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Climate Change - Defoliation Interactions in Canadian Rangelands

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Primary Investigators
Edward W. Bork

Primary themes of research include improving the level of productivity and long-term sustainability of range and pasture communities and their associated ecosystems. This includes research in planned grazing, rangeland monitoring and assessment, as well as range improvement and restoration. Past research areas include the integrated control of Canada thistle in pastures, establishing guidelines for manure application to range and pasture, and research into the ecology and management of burned and grazed prairie and forested rangelands. Other areas of research include parkland landscape ecology and riparian grazing management, documenting the impacts of shrub and tree expansion on biodiversity and grazing opportunities, examining rangeland resilience to wild ungulate impacts, and investigations into the feasibility of agro-forestry production systems.

Recently completed areas of research include programs on the impact of artificial flooding on wetland development in the Dry Mixedgrass Prairie, and investigations on the role of tannins in diets of whitetail deer. Ongoing studies include the assessment of agronomic and economic thresholds of weeds in permanent pastures containing legumes, studies evaluating the comparative ecological impact of historical and contemporary grazing systems, and a long-term evaluation of the cost:benefit of various aspen management strategies. Most recently, my research has examined the factors regulating the invasion of bluegrass into fescue grasslands, including a multi-disciplinary study on the impacts of climate change and grazing in the parkland.

I have supervised over 20 graduate students over the last 10 years and teach several classes in rangeland ecology and management. I also work closely with industry and provincial extension specialists in my research.


James F. Cahill, Jr.
Scott X. Chang

I am a soil scientist with main research interests in soil C and N cycling and in applying our understanding of nutrient cycling in soil fertility, plant nutrition, global climate change, and land reclamation research. I have conducted research on a variety of ecosystem types, from agricultural to rangeland and forest ecosystems. Examples of equipment/techniques being used in our research include: automated soil respiration chambers, static gas chambers, datalogging equipment, stable isotopes (13C and 15N), lysimeters, throughfall and stemflow collectors, and the list goes on. My lab is equipped with modern instrumentation: a Shimadzu TOC/TN analyzer, a Biolog plate reader and software, a Varian GC with TCD, ECD and FID detectors, a Fourier Transform Infrared Spectrometer, incubators, autotitrators, a spectrophotometer, and a range of other equipment for routine lab analysis. I am currently supervising or co-supervising ten graduate students with thesis research topics ranging from climate change to soil acidification. I have been heavily involved in running the Alberta Soil Science Workshop (ASSW, and currently serve as the Chair. I serve as an associate editor or as an editorial board member for Canadian Journal of Soil Science, Biology and Fertility of Soils and Journal of Soils and Sediments.


Heather C. Proctor

Soil has been termed the "poor man's rainforest" because it is home to a bewildering diversity of organisms packed into an easily accessible area. These organisms both respond to and create variation in the physical and chemical nature of soil through their feeding, excretion, and movement. In this project I am chiefly interested in two things: (1) how do changes in moisture and temperature affect the number and diversity of microarthropods (mites, springtails, insects, etc.) that co-occur in small patches of soil, and (2) do changes in microarthropods correlate with changes in bacterial abundance or functional diversity? In addition to finding answers to these ecological questions, we will likely discover many species of mites that have not previously been recorded from Alberta, and perhaps some that are entirely new to science.


Graduate Students
Behnaz Attaeian

Global concern has been raised about climate change and its positive feedback loops. Conceptually, climate change mitigation may be possible through carbon uptake in natural ecosystems; referred to as carbon sequestration. Rangelands may have a considerable potential for carbon sequestration; however, rangelands are directly affected by grazing practices. The process of carbon sequestration, and carbon cycling in general, can be constrained by nitrogen deficiency. Rangeland ecosystem productivity can be affected by this carbon-nitrogen relationship. However, many models of climate change have been criticized due to their ignoring the role of nitrogen availability upon carbon uptake in natural ecosystems. The “Law of the Minimum” could explain how nitrogen deficiency can regulate ecosystem productivity and, consequently, carbon sequestration in N-limited ecosystems such as rangelands. These carbon-nitrogen processes are mainly managed by a misunderstood community: the soil microbial community.

My research involves studying the response of soil biological and physiochemical properties to climate change and grazing practices (defoliation) including: microbial community function and composition, and carbon and nitrogen dynamics. Research expectations are that plant defoliation will decrease soil nitrogen and carbon dynamics in rangelands; considering that defoliation can potentially change the soil to a drier microclimate. Defoliation can also induce defensive chemical secretions in plants, which may retard mineralization rates. Ecosystem responses to defoliation and environmental variables such as warming and precipitation are more complicated. At low defoliation intensity, this interaction could potentially change the soil to a wetter and a warmer microclimate. Consequently, this could increase nutrient cycling dynamics within the soil. Due to variations in defoliation, temperature, and precipitation magnitudes, the balance between mechanisms that enhance or retard soil carbon and nitrogen cycling is spatially and temporally variable, and it is therefore difficult to predict the outcome.


