University of Northern British Columbia

www.unbc.ca/
Prince George, Canada

The University of Northern British Columbia is a small, primarily undergraduate university, the main campus of which is located in Prince George, British Columbia. UNBC also has regional campuses in the northern British Columbia cities of Prince Rupert, Terrace, Quesnel, and Fort St. John. The enabling legislation is the University of Northern British Columbia Act 1996. In the 2007–2008 academic year, 4,177 students were enrolled at UNBC.In 2007, the university obtained the trademark for "Canada's Green University". Because of its northern latitude, UNBC is a member of the University of the Arctic. Wikipedia.


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News Article | May 17, 2017
Site: www.nature.com

One building stands out in the old logging town of Prince George, Canada. Encased in a sleek glass facade, the structure towers above most of its neighbours, beckoning from afar with the warm amber glow of Douglas fir. Constructed almost entirely from timber in 2014, the 8-storey, 30-metre building is among the tallest modern wooden structures in the world. But it is more than an architectural marvel. As the home of the Wood Innovation and Design Centre at the University of Northern British Columbia (UNBC), it is also an incubator for wooden buildings of the future — and a herald for a movement that could help to tackle global warming. The building is less like a log cabin and more like a layered cake, constructed from wooden planks glued and pressed together, precision cut by factory lasers and then assembled on site. All told, the university avoided the release of more than 400 tonnes of carbon dioxide by eschewing energy-intensive concrete and steel, and the building locks up a further 1,100 tonnes of CO that was harvested from the atmosphere by British Columbian trees. In total, that's enough to offset the emissions from 160 households for a year. Wooden construction has ancient roots, but only in the past two decades have scientists, engineers and architects begun to recognize its potential to stave off global warming. By substituting concrete and steel with wood from sustainably managed forests, the building industry could curb up to 31% of global carbon emissions, according to research1 by Chad Oliver, a forest ecologist at Yale University in New Haven, Connecticut. In time, such a shift could help humanity to pull CO out of the atmosphere, potentially reversing the course of climate change. “It's the plywood miracle,” says Christopher Schwalm, an ecologist at Woods Hole Research Center in Falmouth, Massachusetts. “This is something that could have a significant impact on the riddle that is global environmental change.” The renaissance in tall wooden buildings is already under way. Norway set a world height record in late 2015 with a 52.8-metre tower block; that was edged out in September 2016 by a 53-metre student dormitory at the University of British Columbia in Vancouver. This year, Austria will take the lead with the 84-metre HoHo building in Vienna, comprising a hotel, apartments and offices. The United States saw its first tall wooden building go up in Minneapolis, Minnesota, in 2016, and others are in the works in Portland, Oregon, and in New York City. Wooden construction has attracted political interest in part because of the economic benefits for rural communities surrounded by forests. But turning these pioneering projects into a global trend won't be easy. Building costs are often high, and the global construction industry is almost entirely focused on concrete and steel, particularly when it comes to big buildings. And the climate benefits of building with wood hinge on a questionable assumption: that the world's forests will be managed sustainably. Some researchers worry that harvesting more timber could harm forest ecosystems, particularly in developing countries that are already plagued by poor and often illegal logging practices. “If we're going to cut wood, we've got to do it in a way that not only sustains the forest but also sustains the biodiversity and everything else,” says Oliver. Steel and concrete weren't an option when Buddhist monks set about building a 32-metre pagoda at the Learning Temple of the Flourishing Law in Ikaruga, Japan, 14 centuries ago. They put their faith in wood, as did the monks at the Sakyamuni Pagoda in Yingxian, China. Erected in 1056, that structure rises a staggering 67 metres towards the heavens. These pagodas are still standing today, a testament to the strength and durability of wood. Kilogram for kilogram, wood is stronger than both steel and concrete, and wooden buildings are generally good at withstanding earthquakes. But wood has developed a bad reputation over the centuries, because of catastrophic blazes that levelled cities such as London, New York and Chicago before modern fire-suppression strategies emerged. In fact, in case of fire wood maintains its structurally integrity much better than the non-flammable alternatives favoured by modern building codes. It chars at a predictable rate, and doesn't melt like steel or weaken like concrete. “The fact that it actually can withstand fire better than steel took a long time for people to realize,” says Guido Wimmers, who chairs a master's programme in wood engineering at