南京市春季外来杂草调查及生态位研究

利用样方法调查了南京市不同生境下外来杂草的种类、盖度、密度情况,探讨了不同生境中外来杂草对杂草群落的影响,同时分析了10种主要外来杂草和本地伴生种的生态位特点.结果表明,南京市春季外来杂草有36种,在74个样点中外来杂草出现的频率达到98.65%;外来杂草的入侵对生物多样性有不利影响;外来杂草平均优势度在不同生境中大小次序为:水边>菜地>荒地>路旁>景区>田埂>草坪>果茶园>墙缝>农田>宅旁>山坡.生态位的研究结果表明:野塘蒿 Conyzabonariensis L. Cronq. 、野老鹳草 GeraniumcarolinianumL. 和阿拉伯婆婆纳 VeronicapersicaPoir. 是生态位宽度最高的外来杂草,其入侵性最强;具有较高生态位宽度的外来杂草与其它杂草的生态位重叠较大,具有相似形态特征的杂草间的生态位重叠较大.

Quantitative survey on spring exotic weeds and the niche characteristics of dominant species in Nanjing

The diversity,coverage,density of exotic weed populations were surveyed with square intercept method in invasive habitats in Nanjing.There were thirty-six exotic weed species recorded in spring of this region.The frequency of exotic weed emergence in 74 samples is 98.65%.The difference of species richness in different habitats was analyzed and showed that invasion of exotic weeds had harmful influence on biological diversity.The sequence of the average predominance of exotic weeds in different habitats is:waterside>kitchen garden>wasteland>roadside>beauty spot>ridge>lawn>orchard>wall slot>fields>habitats around house>brae.The highest niche breadths and niche overlaps of nine exotic weeds out of 25 main weed populations with more than 30% frequency were compared with concomitant native weed populations.Conyza bonariensis (L.) Cronq.,Geranium carolinianum L.and Veronica persica Poir.were the most invasive among the total 36 main weeds in Nanjing region since they had the highest niche breadth.It could be seen that the species with greater niche breadths generally had greater niche overlaps with other species,and the niche overlaps among species that had similar morphological characters were much greater.