Soil microbial changes during the spring thaw period

High nitrous oxide (N2O) emissions during spring thawing period have been observed in many different ecosystems. However, its effect on N2O emissions from wetland soil and the associated microbial mechanisms are still unclear. This study sampled wetland soil from riparian that experienced vegetation changes, XiLin River of China, to explore the features of bacterial community in response to thaw progression changes. The results showed that the freeze-thaw periods predominant impacts on the diversity and composition of the bacterial communities. The phyla composition of the soil bacteria communities of the three periods are similar in level, with Proteobacteria, Chloroflexi, Actinobacteria and Acidobacteria dominated the microbial communities. The Alpha diversity of bacterial communities in different periods varies that the freezing period is higher than that of the freeze-thaw period (p<0.05). Soil water content, total carbon and ammonia nitrogen were the primary factors regulating the abundance and compositions of the bacterial communities during spring thawing periods. Large N2O was produced by nitrification during spring freeze-thaw. The correlation results indicated that the soil temperature, soil water content, TC, MBC, NH4+-N, NO3--N were the environmental factors which significant effecting the N2O emissions. Collectively, this study revealed spring thaw period is an important source of N2O emission and spring thaw caused only minor changes in the bacterial community structure.