UNBC. By some accounts, the modern era of tall wooden buildings began 20 years ago, with a simple experiment at the Technical University of Graz in Austria. Researchers glued layers of standard planks perpendicular to each other, and discovered that alternating the direction of the grain effectively negated the imperfections and weaknesses in any given plank. The result, known as cross-laminated timber, is a strong and lightweight wood panel that puts conventional plywood to shame. It can be made as large as desired and cut with sub-millimetre precision at the factory, which speeds up construction and reduces waste. And given the strength of these panels, there's no theoretical limit to how high wooden buildings can grow. “It transforms wood from a suburban material to a very urban material,” says Michael Green, the Vancouver-based architect behind UNBC's design centre, and a leading advocate for wooden construction. Wimmers says the initial goal of the technology was to make better use of low-grade wood products. “The wood construction industry was slowly vanishing, so they started to reinvent themselves,” he says. Then the market for advanced timber technologies — including beams that are either glued or nailed together to increase strength — expanded as European countries put strict regulations on energy efficiency and greenhouse-gas emissions, forcing architects to reduce the climate footprints of their buildings. Wimmers estimates that in Europe, wood is now used in about 25% of residential construction, up from 5–10% in the 1990s. The science of safety and engineering has also advanced. Douglas fir — the exposed layer at the UNBC centre — chars at 39 millimetres per hour. The provincial building code requires that the structure be able to endure at least one hour of fire on any given storey, so Green's team opted for floors made of a 5-layer panel that could afford to sacrifice a portion without losing its structural integrity. Meanwhile, Wimmers's team is collaborating on the Tall Wood Project, funded by the US National Science Foundation, to improve earthquake resistance for high wooden buildings. Work by the consortium has shown that the buildings can withstand earthquakes as well as or better than concrete and steel2, and the researchers will begin testing a two-storey wooden structure on a quake-simulator table at the University of California, San Diego, in June. They aim to test a ten-storey building there by 2020. Asif Iqbal, a civil engineer who is working on the project, came to UNBC from New Zealand, where he saw the damage from the 2011 earthquake in Christchurch at first hand. Most of the steel-reinforced concrete buildings in the city remained standing, but around 1,800 were irreparably damaged owing to cracked concrete and warped steel. Iqbal says that many of the replacement buildings are being constructed from wood, precisely because it is more likely to survive another major earthquake and the steel connectors can be replaced relatively easily if damaged. The long-term performance and economic viability of these buildings remains an open question. Wood is susceptible to mould and water damage, for example, and there is a higher risk of fire during construction. In September 2014, a £20-million (US$26-million) wooden sustainable-chemistry building being built at the University of Nottingham, UK, was destroyed by an electrical fire — in part because fire doors and windows were not yet in place to contain the blaze. Still, advocates say the future looks bright. “We are still fine-tuning wood technologies, but so far we haven't found any major issues that we cannot solve,” Iqbal says. One of the main attractions of wooden construction is its potential to help stave off global warming. Oliver's research1 suggests that humans currently harvest only 20% or so of the global forest growth each year, and more timber could be extracted without reducing the overall amount of carbon locked up in forests. The eventual climate impact of this harvest depends on the end use. If the wood were simply burned for energy, the CO that the tree had absorbed years earlier would immediately return to the atmosphere. Regrowing forests eventually pull that CO back out of the air, so the idea of carbon-neutral wood energy is a function of time. It is also controversial: some argue that current policies in Europe overstate the climate benefits of wood fuel and create perverse incentives to cut down trees. But this debate doesn't apply to wooden buildings. “Just the fact that you have solid wood means that you are keeping CO out of the atmosphere,” says Oliver. Aside from the carbon sequestered in the wood itself, wooden construction offers further emissions savings. When researchers tallied the environmental impact of UNBC's building, they accounted for the manufacture and transport of every material — right down to the fossil-fuel-derived glue that binds the plywood together. Overall, the emissions related to construction were 12% of those for an equivalent concrete building3, largely owing to differences in fossil-fuel use. “When you compare a wood building with a concrete building, wood wins every time,” says Jim Bowyer, an emeritus engineer at the University of Minnesota in St Paul. The UNBC building might have a uniquely low carbon footprint at the outset, but over time its