Plantation and managed forests are major sink of atmospheric CO2 in North America and
across the world. If properly managed, these forests may help to offset anthropogenic
greenhouse gas emissions to mitigate climate change. This study investigated the impacts
of climate variability, extreme weather events, and disturbance (thinning) on the growth
and carbon (C) exchanges of a young temperate coniferous plantation forest (48-year-old
white pine (Pinus strobus)) in the Great Lakes region in Canada using long-term eddy
covariance flux observations. CO2 fluxes, as well as meteorological and soil variables
were continuously measured from 2008 to 2021 (14 years) to estimate net ecosystem
productivity (NEP), ecosystem respiration (RE), and gross ecosystem productivity (GEP).
Soil respiration (Rs) was also measured using automatic soil chambers from 2017 to
2019. Selective thinning was conducted first time in this stand in January 2021 to remove
approximately 1/3 of the basal area. Study results showed that climate conditions in the
early growing season, from late May to mid-July, determined the overall strength of C
uptake in any given year. However, above-average temperature and precipitation in the
late growing season significantly reduced NEP and even in some cases, transformed the
forest into a net C source for short periods due to large pulses of RE. Mean annual GEP,
RE and NEP values were 1660 ±199, 1087 ±96 and 592 ±169 g C m-2 yr-1, respectively,
from 2008 to 2021. Thinning did not significantly impact the C uptake of the forest as the
stand remained a net C sink with an annual NEP of 648 g C m-2 yr-1 in 2021. Changes in
annual GEP, RE and NEP in 2021 remained within the range of interannual variability
over the study period. Overall, Rs accounted for roughly 89% of the annual RE in this
stand. A complete understanding of the response of forest C dynamics to climate
variability and thinning in young plantation forests is critical to guiding future forest
management efforts for enhancing the growth and C uptake of these forest plantations to
maximize their potential in support of providing nature-based climate solutions. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/28983 |
| Date | January 2023 |
| Creators | Tabaei, Farbod |
| Contributors | Arain, M. Altaf, Earth and Environmental Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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