Quantifying peat carbon accumulation in Alaska using a process‐based biogeochemistry model. Issue 8 (24th August 2016)

• Record Type: Journal Article
• Authors: Wang, Sirui; Zhuang, Qianlai; Yu, Zicheng; Bridgham, Scott; Keller, Jason K.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 8(2016:Aug.)
• Page Start: 2172
• Page End: 2185
• Publication Date: 2016-08-24
• Subjects: peatland -- carbon -- accumulation -- modeling -- Alaska -- biogeochemistry; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2016JG003452
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: This study uses an integrated modeling framework that couples the dynamics of hydrology, soil thermal regime, and ecosystem carbon and nitrogen to quantify the long‐term peat carbon accumulation in Alaska during the Holocene. Modeled hydrology, soil thermal regime, carbon pools and fluxes, and methane emissions are evaluated using observation data at several peatland sites in Minnesota, Alaska, and Canada. The model is then applied for a 10, 000 year (15 ka to 5 ka; 1 ka = 1000 cal years before present) simulation at four peatland sites. We find that model simulations match the observed carbon accumulation rates at fen sites during the Holocene ( R 2 = 0.88, 0.87, 0.38, and −0.05 using comparisons in 500 year bins). The simulated (2.04 m) and observed peat depths (on average 1.98 m) were also compared well ( R 2 = 0.91). The early Holocene carbon accumulation rates, especially during the Holocene thermal maximum (HTM) (35.9 g C m − 2 yr − 1 ), are estimated up to 6 times higher than the rest of the Holocene (6.5 g C m − 2 yr − 1 ). Our analysis suggests that high summer temperature and the lengthened growing season resulted from the elevated insolation seasonality, along with wetter‐than‐before conditions might be major factors causing the rapid carbon accumulation in Alaska during the HTM. Our sensitivity tests indicate that, apart from climate, initial water table depth and vegetation canopy are major drivers to the estimated peat carbon accumulation. When the modeling framework is evaluated for various peatland types in the Arctic, it can quantify peatland carbon accumulation at regional scales. Key Points: We develop a model coupling hydrology, soil thermal, methane, ecosystem carbon, and nitrogen to quantify long‐term peat carbon accumulation We compare modeled soil moisture and temperature, water table, methane, and carbon pools with observation and apply the model to Alaskan peatland High summer temperature from elevated insolation seasonality and high precipitation may be main factor for rapid carbon accumulation