ICDSUPL2-E013

Volume: 2, 2023
2^nd International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland:
ENVIRONMENT – PLANT – ANIMAL – PRODUCT

Abstract number: E013

DOI: https://doi.org/10.24326/ICDSUPL2.E013

Published online: 19 April 2023

ICDSUPL, 2, E013 (2023)

Potential reasons of high CO₂ uptake in old-growth pine forest

Mateusz Łukasz Frankiewicz¹*

¹ Department of Construction and Geoengineering, Faculty of Environmental Engineering and Mechanical Engineering, Poznan University of Life Sciences, Piątkowska 94 E, 60-649, Poznań, Poland

^{* Corresponding author: mateusz.frankiewicz@up.poznan.pl}

Abstract

This study reports preliminary result of eddy-covariance (EC) measurements of carbon fluxes exchange conducted above and below canopy in Scots pine (Pinus sylvestris) forest located in Sarbia Forest District in north-western Poland during the 2021–2023 growing seasons. During the first stage of our research only above canopy EC system was used with the aim to estimate net ecosystem exchange (NEE) of this old-growth pine stand. Although, we found that measured NEE fluxes were somewhat unexpectedly high for almost100-years old forest. To investigate such research problem, we formulated a first hypothesis, that the potential reason of what we think is too high NEE might be the decoupling process. In short, decoupling is an atmospheric layers split over land, mainly during the night, under specific conditions such as light winds occurrence and even little local elevation differences. During this process the air mixing weakens and thus is less effective, especially below canopy. This can then evince in CO₂ descentaccording to density gradient and runoff according to elevation differences. Such leakage of CO₂ from the area of interest, would falsely decrease the emission and be seen by EC system as apparently increased NEE fluxes. Foregoing studies seem to confirm our assumption, that decoupling may be the potential reason of apparent absorption of CO₂ when it is not expected. Similar effect was observed and confirmed e.g., in Rosinedalsheden in Northern Sweden, Bílý Kříž and Lanžhot in Moravian-Silesian Beskydy Mountains, the Czech Republic. Despite Sarbia Forest District is characterized as relatively flat area, existing local elevation differences might still lead to CO₂ runoff under specific conditions. To test this hypothesis we thus decided to extend our EC measurements and install below canopy system. We expect to observe the deviation in correlation of vertical wind speed (w) measured above- and below-canopy which suggest the occurrence of decoupling process. In Rosinedalsheden decoupling was observed in 45% of all cases during the measurement period. After filtering out decoupled periods the above-canopy mean winter NEE shifted from −0.52 μmol/m⁻² s⁻¹(negative NEE values means uptake) to a more reasonable positive value of 0.31 μmol/m⁻² s⁻¹ (positive sign indicates net emission). Similar outcome is also expected in our studies.

How to cite

M.Ł. Frankiewicz, 2023. Potential reasons of high CO₂ uptake in old-growth pine forest. In: 2nd International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland: Environment – Plant – Animal – Product. https://doi.org/10.24326/ICDSUPL2.E013