| 英文摘要： |
Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are very important in regulating the process of soil nitrification. However, little is known how responses of AOB and AOA communities to yak excreta application in wetland soils. We investigated AOB and AOA community composition using excreta application treatments to examine how nitrification response to yak excreta application by regulating the ammonia-oxidizing microorganism communities in meadow marsh soil (MMS) and marsh soil (MS). The microcosm experiments of excreta application were established in MMS and MS. The microcosms were subject to dung application (DA), urine application (UA) and control (CK). Molecular methods were applied to determine the compositions of AOA and AOB. Chao, ACE, Shannon and Simpson indices were applied to measure species richness and diversity. Potential nitrification rate (PNR) was higher in MMS than in MS. DA significantly increased PNR in MMS, whereas DA decreased PNR in MS. The urease activity was lower in MMS than in MS, whereas catalase activity was opposite. DA increased urease and catalase activities significantly in MMS and MS. Excreta application decreased the alpha diversity of AOB in MMS whereas the trend was opposite in MS, and it was higher in MMS than in MS. The canonical correspondence analysis (CCA) demonstrated that the urease and catalase activities were the important factors to change the AOB community structure in MS. Structural equation modelling (SEM) showed PNR was indirectly influenced by total phosphorus (TP) through mediation of the ACE index and Simpson index of AOB. Yak excreta application can alter soil environmental conditions resulted in changes in AOB community composition. However, the response of AOA to yak excreta application was much weaker than that of AOB in both MMS and MS. |
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