Effects of continuous periodic Phragmites harvesting on microbial characteristics and soil multifunctionality in wetlands adjacent to residential and agricultural areas

Abstract

Phragmites–dominated wetlands adjacent to residential and agricultural areas face persistent nitrogen/phosphorus loading pressures. The mechanistic impacts of periodic harvesting on soil multifunctionality remain poorly understood. This study systematically investigated how sustained harvesting regulates wetland soil functions through microbial community restructuring and metabolic shifts. The results demonstrated that harvesting treatment significantly enhanced microbial community evenness and induced structural homogenization. At the phylum level, harvested plots (HP) showed significantly greater abundances of Chloroflexi, Acidobacteriota, and Firmicutes, whereas Proteobacteria and Gemmatimonadota were enriched in unharvested plots (IP, natural growth). The microbial assembly in HP was influenced mainly by homogeneous selection (HoS, 27.31 %) and dispersal limitation (DL, 37.98 %). In IP, drift (DR, 34.56 %) was the main factor. Functional prediction revealed that nitrate reduction was increased in HP (P = 0.003), with reduced abundances of phototrophic taxa and a metabolic shift toward chemoheterotrophic strategies. Soil analyses revealed decreased total nitrogen (TN) and C/N–regulated keystone taxa. The soil multifunctionality index (SMF) was greater in HP and was associated with chemoheterotrophic functions and C/N metabolic pathways. This study elucidated that the increase in SMF caused by Phragmites harvesting primarily stemmed from deterministic microbial assembly and C/N–coupled chemoheterotrophic activation, establishing a science–based framework for sustainable wetland management.