Eco–enzymatic stoichiometry unveils resource limitations in soil microorganisms during subtropical vegetation restoration

Eco–enzymatic stoichiometry provides insights into how soil microorganisms allocate resources to meet their energy and nutrient needs. Subtropical ecosystems are known to be strongly resource-limited, particularly for phosphorus (P) limitation. Vegetation restoration usually sustainably further alters the relative availability of soil carbon (C), nitrogen (N), and P. However, the patterns of microbial nutrient limitation and their drivers along vegetation restoration remain largely unclear.

Here, using eco–enzymatic stoichiometry modeling, we investigated soil microbial resource limitations and identified primary factors driving them across five stages of vegetation restoration [grassland (GL), shrubland (SL), early–, mid–, and late–forest (EF, MF, and LF)] in subtropical China.

β–1,4–glucosidase (BG), β–N–acetyl glucosaminidase (NAG), and acid phosphatase (ACP) activities in forest stages (EF, MF, and LF) were significantly higher than the GL and SL stages. Cellobiohydrolase (CBH) and leucine aminopeptidase (LAP) activities exhibited a consistent increase solely within the forest stages (EF, MF, and LF). Soil microbial resources are co–limited by C and P. Soil nutrients had the strongest overall impact, positively affecting microbial C limitation and negatively affecting P limitation, while litter biomass positively regulated P limitation.

Synthesis and applications: This research provides key insights into the limitations of microbial resources following vegetation restoration and would contribute to designing more effective forest restoration strategies to promote the recovery and stability of subtropical ecosystems.