EFFECT OF LAND-USE PATTERNS ON SOIL ENZYMATIC ACTIVITY AND MICROBIAL DYNAMICS IN CARBON, NITROGEN AND PHOSPHORUS CYCLING OF WETLANDS IN THE LESSER KHINGAN MOUNTAINS, NORTHEASTERN CHINA

Abstract

Land use patterns significantly influence soil enzyme activities, microbial communities, and soil physicochemical properties. This study investigates the effects of land use changes on enzyme activity, soil properties, and bacterial communities in soil aggregates within reclaimed and no-tillage wetlands in the Lesser Khingan Mountains, Northeastern China. Forest wetlands converted to reclaimed and no-tillage systems showed declines in soil organic carbon (SOC), total nitrogen, total phosphorus, total potassium, cation exchange capacity, enzyme activities, and available phosphorus. Microbial diversity increased with changes in community composition, including higher relative abundances of Proteobacteria and Actinobacteria. Soil aggregate micro-environments modulated enzyme response intensity, with SOC negatively correlated with Firmicutes, Acidobacteriota, Chloroflexi, and Gemmatimonadota, while available phosphorus (AP) positively correlated with Nitrospirota, Latescibacterota, and Bacteroidota. The results reveal that land use changes have a more pronounced impact on microbial communities than aggregate size, emphasizing the critical role of sustainable land management in maintaining soil health. This study highlights the need for rational development of marshes in the Lesser Khingan Mountains, considering enzyme activities and microbial dynamics in nutrient cycling. These findings contribute to understanding the ecological implications of land use changes and support evidence-based conservation and sustainable management practices.