Assessment of organic matter changes in the soil of the Brdo plot under different climate change scenarios through the Yasso07 model application

Abstract

The forest soil can act as an important sink for CO 2 and in that respect also appears in the national Kyoto reports, where a distinction is made between carbon accumulated in litter and organic soil horizons and carbon accumulated in mineral soil layers. There is a multitude of dynamic models of organic carbon (C org ) change in the soil particularly due to different environmental and anthropogenic factors. The purpose of this paper is the Yasso07 model application on the "Brdo" plot, which is part of the ICP Forest Level II plots of Slovenia. The Yasso07 model describes the decomposition of organic matter in the forest soil by dividing litter inputs into different components with varying decomposition rates. Here, the temporal change of soil C org in various scenarios of future climate change (increase in air temperature, change in precipitation) was predicted. The difference between the measured amount and the model-predicted amount of C org in the soil for the current climate on the Brdo plot is 6.4 t C ha -1 (88.6 t C ha -1 measured vs. 95.0 t C ha -1 predicted). Taking into consideration the climate change scenarios for Slovenia, C org stock is expected to decrease in the future according to Yasso07 projections in all scenarios of climate change. The estimate of 100-year decrease of C org is the largest for scenario, when large increase of both temperature and precipitation is expected (18.2%) and smallest when small temperature increase and precipitation decrease are predicted (9.3%). Assuming stable litter input, larger influence on C org decrease was predicted for the temperature change compared to precipitation change. However, many uncertainties are included in model estimates ranging from litter input estimates, climate change uncertainties, climate-litter production feedbacks, starting value estimates, etc. The determination of the uncertainty of model calculations is a requirement for conducting simulations and their interpretation. key words: litter decomposition, litter components, soil carbon, model uncertainty, Slovenia IzvlečekGozdna tla lahko delujejo kot pomemben ponor za CO 2 in v zvezi s tem se pojavljajo tudi v nacionalnih poročilih Kjota, kot skladišče organskega ogljika organskega ogljika (C org ) v organskem in mineralnem delu tal. Obstaja množica dinamičnih modelov sprememb C org v tleh predvsem zaradi različnih okoljskih in antropogenih dejavnikov. Namen tega prispevka je uporaba modela Yasso07 na ploskvi "Brdo", ki je del ICP Forest ploskev intenzivnega spremljanja stanja gozdov. Model Yasso07 opisuje razgradnjo organskih snovi v gozdnih tleh z deljenjem vnosov opada v tla z različnimi stopnjami hitrosti razgradnje. V prispevku prikazujemo časovno spremembo zalog C org v tleh glede na različne scenarije prihodnjih podnebnih sprememb (povečanje temperature zraka, spremembe v padavinah). Razlika med izmerjeno vrednostjo in vrednostjo modela, napovedano za C org v tleh pri trenutnih razmerah na ploskvi Brdo, je 6,4 t C ha -1 (88,6 t C ha -1 merjeno proti 95,0 t C ha -1 napoveda...