ERA

Journal Articles (Renewable Resources)

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  1. Prescribed fire as a tool to regenerate live and dead serotinous jack pine (Pinus banksiana) stands [Download]

    Title: Prescribed fire as a tool to regenerate live and dead serotinous jack pine (Pinus banksiana) stands
    Creator: Sharpe, Maria
    Description: This study documents cone opening and natural regeneration of jack pine (Pinus banksiana Lamb.) after burning live and dead stands similar to those killed by the mountain pine beetle (Dendroctonus ponderosae). Trees were killed by girdling in May and were burned in late July, 26 months later. Pairs of live and dead plots were simultaneously burned using three types of fire: surface, intermittent crown and continuous crown fires. Each type of fire was replicated three times; the nine pairs of burns were completed in a 4-day period. After fire, more cones were opened on dead trees than live trees. On dead trees, there was cone opening even when fire charred only the lower part of the bole. Three years after burning, dead stands with continuous crown fires had some of the densest regeneration and the highest rates of stocking. Across all burns in this study, seedling regeneration was best in shallow residual duff and in the more intensely burned plots. Without burning, there was virtually no regeneration 5 years after mortality. The results also show that burning, especially under continuous crown fire, could be used to promote regeneration in dead stands.
    Subjects: Mountain Pine Beetle, Serotiny, Precribed Fire, Jack Pine
    Date Created: 2017
  2. Diversity of Carabidae (Insecta, Coleoptera) in Epiphytic Bromeliaceae in Central Veracruz, Mexico [Download]

    Title: Diversity of Carabidae (Insecta, Coleoptera) in Epiphytic Bromeliaceae in Central Veracruz, Mexico
    Creator: de Oca, E.M.
    Description: This paper documents the existence of carabid assemblages associated with bromeliads on the Cofre de Perote, Veracruz, Mexico. Based on bromeliads sampled over three altitudinal ranges, the assemblages included at least 26 species with an arboreal lifestyle and another 11 species that are not strictly arboreal. Seven species are new to science, urging us to pay attention to the arboreal fauna in forest conservation studies. Composition of carabid assemblages associated with bromeliads changes with altitude. In lowlands, it is comprised almost entirely of species of Lebiini, with the Platynini dominating assemblages found in bromeliads >1,000 m above sea level. Our data suggest that carabids use bromeliads to reduce stresses associated with drought periods, the exact timing of which depends on altitude. The unexpected low diversity of the carabid fauna associated with bromeliads at middle altitude is explained in terms of anthropogenic conversion of the original forest to pastureland. Given the importance of arboreal elements, further fragmentation of subtropical and tropical mountain forest significantly threatens overall carabid diversity.
    Subjects: Carabids, Bromeliads, Diversity, Altitude, Mexico
    Date Created: 2007
  3. Scale-dependent controls on the area burned in the boreal forest of Canada, 1980-2005 [Download]

    Title: Scale-dependent controls on the area burned in the boreal forest of Canada, 1980-2005
    Creator: Parisien, M.A.
    Description: In the boreal forest of North America, as in any fire-prone biome, three environmental factors must coincide for a wildfire to occur: an ignition source, flammable vegetation, and weather that is conducive to fire. Despite recent advances, the relative importance of these factors remains the subject of some debate. The aim of this study was to develop models that identify the environmental controls on spatial patterns in area burned for the period 1980-2005 at several spatial scales in the Canadian boreal forest. Boosted regression tree models were built to relate high-resolution data for area burned to an array of explanatory variables describing ignitions, vegetation, and long-term patterns in fire-conducive weather (i.e., fire climate) at four spatial scales (10(2) km(2), 10(3) km(2), 10(4) km(2), and 10(5) km(2)). We evaluated the relative contributions of these controls on area burned, as well as their functional relationships, across spatial scales. We also assessed geographic patterns of the influence of wildfire controls. The results indicated that extreme temperature during the fire season was a top control at all spatial scales, followed closely by a wind-driven index of ease of fire spread. However, the contributions of some variables differed substantially among the spatial scales, as did their relationship to area burned. In fact, for some key variables the polarity of relationships was inverted from the finest to the broadest spatial scale. It was difficult to unequivocally attribute values of relative importance to the variables chosen to represent ignitions, vegetation, and climate, as the interdependence of these factors precluded clear partitioning. Furthermore, the influence of a variable on patterns of area burned often changed enormously across the biome, which supports the idea that fire-environment relationships in the boreal forest are complex and nonstationary.
    Subjects: Area burned, Climate, Canadian boreal forest, Ignitions, Spatial scale, Boosted regression trees, Topography, Vegetation, Wildfire, Regression modeling
    Date Created: 2011
  4. Boreal forest CO2 exchange and evapotranspiration predicted by nine ecosystem process models: Inter-model comparisons and relationships to field measurements [Download]

