Land-use change alters microbial metabolic activity while maintaining functional diversity in tropical peat

Contrasting peatland land-use types differ markedly in peat soil physicochemical conditions and are associated with microbial functional responses in tropical peat ecosystems.However, the extent to which these land-use types are associated with differences in microbial biomass, metabolic activity, and community-level metabolic characteristics remains poorly understood.This study evaluated peat soil physicochemical properties, culturable microbial populations, microbial biomass carbon (MBC), microbial biomass phosphorus (MBP), extracellular enzyme activities, and community-level metabolic profiles across six peatland land-use types in the Giam Siak Kecil-Bukit Batu Biosphere Reserve, Riau Province, Indonesia.The secondary forest was characterized by high gravimetric water content (GWC), low bulk density (BD), and higher soil organic carbon, total nitrogen, MBC, and MBP.In contrast, converted peatland sites generally exhibited lower GWC, higher BD, and lower microbial biomass, although culturable microbial populations were higher at several sites.Increased β-glucosidase and acid phosphatase activities, together with higher average well color development (AWCD) values, indicated greater microbial metabolic activity at several converted sites.Despite these differences, the H′, E′, and S indices remained relatively similar and did not differ significantly among land-use types, suggesting comparable community-level metabolic functional capacity under contrasting peat soil conditions.In contrast, AWCD values varied considerably among sites, indicating differences in the rate and intensity of substrate utilization.Overall, the results suggest that differences among peatland land-use types were more strongly associated with microbial metabolic intensity than with community-level metabolic functional capacity.