Expansion of Agriculture in Northern Cold-Climate Regions: A Cross-Sectoral Perspective on Opportunities and Challenges

Agriculture in the boreal and Arctic regions is perceived as marginal, low intensity and inadequate to satisfy the needs of local communities, but another perspective is that northern agriculture has untapped potential to increase the local supply of food and even contribute to the global food system. Policies across northern jurisdictions target the expansion and intensification of agriculture, contextualized for the diverse social settings and market foci in the north. However, the rapid pace of climate change means that traditional methods of adapting cropping systems and developing infrastructure and regulations for this region cannot keep up with climate change impacts. Moreover, the anticipated conversion of northern cold-climate natural lands to agriculture risks a loss of up to 76% of the carbon stored in vegetation and soils, leading to further environmental impacts. The sustainable development of northern agriculture requires local solutions supported by locally relevant policies. There is an obvious need for the rapid development of a transdisciplinary, cross-jurisdictional, long-term knowledge development, and dissemination program to best serve food needs and an agricultural economy in the boreal and Arctic regions while minimizing the risks to global climate, northern ecosystems and communities

Isotope applications to soil science at the University of Alberta - an historical perspective

For the past 70 yr, researchers in the Soil Science/Renewable Resources Department at the University of Alberta have used isotopes to study topics of ecological importance. This review highlights the soil isotope research conducted within our department over this time, including an historical overview of studies of interest. Analytical techniques and advances in instrumentation are discussed, focusing on the measurement of light stable isotope ratios (i.e., for C, H, N, S, and O) using isotope ratio mass spectrometry (IRMS). Early soil isotope work (1950–2000s) focused on agricultural soils and soil fertility issues. These studies included the use of radioactive isotopes such as 14C and 35S, and (or) artificially enriched stable isotopes including 15N-labelled fertilizers. More recently (2000–present), the scope of research widened to include natural-abundance stable isotope ratio studies as higher-sensitivity IRMS systems became more prevalent. Current isotope research topics include N biogeochemistry in natural and managed ecosystems, land management effects on greenhouse gas emissions, carbon cycling in northern landscapes, paleo-reconstruction in peatlands, carbon sequestration in boreal forests, and biodegradation of petroleum hydrocarbons. Further technological progress also enabled new techniques such as compound-specific IRMS analysis, including δ13C and δ2H measurements of soil n-alkanes and phospholipid fatty acids. In conclusion, current IRMS instrumentation presents unparalleled opportunities for multidisciplinary research to track carbon, plant nutrients, and pollutants as they move through soils.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Evidence of rapid non-targeted effects of cycloheximide on soil bacteria using 13C-PLFA analysis

Stable isotope probing of phospholipid fatty acids (PLFA-SIP) is useful when studying bacterial contributions to soil processes, and it is an effective way to separate fungal and bacterial activity by linking 13C enrichment to specific PLFAs. Distinguishing bacterial contributions to soil processes often employs selective inhibitors; however, studies demonstrating their efficacy when using PLFA-SIP are less common. Here, we determined the effect of the fungal inhibitor cycloheximide (4.8 mg g−1 dry soil) and the bacterial inhibitor bronopol (0.48 mg g−1 dry soil) on microbial communities white spruce [Picea glauca (Moench) Voss] forest floor by measuring the uptake of 13C-enriched glucose (2 mg g−1 dry soil) in microbial PLFAs. We targeted [13C]glucose uptake by the bacterial community conditioned to a stable soil environment of 23 °C for over 2 wk rather than new bacteria generated from active colony growth caused by glucose addition. Nearly all bacterial PLFAs exhibited pronounced inhibition of 13C enrichment in the presence of bronopol. Limited inhibition of 13C enrichment in the presence of cycloheximide was observed as bacterial PLFA affected by cycloheximide had roughly one third less 13C enrichment than samples emended with [13C]glucose alone. Inhibitory effects only reduced 13C enrichment and did not affect total PLFA concentrations, implying that the inhibitors in the concentrations applied were impeding bacterial activity without causing cell death. Based on this work, we conclude that bronopol is an effective inhibitor for bacteria. Additionally, non-targeted effects of cycloheximide on soil bacteria must be accounted for when it is used in soil incubations.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Microbial response to carbon and nutrient additions in boreal forest soils and coversoils used during post-mining reclamation