environmental impact will grow as its heating, cooling and lighting requirements generate greenhouse-gas emissions. Day-to-day energy use and maintenance account for 80–90% of lifetime emissions for a typical building, and unfortunately the UNBC centre is no different. The consequence is that its long-term climate benefits are relatively modest. But the most advanced buildings today, which combine energy-efficient designs and technologies with on-site renewable energy generation, can eliminate emissions over the life of the structure. In such scenarios, construction and materials — the building's 'embodied emissions' — account for 100% of a building's climate impact, giving wood an increasingly important advantage. “We're moving towards really low-energy buildings,” says Jennifer O'Connor, president of the Athena Sustainable Materials Institute, a non-profit research organization in Ottawa. “Quite frankly, if we are going to make a difference, then we had better start looking at those embodied emissions.” The wooden-building movement is, for now, focused mostly on Europe and North America. In the United States, more than 80% of houses are already wood-based, says Bowyer. Yet with the nation's timber industry currently extracting roughly one-third of annual forest growth, there is capacity to expand wood construction in mid-rise commercial and industrial structures without reducing the volume of carbon that is locked up in forests. Bowyer is leading an expert assessment convened by the American Wood Council, an industry body in Leesburg, Virginia; the team has found that the United States could roughly double the amount of carbon that it sequesters in buildings each year, offsetting the emissions from nine additional coal-fired power plants. By contrast, builders in Europe still rely mostly on concrete and steel: a 2010 Finnish government report4 estimated that a mere 4% increase in annual wood use in construction throughout Europe would avoid 150 million tonnes of carbon emissions, almost as much as the Netherlands emits each year. But to have a truly global impact, the movement must expand to developing countries, where forest management remains a challenge. Forests across the tropics are already being pillaged for timber and razed for agriculture. Indonesia, for example, has struggled to halt the palm-oil industry's destruction of rainforests. And although Brazil has made huge improvements in forest management over the past decade, demand for beef and soya beans is once again boosting land-clearing in the Amazon. Some fear that wooden construction would mean more trouble for some of the world's most precious ecosystems. “I've seen enough abuses of what you would call the wood-product sector that I'm leery of sweeping solutions that make big assumptions,” says William Laurance, a tropical ecologist at James Cook University in Cairns, Australia. Oliver argues that the push for wooden construction could help developing countries to establish sustainable industries that actually protect forests, if they are pursued in parallel with efforts to bolster governance. The challenge is to ensure that managed forests maintain the full suite of crucial ecosystems, including old-growth habitat and forest clearings. “It should all be preplanned and transparent,” says Oliver. “That's kind of a utopia, but you've got to dream.” He is working with the United Nations Development Programme (UNDP) to design a comprehensive forest-management plan that would kick-start modern wooden construction in Turkey. Government figures indicate that the country erected 956 million square metres of building space between 2004 and 2014, and just 0.13% of that total was framed in wood. Yet 27% of the country is forested, and 7 million of Turkey's poorest citizens live in these areas, says Nuri Özbağdatlı, a forestry expert with the UNDP in Ankara. “We want to create a new value chain for wood,” he says. “It will start with the forest villages and end up with the construction sector.” As wooden construction matures, it will face one final challenge: what happens when a building is decommissioned and torn down. Buddhist pagodas may last for centuries, but the general assumption for many modern buildings — including UNBC's centre in Prince George — is that they will outlive their usefulness and be replaced in several decades. If the wood is dumped into landfill and left to rot, its carbon will slowly leak back into the atmosphere. But if the wood is recycled — reused in future construction projects, for example — then the climate benefits are locked in. Advocates of wood are pushing long-term strategies that promote recycling and other carbon-neutral options, but Green isn't too worried about the longevity of his building. Properly maintained, he says, there's no reason why it can't last as long as a Buddhist pagoda. Instead, he's focusing on getting this budding industry off the ground through a free online training course that will be translated into 30 languages, giving anybody with an interest — from architects and engineers to builders, developers and government officials — a more technical understanding of wooden construction. “We need to globalize the conversation,” Green says. “This is the only hope of accelerating this to be competitive with concrete and steel, which have a 150-year head start.”


