关键词: 害虫, 天敌, 群落动态, 桃园, 相互作用

Abstract: In this paper,a greenhouse experiment was conducted to study the responses of different functional groups of weeds to simulated nitrogen deposition (4.0 g N· m^-2·yr^-1).Native weed species-Poa annua,Lolium perenne,Avena fatua,Medicago lupulina,Trifolium repens,Plantago virginica,Veronica didyma,Echinochloa crusgalli var.mitis,Eleusine indica and Amaranthus spinosus in orchard ecosystem were used as test materials,and their above-and underground biomass and nitrogen uptake were measured.The results showed that under simulated N deposition,the total biomass,shoot biomass and root biomass of all weed species tended to increase,while the total biomass was differed for different functional groups of weeds.The biomass of C₄ grass,C₃ legumes and C₃ grass was significantly increased under N deposition,while that of C₃ and C₄ forbs was not significantly impacted.The root/shoot biomass ratio of Avena fatua and Plantago virginica was enhanced by N deposition,but that of Poa annu,Lolium perenne,Medicago lupulina,Trifolium repensand Amarathus spinosus was not impacted significantly.N deposition had no significant effect on plant N concentration,but significantly enhanced the N uptake of all test weed species except Amarathus spinosus,Poa annua and Veronica didyma.It was suggested that the further increase of N deposition might speed up the changes of the community structure of weed species due to their different responses to N deposition.

Key words: Pests, Natural enemies, Community dynamics, Peach orchards, Interaction