, high intensity, large-area lightning fires that burn during droughts dominate Canada's fire regimes. However, studies from several disciplines clearly show that humans historically ignited burns within this matrix of large fires. Two approaches for fire research and management have arisen from this pattern: a "large-fire biophysical paradigm" related to lightning-ignited fires, and an "eco-cultural paradigm" related to human-caused burning. Working at the edge between biophysically driven fires and eco-cultural burns, and their associated management and research paradigms, presents unique challenges to land managers. We proceed by describing fire frequency trends across Canada, and how an interaction between changing climatic and cultural factors may provide better causal explanations for observed patterns than either group of factors alone. We then describe four case histories of fire restoration into Canadian landscapes moving through evolution, or deliberate intent, towards increasing emphasis on an eco-cultural paradigm. We show that use of cultural burns maintains this facet of the long-term regime while providing greater capacity for larger, higher intensity fires to occur with fewer negative ecological and socio-economic implications. Key lessons learned by practitioners restoring fire to landscapes include: 1) fire is only one process in ecosystems that also include other complex interactions, and thus restoration of fire alone could have unintended consequences in some ecosystems; 2) recognizing long-term human roles of not only fire managers, but also hunters and gatherers is critical in restoration programs; and 3) this diversity of past, present, and future ecological and cultural interactions with fire can link managers to a broad constituency of stakeholders. Bringing this variety of people and interests into the decision-making processes is a necessary pre-requisite to successful fire management at the edge. Source

Woods A.,British Columbia Ministry of Natural Resource Operations
Canadian Journal of Plant Pathology

Over 14 million hectares of lodgepole pine-dominated forests in British Columbia (BC), Canada, have been severely impacted by the current mountain pine beetle epidemic. Simultaneously, a Dothistroma needle blight epidemic in northwest BC has been responsible for killing thousands of hectares of pine plantations and has even resulted in the death of mature trees, which is unprecedented. Both of these globally significant forest pest epidemics have been linked to climate change. The beetle epidemic has grossly exceeded the scale of all previously recorded outbreaks, in large part due to a lack of cold winters. In this sense, the link to global warming is relatively straightforward and foreseeable. Of all climate change projections, the prediction of an increase in winter temperatures has been associated with as high a degree of confidence as any. The Dothistroma needle blight epidemic and its link to climate change were not so predictable. Based on weather records over the past four decades, short-term increases in mean summer precipitation correlate closely with historical records of Dothistroma outbreaks in the northwest. The current most severe outbreak has occurred during a prolonged period of above-average summer precipitation. An increase in summer precipitation would more typically be thought of as beneficial for forests, but that increase in moisture has improved the conditions for a pathogen that has outweighed any benefits. Similar trends of increasing incidence and severity for other forest pathogens in BC appear in areas that have been receiving increased summer precipitation. Conversely, in the southern interior of the province decreased summer precipitation and increased drought conditions are resulting in stressed trees which can favour root diseases. Early indications are that climate change will have profound effects on forest health. Some effects will be more predictable than others. © 2011 The Canadian Phytopathological Society. Source

McLellan M.L.,Columbia Mountains Caribou Project | Serrouya R.,University of Alberta | McLellan B.N.,British Columbia Ministry of Natural Resource Operations | Furk K.,Columbia Mountains Caribou Project | And 2 more authors.

Both top-down and bottom-up processes influence herbivore populations, and identifying dominant limiting factors is essential for applying effective conservation actions. Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou) that have been declining, and unsustainable predation has been identified as the proximate cause. To investigate the role of poor nutrition, we examined the influence of sex, season, age class, and available suitable habitat (i. e., old-growth forest >140 years) per caribou on bone marrow fat content of caribou that died (n = 79). Sex was the only strong predictor of marrow fat. Males that died during and post rut had lower marrow fat than females or males at other times of year. Old-growth abundance per caribou, season, and age class did not predict marrow fat. Caribou killed by predators did not have less marrow fat than those that died in accidents, suggesting that nutritionally stressed caribou were not foraging in less secure habitats or that predators selected nutritionally stressed individuals. Marrow fat in endangered and declining populations of mountain caribou was similar to caribou in other, more viable populations. Our results support previous research suggesting that observed population declines of mountain caribou are due to excessive predation that is not linked to body condition. © 2011 Springer-Verlag. Source

Cleary M.R.,British Columbia Ministry of Natural Resource Operations | Cleary M.R.,Natural Resources Canada | Holmes T.,British Columbia Ministry of Natural Resource Operations | Holmes T.,Natural Resources Canada
IAWA Journal

Anatomical changes involved in traumatic phloem resin duct (TPRD) formation in western redcedar (Thuja plicata) roots were examined following abiotic wounding and fungal invasion by Armillaria ostoyae. Following necrophylactic periderm formation, hyperplasia and expansion of a band of phloem parenchyma cells occurred in close proximity to the vascular cambium and schizogenous and lysigenous separation of its derivatives resulted in a series of longitudinal resin ducts in the inner to mid-phloem region. Fungal invasion appeared to amplify traumatic resin duct formation in the phloem. While traumatic cavities in the phloem have been reported for other Cupressaceae, this is the first report documenting TPRD formation in western redcedar. Source

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