    Title: Boreal forest CO2 exchange and evapotranspiration predicted by nine ecosystem process models: Inter-model comparisons and relationships to field measurements
    Creator: Amthor, J.S.
    Description: Nine ecosystem process models were used to predict CO2 and water vapor exchanges by a 150-year-old black spruce forest in central Canada during 1994-1996 to evaluate and improve the models. Three models had hourly time steps, five had daily time steps, and one had monthly time steps. Model input included site ecosystem characteristics and meteorology. Model predictions were compared to eddy covariance (EC) measurements of whole-ecosystem CO2 exchange and evapotranspiration, to chamber measurements of nighttime moss-surface CO2 release, and to ground-based estimates of annual gross primary production, net primary production, net ecosystem production (NEP), plant respiration, and decomposition. Model-model differences were apparent for all variables. Model-measurement agreement was good in some cases but poor in others. Modeled annual NEP ranged from -11 g C m(-2) (weak CO2 source) to 85 g C m(-2) (moderate CO2 sink). The models generally predicted greater annual CO2 sink activity than measured by EC, a discrepancy consistent with the fact that model parameterizations represented the more productive fraction of the EC tower \"footprint.\" At hourly to monthly timescales, predictions bracketed EC measurements so median predictions were similar to measurements, but there were quantitatively important model-measurement discrepancies found for all models at subannual timescales. For these models and input data, hourly time steps (and greater complexity) compared to daily time steps tended to improve model-measurement agreement for daily scale CO2 exchange and evapotranspiration (as judged by root-mean-squared error). Model time step and complexity played only small roles in monthly to annual predictions.
    Subjects: Climate variability, Land-surface scheme, Soil, Net primary production, Photosynthesis model, Black spruce forest, General-model, Jack pine forest, Atmospheric carbon-dioxide, Regional applications
    Date Created: 2001
  5. Spring flowering response to climate change between 1936 and 2006 in Alberta, Canada [Download]

    Title: Spring flowering response to climate change between 1936 and 2006 in Alberta, Canada
    Creator: Beaubien, E.
    Description: Abstract: In documenting biological responses to climate change, the Intergovernmental Panel on Climate Change has used phenology studies from many parts of the world, but data from the high latitudes of North America are missing. In the present article, we evaluate climate trends and the corresponding changes in sequential bloom times for seven plant species in the central parklands of Alberta, Canada (latitude 52 degrees-57 degrees north). For the study period of 71 years (1936-2006), we found a substantial warming signal, which ranged from an increase of 5.3 degrees Celsius (degrees C) in the mean monthly temperatures for February to an increase of 1.5 degrees C in those for May. The earliest-blooming species' (Populus tremuloides and Anemone patens) bloom dates advanced by two weeks during the seven decades, whereas the later-blooming species' bloom dates advanced between zero and six days. The early-blooming species' bloom dates advanced faster than was predicted by thermal time models, which we attribute to decreased diurnal temperature fluctuations. This unexpectedly sensitive response results in an increased exposure to late-spring frosts.
    Subjects: Flowering, Canada, Global warming, Phenology, Climate change
    Date Created: 2011
  6. The soil microbial community and grain micronutrient concentration of historical and modern hard red spring wheat cultivars grown organically and conventionally in the Black soil zone of the Canadian prairies [Download]

