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Quantifying the emissions of the three main biogenic greenhouse gases (GHGs), carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4), from agroecosystems is crucial. In this study continuous measurements of N2O, and CH4 emissions from potato and pea crops in southwest British Columbia, Canada were made using the eddy‐covariance (EC) technique. Flux footprint analysis, coupled with EC and manual nonsteady state chamber measurements, was used to address the spatial heterogeneity resulting from the field edge at the study site. Flux footprint corrections had a larger effect on N2O fluxes than CO2 fluxes because of a more pronounced difference in N2O fluxes between the crop and edge areas. After flux footprint corrections, the potato and pea crops were both weak CO2 sinks with annual net ecosystem exchange values of −57 ± 9 and −97 ± 16 g C m−2 yr−1, respectively. However, after taking carbon (C) export via crop harvest and C import via seeding into account, the potato crop shifted to being a moderate C source of 284 ± 55 g C m−2 yr−1, while the pea crop became near C neutral, sequestering only 30 ± 26 g C m−2 yr−1. Annual GHG balances, quantified by converting N2O and CH4 to CO2 equivalents as pulse emissions using respective global warming potentials on a 100‐year timescale, were 417 ± 88 and 152 ± 106 g CO2e m−2 yr−1 for the potato and pea crops, respectively, with N2O contributing the largest proportion to annual total GHG balances and outweighing the CO2 uptake from the atmosphere. Plain Language Summary: To better mitigate climate change, quantifying the emissions of the three main biogenic greenhouse gases (GHGs), carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4), from agroecosystems is critical. Therefore, in this study we made continuous half‐hourly measurements of CO2, N2O, and CH4 emissions from potato and pea crops in southwest British Columbia, Canada using micrometeorological instrumentation installed at the field edge. To correct for the effects of the field edge on the micrometeorological measurements, we used supplementary chamber measurements and a footprint model. This enabled us to estimate the actual GHG budgets of the study crop areas. The correction had a larger effect on N2O fluxes than CO2 fluxes because of a more pronounced difference in N2O fluxes between the crop and edge areas. Both crops sequestered CO2 on an annual basis. However, after taking carbon (C) export via crop harvest and C import via seeding into account, the potato crop shifted to being a moderate C source while the pea crop became near C neutral. Even though CH4 emissions were low, substantial N2O emissions outweighed the CO2 uptake from the atmosphere by both crops, resulting in both being GHG sources. Key Points: Combining eddy‐covariance and flux‐chamber data with flux analysis allowed estimation of actual greenhouse gas fluxes from crop fieldsIncluding export (harvesting) and import (seeding), peas were near carbon neutral while potatoes were a moderate carbon sourceFor both potato and pea crops, nitrous oxide contributed the largest proportion of the annual total greenhouse gas emissions [ABSTRACT FROM AUTHOR]

Area burned, number of fires, seasonal fire severity, and fire season length are all expected to increase in Canada, with largely unquantified ecosystem feedbacks. However, there are few observational studies measuring ecosystem-scale biogeochemical (e.g., carbon dioxide exchanges) and biophysical (e.g., energy partitioning) properties during smoke episodes and hence assessing responses of gross primary production (GPP) to changes in incoming diffuse photosynthetically active radiation (PAR). In this study, we leveraged two long-term eddy covariance measurement sites in forest and wetland ecosystems to study four smoke episodes, which happened at different times and differed in length, over 4 different years (2015, 2017, 2018, and 2020). We found that the highest decrease in shortwave irradiance due to smoke was about 50 % in July and August but increased to about 90 % when the smoke arrived in September. When the smoke arrived in the later stage of summer, impacts on sensible and latent heat fluxes were very different than the earlier ones. Smoke generally increased the diffuse fraction (DF) from ∼ 0.30 to ∼ 0.50 and turned both sites into stronger carbon dioxide (CO2) sinks with increased GPP up to ∼ 18 % and ∼ 7 % at the forest and wetland site, respectively. However, when DF exceeded 0.80 as a result of dense smoke, both ecosystems became net CO2 sources as total PAR dropped to low values. The results suggest that this kind of natural experiment is important for validating future predictions of smoke–productivity feedbacks. [ABSTRACT FROM AUTHOR]

Rewetting of disturbed peatlands is an important restoration strategy for climate change mitigation. Previous work primarily focuses on the biogeochemical processes altered by rewetting and few studies have investigated the biophysical impacts, which can diminish or amplify biogeochemical effects beyond the ecosystem scale. We used a paired flux tower approach in a restored peatland to collect year‐round eddy covariance data to assess the biophysical impacts of disturbance and management practices. The first site was actively rewetted and is characterized by Sphagnum and white beak‐rush with patches of open water. The second site represents a disturbed ecosystem, which underwent natural regeneration and is dominated by scrub pine, Sphagnum, and low shrubs. We found that the actively restored site had higher net radiation compared to the second site due to more surface water ponding; however, the higher aerodynamic conductance at the passively restored site contributed to enhanced daytime turbulent fluxes, and hence, both sites had similar aerodynamic temperatures during the daytime. The actively restored site experienced warmer nighttime and seasonal aerodynamic temperature as much of the excess radiation during the day was stored in the water column and released at night. To achieve restoration goals, higher water tables are now maintained throughout large sections of the bog. The study implies that water table manipulation has the potential to minimize greenhouse gas emissions from the bog, thereby allowing the biophysical impacts of peatland restoration to enhance the biogeochemical benefits. Therefore, it is important to consider both biophysical and biogeochemical changes in peatland restoration management. Plain Language Summary: Peatland restoration through rewetting influences the climate by altering land‐atmosphere greenhouse gas dynamics and energy and water exchanges. The energy and water exchanges altered by rewetting can influence surface and air temperature, and hence local and regional climate; however, they are understudied. This study analyzed year‐round water and energy exchange measurements at two sites in the Burns Bog peatland in British Columbia, Canada, which represent two different dominant ecosystem types that experienced different restoration strategies. We found that the rewetted site with more open water had warmer nighttime and seasonal surface temperature. The results indicate that water levels and vegetation type influenced by restoration strategies have a strong impact on energy partitioning, surface aerodynamic characteristics, and consequently surface and air temperatures. Peatland restoration management should recognize the implications of both greenhouse gas fluxes and energy and water exchanges to fully understand climatic impacts of restoration. Key Points: Significant surface temperature differences at night between the two restored peatland sites with different surface characteristicsThe warmer nighttime and seasonal temperatures at the actively rewetted site were due to energy stored in standing water during daytimeRestoration management has to consider biophysical impacts in addition to biogeochemical changes [ABSTRACT FROM AUTHOR]