查看更多>>摘要：Ammonia(NH3)emissions,the most important nitrogen(N)loss form,always induce a series of environmental problems such as increased frequency of regional haze pollution,accelerated N deposition,and N eutrophication.Arbuscular mycorrhizal(AM)fungi play key roles in N cycling.However,it is still unclear whether AM fungi can alleviate N losses by reducing NH3 emissions.The potential mechanisms by which AM fungi reduce NH3 emissions in five land-use types(grazed grassland,mowed grassland,fenced grassland,artificial alfalfa grassland,and cropland)were explored in this study.Results showed that AM fungal inoculation significantly reduced NH3 emissions,and the mycorrhizal responses of NH3 emissions were determined by land-use type.Structural equation modeling(SEM)showed that AM fungi and land-use type directly affected NH3 emissions.In addition,the reduction in NH3 emissions was largely driven by the decline in soil NH4-N and pH and the increases in abundances of ammonia-oxidizing archaea(AOA)amoA and bacteria(AOB)amoB genes,urease activity,and plant N uptake induced by AM fungal inoculation and land-use type.The present results highlight that reducing the negative influence of agricultural intensification caused by land-use type changes on AM fungi should be considered to reduce N losses in agriculture and grassland ecosystems.
查看更多>>摘要：Intensive management is known to markedly alter soil carbon(C)storage and turnover in Moso bamboo forests compared with extensive management.However,the effects of intensive management on soil respiration(RS)components remain unclear.This study aimed to evaluate the changes in different RS components(root,mycorrhizal,and free-living microorganism respiration)in Moso bamboo forests under extensive and intensive management practices.A 1-year in-situ microcosm experiment was conducted to quantify the RS components in Moso bamboo forests under the two management practices using mesh screens of varying sizes.The results showed that the total RS and its components exhibited similar seasonal variability between the two management practices.Compared with extensive management,intensive management significantly increased cumulative respiration from mycorrhizal fungi by 36.73％,while decreased cumulative respiration from free-living soil microorganisms by 8.97％.Moreover,the abundance of arbuscular mycorrhizal fungi(AMF)increased by 43.38％,but bacterial and fungal abundances decreased by 21.65％and 33.30％,respectively,under intensive management.Both management practices significantly changed the bacterial community composition,which could be mainly explained by soil pH and available potassium.Mycorrhizal fungi and intensive management affected the interrelationships between bacterial members.Structural equation modeling indicated that intensive management changed the cumulative RS by elevating AMF abundance and lowering bacterial abundance.We concluded that intensive management reduced the microbial respiration-derived C loss,but increased mycorrhizal respiration-derived C loss.
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