Determination of root and microorganism components of soil respiration in beech and spruce stands in Artvin area

Soil respiration is the major pathway for carbon from terrestrial ecosystems and is the result of a heterotrophic process that handles organic substrates by reacting to soil temperature or moisture together with an autotrophic process of plant metabolism that sequestrates carbon. The aim of this study is to determine soil respiration and its root and microorganism components and to examine the relationship between biogeochemical and environmental factors and respiration in Oriental beech and Oriental spruce stands. For this purpose, in beech stands in Saçinka region and spruce stands in Kafkasör region in Artvin; trenching was carried out in order to separate respiration components in summer of 2017. Measurements started 6 months after from trenching. Monthly soil respiration, temperature and moisture measurements, seasonal soil (0-10 cm) and root (0-30 cm) sampling were done, from April to November 2018, and only respiration, temperature and moisture measurements and root sampling were done in 2019. Texture, soil reaction, organic matter, mineral nitrogen, microbial biomass, total carbon and nitrogen, microbial basal respiration analyzes were performed in the collected soil samples. The values of carbon emission from the soil varied between 0.38 - 7.56 µ mol m-2 s-1 across the study. The average contribution of root and microorganism components to total soil respiration were found to be 57.6% and 42.4%, respectively in the first year and 60.05% and 39.95%, respectively in the second year, for the beech field. For the spruce field, they were found 41.7% and 58.3%, respectively in the first year and 49.96% and 50.04%, respectively in the second year. Very strong positive correlations of soil respiration with soil temperature and mineral nitrogen were found. Soil temperature, soil moisture, and other bio-physical-chemical soil properties significantly explained the major (60-70%) change in soil respiration. As a result, soil respiration and its components varied by species and seasons, and it can be said that they were related to soil temperature as well as bio-chemical factors in the soil.