Studies On Soil Nitrous Oxide Fluxes And Ammonia-oxidizing Archaea Diversity In Three Forest Types From Tropical Montane Rainforest

Studies on tropical forest soil nitrogen emission and ammonia-oxidizing microbe also relatively lag behind. There are several forest types and abundant species resources in Jiangfengling natural reserve (JFNR), which is typical tropical montane rainforest on Hainan Island. We selected primary montane rainforest (PF), secondary montane rainforest (SF) and Podocarpus imbricatus plantation (PP) in JFNR as study sites and studied their spatial and temporal heterogeneity of soil nitrous oxide (N2O) fluxes and ammonia-oxidizing archaea (AOA) diversity by static chamber-gas chromatograph technique and PCR-denaturing gradient gel electrophoresis (PCR-DGGE) for one year.Firstly, results suggest the average soil N2O fluxes for three forest types is 0.0501± 0.0938 mg m-2 h-1 (4.39 kg ha-2 yr1) and show highly significant seasonal variation (P< 0.01), no significant difference between SF and PP (0.0583±0.1204 mg m-2 h-1 and 0.0629 ±0.0917 mg m-2 h-1, respectively) (P> 0.05), but all significantly higher than PF (0.0289± 0.0992 mg m-2 h-1) (P< 0.05). What’s more, temperature significantly effects on soil N2O fluxes (P< 0.01), in other words, temperature is the key factor to affect soil N2O fluxes.Secondly, AOA community structures of SF and PP are mainly affected by the soil moisture (SM), dissolved organic carbon (DOC), and the effects of N-NO3-, and during the winter, soil pH and N-NH4+ are key factors for PF. Overall, AOA diversity has no significant difference between the three forest types, and it is slightly higher for PF than that of others. AOA community structure for three forest types are also affected by seasonal variation, for PF significant higher during autumn and summer (P< 0.05), for SF significant higher during summer and winter (P< 0.05), and for PP significant higher during summer and autumn (P< 0.05). For all the forest types in the summer, autumn, winter season the AOA diversity index is higher. From the point of all year, richness index of PF is obviously higher than that of the other two forest types (P< 0.05), and that might be related with the plant diversity of PF.