News Article | May 29, 2017
Site: marketersmedia.com

VANCOUVER, B.C. / ACCESSWIRE / MAY 29, 2017 / Canadian Zeolite Corp. (the “Company”) (TSX.V: CNZ) (OTCQB: CNZCF) (FSE: ZEON) is pleased to announce that it has commenced the 2017 shipping season with a new Distribution Agreement with Shift Supplies Ltd. as a Canadian distributor of the Company's natural zeolite product line. Shift Supplies Ltd. brings a proven marketing team as well as a well-established customer base that spans from British Columbia to Ontario. From their 12,000 square foot facility in British Columbia and their warehouse in Ontario they are well-positioned to supply smaller dealers with our Z-Lite 2% Animal Feed, animal bedding products and packaged zeolite for composting and soil remediation. Shift's larger customers will be shipped directly from the Kamloops mill. The agreement with Shift is a direct result of our successful natural zeolite distribution relationship with Bella Turf www.bellaturf.ca. We would like to thank the Bella Turf team for their continued business and this new opportunity. Mr. Ray Paquette, CEO says, "Over the winter months the Company's Bromley Creek natural zeolite received approval from the Canadian Food Inspection Agency (CFIA) for Z-Lite 2% as an animal feed additive. In the United States the product is also currently registered for use in 14 states. In addition, Z-Lite has been registered by the Organic Materials Review Institute (OMRI) in both Canada and the United States. These registrations provide us with an expanded customer base as well as credibility that our zeolite has been tested and proven to supply their markets. These registrations gave the Company the ability to conduct real-time testing with large end-users in Canada and the United States. Our natural zeolite has proven effective for their applications and as a result we are now starting to receive orders." Canadian Zeolite continues to work closely with the University of Havana in Cuba and the University of Northern British Columbia on product development, new technologies and future business opportunities. On behalf of the Board of Directors "Ray Paquette" President & CEO 604.684.3301 www.canadianzeolite.com Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release. Some statements in this news release contain forward-looking information. These statements include, but are not limited to, statements with respect to future expenditures. These statements address future events and conditions and, as such, involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the statements. Such factors include, among others, the ability to complete contemplated work programs and the timing and amount of expenditures. Canadian Zeolite does not assume the obligation to update any forward-looking statement. VANCOUVER, B.C. / ACCESSWIRE / MAY 29, 2017 / Canadian Zeolite Corp. (the “Company”) (TSX.V: CNZ) (OTCQB: CNZCF) (FSE: ZEON) is pleased to announce that it has commenced the 2017 shipping season with a new Distribution Agreement with Shift Supplies Ltd. as a Canadian distributor of the Company's natural zeolite product line. Shift Supplies Ltd. brings a proven marketing team as well as a well-established customer base that spans from British Columbia to Ontario. From their 12,000 square foot facility in British Columbia and their warehouse in Ontario they are well-positioned to supply smaller dealers with our Z-Lite 2% Animal Feed, animal bedding products and packaged zeolite for composting and soil remediation. Shift's larger customers will be shipped directly from the Kamloops mill. The agreement with Shift is a direct result of our successful natural zeolite distribution relationship with Bella Turf www.bellaturf.ca. We would like to thank the Bella Turf team for their continued business and this new opportunity. Mr. Ray Paquette, CEO says, "Over the winter months the Company's Bromley Creek natural zeolite received approval from the Canadian Food Inspection Agency (CFIA) for Z-Lite 2% as an animal feed additive. In the United States the product is also currently registered for use in 14 states. In addition, Z-Lite has been registered by the Organic Materials Review Institute (OMRI) in both Canada and the United States. These registrations provide us with an expanded customer base as well as credibility that our zeolite has been tested and proven to supply their markets. These registrations gave the Company the ability to conduct real-time testing with large end-users in Canada and the United States. Our natural zeolite has proven effective for their applications and as a result we are now starting to receive orders." Canadian Zeolite continues to work closely with the University of Havana in Cuba and the University of Northern British Columbia on product development, new technologies and future business opportunities. On behalf of the Board of Directors "Ray Paquette" President & CEO 604.684.3301 www.canadianzeolite.com Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release. Some statements in this news release contain forward-looking information. These statements include, but are not limited to, statements with respect to future expenditures. These statements address future events and conditions and, as such, involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the statements. Such factors include, among others, the ability to complete contemplated work programs and the timing and amount of expenditures. Canadian Zeolite does not assume the obligation to update any forward-looking statement.


