Kirsten Hannam

Kirsten Hannam
Agriculture and Agri-Food Canada | AAFC · Science and Technology Branch

MSc, PhD

About

50
Publications
15,278
Reads
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1,318
Citations
Additional affiliations
August 2017 - present
University of British Columbia - Okanagan
Position
  • Research Associate
August 2015 - July 2017
Natural Resources Canada
Position
  • Analyst
April 2013 - July 2015
University of British Columbia - Okanagan
Position
  • Research Associate

Publications

Publications (50)
Article
Full-text available
Over the last 200 years, conversion of noncultivated land for agriculture has substantially reduced global soil organic carbon (SOC) stocks in upper soil layers. Nevertheless, practices such as no‐ or reduced tillage, application of organic soil amendments, and maintenance of continuous cover can increase SOC in agricultural fields. While these man...
Article
Full-text available
Agricultural practices such as annual crop production, land use change and grazing on marginal lands lead to a loss of soil carbon (C) stock. But soil C losses are not universal in agricultural systems and modest soil C gains can occur when constraints such as a lack of water are removed. To characterize this we used a meta-analysis of published da...
Article
Fruit production in the Okanagan Valley of British Columbia is dominated by apple, sweet cherry, and wine grape. The relative importance of sweet cherry and grape has increased in recent decades, but little was known of the plant-parasitic nematodes associated with those crops. Soil samples analyzed for plant-parasitic nematodes were collected from...
Article
Increasing the carbon (C) content of agricultural soils can help mitigate rising atmospheric CO2 concentrations, improve soil health and increase crop yield. Unlike annual cropping systems, soils planted to perennial woody crops, such as vineyards and orchards, are left undisturbed for many years making them particularly amenable to soil C storage....
Article
Full-text available
Tree responses to fertilizer management are complex and are influenced by the interactions between the environment, other organisms, and the combined genetics of composite trees. Increased consumer awareness of the environmental impact of agriculture has stimulated research toward increasing nutrient-use efficiency, improving environmental sustaina...
Conference Paper
Sudden apple decline (SAD) is a recent and little understood disorder, associated with wilted leaves and rapid death of apple trees. In 2018, orchard surveys were conducted in seven apple orchards in the Okanagan Valley reporting high tree mortality and potentially SAD. Of 350 trees observed, 28.4% were assessed as declining; of those, necrotic ste...
Article
Full-text available
To successfully reduce atmospheric CO 2 by sequestering additional soil carbon, it is essential to understand the potential of a given soil to store carbon in a stable form. Carbon that has formed organo-mineral complexes with silt and clay particles is believed to be less susceptible to decay than non-complexed, or particulate, organic carbon. Usi...
Article
Full-text available
Wood and bark chip mulch has been shown to reduce net orchard greenhouse gas (GHG) emissions on an Okanagan Valley (British Columbia, Canada) apple orchard. However, this benefit was shown to be outweighed by the (attributional) life cycle impacts associated with mulch production. The current study expanded the scope of prior investigations to perf...
Article
Full-text available
Food production contributes substantially to anthropogenic environmental impacts, including 19–29% of greenhouse gas (GHG) emissions. Use of wood and bark chip mulch as a soil cover has previously been found to reduce direct N2O emissions and increase soil organic carbon on apple orchards. The current study expanded the scope of this prior investig...
Presentation
Full-text available
Apple decline', also known as 'rapid apple decline' or 'sudden apple death' has been reported over the last several years in apple growing regions across North America (e.g., New York, Pennsylvania, Ontario). A number of potential signs and symptoms of apple decline in British Columbia have been identified. While we are not yet sure of the associat...
Presentation
Full-text available
Ces dernières années, une affection du pommier nommée « déclin rapide des pommiers », « dépérissement soudain des pommiers » ou « mort subite des pommiers » a été rapportée dans certaines régions pomicoles d'Amérique du Nord (États de New York et de Pennsylvanie, Ontario). En Colombie-Britannique, des signes et symptômes pouvant être associés à cet...
Conference Paper
Full-text available
‘Apple decline’, also known as ‘rapid apple decline’ or ‘sudden apple death’ has been reported over the last several years in apple growing regions across North America (e.g., New York, Pennsylvania, Ontario). A number of potential signs and symptoms of apple decline in British Columbia have been identified, but a causal trigger has yet to be ident...
Article
Full-text available
