Effects of observed and experimental climate change on terrestrial ecosystems in northern Canada: results from the Canadian IPY program

Published VersionTundra and taiga ecosystems comprise nearly 40 % of the terrestrial landscapes of Canada. These permafrost ecosystems have supported humans for more than 4500 years, and are currently home to ca. 115,000 people, the majority of whom are First Nations, Inuit and Métis. The responses of these ecosystems to the regional warming over the past 30–50 years were the focus of four Canadian IPY projects. Northern residents and researchers reported changes in climate and weather patterns and noted shifts in vegetation and other environmental variables. In forest-tundra areas tree growth and reproductive effort correlated with temperature, but seedling establishment was often hindered by other factors resulting in sitespecific responses. Increased shrub cover has occurred in sites across the Arctic at the plot and landscape scale, and this was supported by results from experimental warming. Experimental warming increased vegetation cover and nutrient availability in most tundra soils; however, resistance to warming was also found. Soil microbial diversity in tundra was no different than in other biomes, although there were shifts in mycorrhizal diversity in warming experiments. All sites measured were sinks for carbon during the growing season with expected seasonal and latitudinal patterns. Modeled responses of a mesic tundra system to climate change showed that the sink status will likely continue for the next 50–100 years, after which these tundra systems will likely become a net source of carbon dioxide to the atmosphere. These IPY studies were the first comprehensive assessment of the state and change in Canadian northern terrestrial ecosystems and showed that the inherent variability in these systems is reflected in their site-specific responses to changes in climate. They also showed the importance of using local traditional knowledge and science, and provided extensive data sets, sites and researchers needed to study and manage the inevitable changes in the Canadian North

Tundra Trait Team: A database of plant traits spanning the tundra biome

Abstract Motivation: The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained: The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (> 1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain: Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain: All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement: Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format: csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release

Naammaktunga (“I am well”)! Feeding families and people-food relationships in Kugluktuk, Nunavut : exploring what the lenses of food sovereignty and Indigenous resilience can offer to food system governance

Despite extremely high costs of living, many people in small, remote communities in the Canadian Arctic appear to be successfully feeding their families. In academic and policy literatures, the food security lens has contributed important knowledge about hunger in the north; however, its emphasis on deficits and problems risks overlooking enabling mechanisms of people-food relationships. Lenses (and their underlying worldviews) have been shown to shape food system governance, including responses to food-related phenomena such as hunger. By exploring the capacities of different lenses (food security, food sovereignty, Indigenous resilience) to characterise key aspects of people-food relationships, this in-depth ethnographic research examines and illustrates their potential impacts on northern food system governance. In order to achieve this, I developed a grassroots, holistic understanding of people-food relationships in the hamlet of Kugluktuk, Nunavut using a modified grounded theory approach. Three key overarching themes emerged: identity, living in relation and power/resources. Individual/collective wellbeing is at the heart of these themes. Food nourishes a sense of ‘self’ and identity, which is foundational to living in relation through (food) sharing, being on the land together, visiting and knowledge transmission. Identity and relationships are shaped by participation in power systems (e.g. local/external institutions) and control of resources (e.g. food, livelihood, governance). The lenses under investigation were then applied to emergent themes, revealing that Indigenous resilience was most capable of representing these. This is the first study of its kind in Nunavut, with several important research findings. Northern food system governance may benefit by continuing to enhance community-level decision-making authority, and acknowledging/enabling peoples’ abilities to successfully feed their families and foster individual/collective wellbeing. Continued focus on mitigating factors –what enables – will likely benefit future food-related policy practice and research, and help recognise and support the strengths, resiliencies and wellbeing of northerners. The complexity and nuance of people-food relationships necessitates consideration of appropriate food lenses, such as those informed by Indigenous and wellbeing practices (e.g. living in relation, reciprocity, occupancy) and scholarship, as well as how these are interpreted (e.g. user perspectives), in order to further enhance northern food system governance.Forestry, Faculty ofGraduat

Long-term experimental warming effects on tundra plant sexual reproduction in the high Arctic

Predictions that climate warming will enhance plant sexual reproduction in the High Arctic were examined using a field experiment at a polar oasis and a polar semi-desert site in the eastern Canadian High Arctic. Small open top chambers (OTCs), which simulated climate warming, were established in plant communities along a soil moisture gradient in 1992. Over two growing seasons, fresh and over-wintered seeds across a range of species were collected from aerial seed banks exposed to experimental warming and ambient conditions. Seeds were weighed and germinated to measure changes in reproductive effort and success in response to experimental warming. OTCs increased within-plot growing season air temperatures by 1 - 2°C, which is within range of general circulation model (GCM) predictions for climate warming in the Arctic. Reproductive effort and success of fresh seeds were enhanced by warming in most species, depending on initial site conditions. Enhanced reproductive effort and success may be attributed to warming conditions, which advanced dates of snowmelt and extended the growing season. Similar effects on over-wintered seeds were likely, but seed dispersal prior to over-wintered seed harvests confounded these results. Inter-annual variability in reproductive success appeared to be diminished by experimental warming. Further testing will verify if this result is an indicator of long-term (> 10 y) warming effects. Results of this study confirm predictions that long-term warming will enhance sexual reproduction in high arctic plants. These changes will have implications for plant demographics at the community-level and the rate and extent of bare-ground colonization, particularly if rates of seedling establishment also increase.Arts, Faculty ofGeography, Department ofGraduat