    Title: The soil microbial community and grain micronutrient concentration of historical and modern hard red spring wheat cultivars grown organically and conventionally in the Black soil zone of the Canadian prairies
    Creator: Nelson, A. G.
    Description: Abstract: Micronutrient deficiencies in the diet of many people are common and wheat is a staple food crop, providing a carbohydrate and micronutrient source to a large percentage of the world’s population. We conducted a field study to compare five Canadian red spring wheat cultivars (released over the last century) grown under organic and conventional management systems for yield, grain micronutrient concentration, and soil phospholipid fatty acid (PLFA) profile. The organic system had higher grain Zn, Fe, Mg and K levels, but lower Se and Cu levels. There was no trend in the results to suggest that modern western Canadian hard red spring cultivars have lower grain micronutrient content than historical cultivars. Wheat cultivar choice is important for maximizing grain nutrient levels, which was influenced by management system. It is evident that the emphasis on elevated grain quality in the western Canadian hard red spring class has resulted in the retention of micronutrient quality characters. Three fungal PLFAs were indicators for the organic system, and all three of these indicators were positively correlated with grain Cu concentration. In the organic system, percent arbuscular mycorrhizal fungi were negatively correlated with grain Zn and Fe concentrations, and positively correlated with grain Mn, Cu, K concentrations and grain yield. The organic system had higher levels of fungi in the soil, including arbuscular mycorrhizal fungi. Organic management practices appear to result in elevated levels of grain micronutrient concentration. The hard red spring breeding effort in and for the black soil zone of the northern Great Plains also appears to have led to no diminishment of grain micronutrient concentration. It is evident that both the agronomic system and breeding strategies in this region can be exploited for future increases in grain micronutrient concentration.
    Subjects: Micronutrients, Phospholipid fatty acid analysis, Triticum aestivum L., Arbuscular mycorrhizal fungi, Antioxidants, Conventional agriculture, Organic agriculture
    Date Created: 2011
  7. Net ecosystem productivity of temperate and boreal forests after clearcutting - a Fluxnet-Canada measurement and modelling synthesis [Download]

    Title: Net ecosystem productivity of temperate and boreal forests after clearcutting - a Fluxnet-Canada measurement and modelling synthesis
    Creator: Grant, R. F.
    Description: Abstract: Clearcutting strongly affects subsequent forest net ecosystem productivity (NEP). Hypotheses for ecological controls on NEP in the ecosystem model ecosys were tested with CO(2) fluxes measured by eddy covariance (EC) in three post-clearcut conifer chronosequences in different ecological zones across Canada. In the model, microbial colonization of postharvest fine and woody debris drove heterotrophic respiration (R(h)), and hence decomposition, microbial growth, N mineralization and asymbiotic N(2) fixation. These processes controlled root N uptake, and thereby CO(2) fixation in regrowing vegetation. Interactions among soil and plant processes allowed the model to simulate hourly CO(2) fluxes and annual NEP within the uncertainty of EC measurements from 2003 to 2007 over forest stands from 1 to 80 yr of age in all three chronosequences without site- or species-specific parameterization. The model was then used to study the impacts of increasing harvest removals on subsequent C stocks at one of the chronosequence sites. Model results indicated that increasing harvest removals would hasten recovery of NEP during the first 30 yr after clearcutting, but would reduce ecosystem C stocks by about 15% of the increased removals at the end of an 80-yr harvest cycle.
    Subjects: Douglas-fir stand, British Columbia, Spruce stands, Carbon-dynamics, Norway spruce, Vancouver Island, Coarse woody debris, Old-growth, Southern Finland, Scots pine forests
    Date Created: 2010
  8. A 15,800-year record of atmospheric lead deposition on the Devon Island Ice Cap, Nunavut, Canada: Natural and anthropogenic enrichments, isotopic composition, and predominant sources [Download]

