Influence of stand type and stand age on soil carbon storage in China's arid and semi-arid regions

Afforestation implemented on available lands that have a poor fertility with a low primary productivity is considered to be a significant land use change issue globally, especially in the current phase of increasing atmospheric CO2 concentrations. However, different stand types and stand ages, where afforestation is initiated, may have a different effect on soil carbon storage. Two stand types, including the apricot and poplar stand, both with 40 years, and two stand ages, including the apricot stand with 40 years and apricot stand with 16 years were sampled on the Loess Plateau, to explore the differences in soil carbon storage between both of them, respectively. The results showed that the total soil carbon storage up to the 1.0 m soil depth for the poplar stand was 79.07 Mg ha−1, and for the apricot stand with 40 years was 88.36 Mg ha−1, while for the apricot stand with 16 years, it was 56.16 Mg ha−1. About 50% the soil carbon was stored in the 0-0.4 m soil layer for all these forested lands. This ascertains that the soil carbon was very sensitive to climate change and anthropogenic disturbances. Based on these results, if we are interested in combating global warming issue, the apricot trees can be a preferred option for future plantations. However, these plants are likely to consume more water than any other vegetation types. Since water is a limited resource both in arid and semi-arid regions, a tradeoff between soil carbon and soil water should also be considered in future afforestation policy options.