Afforestation strengthens aggregational differentiation of soil nutrients and microbiomes in erosive degraded ecosystem

Abstract

Abstract Aims Afforestation has been viewed as the most effective natural method to restore the erosive degraded ecosystem. However, the effect of soil inherent heterogeneity on soil quality, microbial community dynamics and assembly after afforestation in rocky desertification area remains indistinct. Methods In the present study, we set up 3 standard quadrats for each soil type, i.e., bareland, farmland and woodland, in the study area and separated the soils into four aggregate size fractions. Soil nutrition status, enzymatic activities, bacterial and fungal community composition in different aggregate fractions were determined. Results Generally, afforestation promoted soil nutrients and enzyme activities, and strengthened their aggregational differentiation. Interestingly, the aggregational differentiation of bacterial alpha-diversity was more sensitive to afforestation than fungal alpha-diversity. Conversely, afforestation caused that more fungal taxa were susceptible to soil aggregates than bacterial taxa. In the bareland, deterministic process was the decisive factor for the bacterial community, while fungal community was determined by both stochastic and deterministic processes. Afforestation regulated the balance between stochastic and deterministic processes Dispersal limitation, belonging to stochastic process, determined bacterial community assembly; whereas, fungal community assembly was governed by variable selection belonging to deterministic process. Conclusions Afforestation on the bareland promoted the aggregation differentiation of soil nutrients, microbial community composition and diversity, and changed the mechanism of microbial community assembly in the rocky desertification area of Danjiangkou Reservoir. This study provides critical insights into the responses of soil nutrition and microbial community to vegetation restoration at the soil aggregate level.