The lower Fraser Valley is one of the most intensively cropped regions in Canada. Yet, how soil health indicators respond to long-term intensive agricultural management is poorly documented in this region. Thus, we evaluated a suite of soil health indicators in response to 21 growing seasons of continuous silage corn (Zea mays L.) under conventiona...
Article
Understanding the processes that drive the release of carbon dioxide (CO2) from soil is essential to combat rising atmospheric greenhouse gases. Whilst significant research has focused on soil organic carbon (C) dynamics, soil inorganic C has received much less attention. In arid and semi-arid regions, crops are often irrigated with water containin...
Technical Report
Full-text available
AshNet is a network of Canadian government, academic, and industry researchers, foresters and policy makers investigating the potential beneficial diversion of wood ash, a by-product of the growing bioenergy industry, from landfills across Canada to forest soils. AshNet currently consists of 14 wood ash application experiments established at sites...
Technical Report
Full-text available
AshNet est un réseau de représentants du gouvernement du Canada, d’universitaires, de chercheurs de l’industrie, de forestiers et de décideurs politiques qui étudient les avantages potentiels d’utiliser les cendres de bois, issue de l’industrie grandissante de la bioénergie et normalement envoyée dans les centres d’enfouissement au Canada, pour ame...
Article
Laboratory studies have shown that priming effects, caused by inputs of carbon into the rhizosphere, can change the rate of soil organic matter (SOM) decomposition and could have significant impacts on soil carbon cycling. However, there have been few studies in field conditions because of experimental constraints but field data are needed to impro...
Article
The contribution of forest biomass to Canada’s energy production is small but growing. As the forest bioenergy industry in Canada expands, there is growing interest in more sustainably managing the wood ash that is generated as a by-product. Despite being rich in nutrients, wood ash is usually landfilled in Canada. Soil applications of ash in Canad...
Article
Full-text available
The growing demand for bioenergy has raised concerns about the sustainability of intensive forest biomass removal. Less attention has been paid to the ash generated when forest biomass is combusted to produce energy. In Canada, this ash is often landfilled, but in some countries, wood ash is applied to the soil to maintain or improve soil fertility...
Technical Report
Full-text available
Au Canada, les cendres générées au cours de la production de bioénergie à partir de résidus ligneux sont généralement considérées comme des déchets et sont enfouies. Cependant, la cendre de bois est riche en calcium, en magnésium, en potassium et en phosphore. Ainsi, les aménagistes forestiers de quelques pays européens sont fortement encouragés à...
Technical Report
Full-text available
In Canada, the ash generated during bioenergy production from woody residues is generally treated as a waste material and landfilled. However, wood ash is rich in calcium, magnesium, potassium and phosphorus. As a consequence, forest managers in some European countries are actively encouraged to use wood ash as a soil amendment to replace the nutri...
Article
Full-text available
Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about the overall structure of terrestrial microbial communities. PLFA profiling has been extensively used in a range of ecosystems as a biological index of overall soil quality, and as a quantitative i...
Article
Full-text available
Micro-irrigation, fertigation, and mulching have been proposed to improve the nutrient and water-use efficiency of crop production. The effect of these management practices on the emission of nitrous oxide (N2O) from vineyards is not well understood and most prior studies were short-term (<1 year). To investigate longer-term effects, a study was co...
Article
There is growing interest among commercial wine grape (Vitis vinifera L.) growers in reducing water and fertilizer consumption, but little information exists on how best to combine conservative irrigation and soil management practices in the vineyard. In a 3-year-old Merlot vineyard in the semi-arid Okanagan Valley, British Columbia, the interactiv...
Article
Full-text available
Applications of nitrogen to vineyard foliage or soil at veraison can improve grape juice yeast assimi- lable nitrogen concentrations and may prevent the excessive vine growth, delayed maturity, and adverse changes in fruit properties sometimes associated with high applications of N earlier in the growing season. However, the consequences of late-se...
Article
Full-text available
Achieving fruit maturity can be a challenge on some Okanagan vineyards in some years. Cluster thinning is widely used to hasten ripening but may not be effective on sites with balanced crop loads. In a Merlot vineyard in Summerland, BC, the effects of cluster thinning on juice soluble solids (an indicator of fruit maturity), yield and vine growth w...
Article
Full-text available
