Comparison of litterfall production and leaf litter decomposition between an exotic black locust plantation and an indigenous oak forest near Yan'an on the Loess Plateau, China

Litterfall production, the amount of organic matter on the forest floor, and litter decomposition rates were studied in an exotic nitrogen (N)-fixing black locust (Robinia pseudoacacia) plantation and an indigenous non-N-fixing oak (Quercus liaotungensis) forest near Yan'an, on the Loess Plateau, China. The chemical composition of litterfall and soil was also examined. Litterfall production was similar in the two forests; however, the amount of N in litterfall was greater in the black locust plantation than in the oak forest because of the high N concentration of black locust leaves. The decomposition rate of black locust leaves was higher than that of oak leaves, most likely because of the higher N content of black locust leaves. These results suggested that N cycling was greater and faster in the black locust plantation than in the oak forest. However, faster decomposition caused the disappearance of the organic layer from the forest floor in the black locust plantation. Furthermore, despite greater N cycling in the black locust plantation, the soil N content was lower than in the oak forest. Our results indicated that the black locust plantation might be more susceptible to soil erosion than the oak forest. In addition, our study suggested that the black locust plantation had advantages in short-term N uptake, growth, and N cycling; however, it had disadvantages in soil development and regeneration and sustainable land management.