Assessment of litter decomposition in temperate deciduous forest: case study in Fruška gora, Serbia Andrijana Andrić1, Dušanka Vujanović1, Snežana Popov2, Zlata Markov Ristić2 INTRODUCTION. The litter decomposition is one of the largest fluxes in the global terrestrial carbon cycle, thus diverse extensive experiments have been focusing on this fundamental soil process. Our study has been conducted as a part of the large-scale decomposition experiment within the global collaborative network TeaComposition initiative. The aim of this initiative was to estimate short- to long-term plant litter decomposition rates by using standard protocols and substrates— commercially available Green tea and Rooibos tea with different decomposition rates—for comparison of the litter mass loss at numerous sites across various ecosystems worldwide. The objective of our study was to test the effects of both litter type and land-use on litter decomposition in three, 12, 24 and 36 months of incubation (year 2016 to 2019), by comparing the percentages of the tea mass lost. References: •Djukic I et al. 2018. Early stage litter decomposition across biomes. Science of the Total Environment 628-629:1369-1394. •Keuskamp J et al. 2013. Tea Bag Index: a novel approach to collect uniform decomposition data across ecosystems. Methods in Ecology and Evolution 4:1070-1075. •Kwon T et al. 2021. Effects of climate and atmospheric nitrogen deposition on early to mid-term stage litter decomposition across biomes. Frontiers in Forests and Global Change 4:678480. 1University of Novi Sad, BioSense Institute, Dr Zorana Đinđića 1, 21000 Novi Sad, Serbia 2University of Novi Sad, Faculty of Sciences, Department of Biology and Ecology, Trg Dositeja Obradovića 2, 21000 Novi Sad, Serbia METHOD & DESIGN. The TeaComposition method (modified Tea bag method by Keuskamp et al. 2013) involves measuring a tea bag before and after incubation in the field, and using mass loss as a measure of the organic material decomposed. The three localities chosen for our experiment corresponded to the three levels of protection regime established for the National park Fruška gora, with different management treatments. The 1st sub-site is within the highest level of protection—the least degraded and non-managed forest; 2nd and 3rd sub-sites are under 2nd and 3rd level of protection, both characterized by controlled wood exploitation. The guidelines of the standardized protocol of the TeaComposition initiative (Djukic et al. 2018) were followed throughout. Two homogenous plots were selected at each of the three sub-sites; two replicates of the two tea types were buried in the topsoil layer in each plot, resulting in four bags of each tea type per sub-site and sampling time (Figure 1). Acknowledgements: This study has been conducted within the TeaComposition initiative, as a part of the research campaign Global litter decomposition study initiated and supported by the ILTER (International Long Term Ecological Research network) Initiative Grant (2016). RESULTS. The values of the tea mass lost during all four incubation periods were higher for the Green tea than for the Rooibos tea (Table 1). This pattern was expected because of the faster decomposition rate of Green tea due to higher content of non-lignified cellulose and of water-soluble compounds (Keuskamp et al. 2013). Furthermore, the difference of the two tea types' mass loss was the highest in three- months incubation. Our study has also shown no clear pattern regarding the values variation of the tea mass loss among plots of three different sub-sites. However, the highest level of variation was found for the Green tea in the longer incubation periods (24 and 36 months). CONCLUSIONS. Our results are in accordance with previous research (e.g. Djukic et al. 2018; Kwon et al. 2021) showing that, in the early stage of litter decomposition, the litter quality had the strongest influence on mass loss, whereas there was no significant effect of land-u