Title: Litter decomposition rates on two different forest types in Lake Engure Nature Park (north-west Latvia)
Litter decomposition is one of the most important processes in the forest ecosystem; throughout it One of the biggest treats nowadays is climate change, throughout litter decomposition large amounts of CO2 are emitted into in the atmosphere, which has a great impact on climate change, one of the biggest environmental threats nowadays. Litter decomposition is one of the most important processes in the forest ecosystem it is crucial to understand it better. To analyse impacts and changes we need to monitor not only artificial sources but also natural ones, that is why this study investigates how two types of litter decompose in Lake Engure Nature Park on two biomes. This research is part of the larger study: Tea Composition Initiative by ILTER (International long-term ecosystem research infrastructure) that aims to asses litter decomposition rates in different world ecosystems using standardized methodology. This study investigates how two types of litter decompose in Lake Engure Nature Park on two biomes. In this study the tea bag method is used, by replacing litter with two types of tea, green and rooibos. Those two substrates have different chemical composition. In Latvia, study sites were chosen in Lake Engure Nature Park - dry pine forest and moist deciduous forest. There were two plots in each site, created in June 2016. Plots were 2x2 meters big and samples were inserted in the soil in systematic order, the way that four samples can be removed each time. Samples were removed from soil after 3, 12 and 24 months. The analysis shows that decomposition rates strongly depend on the litter type. A litter with high cellulose level decomposes faster in the first stages but reduces its decomposition rate after 3 months, meanwhile, litter with a high level of lignin decomposes more gradually. The relationship between litter decomposition and forest type was not always significant, contrary to meteorological conditions, which affected them. The study proves that many different drivers, for instance, soil quality, water level and temperature are affecting the decomposition process, however, more studies are needed to understand how exactly each of them works. Overall, the results of the study can be used in the development of a model for calculating CO2 emissions emissions and can be taken into account when forest stand management is chosen.