Broadleaved litters had higher decay rate but induced lower priming effect of SOC than needle litters

Abstract:

Introduction of broadleaved tree species with high-quality plant litters was thought to be a promising method to improve the productivity in coniferous plantation forests. However, our knowledge about how the soil carbon cycling in plantation forests was altered by broadleaved litters through priming effect is still limited. To address these knowledge gaps, we studied the 13C isotopic signature of CO2 respired from microcosms where leaf litters of 10 C3 plant species with different foliage shape (6 broadleaf tree species and 4 coniferous tree species) were added to a C4 soil, and then calculated the litter-C loss and priming effect of C4 soil by using natural 13C isotope tracer technique. Our results showed that both the decay process of litter-C and priming effect were related to the foliage shape. For example, the C loss is 24.4% ± 3.9% for broadleaves and this value is much higher than that with needles (16.7% ± 2.5%). The higher decomposition of broadleaf litters versus coniferous litters is generally associated with the initial nutrient status and carbon quality. On the contrary, the broadleaf litters induced lower priming effects compared to needle litters, and the lower priming effects was mainly mediated by preferential utilization of high-quality broadleaf litters and the higher initial lignin concentration in broadleaf litters. Our results have two important implications for plantation forest management. Firstly, introduction of broadleaf tree species can provide benefits to coniferous plantation through higher litter decomposition and more rapid nutrients cycling. Secondly, priming effect appears to become weaker, and the SOC storage may increase if broadleaf tree species with high litter quality was introduced into coniferous plantation forests.