Effects of Mixed Leaf Litters of Iranian Oak, Tree of Heaven, and Wild Pistachio on Decomposition and Dynamics of Nutrients in Zagros Forests (Case Study: Ilam Province)

Leaf litter decomposition plays a key role in the nutrient cycle of forest ecosystems. However, there is not a comprehensive understanding of the non-additive decomposition effects in leaf litter mixing experiments. In this study, the dynamics of nutrients and the rate of decomposition of Iranian oak (Quercus brantii), tree of heaven (Celtis caucasica), and wild pistachio (Pistacia atlantica) were investigated in both pure and mixed stands. For this purpose, 81 single- and double-litter bags were placed in the study area and incubated for 180 days. According to the results, at the end of the incubation period, the decomposition of oak litters in combination with tree of heaven, tree of heaven in combination with wild pistachio, and wild pistachio in combination with oak showed positive results. Based on the results, the nitrogen concentration in oak mixed with tree of heaven was higher than in its pure state. But the concentration of phosphorus in its pure and combined states did not show any significant differences. In general, the findings showed the positive non-additive effects of litter on its decomposition rate. Regarding the dynamics of nutrients, these effects were considered positive only for nitrogen.