CARBON LIFE CYCLE ASSESSMENT OF SHELTERBELTS IN SASKATCHEWAN
Shelterbelts are beneficial for protection against soil erosion, as well as for the promotion of biodiversity and wildlife habitat. Additionally, they play an integral role in carbon sequestration through growth in tree biomass and agricultural soil. The widespread adoption of shelterbelts was, in part, triggered by concerns about erosion of topsoil caused in the drought-prevalent years in the early to mid-20th century. In recent years, it has become more common to remove these shelterbelt trees to convert land to crop production or due to the increasing size of equipment imposing difficulty navigating around the shelterbelt during seeding, spraying, and harvest. In addition, soil erosion is no longer a risk due to wide spread conservation farming practices being employed. Life Cycle Assessment (LCA) is a tool that observes and analyzes the entire life of a phenomenon from ‘cradle to grave’. A Carbon-LCA of planted shelterbelts accounts for the processes by which carbon dioxide is sequestered through the function of photosynthesis by tree species and micro-organisms in agricultural soils as well as its emission produced during various life stages. The pan-Canadian framework outlined by federal government of Canada in 2018 has made a goal of a nation-wide carbon tax or cap and trade equivalent. There is likely potential for financial incentives to adopt management plans, which reduce one’s carbon footprint. There is a lack of information on the amount of carbon sequestered and emitted at each life cycle stage for the six common shelterbelt tree species (hybrid poplar, green ash, Manitoba maple, Scots pine, white spruce, and caragana) found in the Saskatchewan prairies. This study aims to estimate the net carbon sequestered by various tree species by various production stages. Net amount of carbon sequestered was a sum of that emitted as well as sequestered. Overall analysis was divided into two major parts with the first being the carbon dioxide (CO2) emissions for one year of seedling production, roughly 500,000 seedlings, was 1,100 tonnes (t), or 0.002 t per individual seedling. The second LCA stage, transportation a typical full shipment had CO2 emissions of 6.08 t for delivery to Regina, SK from Estevan, SK. For shipments of the same number of seedlings to Saskatoon, SK and Prince Albert, SK, the emissions were 14.10 t and 17.20 t CO2, respectively. Production of seedlings accounted for 95-98% of total emissions during this stage, depending on where the shipment was delivered. The highest emitters in the production phase included electricity at roughly 83% (or 914.71 t CO2) and heating at 11% (or 121.00 t CO2). The planting phase accounted for 1.90 t CO2/1000 seedlings. Maintenance accounted for 0.49 t CO2/1000 trees. These life stages added an insignificant amount of CO2 emissions comparatively to the amount that a shelterbelt can sequester over its life. All of these emissions are balanced by carbon sequestered by trees and the soil. Each shelterbelt species sequestered a different rate of carbon, with hybrid poplar sequestering the most carbon in all three soil zone clusters selected for the study. Hybrid poplar is a rapid growing tree and subsequently sequesters the most carbon of the six species in all soil zones, with a km stretch of shelterbelt sequestering upwards of 1460 t CO2 by age 60. Manitoba maple and white spruce are the next highest carbon sequesters. The final stage of the shelterbelts is its eventual disposal – assumed in this study to be their removal. This stage of removal boasted CO2 emissions for two reasons: the physical process of removing the trees as well as the carbon lost due to burning of removed biomass. The removal of a km long shrub shelterbelt released 0.82 t CO2. The removal of coniferous and deciduous trees in a shelterbelt equated 1.12 t CO2. Removal of a shelterbelt of large sized hybrid poplars produces 2.43 t CO2.
Carbon sequestration, Life Cycle Assessment, Shelterbelt, Seedling Production, Carbon Pricing, Greenhouse gas emission.
Master of Environment and Sustainability (M.E.S.)
School of Environment and Sustainability
Environment and Sustainability