09 Jun 2022
09 Jun 2022
Status: this preprint is open for discussion.

Eddy-covariance carbon fluxes of a heterogeneous forest: one tower - two heights

Alisa Krasnova1,2, Dmitrii Krasnov1, Hans Peter Ernst Cordey1, and Steffen M. Noe1 Alisa Krasnova et al.
  • 1Institute of Forestry and Engineering, Estonian University of Life Sciences, Estonia
  • 2Institute of Science and Technology, University of Tartu, Estonia

Abstract. Eddy-covariance (EC) is a widely used method for measuring ecosystem-scale fluxes of various gases. The sensor placement height is typically constrained by the canopy height and area of interest size. We studied the carbon dioxide fluxes over a hemiboreal mixed forest with two EC measurement systems located at 30 m and 70 m. The lower system NEE (NEE30) values were more positive (smaller sink or higher source) than the NEE of the higher one (NEE70), but this difference was prevalent in low light conditions and in May–November of all studied years. The nighttime and early morning difference (ΔNEE) increased with wind speed until ~2 m s-1 and friction velocity until ~0.35 m s-1 and linearly decreased after. ΔNEE was irregularly distributed over the wind direction sectors with high values overlapping the directions of South-East and South-West guy wire tunnels. Moreover, the shape of the NEE30 seasonal cycle was closer to that of a clear-cut area, and the difference between the systems increased with air temperature. The forest under study varied between a weak net sink and a strong net source on the annual scale. Directional heterogeneity correction shifted the annual NEE towards more negative values, but neither removed the difference between the systems nor changed the shape of the seasonal cycle. More studies are needed to assess the impact of clearcutting on the carbon accumulation under the measurement point.

Alisa Krasnova et al.

Status: open (until 21 Jul 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-384', Anonymous Referee #1, 27 Jun 2022 reply
  • RC2: 'Comment on egusphere-2022-384', Ankur Desai, 27 Jun 2022 reply

Alisa Krasnova et al.

Alisa Krasnova et al.


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Short summary
Forests play important role in global carbon cycle. Hemiboreal forests are located in a transitional zone between boreal and temperate zones and are characterised by higher variability in dominating tree species. We analysed carbon exchange of a hemiboreal forest using two measurement systems located on the same tower. The lower system could detect the influence of clearcuts and tower guywire tunnels, while the higher system allowed to assess the carbon balance of the full landscape.