In the Okanagan Valley of British Columbia, low rates of nitrogen fertilizer are typically applied early in the growing season to prevent excessive vine growth, disease, and adverse changes in grape juice composition. As a consequence, grape juice yeast assimilable nitrogen (YAN) concentrations at harvest are often below the level considered suffic...
Article
Wine grapes (V. vinifera L.) in western North America commonly have deficient yeast-assimilable N concentrations (YANCs), necessitating the addition of diammonium phosphate to the must prior to fermentation. To examine strategies for alleviating this condition, N treatments were applied three times, centered around veraison, in replicated trials on...
Article
Full-text available
Vineyard management practices that can be used to elevate YAN above the 140 mg N L-1 required for efficient fermentation are of critical interest. The effects of N fertilization and reduced irrigation frequency on grape juice YAN, fruit quality and yield were examined in a five-year study on Merlot (Vitis vinifera L.) vines. Fertilization with N in...
Article
Full-text available
Stump extraction for forest health has been carried out operationally in British Columbia (BC) for many years. Emerging bioenergy opportunities plus the anticipated need for more fibre because of reductions in timber supply may increase interest in stump harvesting, but there are numerous environmental, economic and policy barriers that must be ove...
Article
Full-text available
Concerns about climate change and the desire to develop a domestic, renewable energy source are increasing the interest in forest biomass extraction, especially in the form of logging residues, i.e., tree tops and branches. We reviewed the literature to determine the site and soil conditions under which removal of logging residues along with the st...
Article
1 Rising economic demands for boreal forest resources along with current and pre-dicted increases in wildfire activity have increased salvage logging of burned forests. Currently, the ecological consequences of post-fire salvage logging are insufficiently understood to develop effective management guidelines or to adequately inform policy decision-...
Article
Full-text available
In boreal forests of eastern Canada, wildfire has gradually been replaced by clearcut harvesting as the most extensive form of disturbance. Such a shift in disturbance may influence the chemical properties of the forest floor and its capacity to cycle and supply nutrients, with possible implications for forest productivity. We compared the effects...
Article
Previous studies have shown that forest floors from stands dominated by trembling aspen (ASPEN; Populus tremuloides Michx.) tend to support a greater microbial biomass with a different microbial community structure than forest floors from stands dominated by white spruce (SPRUCE; Picea glauca (Moench) Voss). A reciprocal transfer experiment, in con...
Article
With the growing interest in silvicultural techniques that more closely emulate natural disturbance regimes, there is a need to better understand how partial harvesting affects the soil microbial community in stands with varying ecological characteristics, e.g., tree species composition. Four and a half and 5.5 years post-harvest, we used phospholi...
Article
Alterations in the chemical properties of the forest floor following clear-cut harvesting may have implications for forest productivity in boreal stands. We used proximate analysis, carbon-13 (C-13) isotopic determination, and cross- polarization, magic-angle spinning (CPMAS) C-13 nuclear magnetic resonance (NMR) spectroscopy to examine differences...
Article
Full-text available
Soil particle density (rho(s)), the ratio of the mass of soil solids to the volume of solids, is used to derive such properties as soil porosity and heat capacity, which are critical to understanding and modeling water, energy, and nutrient fluxes through forested landscapes. Values of forest floor rho(s) and organic matter particle density (rho(o)...
Article
Full-text available
The ability of high-resolution cross-polarization magic-angle spinning 13C nuclear magnetic resonance spectroscopy (CPMAS 13C NMR) to characterize soil organic matter (SOM) has been previously demonstrated, but rarely has this information been directly related to local environmental conditions that affect SOM formation. In this study, CPMAS 13C NMR...
Article
Full-text available
Soluble organic N (SON) is recognized to be a source of N for plants, but the few studies of the effects of clear-cut harvesting on SON levels have reported inconsistent results. SON and soluble inorganic N (SIN) contents were measured in 1 mol/L KCl extracts of soil from forests and clearcuts in coastal cedar-hemlock forests near Port McNeill, B.C...
Article
Growth and survival responses of 8 year-old interior spruce to reductions in paper birch density from 2500 to 1000, 50 and 0 overtopping stems ha−1 were examined after five years on a single site in the Interior Cedar Hemlock biogeoclimatic zone of southern British Columbia. Stem diameter increased and height : diameter ratio decreased when birch d...

