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3. Increasing contribution of peatlands to boreal evapotranspiration in a warming climate

Author

Helbig, Manuel, Waddington, James Michael, Alekseychik, Pavel, Amiro, Brian D., Aurela, Mika, Barr, Alan G., Black, T. Andrew, Blanken, Peter D., Carey, Sean K., Chen, Jiquan, Chi, Jinshu, Desai, Ankur R., Dunn, Allison, Euskirchen, Eugenie S., Flanagan, Lawrence B., Forbrich, Inke, Friborg, Thomas, Grelle, Achim, Harder, Silvie, Heliasz, Michal, Humphreys, Elyn R., Ikawa, Hiroki, Isabelle, Pierre-Erik, Iwata, Hiroki, Jassal, Rachhpal, Korkiakoski, Mika, Kurbatova, Juliya, Kutzbach, Lars, Lindroth, Anders, Löfvenius, Mikaell Ottosson, Lohila, Annalea, Mammarella, Ivan, Marsh, Philip, Maximov, Trofim, Melton, Joe R., Moore, Paul A., Nadeau, Daniel F., Nicholls, Erin M., Nilsson, Mats B., Ohta, Takeshi, Peichl, Matthias, Petrone, Richard M., Petrov, Roman, Prokushkin, Anatoly, Quinton, William L., Reed, David E., Roulet, Nigel T., Runkle, Benjamin R. K., Sonnentag, Oliver, Strachan, Ian B., Taillardat, Pierre, Tuittila, Eeva-Stiina, Tuovinen, Juha-Pekka, Turner, Jessica, Ueyama, Masahito, Varlagin, Andrej, Wilmking, Martin, Wofsy, Steven C., and Zyrianov, Vyacheslav

Published
2020
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4. Transpiration and evaporative partitioning at a boreal forest and shrub taiga site in a subarctic alpine catchment, Yukon territory, Canada.

Author

Nicholls, Erin M., Clark, M. Graham, and Carey, Sean K.

Subjects
TAIGAS, MOUNTAIN watersheds, WHITE spruce, GROWING season, GROUND vegetation cover, SHRUBS
Abstract

Despite widespread observations of climate‐change induced treeline migration and shrubification, there remains few direct measurements of transpiration and dynamics of evaporative partitioning in northern climates. Here, we present eddy covariance and sap flow data at a low elevation boreal white spruce forest and a mid‐elevation shrub taiga comprised of tall willow (Salix spp.) and birch (Betula spp.) in a subarctic, alpine catchment in Yukon Territory, Canada over two hydrologically distinct years. Specific research questions addressed were: (1) How do contributions of T to ET vary between sites and years? and (2) What are the primary meteorological, phenological, and soil moisture controls and limits on ET and T across vegetation covers? In the mid‐growing season, mean T rates were greater at the dense shrub site (2.0 ± 0.75 mm d−1) than the forest (1.47 ± 0.52 mm d−1). During this time, T:ET was lower at the forest (0.48) than at the tall, dense shrub site (0.80). Of the 2 years, 2020 was considerably wetter and cooler than 2019 during the growing season. At the shrub site, during the mid‐growing season (July 1‐Aug 15), T dropped considerably in 2020 (−26%), as T was suppressed during the short, wet growing season. In contrast, T at the forest was only moderately suppressed (−3%) between years in this same period. Evapotranspiration was more strongly controlled by air temperature during the early and late season at the forest, while ET at the shrub site was more sensitive to warmer temperatures in the mid‐growing season. Distinct differences in sap flux densities, sensitivities to environmental drivers, and stomatal resistances existed between shrub species. Results suggest that warming temperatures, increases in growing season length, and increased rainfall will cause differences in evaporative response and partitioning over complex, heterogenous alpine watersheds. [ABSTRACT FROM AUTHOR]

Published
2023
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5. The biophysical climate mitigation potential of boreal peatlands during the growing season

