TY - JOUR

T1 - Model-data fusion to assess year-round CO2 fluxes for an arctic heath ecosystem in West Greenland (69°N)

AU - Zhang, Wenxin

AU - Jansson, Per Erik

AU - Sigsgaard, Charlotte

AU - McConnell, Alistair

AU - Jammet, Mathilde Manon

AU - Westergaard-Nielsen, Andreas

AU - Lund, Magnus

AU - Friborg, Thomas

AU - Michelsen, Anders

AU - Elberling, Bo

N1 - CENPERM[2019]

PY - 2019

Y1 - 2019

N2 - Quantifying net CO 2 exchange (NEE)of arctic terrestrial ecosystems in response to changes in climatic and environmental conditions is central to understanding ecosystem functioning and assessing potential feedbacks of the carbon cycle to future climate changes. However, annual CO 2 budgets for arctic tundra are rare due to the difficulties of performing measurements during non-growing seasons. It is still unclear to what extent arctic tundra ecosystems currently act as a CO 2 source, sink or are in balance. This study presents year-round eddy-covariance (EC)measurements of CO 2 fluxes for an arctic heath ecosystem on Disko Island, West Greenland (69 °N)over five years. Based on a fusion of year-round EC-derived CO 2 fluxes, soil temperature and moisture, the process-oriented model (CoupModel)has been constrained to quantify an annual budget and characterize seasonal patterns of CO 2 fluxes. The results show that total photosynthesis corresponds to -202 ± 20 g C m −2 yr -1 with ecosystem respiration of 167 ± 28 g C m -2 yr -1 , resulting in NEE of -35 ± 15 g C m -2 yr -1 . The respiration loss is mainly described as decomposition of near-surface litter. A year with an anomalously deep snowpack shows a threefold increase in the rate of ecosystem respiration compared to other years. Due to the high CO 2 emissions during that winter, the annual budget results in a marked reduction in the CO 2 sink. The seasonal patterns of photosynthesis and soil respiration were described using response functions of the forcing atmosphere and soil conditions. Snow depth, topography-related soil moisture, and growing season warmth are identified as important environmental characteristics which most influence seasonal rates of gas exchange.

AB - Quantifying net CO 2 exchange (NEE)of arctic terrestrial ecosystems in response to changes in climatic and environmental conditions is central to understanding ecosystem functioning and assessing potential feedbacks of the carbon cycle to future climate changes. However, annual CO 2 budgets for arctic tundra are rare due to the difficulties of performing measurements during non-growing seasons. It is still unclear to what extent arctic tundra ecosystems currently act as a CO 2 source, sink or are in balance. This study presents year-round eddy-covariance (EC)measurements of CO 2 fluxes for an arctic heath ecosystem on Disko Island, West Greenland (69 °N)over five years. Based on a fusion of year-round EC-derived CO 2 fluxes, soil temperature and moisture, the process-oriented model (CoupModel)has been constrained to quantify an annual budget and characterize seasonal patterns of CO 2 fluxes. The results show that total photosynthesis corresponds to -202 ± 20 g C m −2 yr -1 with ecosystem respiration of 167 ± 28 g C m -2 yr -1 , resulting in NEE of -35 ± 15 g C m -2 yr -1 . The respiration loss is mainly described as decomposition of near-surface litter. A year with an anomalously deep snowpack shows a threefold increase in the rate of ecosystem respiration compared to other years. Due to the high CO 2 emissions during that winter, the annual budget results in a marked reduction in the CO 2 sink. The seasonal patterns of photosynthesis and soil respiration were described using response functions of the forcing atmosphere and soil conditions. Snow depth, topography-related soil moisture, and growing season warmth are identified as important environmental characteristics which most influence seasonal rates of gas exchange.

KW - Arctic tundra

KW - Carbon budget

KW - CoupModel

KW - Eddy covariance

KW - Net ecosystem exchange

KW - Year-round measurements

U2 - 10.1016/j.agrformet.2019.02.021

DO - 10.1016/j.agrformet.2019.02.021

M3 - Journal article

AN - SCOPUS:85064630872

VL - 272-273

SP - 176

EP - 186

JO - Agricultural and Forest Meteorology

JF - Agricultural and Forest Meteorology

SN - 0168-1923

ER -