News Article | May 29, 2017
Site: www.accesswire.com

VANCOUVER, B.C. / ACCESSWIRE / MAY 29, 2017 / Canadian Zeolite Corp. (the “Company”) (TSX.V: CNZ) (OTCQB: CNZCF) (FSE: ZEON) is pleased to announce that it has commenced the 2017 shipping season with a new Distribution Agreement with Shift Supplies Ltd. as a Canadian distributor of the Company's natural zeolite product line. Shift Supplies Ltd. brings a proven marketing team as well as a well-established customer base that spans from British Columbia to Ontario. From their 12,000 square foot facility in British Columbia and their warehouse in Ontario they are well-positioned to supply smaller dealers with our Z-Lite 2% Animal Feed, animal bedding products and packaged zeolite for composting and soil remediation. Shift's larger customers will be shipped directly from the Kamloops mill. The agreement with Shift is a direct result of our successful natural zeolite distribution relationship with Bella Turf www.bellaturf.ca. We would like to thank the Bella Turf team for their continued business and this new opportunity. Mr. Ray Paquette, CEO says, "Over the winter months the Company's Bromley Creek natural zeolite received approval from the Canadian Food Inspection Agency (CFIA) for Z-Lite 2% as an animal feed additive. In the United States the product is also currently registered for use in 14 states. In addition, Z-Lite has been registered by the Organic Materials Review Institute (OMRI) in both Canada and the United States. These registrations provide us with an expanded customer base as well as credibility that our zeolite has been tested and proven to supply their markets. These registrations gave the Company the ability to conduct real-time testing with large end-users in Canada and the United States. Our natural zeolite has proven effective for their applications and as a result we are now starting to receive orders." Canadian Zeolite continues to work closely with the University of Havana in Cuba and the University of Northern British Columbia on product development, new technologies and future business opportunities. On behalf of the Board of Directors "Ray Paquette" President & CEO 604.684.3301 www.canadianzeolite.com Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release. Some statements in this news release contain forward-looking information. These statements include, but are not limited to, statements with respect to future expenditures. These statements address future events and conditions and, as such, involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the statements. Such factors include, among others, the ability to complete contemplated work programs and the timing and amount of expenditures. Canadian Zeolite does not assume the obligation to update any forward-looking statement. SOURCE: Canadian Zeolite Corp.