    Title: A 15,800-year record of atmospheric lead deposition on the Devon Island Ice Cap, Nunavut, Canada: Natural and anthropogenic enrichments, isotopic composition, and predominant sources
    Creator: Zheng, J.
    Description: Abstract: Using appropriate clean methods for handling and preparation, 57 ice samples from the Devon Island Ice Cap, representing the period 134 to 15,800 years before present (BP), were analyzed for Pb, Sc, and Pb isotopes (Pb-206, Pb-207, Pb-208) using ICP-SMS. The greatest Pb concentrations were found in samples dating from the Younger Dryas. Despite the large range in Pb concentrations (from 2.2 to 181 pg g(-1)), the Pb concentrations were proportional to those of Sc until 3100 BP when the Pb/Sc ratio exceeded by a factor of 2 the natural \"background\" value (Pb/Sc = 6.3 +/- 1.8) for the first time. The uniform ratio of Pb to Sc until 3100 BP is consistent with the hypothesis that soil dust particles derived from physical and chemical weathering dominate the inputs of Pb to the atmosphere, with the magnitude of these sources climate-dependent. Isotopic analyses of Pb further support this paradigm, with the average ratio of Pb-206/Pb-207 (1.230) and Pb-208/Pb-206 (2.059) well within the range given for the Upper Continental Crust (UCC). The shift to higher Pb/Sc ratios and lower Pb-206/Pb-207 values starting at 3100 BP is consistent with historical records and other archival evidence of the onset of atmospheric Pb contamination caused by Pb mining and smelting in the Iberian Peninsula. Since that time, the Devon Island ice core records several other episodes of notable atmospheric Pb contamination, including those dating from Roman and medieval times, as well as the industrial period. The Pb, Sc, and Pb isotope data presented here represent the first chemical and isotopic record of the natural, \"background\" atmospheric inputs to the Canadian Arctic, against which modern values may be compared.
    Subjects: Swedish lake sediments, Antarctic Ice, Trace-element, Northern hemisphere, Heavy-metals, C-14 YR BP, Ellesmere-Island, Central Greenland, Peat bog, Environmental impact
    Date Created: 2007
  9. Secondary ion mass spectrometry (SIMS) and its application to chemical weathering [Download]

    Title: Secondary ion mass spectrometry (SIMS) and its application to chemical weathering
    Creator: Shotyk, W.
    Description: Abstract: Secondary ion mass spectrometry (SIMS) is the mass spectrometry of atomic species which are emitted when a solid surface is bombarded by an energetic primary ion beam. By continually bombarding the surface of the sample with the ion beam, the atoms making up the material being studied are sputtered away. The secondary ions emitted from the surface are continually analyzed and their intensities recorded over time. The secondary ion intensities are proportional to the concentration of elements in the sample, thereby producing a semiquantitative concentration depth profile. The depth profile provides an illustration of the chemical composition of a sample as a function of depth through the surface. The SIMS technique has been applied to a wide variety of surface analytical problems and can easily be used to analyze reacted glass and mineral surfaces which have been exposed to weathering solutions. Traditional experimental studies of chemical weathering were based primarily on the analyses of aqueous solutions generated during leaching experiments. Such studies have provided valuable information concerning rates and stoichiometry of mineral dissolution reactions but have led to some confusion and much speculation regarding the mechanisms of surface processes. SIMS analyses of the surfaces of dissolving glasses and plagioclase feldspars have recently been used to help resolve a number of unanswered questions. For example, SIMS analyses of dissolving feldspars have shown how the chemical COMPosition of reacted surfaces and depth of attack vary, depending on the composition of the mineral, the pH of the leaching solution, and the presence of dissolved salts and complex-forming organic ligands.
    Subjects: Aqueous-solutions, Labradorite feldspar, Auger-electron spectroscopy, Ray photoelectron-spectroscopy, Oxygen isotope analysis, Soluble organic-acids, Ph = 2, Steady-state kinetics, Rare-earth elements, Dissolution rates
    Date Created: 1994
  10. Increasing woody species diversity for sustainable limestone quarry reclamation in Canada [Download]

    Title: Increasing woody species diversity for sustainable limestone quarry reclamation in Canada
    Creator: Cohen-Fernandez, A.C.
    Description: Environmental sustainability of post mined limestone quarries often requires reclamation to a diverse woody plant community. Woody species diversity may be severely limited if only nursery stock is relied on for propagation material; thus other sources must be evaluated. To address woody species establishment and survival from different propagule sources at a limestone quarry in western Canada, native trees (4) and shrubs (3) were seeded and transplanted into amended substrates (wood shavings, clean fill, unamended control) in two seasons (spring, fall). Plant sources were nursery stock, local forest wildlings, seeds and forest soil (LFH mineral soil mix). Plant emergence, survival, height, health and browsing were evaluated over four years. Survival was greater with fall transplanted seedlings than with spring transplanted. Survival was greater for Picea glauca, Pseudotsuga menziesii and Populus tremuloides from nursery than local source stock. Seedlings from seeds and LFH did not survive for any of the species. Growth and survival were affected by bighorn sheep. Amendments did not improve plant establishment. Diversity of the woody plant community was increased at the quarry in spite of the severe conditions.
    Subjects: LFH mineral soil mix, Fall planting, Local wildlings, Reclamation, Spring planting, Woody vegetation, Nursery stock, Limestone quarry, Seeds, Bighorn sheep
    Date Created: 2013