大气CO_2浓度升高和氮肥管理对稻麦轮作系统土壤线虫群落组成的影响

Effect of Elevated Atmospheric CO_2 and N Fertilization on Soil Nematode Community in a Rice-Wheat Rotation System

【目的】揭示大气CO2浓度升高和氮肥管理对地下生态系统的影响。【方法】采用中国稻麦轮作FACE(Free-Air CO2 Enrichment)系统平台,开展了大气CO2浓度升高和氮肥管理对土壤线虫群落组成影响的研究。【结果】在稻麦轮作系统共观察到线虫35属,15个功能团。拟丽突属、真头叶属、丝尾属和潜根属为优势属,其中丝尾属和真头叶属对CO2浓度升高和氮肥管理反应敏感。在CO2浓度升高条件下土壤线虫总数、功能团Fu2和Om4的线虫多度均显著增加,其中Fu2多度在CO2和氮肥的交互影响下变化明显。【结论】CO2浓度升高和氮肥管理改变了土壤腐屑食物网的结构和有机质的分解途径。高氮条件下,CO2浓度升高降低了线虫的通路指数(CI),细菌为主的分解通道在小麦季的FACE(HN)处理中占优势。不同施氮水平对线虫结构指数(SI)产生显著影响,低氮条件下较高的SI值表明土壤环境受到的扰动较小,食物网处于结构化状态。

【Objective】The effect of elevated CO2 and N fertilization on the below-ground ecosystem was studied.【Method】A study was conducted in the rice-wheat rotational FACE platform in China to quantify the effect of elevated CO2 and N fertilization on soil nematode community.【Result】Thirty-five genera and 15 functional guilds were observed in this system,and Acrobeloides,Eucephalobus,Filenchus and Hirschmanniella were dominant genera.Filenchus and Eucephalobus were sensitive to the treatment of elevated CO2 and N fertilization,respectively.Under the FACE condition,the abundance of total nematodes,functional guilds of Fu2 and Om4 increased significantly.The interactive treatment of elevated CO2 and N fertilization influenced the abundance of Fu2.【Conclusion】Elevated CO2 and N fertilization resulted in the changes of soil nematode community structure and decomposition pathways.Under the high N conditions（HN）,elevated CO2 decreased the channel index（CI）,and bacteria dominated decomposition pathway was found in the FACE（HN） treatments in the wheat season.Different N fertilization managements influenced the values of structural index（SI）,and the higher SI was observed under the low N condition（LN）,which suggested a stable ecologically successional status with less disturbance.