Soil carbon emissions and influential factors across various stages of vegetation succession in vegetated concrete

Abstract

After ecological restoration of high and steep slopes in the project disturbed area, soil properties, soil microorganisms, litter types and root types change with the succession of vegetation cover communities. However, the effects of different vegetation successional stages on soil respiration dynamics remain unclear. To elucidate trends and drivers of soil respiration in the context of vegetation succession, we used spatio-temporal alternative applied research. Vegetated concrete-restored slopes (VC) with predominantly herbaceous (GS), shrub (SS), and arborvitae (AS) vegetation were selected, and naturally restored slopes (NS) were used as control. SRS1000 T soil carbon flux measurement system was used to monitor soil respiration rate. The results showed that soil respiration (RS) and fractions of all four treatments showed a single-peak curve, with peaks concentrated in July and August. During the succession of vegetation from herbaceous to arborvitae on VC slopes, RS showed a decreasing trend, and GS was significantly higher than AS by 45%; Compared to NS, RS was 29.81% and 21.56% higher in GS and SS successional stages, respectively, and 27.51% lower in AS stage. RS was significantly and positively correlated with nitrate nitrogen (NO3–-N) and microbial biomass nitrogen (MBN), both of which are important factors in regulating RS under vegetation succession. A bivariate model of soil temperature and water content explains the variability of Rs better. Overall, RS was higher than NS in the transition stage and lower than NS in the equilibrium stage of the vegetation community on VC slopes, and the RS decreases gradually with the vegetation succession of artificial ecological restoration slopes.