Margulis M.E.,University of Northern British Columbia
Global Governance | Year: 2013

Recurrent food price crises, coupled with the steady deterioration of world food security over the past two decades, have prompted efforts to reform the global governance of food security. This article argues that diverging rules and norms across the elemental regimes of agriculture and food, international trade, and human rights over the appropriate role of states and markets in addressing food insecurity are a major source of transnational political conflict. It analyzes (1) the role of norms in the construction of the international food security regime; (2) the transition from an international food security regime to a regime complex for food security; and (3) rule and norm conflicts within this regime complex. It concludes with a discussion of the impacts of diverging norms on the politics of regime complexity and its policy implications for current efforts to reform the global governance of food security. © 2013 Lynne Rienner Publishers, Inc.


Haeussler S.,University of Northern British Columbia
Environmental Reviews | Year: 2011

Biogeoclimatic ecosystem classification (BEC) has underpinned terrestrial ecosystem management and conservation planning in British Columbia, Canada since the early 1970s, serving the province well for over 40 years as expectations for the use and management of the public land base have evolved. The system is now critically challenged because (1) BEC champions in government, academia, and the private sector are disappearing through retirement and layoffs; (2) BEC is based on outdated notions of climax ecosystems in equilibrium with climate; and (3) the contemporary relevance and intellectual richness of this approach to ecosystem science is not comprehended by a generation of scientists and resource managers grappling with accelerating rates of change in climate and other environmental drivers. This review addresses ways to ensure that BEC remains robust and useful in an uncertain future. The Author proposes that BEC embrace complex systems science. Through a dialectical analysis of alternative paradigms in ecology, it is argued that BEC's holistic, developmental view of terrestrial ecosystems is fundamentally compatible with complexity theory and provides the information content missing from contemporary ecosystem ecology. Two examples of nonlinear modelling (adaptive landscapes and agent-based) to illustrate how the classification system can adapt from a largely linear and equilibrium, to a nonlinear, nonequilibrium perspective of ecosystem dynamics. The BEC program itself must function as a complex adaptive system to survive government downsizing and guide ecosystem management during difficult times, and to challenge and enlighten a new generation of scientists and citizens. © 2011 Published by NRC Research Press.


Johnson C.J.,University of Northern British Columbia
Biological Conservation | Year: 2013

Increasingly, conservation professionals and regulatory agencies are attempting to identify ecological thresholds that define a point at which populations or communities demonstrate a marked response to human disturbance. Such thresholds may serve as the foundation for recognizing and then imposing limits on the levels of disturbance or types of land use. Although an intuitive concept, I argue that there are numerous scientific and practical limitations to applying ecological thresholds to conservation decision making. First, the concept is limited by the lack of a clear and universally accepted definition. Often, a threshold is defined as the point at which a population demonstrates a nonlinear ecological or biological response to some critical level of disturbance. Alternative definitions are premised on different trajectories of response or a direct recognition of conservation risks when prioritising socioeconomic values. Second, there is no clear or consistent method for identifying ecological thresholds including the appropriate response variables. Third, there is little evidence to suggest that ecological thresholds generalize to other species or populations; this limits the efficiency of thresholds as a decision making tool. Fourth, even where ecological thresholds are identified for the purpose of regulation or conservation planning, there are few examples of effective implementation. In comparison, regulatory limits are premised on the ecological response of populations to disturbance, but also consider the socioeconomic realities of conservation decision making including the risk associated with greater levels of development. Limits can be identified through participatory decision making processes that allow a consideration of potential future conditions within the context of current ecological and economic circumstances. When followed with long-term monitoring, regulatory limits can improve existing or provide new avenues for conservation planning and regulation. © 2013 Elsevier Ltd.


