STUDY ON WEED ECOLOGICAL RELATIONSHIPS IN AUTUMN-HARVESTED DRY CROP FIELDS IN JINHUA,ZHEJING PROVINCE

in the autumn-harvested dry crop fields in Jinhua, 17 sites on different ecological conditions were surveyed in detail with seven scales by visualization of weed dominance to crop to obtain the weed important values,the species niche breadthes and nicheoverlaps of 22 species were then worked out on the basis of the data above. The minimalspanning tree revealing weed ecological similarity was drawn based on the niche overlaps. The resluts showed that Digitaria sanguinalis、Setaria viridis、Leptochloa chinensis、Cyperus iria、Eleusine indica、Centipeda minima、Echinochloa crusgalli var. hispidula were the main weeds in autumn-harvested dry crop fields in Middle Zhejiang. Amongthe 22 weeds, the niche overlaps of Dingitaria sangualis、Setaria viridis、 Cyperus iria、Cyperus rotundus、Eleusine indica were high,while the niche overlaps of Lertochloa chinensis、Eclipta prostrata、Mollugo pentaphylla、Lindernia antipoda、Luwdigia prostrata、CentiPeda minima、Mazus japonicus were also high, those of Cleome viscosa、Bulbostylis barbata、Alternanthera philoxeroides with other weeds were small, which indicated thattheir ecological demands were special compared with other weeds' in the autumn-harvested dry crop fields in Jinhua.