Contribution of the Root Component to Soil Respiration in Oriental Beech Stands in Artvin, Turkey

Autotrophic (root) and heterotrophic respiration components respond differently to environmental variables, and each component behaves differently at different time scales, so it is necessary to partition total soil respiration into its components. The aims of this study were determine soil respiration and its root and heterotrophic components in beech stands, examine the relationship between respiration and biogeochemical factors, and assess seasonal variation in soil respiration. Trenching was applied to separate soil respiration components 6 months before measurements. Monthly soil respiration, temperature and moisture measurements, and seasonal soil and root sampling were carried out in Oriental beech (Fagus orientalis L.) stands located in Artvin Sacinka, Turkey from April 2018 to November 2018 and also (except soil sampling) from May 2019 to November 2019. The average contribution of root respiration and heterotrophic respiration to total soil respiration were 58.8% and 41.2%, respectively. Carbon and nitrogen dynamics explained variations of soil respiration with significant models. This study indicates that soil respiration and its components are associated with biogeochemical factors as well as environmental climatic conditions, and each component of respiration responds differently to changes in them. Study Implications In this study, the trenching application in the beech stand considerably reduced carbon dioxide release. According to corrected soil respiration data by considering increased soil moisture and root decomposition, the dominant respiratory component was root respiration, whereas the contribution from root and microorganism respiratory components varied depending on the season. The mean contribution of root respiration was 58.8% and the mean contribution of heterotrophic respiration was 41.2%. Total soil respiration and its components were affected by changes in soil temperature across seasons. Species-specific biotic factors might also affect the variability in root respiration. In addition, seasonal changes in carbon and nitrogen dynamics affected respiratory components. This study showed that soil respiration and its components were affected by biogeochemical factors as well as climatic conditions, and each component of respiration responds differently to changes in these factors. Therefore, to better understand the dynamics of the carbon cycle in oriental beech stands and other forested ecosystems, similar studies need to be done