Belowground carbon dioxide efflux in the contrast ecosystems of the north West Siberia: partitioning into different sources Olga Goncharova ([email protected]), G. Matyshak, A. Sefilian, M. Timofeeva, and A. Bobrik Lomonosov Moscow State University, Moscow, Russia

THE MAIN QUESTION FOREST ECOSYSTEMS PEATLANDS Climate change caused by the growth of greenhouse gas The contribution concentrations in the atmosphere focused the attention of 13% of root respiration researchers on the estimation of carbon budgets of by SHADING 14% The contribution of root various types of ecosystems, including the Arctic. experiment was 15% respiration by Partitioning soil carbon dioxide efflux into individual more than 14% SHADING experiment components is necessary, as differential responses of (only shrubby and was from 14 to 26% these components to environmental change have grassy vegetation 15% profound implications for the soil and ecosystem carbon without trees) balance. The main objective of the study was to evaluate the contribution of autotrophic and heterotrophic Total root respiration components to CO emission by soils of north ecosystems O 2 AE <1mm 1-5mm BHF The contribution of root using field, laboratory and calculation methods >5mm С respiration by 0 50 100 150 200 250 300 350 COMPARISON OF PLANTED Total microbial respiration RESEARCH AREA AND RESEARCH SITES AND UNPLANTED SOIL The contribution of O 300

AE 250 1

was about 50%. In this - h

BHF 2 200

root respiration by - m

2 150 С approach, it is possible to COMPONENT 100 0 200 400 600 800 1000 North of West mg CO mg СО /horizon/hour 50 2 underestimate the INTEGRATION 0 Siberia (Russia) 2014 2015 2016 differences in microbial experiment was 29±6% пятнаspots растительностьvegetation in discontinuous respiration. and continuous The contribution of Total root respiration By permafrost zone. root respiration by ROOT Т1 Т2 <1mm COMPONENT 1-5mm MASS REGRESSION Т3 INTEGRATION experiment was from 16 0 20 40 60 80 100 Total microbial respiration the contribution to 60% depending on the Т1 Т2 of root vegetation projective Т3 0 100 200 300 400 respiration was cover mg СО2/horizon/hour 14±3%

2 CONCLUSION 3 FROST-BOIL ECOSYSTEMS  Belowground carbon dioxide efflux including the autotrophic and heterotrophic component, varies considerably in the ecosystems of the By SHADING 3. Tundra frost-boil ecosystem north West Siberia. In the middle of the growing season, it averages experiment the -2 -1 («spotted» tundra) from 80 mg CO2 m h in tundra and permafrost peatland ecosystems contribution of to 600 mg CO m-2 h-1 in forests. High values of СО production by 1. Permafrost peatlands () root respiration 2 2 forest soils are due to both high values of total microbial respiration 2. Forest ecosystems ( and green pine forest) was more than 34% and high root biomass (3-10 times more in comparison to peatland and tundra). METHODS ROOT MASS REGRESSION method is not acceptable on frost boil tundra ecosystems  The contribution of root respiration, calculated based on a complex of Method are base on stopping leaf photosynthesis and methods, varies significantly in all ecosystems. The minimum  Shading thus excluding new assimilate transport to the roots because of the high heterogeneity of the physical, chemical and microbiological contribution was found for peatlands – from 14 to 26%, in forest and Method is based on the physical frost-boil tundra – from 15 to 60%. separation of C pools and measuring properties of soils  Component integration the specific rates of CO2 efflux from  High variability of data is due both to the great heterogeneity of the each component part By COMPONENT INTEGRATION environmental conditions of permafrost-affected ecosystems and to the the contribution of root respiration  Root exclusion Comparison of planted methodological aspects. The use of a complex of methods makes it and unplanted soil was from 15 to 60% along the possible to reduce the methodological uncertainty of the results. Method is based on the assumed linear transect, covering the all elements of  Root mass regression relationship between root biomass and the landscape (boils, inter-boils) ACKNOWLEDGMENT the amount of CO2 respired by roots This work was founded by the Russian Foundation for Basic Research grant № 16-04-00808