Optimizing tradeoff strategies of soil microbial community between metabolic efficiency and resource acquisition along a natural regeneration chronosequence.

The tradeoff between community-level soil microbial metabolic efficiency and resource acquisition strategies during natural regeneration remains unclear. Herein, we examined variations in soil extracellular enzyme activity, microbial metabolic quotient (qCO), and microbial carbon use efficiency (CUE) along a chronosequence of natural regeneration by sampling secondary forests at 1, 10, 20, 30, 40, and 100 years after rubber plantation (RP) clearance. The results showed that the natural logarithms of carbon (C)-, nitrogen (N)-, and phosphorus (P)-acquiring enzyme activities were 1:1.68:1.37 and 1:1.54:1.38 in the RP and secondary forests, respectively, thus demonstrating that microbial metabolism was co-limited by N and P. Moreover, the soil microbial C limitation initially increased (1-40 years) and later decreased (100 years). Overall, the qCO increased, decreased, and then increased again in the initial (< 10 years), middle (10-40 years), and late (100 years) successional stages, respectively. Except for specific P-acquiring enzyme activities, the changes in other indicators with natural regeneration were consistent in the dry and wet seasons. Both qCO and CUE were mainly predicted by microbial community composition and physiological traits. These results indicate that soil microbial communities could employ tradeoff strategies between metabolic efficiency and resource acquisition to cope with variations in resources. Our findings provide new information on tradeoff strategies between metabolic efficiency and resource acquisition during natural regeneration.