Author

Helbig, Manuel, Waddington, James M, Alekseychik, Pavel, Amiro, Brian, Aurela, Mika, Barr, Alan G, Black, T Andrew, Carey, Sean K, Chen, Jiquan, Chi, Jinshu, Desai, Ankur R, Dunn, Allison, Euskirchen, Eugenie S, Flanagan, Lawrence B, Friborg, Thomas, Garneau, Michelle, Grelle, Achim, Harder, Silvie, Heliasz, Michal, Humphreys, Elyn R, Ikawa, Hiroki, Isabelle, Pierre-Erik, Iwata, Hiroki, Jassal, Rachhpal, Korkiakoski, Mika, Kurbatova, Juliya, Kutzbach, Lars, Lapshina, Elena, Lindroth, Anders, Löfvenius, Mikaell Ottosson, Lohila, Annalea, Mammarella, Ivan, Marsh, Philip, Moore, Paul A, Maximov, Trofim, Nadeau, Daniel F, Nicholls, Erin M, Nilsson, Mats B, Ohta, Takeshi, Peichl, Matthias, Petrone, Richard M, Prokushkin, Anatoly, Quinton, William L, Roulet, Nigel, Runkle, Benjamin R K, Sonnentag, Oliver, Strachan, Ian B, Taillardat, Pierre, Tuittila, Eeva-Stiina, Tuovinen, Juha-Pekka, Turner, Jessica, Ueyama, Masahito, Varlagin, Andrej, Vesala, Timo, Wilmking, Martin, Zyrianov, Vyacheslav, Schulze, Christopher, Helbig, Manuel, Waddington, James M, Alekseychik, Pavel, Amiro, Brian, Aurela, Mika, Barr, Alan G, Black, T Andrew, Carey, Sean K, Chen, Jiquan, Chi, Jinshu, Desai, Ankur R, Dunn, Allison, Euskirchen, Eugenie S, Flanagan, Lawrence B, Friborg, Thomas, Garneau, Michelle, Grelle, Achim, Harder, Silvie, Heliasz, Michal, Humphreys, Elyn R, Ikawa, Hiroki, Isabelle, Pierre-Erik, Iwata, Hiroki, Jassal, Rachhpal, Korkiakoski, Mika, Kurbatova, Juliya, Kutzbach, Lars, Lapshina, Elena, Lindroth, Anders, Löfvenius, Mikaell Ottosson, Lohila, Annalea, Mammarella, Ivan, Marsh, Philip, Moore, Paul A, Maximov, Trofim, Nadeau, Daniel F, Nicholls, Erin M, Nilsson, Mats B, Ohta, Takeshi, Peichl, Matthias, Petrone, Richard M, Prokushkin, Anatoly, Quinton, William L, Roulet, Nigel, Runkle, Benjamin R K, Sonnentag, Oliver, Strachan, Ian B, Taillardat, Pierre, Tuittila, Eeva-Stiina, Tuovinen, Juha-Pekka, Turner, Jessica, Ueyama, Masahito, Varlagin, Andrej, Vesala, Timo, Wilmking, Martin, Zyrianov, Vyacheslav, and Schulze, Christopher

Abstract

Peatlands and forests cover large areas of the boreal biome and are critical for global climate regulation. They also regulate regional climate through heat and water vapour exchange with the atmosphere. Understanding how land-atmosphere interactions in peatlands differ from forests may therefore be crucial for modelling boreal climate system dynamics and for assessing climate benefits of peatland conservation and restoration. To assess the biophysical impacts of peatlands and forests on peak growing season air temperature and humidity, we analysed surface energy fluxes and albedo from 35 peatlands and 37 evergreen needleleaf forests—the dominant boreal forest type—and simulated air temperature and vapour pressure deficit (VPD) over hypothetical homogeneous peatland and forest landscapes. We ran an evapotranspiration model using land surface parameters derived from energy flux observations and coupled an analytical solution for the surface energy balance to an atmospheric boundary layer (ABL) model. We found that peatlands, compared to forests, are characterized by higher growing season albedo, lower aerodynamic conductance, and higher surface conductance for an equivalent VPD. This combination of peatland surface properties results in a ∼20% decrease in afternoon ABL height, a cooling (from 1.7 to 2.5 °C) in afternoon air temperatures, and a decrease in afternoon VPD (from 0.4 to 0.7 kPa) for peatland landscapes compared to forest landscapes. These biophysical climate impacts of peatlands are most pronounced at lower latitudes (∼45°N) and decrease toward the northern limit of the boreal biome (∼70°N). Thus, boreal peatlands have the potential to mitigate the effect of regional climate warming during the growing season. The biophysical climate mitigation potential of peatlands needs to be accounted for when projecting the future climate of the boreal biome, when assessing the climate benefits of conserving pristine boreal peatlands, and when restoring peatlands that

Published
2020

6. The biophysical climate mitigation potential of boreal peatlands during the growing season

Author

Helbig, Manuel, primary, Waddington, James M, additional, Alekseychik, Pavel, additional, Amiro, Brian, additional, Aurela, Mika, additional, Barr, Alan G, additional, Black, T Andrew, additional, Carey, Sean K, additional, Chen, Jiquan, additional, Chi, Jinshu, additional, Desai, Ankur R, additional, Dunn, Allison, additional, Euskirchen, Eugenie S, additional, Flanagan, Lawrence B, additional, Friborg, Thomas, additional, Garneau, Michelle, additional, Grelle, Achim, additional, Harder, Silvie, additional, Heliasz, Michal, additional, Humphreys, Elyn R, additional, Ikawa, Hiroki, additional, Isabelle, Pierre-Erik, additional, Iwata, Hiroki, additional, Jassal, Rachhpal, additional, Korkiakoski, Mika, additional, Kurbatova, Juliya, additional, Kutzbach, Lars, additional, Lapshina, Elena, additional, Lindroth, Anders, additional, Löfvenius, Mikaell Ottosson, additional, Lohila, Annalea, additional, Mammarella, Ivan, additional, Marsh, Philip, additional, Moore, Paul A, additional, Maximov, Trofim, additional, Nadeau, Daniel F, additional, Nicholls, Erin M, additional, Nilsson, Mats B, additional, Ohta, Takeshi, additional, Peichl, Matthias, additional, Petrone, Richard M, additional, Prokushkin, Anatoly, additional, Quinton, William L, additional, Roulet, Nigel, additional, Runkle, Benjamin R K, additional, Sonnentag, Oliver, additional, Strachan, Ian B, additional, Taillardat, Pierre, additional, Tuittila, Eeva-Stiina, additional, Tuovinen, Juha-Pekka, additional, Turner, Jessica, additional, Ueyama, Masahito, additional, Varlagin, Andrej, additional, Vesala, Timo, additional, Wilmking, Martin, additional, Zyrianov, Vyacheslav, additional, and Schulze, Christopher, additional

Published
2020
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