Variability in Trends and Indicators of CO2 Exchange Across Arctic Wetlands

Abstract

AbstractArctic wetlands store nearly half of the world's soil organic carbon and are crucial to the global carbon cycle. However, most Earth system models fail to account for wetlands given heterogeneity and uncertainty surrounding the response of different wetland types to climate change. We analyzed summer (June–August) carbon dioxide (CO2) exchange, meteorological conditions, and ecological conditions at four Arctic wetlands. Micrometeorological flux tower data were used to assess CO2 exchange and meteorological conditions across 7 to 9 years of data. Climate data were used to assess meteorological conditions across 30 years of data. Satellite data described ecological conditions. Each site acted as a CO2 sink, but strength varied, ranging from −49 to −93 g C/m2 per summer. A trend analysis was used to investigate how CO2 balance and surrounding conditions may have changed. CO2 exchange significantly changed at one site, becoming a stronger sink. Changes in meteorological conditions were variable across sites with the exception of air temperature which, when considering significant trends, unanimously increased across sites. Ecological conditions suggested increased vegetation cover regardless of statistical significance at all sites. A conditional random forest algorithm was used to evaluate drivers of CO2 exchange. Cumulative precipitation and evapotranspiration were the main drivers of net ecosystem exchange and gross primary productivity, while ecosystem respiration was primarily driven by air temperature, suggesting that projected changes in temperature and precipitation patterns will influence the carbon balance of Arctic wetlands. Variability across sites emphasizes the need for long‐term observations across wetland types and climatic gradients.