摘要
Bcakground Soil respiration(Rs),as the second largest CO_(2) emissions of terrestrial ecosystems,is sensitive to disturbance and consequent environmental changes.Mowing is strategically implemented as an management approach and has the potential to infuence carbon cycling in meadow steppes.However,it remains unclear how and why Rs and its heterotrophic(Rh)and autotrophic(Ra)components respond to consecutive mowing and associated ecological consequences.Here,we conducted a feld mowing experiment in a meadow steppe in 2018 and monitored Rs,Rh,and Ra from 2019 to 2022.Results We observed a signifcant reduction in Rs by 4.8%across four years,primarily attributed to a decrease in Rh.This decline in Rs intensifed over time,indicating an accumulative efect of mowing.In addition,mowing induced an generally increasing Ra/Rs ratio over the experimental years with a simultaneous increase in the ratio of belowground to aboveground biomass(BGB/AGB).Furthermore,structural equation modeling results revealed that the decline in Rs was largely ascribed to reduced microbial biomass carbon(MBC)under mowing,while the increased Ra/Rs was primarily explained by the enhanced BGB/AGB.Partial regression analysis suggested that the biotic factor of microbial biomass dominated changes in soil respiration induced by mowing rather than abiotic soil temperature.Conclusions Our fndings showed that consecutive mowing decreased Rs and raised Ra/Rs in meadow steppe by decreasing plant biomass and altering the proportion of biomass allocation.This observed decline in Rs would help to reduce CO_(2) concentration in atmosphere as well as alleviate global warming.However,considering the concurrent lower microbial biomass,the potential positive impacts of mowing on climate and ecosystem function should be reevaluated in future grassland management practices.
基金
fnancially supported by the National Natural Science Foundation of China(42141006,32171595)
the Agricultural Science and Technology Innovation Program(ASTIP).
