Abstract: In October, 2011 and 2012, an investigation was made on the weed species and their density and height in the tea gardens in southern hilly regions of Jiangsu Province. The obtained data were transformed into weed relative abundance and importance values. The niche breadth and niche overlap values of selected 25 main weeds were calculated, and twodimensional scatter plot of DCA ordination was drawn based on the importance values. The results showed that there were 100 weed species, belonging to 90 genera and 40 families. Among them, 25 weed species occurred with a frequency of >15%. Among these 25 species, Digitaria sanguinalis, Acalypha australis,
Erigeron annuus, Echinochloa crusgalli var. austrojaponensis, and Eleusine indica had wider niche breadth, being the important weeds in the tea gardens in southern hilly regions of Jiangsu Province. The higher niche overlap values were found between D. sanguinalis, E. crusgalli var. austrojaponensis, A. australis, E. indica, and E. annuus, indicating that the resource competition was more intense, and thus, these weed communities had greater harm to tea. All the sampling sites were quantitatively clustered into five groups based on the similarity coefficient. These five groups included limestone soil tea garden, plowing and well-managed tea garden, noplowing and generalmanaged tea garden, extensivemanaged and almost abandoned tea garden, and understory tea garden. The dominant weed species in each group in autumn were evident, which formed relatively different weed communities in the tea gardens. The results would provide theoretical basis for the integrated management of weeds in tea gardens.

Key words: nitrogen utilization rate., melon, nitrogen transfer, nitrogen distribution