RELATIONSHIPS BETWEEN ALLELOPATHY AND INVASIVENESS BY EUPATORIUM ADENOPHORUM AT DIFFERENT SITES
不同生境条件下紫茎泽兰化感作用的变化与入侵力关系的研究

With an increase in the abundance and cover of Eupatorium adenophorum, there is a concurrent decrease in the abundance and cover of native species; how ever, this decrease varies at different sites and in different forests. The rela tive abundance and cover of E. adenophorum in deciduous broad-leaved forests and a long the roadside were 3-5 times greater than in evergreen broad-leaved forests. T he composition, relative abundance and cover of native plants in deciduous b road-leaved forests and along the roadside decreased by 30%, 50% and 70%, respec tively, as compared to the evergreen broad-leaved forest. By bioassay, we investigated the allelopathy of aquatic extract from E. adenop horum that grew under evergreen broad-leaved forests, deciduous broad-leaved f orests a nd along the roadside. We found that allelopathy of aquatic extract of E. aden ophorum was different among sites, viz. roadside > deciduous broad-leaved fore sts > e vergreen broad-leaved forests. Correlation analysis showed that allelopathy of E. adenophorum was significantly correlated to the relative abundance of native spec ies at each of the sites. These results showed that differences in invasiveness among sites are due to differences in allelopathy at the different sites. The ca bbage biomass showed that the allelopathy of aquatic extract from E. adenophor um s hoots was greater among sites than its roots. This suggests that the allelopathy o f aquatic extract from E. adenophorum shoots contributes to different levels of invasiveness among sites more than its roots. The growth of E. adenophorum is hearty and the biomass per unit area is grea t al ong roadsides and under deciduous broad-leaved forests, so the allelopathy of E. adenophorum populations per unit area along roadsides and under deciduous bro ad-leaved forests must be much more than in evergreen broad-leaved forests. Henc e, the a ffects of E. adenophorum will be greater on these communities accelerating t heir decline.