Effects Of Litter Input On Soil Nitrogen Mineralization And Its Microbiological Mechanism In An Invasive Habitat Of Phyllostachys Pudostachys

The type of litter input play a prominent role in soil nitrogen mineralization;however,how litter input changes soil nitrogen mineralization and microbial community characteristics during plant invasion is still unclear.This study was conducted on litter removal,litter replacement,and control in the uninvaded broadleaf forest,and the moso bamboo forest invaded heavily.We investigated the Effects of litter input on soil nitrogen mineralization and its microbiological mechanism in an invasive habitat of Phyllostachys pudostachys.The soil net-ammonification and nitrification rates were measured by laboratory incubation by adding inhibitors(streptomycin and cycloheximide).Moreover,we measured the microbial community structure,functional genes abundance,soil physical and chemical properties,and litter chemical properties to elucidate the role of litter input in altering soil nitrogen mineralization by plant invasion.The results of effects of litter input on soil nitrogen mineralization and contribution of microbial community were as followed:1)After litter removal,the soil net-ammonification rate in the broadleaf forest increased by 27.0%,and which in the bamboo forest increased by 23.4%.In comparison,the soil net-nitrification rate in the bamboo forest decreased by 11.4%.After litter replacement,the soil net-ammonification rate increased by 43.8%,while the soil net-nitrification rate decreased by 33.5% in the broadleaf forest,and the soil netnitrification rate in the bamboo forest increased by 73.1%.2)After adding inhibitors,soil fungal and bacterial communities played a significant role in the soil net-ammonification in the broadleaf forest after litter replacement compared with the control.Fungi played a considerable role in the soil net-nitrification in both forest types,and bacteria played an important role in the soil net-nitrification only in the broadleaf forest.3)Combined with the measured litter chemical properties of litter,the contribution of fungi and bacterial communities to soil nitrogen mineralization altered after litter replacement due to the lignin and cellulose content of the input litters changed.On the other hand,effects of litter input on soil nitrogen mineralization and microbial community functions was as showed:1)After litter removal and replacement in both forest types,litter in the broadleaf forest promoted the soil net-ammonification rate,and litter in the bamboo forest promoted soil net-nitrification rate.In contrast,litter in the broadleaf forest inhibited soil net-nitrification rate.2)The soil net-ammonification rate was positively correlated with SOM,?-glucosidase and lcc gene abundance.However,it was negatively correlated with litter's lignin content,indicating that litter in the broadleaf forest could increase the soil net ammonification rate by increasing soil organic matter,enzyme activities and functional genes related to carbon degradation.3)The soil net-nitrification rate was positively correlated with the content of litter's total N,lignin contents,soil total N,and the abundance of soil bacteria as well as AOB gene abundance.Moreover,it was also positively correlated with the soil fungal components after litter removal in the broadleaf forest,while it was negatively correlated with the litter's total C and cellulose contents,indicating that the litter in the bamboo forest could promote the soil net nitrification rate in the broadleaf forest by increasing the soil's total N,bacterial and AOB gene abundance.In general,the difference in litter's lignin and cellulose content in both forest types changed the contribution of fungi and bacteria to the soil net-ammonification and nitrification.Litter in the broadleaf forest promoted the soil net-ammonium nitrogen,due to the degradation of SOM,and microbial carbon increased by the litter in the broadleaf forest.Litter in the bamboo forest promoted the soil net nitratenitrogen production mainly due to the soil total N,bacteria and AOB gene abundance increased by the litter in the bamboo forest.