Patterns of carbon allocation in a chronosequence of caragana intermedia plantations in the qinghai-tibet plateau

Abstract

Revegetation is being considered as a mitigation option to improve the ecological environment and reduce the atmospheric carbon (C) dioxide concentrations of regions experiencing desertification. This study assessed the development of the above-and belowground ecosystem C pools in a chronosequence of four Caragana intermedia plantations (3, 12, 27, and 37 years old) in the desertified region of the Qinghai-Tibet Plateau, China. The biomass C stock of the total shrub and under-canopy increased with stand age. The soil inorganic carbon (SIC) pool in the soil C stocks was approximately 3 to 7 times larger than the soil organic carbon (SOC) storage. Both SIC and SOC increased after revegetation. However, the contribution of SIC to the total ecosystem C stock decreased from 87% in the 3-year-old plantation to 85%, 75%, and 72% in the 12-, 27-, and 37-year-old plantations, respectively. The total ecosystem C pool exhibited a greater increase in the shrub plantations than in the mobile dunes, but the total C stock of the stands changed slightly with time. Soil C, including SOC and SIC, was the major contributor to the total ecosystem C stock for all shrub plantations. The aboveground shrub biomass became the secondary ecosystem C pool in older srands. The results of this study indicate that revegetation in desertification ecosystems has a significant impact on SIC, SOC, and total ecosystem C pools. Furthermore, the total ecosystem C pool reached a relatively stable state after sand-binding stands.