Projects

Projects (4)
Project
In the past 2-3 years in Canada, fruit trees including apple, pear and apricot, have shown evidence of serious and unprecedented mortality rate exceeding 40%. This fruit tree decline is evident in apples and tender fruits, and may be caused by a complex combination of biotic and abiotic stresses. Symptoms of decline leading to mortality have been reported in Ontario, British Columbia, Prince Edward Island and Nova Scotia. Preliminary research and literature reports have identified bacterial, fungal, nematode, arthropod and viral agents as biotic contributing factors. A thorough understanding of the etiology of the causal agent(s) is vital for preventing the spread of these diseases and minimizing their affects on tree fruit production in Canada. In apples, this disease is known as Sudden Apple Decline (SAD). SAD occurs rapidly, with tree mortality occurring within a few weeks following the onset of symptoms. Apple Luteovirus 1 was recently identified in diseased trees but it is not clear if this virus is responsible for SAD. In Ontario, British Columbia and Prince Edward Island, a second tree decline disease was recently reported in tender fruits. We have called this disease Tender Fruit Tree Decline (TFTD). TFTD proceeds slowly over 2-3 years before tree death, with yellowing of leaves, vasculature rot, stunted growth and poor fruit set. We have identified Tomato ringspot virus in symptomatic apricot trees, but it is unlikely that this pathogen alone, is causing this mortality. Both SAD and TFTD are likely caused by a complex combination of pathogen pressures and abiotic factors. Identifying causal agents of SAD and TFTD are the primary objective of this proposal. The research team assembled to identify these causes will include a diverse and multidisciplinary team of highly qualified AAFC scientists across Canada. Microbiology, nematology, entomology, physiology, plant pathology, genomics and molecular biology will be used to identify pathogens related to these syndromes. Once major pathogens have been identified, we will determine their contributions to diseased fruit trees by following Koch's postulates. The overarching goal is divided into two main objectives: identification of pathogens and abiotic factors including characterization of tree fruit decline symptoms associated with individual pathogens, and implementation of Koch's postulates to conclusively demonstrate which pathogen(s) are required for the characteristic diseases symptoms in apple and tender fruit. The positive identification of contributing pathogens to fruit tree decline, will then allow the development and implementation of future integrated management practices for the control of tree fruit decline in Canadian orchards.
Project
The main goal of this project is to summarize the methods and results of forest wood ash amendment trials across Canada (AshNet: http://www.nrcan.gc.ca/forests/research-centres/glfc/ashnet/20279) with the aim of informing future wood ash amendment research and exploring the potential benefits of wood ash amendment practices.
Project
To better understand the effects of irrigation practices on soil nitrogen and soil organic and inorganic C storage. Research will be conducted on sites with a range of soil types, crops, and irrigation practices in the semi-arid Okanagan Valley, British Columbia. Our ultimate goal is to identify management practices that best mitigate greenhouse gas emissions while maintaining crop productivity and enhancing soil health.