Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest-wetland landscape

被引:67
作者
Helbig, Manuel [1 ,2 ]
Chasmer, Laura E. [3 ]
Desai, Ankur R. [4 ]
Kljun, Natascha [5 ]
Quinton, William L. [6 ]
Sonnentag, Oliver [1 ,2 ]
机构
[1] Univ Montreal, Dept Geog, 520 Chemin Cote St Catherine, Montreal, PQ H2V 2B8, Canada
[2] Univ Montreal, Ctr Etud Nord, 520 Chemin Cote St Catherine, Montreal, PQ H2V 2B8, Canada
[3] Univ Lethbridge, Dept Geog, Lethbridge, AB T1K 3M4, Canada
[4] Univ Wisconsin, Dept Atmospher & Ocean Sci, Madison, WI 53706 USA
[5] Swansea Univ, Dept Geog, Singleton Pk, Swansea SA2 8PP, W Glam, Wales
[6] Wilfrid Laurier Univ, Cold Reg Res Ctr, Waterloo, ON N2L 3C5, Canada
基金
加拿大创新基金会; 加拿大自然科学与工程研究理事会;
关键词
boreal forest; carbon dioxide; climate change; ecosystem respiration; eddy covariance; gross primary productivity; permafrost; wetlands; NET ECOSYSTEM EXCHANGE; ELEVATED GROWTH TEMPERATURES; BLACK SPRUCE FORESTS; PERMAFROST THAW; DISCONTINUOUS PERMAFROST; NORTHWEST-TERRITORIES; NORTHERN ECOSYSTEMS; THERMAL ADAPTATION; PEAT ACCUMULATION; METHANE EMISSION;
D O I
10.1111/gcb.13638
中图分类号
X176 [生物多样性保护];
学科分类号
090705 ;
摘要
In the sporadic permafrost zone of northwestern Canada, boreal forest carbon dioxide (CO2) fluxes will be altered directly by climate change through changing meteorological forcing and indirectly through changes in landscape functioning associated with thaw-induced collapse-scar bog (` wetland') expansion. However, their combined effect on landscape-scale net ecosystem CO2 exchange (NEELAND), resulting from changing gross primary productivity (GPP) and ecosystem respiration (ER), remains unknown. Here, we quantify indirect land cover change impacts on NEELAND and direct climate change impacts on modeled temperature-and light-limited NEELAND of a boreal forestwetland landscape. Using nested eddy covariance flux towers, we find both GPP and ER to be larger at the landscape compared to the wetland level. However, annual NEELAND (-20 g C m(-2)) and wetland NEE (-24 g C m(-2)) were similar, suggesting negligible wetland expansion effects on NEELAND. In contrast, we find non-negligible direct climate change impacts when modeling NEELAND using projected air temperature and incoming shortwave radiation. At the end of the 21st century, modeled GPP mainly increases in spring and fall due to reduced temperature limitation, but becomes more frequently light-limited in fall. In a warmer climate, ER increases year-round in the absence of moisture stress resulting in net CO2 uptake increases in the shoulder seasons and decreases during the summer. Annually, landscape net CO2 uptake is projected to decline by 25 +/- 14 g C m(-2) for a moderate and 103 +/- 38 g C m(-2) for a high warming scenario, potentially reversing recently observed positive net CO2 uptake trends across the boreal biome. Thus, even without moisture stress, net CO2 uptake of boreal forest-wetland landscapes may decline, and ultimately, these landscapes may turn into net CO2 sources under continued anthropogenic CO2 emissions. We conclude that NEELAND changes are more likely to be driven by direct climate change rather than by indirect land cover change impacts.
引用
收藏
页码:3231 / 3248
页数:18
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