[M-IS05] Environmental, Socio-economic, and Climatic Changes in Northern Eurasia

[MIS05-02] The effect of anomalous temperature and precipitation on carbon dioxide fluxes in tundra and forest-tundra ecosystems

*Daria Gushchina¹、Elizaveta Gorbarenko^1,2、Maria Tarasova¹、Irina Zheleznova¹、Ekaterina Emelianova^1,2、Ravil Gibadullin¹、Alexander Olchev¹ (1.Department of Meteorology and Climatology, Faculty of Geography, Lomonosov Moscow State University、2.A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Science)

キーワード：temperature and precipitation extremes, carbon dioxide fluxes, Arctic tundra and forest tundra, FLUXNET

The development and functioning of landscapes in different regions of the world, especially at polar latitudes, may be significantly affected by the increased frequency of extreme weather events associated with modern climate change. The Northern Hemisphere tundra and forest-tundra landscapes are considered to be among the most vulnerable to changes in environmental conditions under a changing climate. Based on meteorological and CO₂ flux data from the global FLUXNET network, the regional AmeriFlux and the European flux database cluster as well as the ERA5 reanalysis the spatial variability in the response of daily net ecosystem CO₂ exchange (NEE) of Northern Hemisphere tundra and forest-tundra landscapes to anomalous temperature and precipitation events during the growing season was analyzed. A wide range of observed responses of NEE to extreme temperature and precipitation events was revealed depending on the geographic location and the type of landscape. While most previous studies documented the effect of stressed photosynthesis associated with abnormally high temperatures and consequently increased CO₂ emission in polar ecosystems, we observed the similar response of CO₂ only in ecosystems at the southern boundary of the polar region, where heat waves are more frequent. The opposite response was found in deciduous broadleaf forests, permanent wetlands and open shrublands, where CO₂ uptake prevailed on 16-46% of the abnormally high temperature days. This effect can be attributed to the temperature regime of the polar region with not very high air temperatures, which do not lead to heat stress for the vegetation. The effect of the abnormally low temperature on the CO₂ fluxes is that the positive NEE anomalies are larger than the negative ones, which is mostly associated with an increase in CO₂ emissions. It was shown that the response of CO₂ fluxes to anomalously high and low precipitation is rather similar regardless of the time scale (short-term or long-term response). The simultaneous response of CO₂ fluxes to heavy precipitation is manifested in increased CO₂ emissions to the atmosphere for most of the ecosystems studied. The cumulative effect is similar to the simultaneous one, i.e. heavy precipitation during the preceding 14 days mostly leads to positive NEE anomalies (higher CO₂ emission). The prolonged precipitation deficit is accompanied by negative NEE anomalies in the majority of tundra and forest-tundra ecosystems considered, corresponding to increased CO₂ uptake.
This research was funded by the Russian Science Foundation, grant number 22–17−00073