Carbon sequestration of mature black locust stands on the Loess Plateau, China

Abstract

In Northwestern China, the carbon fixing capacity of black locust (Robinia pseudoacacia) has been questioned because of its slow growth following the return of unproductive farmland to forest. To explore the effects of stand age on the carbon sequestration potential of R. pseudoacacia in a semi-arid, ecologically fragile area, parameters related to carbon fixation were investigated in plots of three stand ages (5, 10, and 25 years). Each plot was divided into four subsystems: R. pseudoacacia, understory vegetation, litter, and soil, and the carbon stored capacity of each subsystem was estimated. The organic carbon density of R. pseudoacacia, understory vegetation, and litter ranged from 3.4-16.8% and increased gradually with increasing stand age. Soil organic carbon increased with increasing stand age and accounted for 83.2-96.6% of the total carbon stored. Soil CaCO3 content also increased with increasing soil depth and stand age. Because total plant and soil carbon storage increased with increasing age of R. pseudoacacia stands, the 25-year-old R. pseudoacacia community had the highest carbon fixation capacity, which was substantial even in this arid region.