Invasive plant Ageratina adenophora(Sprengel)R.King&H.Robinson has invaded majority of the temperate forests in Kumaun,Central Himalaya.Information on A.adenophora invaded forest types,their structural attributes,...Invasive plant Ageratina adenophora(Sprengel)R.King&H.Robinson has invaded majority of the temperate forests in Kumaun,Central Himalaya.Information on A.adenophora invaded forest types,their structural attributes,population demography and regeneration status are still at rudimentary level.Considering this,the present study was conducted to assess the impacts of A.adenophora on vegetational attributes and regeneration status of three forest types,viz.,Oak(Quercus oblongata D.Don),Pine(Pinus roxburghii Sarg.)and Cypress(Cupressus torulosa D.Don).We selected three sites for each forest type and each site was further purposively stratified into paired sampling plots of 1 ha each i.e.,A.adenophora invaded and uninvaded sites.Our results showed large densities of cut stumps or felled trees throughout invaded sites,but with fewer fire signs in comparison to uninvaded sites.In uninvaded sites,total density and basal area calculated for woody species were relatively higher than those in invaded sites,although results were insignificant(p>0.05).With the exception for Cypress forests,vegetation indices showed low woody species richness and diversity in invaded Oak and Pine forests.Also,regeneration of Q.oblongata,P.roxburghii and C.torulosa tree species did not differ significantly(p>0.05)between invaded and uninvaded sites.These insignificant differences clearly imply that A.adenophora's presence has not entirely changed the perennial plant communities in terms of composition,structure and natural regeneration.However,tree species with poor or no regeneration status requires special attention and needs management strategies involving control of invasive species in forest ecosystems.展开更多
Rhizosphere microbial communities play important roles in facilitating or inhibiting the establishment of exotic species.Since some invasive plants interact with soil microbial communities such as rhizosphere bacteria...Rhizosphere microbial communities play important roles in facilitating or inhibiting the establishment of exotic species.Since some invasive plants interact with soil microbial communities such as rhizosphere bacteria,changes triggered by rhizosphere bacteria may alter competitive interactions between exotic and native plants.This study compared the Bacillus cereus content in soils with different degrees of Ageratina adenophora invasion,and investigated the effects of A.adenophora allelochemicals on B.cereus growth and soil characteristics and the feedback effects of B.cereus on A.adenophora growth.Bacillus cereus content in the rhizosphere of A.adenophora increased with intensification of the invasion process,and newly invaded soil contained almost twice as much bacteria as noninvaded soil.When rhizosphere soil was added to the root exudates of A.adenophora,the contents of B.cereus were twice as much as the control,except on the first day.Certain soil parameters increased significantly,such as ammonium nitrogen(NH_(4)^(+)-N)and available phosphorus(AP),which were increased by 41 and 27%,respectively.Soil treatment with B.cereus promoted the degradation of two allelochemicals from the rhizosphere of A.adenophora,amorpha-4,7(11)-dien-8-one and 6-hydroxy-5-isopropy1-3,8-dimethyl-4 a,5,6,7,8,8 ahexahydraphthalen-2(1 H)-one,to varying degrees;and increased the germination rate by 50%,root length by 117%,shoot length by 48%and fresh weight by 81%for A.adenophora compared to those of untreated soil.Our results confirmed that the invasion of A.adenophora will promote an increase of B.cereus,a beneficial rhizosphere bacterium,which in turn induces a positive feedback effect on A.adenophora.展开更多
In order to ascertain the invasive mechanism and control strategy of the invasive Crofton weed, Ageratina adenophora, its ecological adaptability and population differentiation,the formation of single dominant populat...In order to ascertain the invasive mechanism and control strategy of the invasive Crofton weed, Ageratina adenophora, its ecological adaptability and population differentiation,the formation of single dominant population, displacement of native plants and sustainable management strategies were investigated. The present results helped to clarify and explain such issues as the adaptability post invasion,interaction and competition between inter-and intra-species and community resistance, thereby providing important references to researches on other invasive alien species.展开更多