Two types of organic-matter-rich coversoils are used during reclamation in the oil sands region of Alberta: forest floor material (FFM) salvaged from upland forests, and peat material (PM) salvaged from boreal wetlands. In this study, we tested the hypothesis that carbon (C) and nutrient availability may limit microbial activity in these reclamation materials by measuring their response to either 13C-labeled glucose or NPKS addition. Coversoil materials were compared with two natural forest soils corresponding to target sites for reclamation. A shift in microbial community structure (determined using phospholipid fatty acid analysis) was detected after both additions, but it was stronger with glucose than NPKS, especially for the two reclamation materials. For all soils, the increase in microbial respiration was stronger after glucose than after NPKS addition. The majority of CO2 originated from soil organic matter (SOM) for the natural forest soils but from glucose for the reclamation materials. In PM, glucose addition triggered SOM mineralization, as shown by a positive priming effect. Despite the absence of a priming effect for FFM, microbial communities incorporated higher rates of glucose into their biomass and respired double the amount of glucose compared with the other materials. Furthermore, the overall microbial community structure in the FFM became more similar to that of the natural forest soil materials following glucose addition. These findings indicate that C and NPKS limitations were stronger for the two reclamation materials than for the two natural forest soils. Furthermore, microbial communities in the two reclamation materials responded more readily to labile C than to NPKS addition.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Nutrient distribution in sandy soils along a forest productivity gradient in the Athabasca Oil Sands Region of Alberta, Canada

Brunisolic soils developed on sandy deposits comprise a significant portion of the land disturbed by surface mining in the Athabasca Oil Sands Region. These soils support unique forest communities ranging from nutrient limited jack pine to more productive aspen stands. The objective of this study was to determine if and how the physical properties of these sandy soils influence the accumulation and distribution of soil nutrients. Sixteen sites, selected to capture the natural range in forest productivity of the area, were characterized to assess particle size distribution; total and available nutrient stocks in forest floors; and total and extractable nutrients in B horizons. Under jack pine, relatively small decreases in sand content of the upper soil profiles, from 97 to 88 %, were associated with greater total nutrient stocks and lower C/N ratios in the forest floors. In soils under aspen, forest floor nutrient stocks related most strongly with texture of the B horizons, with finer B horizons (from 94 to 78 % sand) leading to larger forest floor nutrient stocks. These results indicate that textural characteristics play an important role in nutrient cycling of these sandy soils and should be a primary focus during their reclamation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Understory Plant Community Composition Is Associated with Fine-Scale Above- and Below-Ground Resource Heterogeneity in Mature Lodgepole Pine (Pinus contorta) Forests.

Understory plant communities play critical ecological roles in forest ecosystems. Both above- and below-ground ecosystem properties and processes influence these communities but relatively little is known about such effects at fine (i.e., one to several meters within-stand) scales, particularly for forests in which the canopy is dominated by a single species. An improved understanding of these effects is critical for understanding how understory biodiversity is regulated in such forests and for anticipating impacts of changing disturbance regimes. Our primary objective was to examine the patterns of fine-scale variation in understory plant communities and their relationships to above- and below-ground resource and environmental heterogeneity within mature lodgepole pine forests. We assessed composition and diversity of understory vegetation in relation to heterogeneity of both the above-ground (canopy tree density, canopy and tall shrub basal area and cover, downed wood biomass, litter cover) and below-ground (soil nutrient availability, decomposition, forest floor thickness, pH, and phospholipid fatty acids (PLFAs) and multiple carbon-source substrate-induced respiration (MSIR) of the forest floor microbial community) environment. There was notable variation in fine-scale plant community composition; cluster and indicator species analyses of the 24 most commonly occurring understory species distinguished four assemblages, one for which a pioneer forb species had the highest cover levels, and three others that were characterized by different bryophyte species having the highest cover. Constrained ordination (distance-based redundancy analysis) showed that two above-ground (mean tree diameter, litter cover) and eight below-ground (forest floor pH, plant available boron, microbial community composition and function as indicated by MSIR and PLFAs) properties were associated with variation in understory plant community composition. These results provide novel insights into the important ecological associations between understory plant community composition and heterogeneity in ecosystem properties and processes within forests dominated by a single canopy species

