Microbial biomass and activity restrict soil function recovery of a post-mining land in eastern Loess Plateau

Soil microbes play an important role in improving soil quality and enhancing carbon cycling, and consequently, are of great significance for the recovery of soil function of degraded lands. However, little is known about soil microbial properties of reconstructed ecosystems established on degraded lands. We investigated soil microbial biomass and enzyme activity for three restored tree types in post-mining lands by field sampling. The results showed that soil microbial biomass carbon increased averagely by 133.9% via planting Quercus liaotungens, Pinus tabuliformis and Rhus typhina. Invertase activity in restored site increased by 138.8% compared with that in the control site. Litter input and root exudate provided carbon sources for soil microbes during vegetation succession, and increases of soil nitrogen content and water-holding capacity were also beneficial to improve microbial growth and activity. Soil microbial biomass and invertase activity displayed significant differences due to tree species (P < 0.01), which could be explained mainly by differences in nutrition content and fine root biomass. However, soil microbial biomass and enzyme activity in restored lands were significantly lower than those in natural forests. Our results suggest that low soil microbial biomass might restrict the recovery of soil function during restoration of post-mining lands in semi-arid region.

Automated summary

The study found that planting Quercus liaotungens, Pinus tabuliformis, and Rhus typhina on degraded lands significantly increased soil microbial biomass and enzyme activity, which can be attributed to the carbon sources provided by vegetation, as well as the increase in soil nitrogen content and water-holding capacity.