Abstract: In order to reveal the species composition, biodiversity and harmfulness of autumn weeds in tea gardens of different natural environments, management practices, and tea planting time, a survey on species number, density and weed height were conducted in October 2011 and 2012 in hilly regions of southern Jiangsu Province. Based on the survey data and habitat characters, all sampling tea gardens were classified into five habitat groups through cluster analysis. The results showed that significant differences in family, genera and species composition, and in weed community structure and ratios of annual to perennial species were found among the different groups, due to the influence of habitat and management practices. In Groups Ⅲ and Ⅳ, Eleusine indica + Echinochloa crusgalli var. austrojaponensis + Digitaria sanguinalis weed community and D. sanguinalis + Rostellularia procumbens + Acalypha australis + Eleusine indica + Erigeron annus + Conyza canadensis + Oxalis corniculata weed community occurred respectively. In these two groups, main species were more than the other groups, and species composition and community structure were stable and complicated, which may allow the communities to buffer from disturbance and environmental fluctuation. Groups Ⅱ and Ⅴ, Leptochloa panicea + C. canadensis + Euphorbia humifusa + Erigeron annus weed communities and Ophiopogon japonicus + C. canadensis + Pieris multifida + Phyllanthus urinaria + Rostellularia procumbens weed communities, had unstable structures and caused little harmfulness. Group Ⅰ had Digitaria sanguinalis + Erigeron annuus + Echinochloa crusgalli var. austrojaponensis +Eleusine indica +Oxalis corniculata + Acalypha australis weed communities, with biodiversity index values contrary to those of the other groups, while the dominant species predominated the community structure, often causing serious harmfulness.

Key words: trophic structure, food web foundation, Haizhou Bay, stable isotope