Responses of soil keystone microbial taxa to metabolic limitation during vegetation restoration in sandy land ecosystem

As the main drivers and modifiers of soil ecosystem change, it remains unclear whether microbial metabolic limitation in sandy soil will affect its community structure and how microbial community responds to resource limitation. Hence, we studied the relationship between soil microbial community and nutrient limitation in Horqin Sandy land, a typical sandy area in northern China. The results of enzyme stoichiometric vector analysis showed that microbial carbon (C) and nitrogen (N) limitation decreased with vegetation restoration, while soil microbial phosphorus (P) limitation increased with vegetation restoration, and there was a shift from N limitation to P limitation from the semi-mobile dunes to semi-fixed dunes. We found that total N (TN) and total P (TP) were most closely related to microbial community richness, and the effects of electrical conductivity (EC), pH and topographic factors (lat, lon and dem) could not be ignored. The co-occurrence network and linear regression analysis revealed that 39.5% of the key microbes (15 key species) had significant correlation with the N/P limitation (P<0.05). The bacterial community was more sensitive to the response of the key microbial taxa than the fungal community. Microbial N/P limitation has a direct positive impact on key microbial taxa, while microbial C limitation has a negative impact on N/P limitation, and then indirectly affects the key microbial taxa, suggesting that soil microorganisms have distinct nutrient preferences and survival strategies to overcome energy restriction and nutrient stress. This study provides important insights into the response of microbial community structure to energy and nutrient constraints in sandy ecosystems.