Jeffrey Newton

My research interests consist mainly of belowground ecology, with emphasis on micro-invertebrates. I find mites (Acari) and springtails (Collembola) most appealing, besides the aesthetic attraction, due to their paradoxical high species richness. The taxa may also play a role as top down controllers in soil systems. In addition, these micro-invertebrates may act as bio-indicators, making them useful tool for studying soil disturbance. Lastly, the obscure nature of soil has left ecological research of this medium lagging behind that of aboveground systems, allowing for novel exciting discoveries and developments. Besides soil ecology, I am also intrigued by succession of necrophilic and coprophilic arthropods on decomposing cadavers and dung respectively. I have worked on these subjects in the past and it ties into soil ecology in the sense that waste from aboveground will form a large part of the nutrient/energy basis (bottom up) for belowground communities.

My role in this project is to study the micro-arthropod community change associated with the different climate change treatments over time. I expect to find particular taxa or functional groups more susceptible to elements of climate change than others (i.e. precipitation increase/decrease and temperature increase). Due to the collaborative effort to join different approaches and very different fields of ecology, it will be possible to get a more complete and accurate understanding of induced changes and their effects on other parts of the system. It is particularly interesting to observe cause and effects over such a broad scale, e.g. if micro-invertebrates drive vegetation changes (aboveground) or if the reverse is true.


Samson Nyanumba

The relative importance of global change factors (temperature, water balance, land-use-change, CO2 enrichment, UV-radiation, pollution) differs among ecosystems. The role of soil organisms to nutrient cycling is well understood. On the other hand, recent evidence suggests that plant phenolics (more so from roots) are likely to have a more important regulatory effect on plant-soil feedbacks because of their influence on soil nitrogen biogeochemistry. Furthermore, it has been hypothesized that the impacts of global change are mediated through the organic matter or detritus which includes above- and belowground litter, root exudates, excreta and corpses. My research work focuses on the effects of climate change (temperature and precipitation) and defoliation on carbon and nitrogen fluxes. Specifically, I will be addressing the impact of these factors on litter decomposition and nitrogen mineralization rates. In addition, I am interested in whether these shifts in environmental conditions alter plant phenolic composition and/or mediation.


Shannon White

I am interested in broad questions of biodiversity, ecosystem function, and sustainability, and humans’ impacts and dependence on natural systems. My M.Sc. thesis is centered on the effects of simulated climate change and grazing on vegetation in grasslands of Alberta, Saskatchewan, and Manitoba. This will include assessments of changes in plant community, productivity, and seed dynamics. This research will help elucidate potential effects of climate change in this area, as well as inform management as these changes unfold in the future. I am also pursuing a feasibility study of the potential of harvesting native prairie for biofuels in Western North American, focused on Alberta.


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Research Technicians
Bryon Shore

My role involves coordinating research activities, managing logistics, and generally making sure that tasks are completed properly and in a timely manner. This requires that I have a finger in all aspects of the project. As an example, major duties have included: budget management; designing and/or fabricating field equipment (rainout shelters, OTCs, minirhizotron tubes); spec-ing, ordering, and installing datalogging equipment; hiring, directing, and coordinating field and lab assistants; plot layout and approval of modifications; field site setup and infrastructure installation; applying experimental treatments and sampling; directing sample processing; data collection, management, and analysis; website development. I continue to learn a wide variety of skills and techniques as required to ensure that this project continues to run smoothly.


Brenda Vaness

My main duties are to collect and analyze the minirhizotron images. Analysis entails measuring root length, growth, mortality, and turnover. I graduated from the University of Wisconsin Stevens Point with a B.Sc. in Biology and Wildlife Ecology and Management. Following graduation I took a position at Lostwood National Wildlife Refuge in North Dakota. I worked as a technician on a leafy spurge-mapping project and became interested in prairie restoration. I am also currently working on my M.Sc. at the University of Regina. For my research, I am looking at the effects of crested wheatgrass invasion on root and resource heterogeneity in native prairie.


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Undergraduates, Field Assistants, and Volunteers

This research wouldn't be possible without a small army of dedicated technicians, field assistants, lab assistants, and volunteers. We would like to thank Oliver Barker, Jon Bennett, Qiting Chen, Christina Colenutt, Amanda Doyle, Amber Greenall, Inga Hiiesalu, Jordan Hulecki, Barret Jackson, Monica Kohler, Agnieszka Kotowska, Qina Li, Kuan Liu, Meng Luo (Dennis), Sylvia Ma, Tianna Magis, Gord McNickle, Kerilynn Mercier, Jon Misskey, Kamalashri Easwara Murthi (Mimmy), Jon Nachtigall, Kylie Pawluk, Melanie Patchell, Dao Phan, Troy Radtke, Megan Rice, Peter Roland, Brandon Schamp, Gerald Singh, Tara Stieglitz, Ping Wang, Katie Williams, and Chakanaka Zinyemba for their invaluable help in making this project work.

Researchers' Home Towns

The members of our research team come from a variety of nationalities. Please visit our new maps page to see the various researchers' home towns.

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