Soil nitrous oxide emissions most sensitive to fertilization history during a laboratory incubation

A 12 wk laboratory incubation examined the effects of application of various nitrogen (N) and sulfur (S) fertilizers on soil plant-available nutrient levels and nitrous oxide (N2O) gas emissions with respect to soil fertilization history using soils sampled from the University of Alberta Breton Classical Plots. Fertilization history and added fertilizer treatments showed significant effects on N2O emissions and NO3−-N and SO4−-S recovered on ion-exchange resins over the 12 wk. Mean cumulative N2O emissions ranged from 0.43 to 1.18 kg N2O-N ha−1. The relationship between observed total resin-recovered NO3−-N and N2O emissions was not consistent for soils receiving long-term applications of various combinations of N, phosphorus, potassium, and S fertilizers. The N2O emission from two soils with a history of long-term N fertilizer applications but different S fertilization histories was significantly different even though resin-recovered NO3−-N levels were similar. When grouped according to added fertilizer treatments, mean cumulative N2O emissions showed a strong linear relationship with mean resin-adsorbed NO3−-N production. We hypothesize that the differences in the relationship between NO3−-N production and N2O-N emissions for soils with different long-term fertilization histories may be a result of the interaction of N and S oxidation processes. Further, soil fertilization history may significantly influence soil N2O emissions in response to N fertilizers added within the growing season of observation but isn’t often considered in short-term experiments, and this may be a significant source of uncertainty in the estimation of greenhouse gases inventories from agricultural soils.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Mobile learning and student engagement in remote field activities

This research is centred on an investigation of the potential for the use of mobile learning in remote field study locations by university students. The study focused on both geospatial concepts and abilities, instructional design methodologies and the impact of learning through the use of mobile devices and online learning. The study group included a total of 118 students enrolled in the University of Alberta, in the Department of Renewal Resources. The research methodology included mixed method approach that included the dissemination of online surveys, feedback forms completed during field study, and anecdotal data collected by instructors. A major pedagogical change in the course design resulted in students accessing mobile devices in place of traditional hard-copy maps in order to conduct their field studies

Perspektivne nove sorte breskev (Prunus persica L.) in nektarin (Prunus persica var. nucipersica L.)

Pyrogenic carbon (PyC), a major by-product of wildfires in boreal forests, plays several critical roles in soil biogeochemical processes. However, PyC properties, including its potential recalcitrance, may vary depending on its formation conditions. Our study aimed to characterize the chemical and physical properties of PyC formed under variable fire severity in Eastern Canada boreal forests; these latter represent an important fraction of fire-affected circumboreal ecosystems. A total of 267 PyC samples, produced by early-season wildfires in 2005-2007, were collected <= 5 years after fire from the forest floors of 14 black spruce sites distributed across Quebec, to cover the range of fire severity encountered in these forests. Early-season fires occur frequently in Eastern Canada, and are predicted to increase in regional and global scenarios of future fire regimes associated with climate change. Selected PyC samples were analyzed using elemental analysis, solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy, and surface area analysis. The NMR spectra of the PyC collected on low-fire-severity sites were dominated by peaks indicative of cellulose, while those for PyC from higher-severity sites were dominated by a broad peak assigned to aromatic carbons. Atomic H/C and O/C ratios decreased with increasing fire severity. By comparing field samples to samples produced in the laboratory under controlled formation conditions, we were able to infer that the temperature of formation in the field was low (75 degrees-250 degrees C). In addition, for all PyC samples, the aromatic carbon : total carbon ratio was small, suggesting that PyC produced by early-season fires in these boreal forests may be susceptible to relatively rapid degradation. Taken together, our data suggest that boreal PyC may not be as recalcitrant as previously assumed, and that its influence on soil biogeochemical processes may be short lived