Interannual variability and seasonality of carbonyl sulfide fluxes of an Austrian Scots pine forest
- Institute of Ecology, Universität Innsbruck, Innsbruck, Austria
The gross primary productivity (GPP), that is the gross uptake of carbon dioxide (CO2) by plants, cannot be measured on ecosystem level but must be inferred by either applying models or measuring proxies. One of those proxies is the trace gas carbonyl sulfide (COS), which is of particular interest, because it shares a very similar pathway into plant leaves as CO2 and is, contrary to the latter, generally not re-emitted.
Due to the need of expensive and sensitive instrumentation, e.g., quantum cascade lasers, only a limited amount of ecosystem measurements and even fewer long-term studies at this scale have been conducted. Consequently, more data focusing on the seasonality and the interannual variability of COS ecosystem fluxes are needed to understand the relationship of the COS to CO2 uptake, i.e., the leaf relative uptake (LRU), for reliable GPP calculations.
To investigate the impact of environmental changes on the LRU we conducted COS, CO2 and H2O eddy covariance flux (EC) measurements at our newly established forest field site in Mieming (Austria) for the last two years. The field site's dominating tree species is Scots pine (Pinus sylvestris) with Juniper trees (Juniper communis) in the understory.
In addition to the EC measurements, we conducted branch chamber measurements within the crown of the Scots pine, two at the treetop and one within the canopy.
Our EC measurements indicate a strong interannual variability of the COS fluxes. While we observed the highest COS uptake in 2021 during May, the COS uptake in 2022 was higher in the period from June to August. We also observed this pattern for the net CO2 fluxes. The fluxes of COS and CO2 concurrently decreased during the winter month and the forest turned into a net source for CO2, while COS was taken up continuously.
The mean LRU across all branch chamber measurements was 1.67 (-) with the chambers within the canopy generally having lower LRUs (1.39 (-)).
How to cite: Spielmann, F. M., Hammerle, A., Scholz, K., and Wohlfahrt, G.: Interannual variability and seasonality of carbonyl sulfide fluxes of an Austrian Scots pine forest, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-10234, https://doi.org/10.5194/egusphere-egu23-10234, 2023.
