Response of soil bacterial community structure in Pisha sandstone areas to different stumping

The Pisha sandstone region of Inner Mongolia is one of the areas most severely affected by soil erosion in the world. Stumping is a widely used practice for rejuvenating degraded sea buckthorn (Hippophae rhamnoides) plantations, but how stumping depth affects soil bacterial communities and the underlying drivers remains unclear. We hypothesized that (1) 15 cm stumping depth would maximize soil nutrient availability and bacterial diversity, and (2) shifts in bacterial community composition would be primarily driven by soil nutrients and physical properties.

We conducted a field experiment in a 10-year-old declining sea buckthorn plantation, applying four stumping heights (0 cm, 10 cm, 15 cm, 20 cm) with uncut forest as control. Soil samples were collected from three compartments (root surface, rhizosphere, non-rhizosphere). Bacterial community composition was characterized by high-throughput sequencing of the 16S rRNA gene V4 region using primers 515F/806R with high-fidelity DNA polymerase. Soil physicochemical properties were measured using standard methods.

Stumping at 15 cm height consistently exhibited the strongest effects across all soil compartments. Compared to other treatments and the control, this treatment significantly increased soil organic carbon, available nitrogen, phosphorus, and potassium, and enhanced bacterial α-diversity (Chao1, Shannon). At the family level, 15 cm stumping most strongly enriched Oxalobacteraceae, with relative abundance peaking at 38.9% in rhizosphere soil. Bacterial community composition shifted with stumping depth; however, β-diversity variation was primarily explained by spatial heterogeneity among the three plots (R ² = 11.89%, P = 0.008), rather than stumping treatment itself (R ² = 9.89%, P = 0.226). Redundancy analysis further revealed that Actinobacteriota abundance was positively correlated with soil organic matter, available nitrogen, available phosphorus, available potassium, and soil water content, but negatively correlated with soil bulk density. Membership function analysis confirmed that 15 cm stumping yielded the highest comprehensive scores across all soil compartments, particularly in root surface soil (0.54, 0.53, and 0.52 for root surface, rhizosphere, and non-rhizosphere soils, respectively). Taken together, these findings demonstrate that 15 cm stumping effectively improves soil nutrient conditions, enriches beneficial bacterial taxa, and reshapes microbial communities in degraded sea buckthorn plantations, with the strongest effects occurring in root-associated soils.