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Wenxin Zhang

Forskare

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

Författare

  • Wenxin Zhang
  • Per-Erik Jansson
  • Charlotte Sigsgaard
  • Alistair McConnell
  • Mathilde Jammet
  • Andreas Westergaard-Nielsen
  • Magnus Lund
  • Thomas Friborg
  • Anders Michelsen
  • Bo Elberling

Summary, in English

Quantifying net CO2 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 CO2 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 CO2 source, sink or are in balance. This study presents year-round eddy-covariance (EC) measurements of CO2 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 CO2 fluxes, soil temperature and moisture, the process-oriented model (CoupModel) has been constrained to quantify an annual budget and characterize seasonal patterns of CO2 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 CO2 emissions during that winter, the annual budget results in a marked reduction in the CO2 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.

Avdelning/ar

  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • MERGE: ModElling the Regional and Global Earth system

Publiceringsår

2019-04-29

Språk

Engelska

Sidor

176-186

Publikation/Tidskrift/Serie

Agricultural and Forest Meteorology

Volym

272-273

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Climate Research
  • Meteorology and Atmospheric Sciences

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1873-2240