基金Department of Science&Technology,New Delhi(DST-SERB/CRG/2019/004139)for providing financial support。
文摘Invasive plant Ageratina adenophora(Sprengel)R.King&H.Robinson has invaded majority of the temperate forests in Kumaun,Central Himalaya.Information on A.adenophora invaded forest types,their structural attributes,population demography and regeneration status are still at rudimentary level.Considering this,the present study was conducted to assess the impacts of A.adenophora on vegetational attributes and regeneration status of three forest types,viz.,Oak(Quercus oblongata D.Don),Pine(Pinus roxburghii Sarg.)and Cypress(Cupressus torulosa D.Don).We selected three sites for each forest type and each site was further purposively stratified into paired sampling plots of 1 ha each i.e.,A.adenophora invaded and uninvaded sites.Our results showed large densities of cut stumps or felled trees throughout invaded sites,but with fewer fire signs in comparison to uninvaded sites.In uninvaded sites,total density and basal area calculated for woody species were relatively higher than those in invaded sites,although results were insignificant(p>0.05).With the exception for Cypress forests,vegetation indices showed low woody species richness and diversity in invaded Oak and Pine forests.Also,regeneration of Q.oblongata,P.roxburghii and C.torulosa tree species did not differ significantly(p>0.05)between invaded and uninvaded sites.These insignificant differences clearly imply that A.adenophora's presence has not entirely changed the perennial plant communities in terms of composition,structure and natural regeneration.However,tree species with poor or no regeneration status requires special attention and needs management strategies involving control of invasive species in forest ecosystems.
基金the National Natural Science Foundations of China(31772229 and 31660546)。
文摘Rhizosphere microbial communities play important roles in facilitating or inhibiting the establishment of exotic species.Since some invasive plants interact with soil microbial communities such as rhizosphere bacteria,changes triggered by rhizosphere bacteria may alter competitive interactions between exotic and native plants.This study compared the Bacillus cereus content in soils with different degrees of Ageratina adenophora invasion,and investigated the effects of A.adenophora allelochemicals on B.cereus growth and soil characteristics and the feedback effects of B.cereus on A.adenophora growth.Bacillus cereus content in the rhizosphere of A.adenophora increased with intensification of the invasion process,and newly invaded soil contained almost twice as much bacteria as noninvaded soil.When rhizosphere soil was added to the root exudates of A.adenophora,the contents of B.cereus were twice as much as the control,except on the first day.Certain soil parameters increased significantly,such as ammonium nitrogen(NH_(4)^(+)-N)and available phosphorus(AP),which were increased by 41 and 27%,respectively.Soil treatment with B.cereus promoted the degradation of two allelochemicals from the rhizosphere of A.adenophora,amorpha-4,7(11)-dien-8-one and 6-hydroxy-5-isopropy1-3,8-dimethyl-4 a,5,6,7,8,8 ahexahydraphthalen-2(1 H)-one,to varying degrees;and increased the germination rate by 50%,root length by 117%,shoot length by 48%and fresh weight by 81%for A.adenophora compared to those of untreated soil.Our results confirmed that the invasion of A.adenophora will promote an increase of B.cereus,a beneficial rhizosphere bacterium,which in turn induces a positive feedback effect on A.adenophora.
基金supported by the National Basic Research Program of China (Grant Nos.2009CB119200 and 2002CB111400)the National Natural Science Foundation of China (Grant No.30871654)
文摘In order to ascertain the invasive mechanism and control strategy of the invasive Crofton weed, Ageratina adenophora, its ecological adaptability and population differentiation,the formation of single dominant population, displacement of native plants and sustainable management strategies were investigated. The present results helped to clarify and explain such issues as the adaptability post invasion,interaction and competition between inter-and intra-species and community resistance, thereby providing important references to researches on other invasive alien species.