Gingerich A.,University of Northern British Columbia
Academic medicine : journal of the Association of American Medical Colleges | Year: 2011

Measurement errors are a limitation of using rater-based assessments that are commonly attributed to rater errors. Solutions targeting rater subjectivity have been largely unsuccessful. This critical review examines investigations of rater idiosyncrasy from impression formation literatures to ask new questions for the parallel problem in rater-based assessments. Raters may form categorical judgments about ratees as part of impression formation. Although categorization can be idiosyncratic, raters tend to consistently construct one of a few possible interpretations of each ratee. If raters naturally form categorical judgments, an assessment system requiring ordinal or interval ratings may inadvertently introduce conversion errors due to translation techniques unique to each rater. Potential implications of raters forming differing categorizations of ratees combined with the use of rating scales to collect categorical judgments on measurement outcomes in rater-based assessments are explored.


Dale M.R.T.,University of Northern British Columbia | Fortin M.-J.,University of Toronto
Annual Review of Ecology, Evolution, and Systematics | Year: 2010

Graph theory is a powerful body of mathematical knowledge, based on simple concepts, in which structural units are depicted as nodes with relationships between them depicted as lines. The nodes may have qualitative and quantitative characteristics, and the edges may have properties such as weights and directions. Graph theory provides a flexible conceptual model that can clarify the relationship between structures and processes, including the mechanisms of configuration effects and compositional differences. Graph concepts apply to many ecological and evolutionary phenomena, including interspecific associations, spatial structure, dispersal in landscapes, and relationships within metapopulations and metacommunities. We review applications of graph theory in biology, emphasizing graphs with spatial contexts. We show how spatial graph properties can be used for description and comparison as well as to test specific hypotheses. We suggest that future applications should include explicit spatial elements for landscape studies of ecological, genetic and epidemiological phenomena. Copyright © 2010 by Annual Reviews. All rights reserved.


Debela F.,University of Northern British Columbia
Chemosphere | Year: 2010

The long-term stability of pyromorphite [Pb(5)(PO(4))(3)Cl] (PY) in root-soil interface (or rhizosphere) where production of organic acids from biological activities takes place is not fully understood. We conducted a 1-year long laboratory batch dissolution experiment to elucidate the release of Pb (and P) from PY by four commonly occurring low molecular weight organic acids (LMWOA) in rhizosphere: acetic, citric, malic and oxalic acid. Mean maximum amount of Pb in milliQ (mQ) water (1.8microM) was lower than in solutions from LMWOA alone or in combination with each other (i.e., mixed acid). However, there was no significant difference in the amount of Pb (and P) in solution in all treatments including mQ water after 6months. Among the 100microM LMWOA, mean of five highest soluble Pb (muM Pb in solution) followed the order: oxalic acid (17.6)>citric (6.2)>malic (5.6)>acetic acid (3.0microM Pb). Mixed acid solution had a maximum amount of 14.0microM Pb. We calculated a range of solubility product constant (K(sp)) of PY in this study from 8.6x10(-54) (mQ) to 7.0x10(-45)(oxalic acid); these values are within the range of PY K(sp) reported elsewhere. Despite the low K(sp) values, LMWOA-induced released Pb from PY are in concentrations higher than both Canadian and international drinking water and agricultural water use quality standards. This suggests that soil organic acids such as in rhizosphere can potentially liberate Pb from PY in contaminated soils.


Garcia O.,University of Northern British Columbia
Canadian Journal of Forest Research | Year: 2013

A biologically inspired whole-stand growth and yield model was developed for even-aged thinned or unthinned stands dominated by trembling aspen (Populus tremuloides Michx.). The estimation used permanent sample plot data from British Columbia, Alberta, Saskatchewan, and Manitoba, supplemented by published site index and young stand information. An ingrowth imputation procedure was devised to facilitate the use of plot measurements where small trees are not measured. Two published site index models were closely approximated by a simple age-base invariant equation. Good parameter estimates for mortality and basal area growth were obtained without using age observations, which were unreliable or missing. Four differential equations describe the dynamics of top height, trees per hectare, basal area, and a site occupancy factor. Current values of these variables are used to estimate total and merchantable volumes up to any diameter limit and diameter distribution parameters. When an independent source of site quality estimates is available, the final model does not require stand age knowledge for making growth and yield predictions.

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