新疆北疆滴灌机采棉田杂草生态位机理研究OA北大核心CSTPCD

[Objective]The aim of this study was to investigate the niche mechanism of weeds in drip-irrigated and machine-harvested cotton fields in North Xinjiang,China.[Methods]A seven-stage visual survey was conducted to investigate the degree of dominance about weeds in 25 cotton fields under drip-irrigated and machine-harvested in 5 regions(143rd corps,145th corps,and 147th corps of the 8th Division of The Xinjiang Production and Construction Corps,Changji city,Kuytun city)of North Xinjiang.According to the degree of dominance,the important value,the niche breadth,and niche overlap values of 20 main weeds were calculated.The ecological similarity were revealed by detrended correspondence analysis(DCA)sorting.And minimum spanning tree of graph theory cluster analysis were drawn on the basis of the niche overlap value.[Results]The results show that Convolvulus arvensis,Chenopodium album,Amaranthus retroflexus,Solanum nigrum,Phragmites australis,Setaria viridis(L.)Beauv.,Abutilon theophrasti Medicus,Hibiscus trionum,and Echinochloa crusgalli with wide niche breadth are the dominant species(malignant weeds)in drip-irrigated and machine-harvested cotton fields in North Xinjiang.The niche overlap values of S.nigrum and C.album,A.theophrasti and A.retroflexus,H.trionum and E.crusgalli,A.retroflexus and E.crusgalli are higher,implying that these weeds may fiercely compete for resources.Based on the relationship between niche overlap values,minimum spanning tree were produced to reflect the similar ecological needs of related weeds.The 20 kinds of main weeds were divided into 4 groups in the minimum spanning tree.In the 25 sites,the integrated ecological demands of 20 kinds of main weeds were sorted by DCA.The results showed that the 9 kinds of malignant weeds clustered in the center of DCA,which are obviously different from those general weeds around DCA.DCA results corresponded well to the minimum spanning tree.[Conclusion]With the increase of years of drip irrigation,there was a extremely significant or significant regression relationship between the dominance values of above mentioned 9 kinds of malignant weeds and years of drip irrigation.There were significant nonlinear regression relationships between their dominant values of C.arvensis and S.viridis and years of drip irrigation,while there were extremely significant linear regression relationships between the dominant values of other 7 kind of malignant weeds and years of drip irrigation.