Effects Of The Invasion Degree Of Solidago Canadensis On Plant Community And The Soil Properties In Different Habitats

With the development of economic globalization,invasion of alien plants has become one of the important ecological problems.Exotic plant invasion decreased global biodiversity and damaged structure and functioning of natural ecosystems.There has been numerous studies on invasion mechanisms,however,controversy remains on the effects of habitat and invasion degree on ecosystems.Solidago canadensis L.is a global invasive plant that can establish into a variety of habitats,and a threat to China's environment and economy.According to results of field survey and controlled experiment,we explored characteristics of resident community structure,soil properties and species traits(including resident species and invasive species)under different levels of S.canadensis,invasion in different habitats.Results showed significant differences in total biomass,individual plant biomass,mean plant height,mean specific leaf area,cover and density of S.canadensis among habitats.Cover,abundance,height and individual plant biomass of S.canadensis increased along invasion degree,while specific leaf area decreased.Community productivity,species richness,Shannon-Wienner diversity index,community functional diversity index,community weighted plant height,and community weighted specific leaf area of plant communities significantly differed among habitats.Augmentation of invasion degree significantly lowered resident community production,species richness and diversity index while increased functional diversity index.Communities with invasion degree between 75%to 100%of invader cover differed the most as compared to the other communities.Among soil properties,S.canadensis significantly affected activities of urease and invertase,but the activities differed among habitats,and invasion degree had different directions and strengths on the activities.In the controlled experiment,cover,above-and belowground biomasses of S.canadensis increased along invader density,while intensity of light significantly changed belowground biomass,total biomass and individual plant biomass of S.canadensis.Invasion degree significantly affected community production and diversity index,communities in habitat under tree crowns were more sensitive to invasion degree.Overall,community productivity,species richness,diversity index,cover,density of alien plant and resident species aboveground biomass performed similarly under invasion in different habitats,they can be used as common indicators to identify S.canadensis invasion degree and impact on ecosystems.Soil properties,enzyme activities,plant height and mean specific leaf area performed differently among habitats,therefore environmental factors and resident communities should be considered specifically when applying these indicators.These results give the theoretical basis and technological support for rapid assessment of the effects of habitat and degree of S.canadensis invasion on ecosystems.