Effect of simulation of throughfall exclusion and increasing ambient temperature on ‎the litter decomposition rate of hornbeam and chestnut-leaved oak species

The rate of litter decomposition is influenced by various factors such as climatic conditions, litter quality and population of decomposers. Changes in precipitation patterns and increasing temperatures are the most important consequences of the climate change may change the decomposition rate of leaf litter. Hence, the present study aimed to simulate the effect of throughfall exclusion and increasing temperature on the process of hornbeam and oak leaf litter decomposition in the oak-hornbeam stand. For this purpose, four treatments were considered including two combined treatments consist of 25 and 50% throughfall exclusion and increasing temperature, warming and the control treatment (natural conditions). The hornbeam and oak leaf litter decomposition rate were studied using litter bags for 200 days. The average soil temperature of the treatments during the study period was 0.2-0.3 °C more than the control treatment, which resulted in a decrease in soil moisture content 13%. The combine effect of increasing temperature and decreasing soil water content cause a significant increase in the leaf litter decomposition rate of hornbeam, especially in the treatments of 25 and 50% compared to the control. The decomposition rate of the control treatment was decreased over time; while the decomposition rate of oak increased in the treatment of 25%. The results showed that changing in the climate conditions (i.e., increasing the temperature and decreasing the precipitation) will significantly change the rate of litter decomposition of thermophilic species (oak). It will lead to increase the rate of nutrient exchange in the forest soil ecosystem. Therefore, in forests with fertile soil, it is possible to shorten the exploitation period‎.