A comparison of the effects of natural vegetation regrowth with a plantation scheme on soil structure in a geological hazard‐prone region

The effects of natural vegetation regrowth and plantation schemes on soil aggregate structure and total soil porosity were examined at a typical landslide hazard site in a semi‐humid region in northwest China. The schemes were started in 2008 using four plots, two of which were kept bare; in one natural local vegetation was allowed to grow and in the other planting was managed. Analysis of soil samples (0–100 cm) taken in 2016 indicated that the proportion of soil aggregates <0.25 mm was 43.22 and 29.01% under natural vegetation and plantation, respectively, which was significantly greater than that in the plots kept bare (23%). Soil tensile stress increased from approximately 12 kPa in the bare plots to 18.34 and 16.45 kPa under natural vegetation and plantation, respectively. Total soil porosity, water retention and rate of infiltration increased, whereas bulk density decreased considerably, after 8 years under natural vegetation and plantation in comparison with those properties in the bare plots. Furthermore, natural vegetation had a greater effect than the plantation on soil structure in terms of aggregation and total porosity. The findings of this study provide some insight into the effects of native vegetation and a plantation on soil structure in semi‐humid regions as a prerequisite to the control of both soil erosion and slope stability in regions prone to seismic activity. Highlights Soil structure was analysed after 8 years of natural vegetation regrowth and plantation. Eight years of revegetation improved aggregation and total porosity compared with bare land. Natural vegetation affected soil structure more than the plantation did. Our results provide some insight into a prerequisite to control soil erosion and slope stability in unstable regions.