The carbon net emissions from the forested areas in Kokemäenjoki river basin are based on the results of the forest growth and gas exchange model PREBAS (Minunno et al. 2016, 2019). The model was used to calculate the amount of harvested biomass (gC m-2 yr-1), as well as the net ecosystem exchange NEE (gC m-2 yr-1) for current climate conditions assuming forest management actions in accordance with current best practices (Sved and Koistinen 2015). NEE is positive when the C flux from the decomposition of soil organic matter is larger than the assimilation of C into growing vegetation, and negative when the assimilation of C into growing vegetation is larger than the C flux from decomposing soil organic matter.
In the case of forests growing on upland soils, the PREBAS model is linked to the soil carbon model YASSO07 (Tuomi et al. 2009) to account for soil respiration. For forests on drained peatland soils, emissions from soil respiration are based on measured soil respiration including both peat decomposition and litter decomposition (or accumulation) (Minkkinen et al. 2018; Ojanen et al. 2010, 2013, 2019).
The net emissions of forests were calculated by adding the NEE to the amount of harvested biomass. Net emissions are positive when the forest acts as a source of CO2 to the atmosphere, and negative when the forest is a sink.
Carbon emissions were converted to CO2 by multiplying with 44/12.
References
Minkkinen, K., Ojanen, P., Penttilä, T., Aurela, M., Laurila, T., Tuovinen, J.-P., Lohila, A., 2018. Persistent carbon sink at a boreal drained bog forest. Biogeosciences 15: 3603-3624. https://doi.org/10.5194/bg-15-3603-2018
Minunno F, Peltoniemi M, Launiainen S, Aurela M, Lindroth A, Lohila A, Mammarella I, Minkkinen K, Mäkelä A, 2016. Calibration and validation of a semi-empirical flux ecosystem model for coniferous forests in the Boreal region. Ecological Modelling 341:37-52. https://doi.org/10.1016/j.ecolmodel.2016.09.020
Minunno F, Peltoniemi M, Härkönen S, Kalliokoski T, Makinen H, Mäkelä A, 2019. Bayesian calibration of a carbon balance model PREBAS using data from permanent growth experiments and national forest inventory. Forest Ecology and Management 440:208-257. https://doi.org/10.1016/j.foreco.2019.02.041
Ojanen, P., Minkkinen, K., Alm, J., Penttilä, T., 2010. Soil–atmosphere CO2, CH4 and N2O fluxes in boreal forestry-drained peatlands. For. Ecol. Manage. 260, 411–421. https://doi.org/10.1016/j.foreco.2010.04.036
Ojanen, P., Minkkinen, K., Penttilä, T., 2013. The current greenhouse gas impact of forestry-drained boreal peatlands. For. Ecol. Manage. 289, 201–208. https://doi.org/10.1016/j.foreco.2012.10.008
Ojanen, P., Penttilä, T., Tolvanen, A., Hotanen, J.-P., Saarimaa, M., Nousiainen, H., Minkkinen, K., 2019. Long-term effect of fertilization on the greenhouse gas exchange of low-productive peatland forests. Forest Ecology and Management 432: 786-798. https://doi.org/10.1016/j.foreco.2018.10.015
Sved, J., Koistinen, A. (ed.) (2015). Metsänhoidon suositukset kannattavaan metsätalouteen, työopas. In Finnish (Best Practices for Profitable Forest Management). Publications by Tapio Group http://tapio.fi Available in Finnish https://tapio.fi/wp-content/uploads/2015/09/MHS_Kannattava_metsatalous_201500814.pdf Accessed 30.6.2020.
Tomppo, E., Katila, M., Mäkisara, K., and Peräsaari, J. (2014). The Multi-source National Forest Inventory of Finland – methods and results 2011. 224 pp. http://urn.fi/URN:ISBN:978-951-40-2516-7
Tuomi, M., Thum, T., Järvinen, H., Fronzek, S., Berg, B., Harmo, M. et al. (2009). Leaf litter decomposition – Estimates of global variability based on Yasso07 model. Ecol. Modell. 220:3362–3371. https://doi.org/10.1016/j.ecolmodel.2009.05.016
