Periodic Reporting for period 1 - COSIF (Carbonyl sulfide and sun-induced fluorescence as joint constraints on terrestrial carbon cycling)
Berichtszeitraum: 2018-01-01 bis 2019-12-31
Major new insights from COSIF include (i) the observation that dead plant organic matter covering soils may turn ecosystems to source of COS during periods of low soil water content combined with high temperatures and in such conditions soil contribution has to be taken into account when using the ecosystem-scale COS fluxes as a proxy of GPP and (ii) that SIF may show an ambiguous relationship to GPP under conditions of stress and that in such situations non-photochemical quenching of radiation energy absorbed by plant chlorophyll needs to be quantified jointly with SIF in order to reliably estimate GPP.
Another important impact was the advanced integration of different novel measurement techniques. This project was, to the best of our knowledge, the first to make use of joint active and passive chlorophyll fluorescence, and CO2/COS measurements to diagnose the functioning of various ecosystems and their response to climate variables.
Moreover, the COSIF project provided new insights on using SIF and COS as GPP proxies, which are crucial for further developing of both methods and will thus provide more reliable future GPP estimates required for designing and implementing decarbonization strategies.