title: Effects of Praxelis clematidea invasion on soil nitrogen fractions and transformation rates in a tropical savanna.
abstract: Plant invasion has been reported to affect a mass of soil ecological processes and functions, although invasion effects are often context-, species- and ecosystem- specific. This study was conducted to explore potential impacts of Praxelis clematidea invasion on contents of total and available soil nitrogen (N) and microbial N transformations in a tropical savanna. Soil samples were collected from the surface and sub-surface layers in plots with non-, slight, or severe P. clematidea invasion in Hainan Province of southern China, which remains less studied, and analyzed for contents of the total and available N fractions and microbial N transformations. Results showed that total N content significantly increased in the surface soil but trended to decrease in the sub-surface soil in the invaded plots relative to the non-invaded control. Slight invasion significantly increased soil alkali-hydrolysable N content in the two soil layers. Soil net N mineralization rate was not significantly changed in both the soil layers, although soil microbial biomass N was significantly higher in plots with severe invasion than the control. There was no significant difference in content of soil N fractions between plots with slight and severe invasion. Our results suggest that invasion of P. clematidea promotes soil N accumulation in the surface soil layer, which is associated with increased microbial biomass N. However, the invasion-induced ecological impacts did not increase with further invasion. Significantly higher microbial biomass N was maintained in plots with severe invasion, implying that severe P. clematidea invasion may accelerate nutrient cycling in invaded ecosystems.
authors.affiliation: Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.|Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China.|Guangdong Engineering Research Center for Modern Eco-agriculture and Circular Agriculture, Guangzhou, 510642, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wei
authors.affiliation: Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.
authors.forename: Jialin
authors.initials: J
authors.lastname: Xu
authors.affiliation: Guangdong Engineering Research Center for Modern Eco-agriculture and Circular Agriculture, Guangzhou, 510642, China.|Department of Urban Construction Engineering, Guangzhou City Polytechnic, Guangzhou, 510405, China.
authors.forename: Guoming
authors.initials: G
authors.lastname: Quan
authors.affiliation: Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China. jeanzh@scau.edu.cn.|Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China. jeanzh@scau.edu.cn.|Guangdong Engineering Research Center for Modern Eco-agriculture and Circular Agriculture, Guangzhou, 510642, China. jeanzh@scau.edu.cn.
authors.forename: Jiaen
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.|Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou, 510642, China.|Guangdong Engineering Research Center for Modern Eco-agriculture and Circular Agriculture, Guangzhou, 510642, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Qin
mesh_terms: D019659:Asteraceae / Q000502:physiology*; D018533:Biomass; D017753:Ecosystem; D065948:Grassland; D009584:Nitrogen / Q000032:analysis*; D012987:Soil / Q000737:chemistry*; D014329:Tropical Climate
chemical_list: D012987:Soil; D009584:Nitrogen
keywords: Global change; Microbial functioning; Plant and soil interactions; Plant invasion; Soil N stock