Aims In recent years,there has been an increasing interest in the impact of invasive alien plant species on the soil seed bank.Soil seed banks play an important role in determining the composition and dynamics of the ...Aims In recent years,there has been an increasing interest in the impact of invasive alien plant species on the soil seed bank.Soil seed banks play an important role in determining the composition and dynamics of the vegetation through time.Therefore,an ability to form a persistent seed bank and/or a capacity to alter the structure of the seed bank of invaded communities could be important factors in determining the success of many alien plant species.In this study,we report on a detailed assessment of the characteristics of the seed bank community associated with the herbaceous plant invader,Gunnera tinctoria,a newly emerging and potentially globally significant invasive plant species.This species,native to South America,is invasive in a range of wet habitats in Europe,Australasia and the USA.Methods A comprehensive assessment of the seed bank of invaded and comparable uninvaded areas was made at two points in time(May and October),at three sites in western Ireland.The seedling emergence approach was used to assess the structure(diversity,dominance and abundance)of the soil seed bank.Differences between invaded and uninvaded seed bank communities were investigated at the spatial scales of site,plot and depth.Important Findings Gunnera tinctoria formed a large persistent seed bank at the study sites.Approximately 30000 seedlings per square metre emerged from soils collected from invaded areas,of which 30%were found in deep soil layers.Seedlings of this invader represented 53–86%of the total number of seedlings associated with invaded areas.Both the transient and the more persistent component of the seed bank of invaded communities were significantly less diverse and abundant than those of uninvaded areas,and were characterized by higher dominance,even when seedlings of the invader were not included in the analysis.The seed bank of invaded areas was largely composed of seeds of agricultural weeds in addition to those of the invader.These results suggest that G.tinctoria has the capacity to profoundly alter the seed bank of invaded communities.These results have direct relevance for the development of control and management strategies,for this and other comparable invasive species,which should account for both quantitative and qualitative alterations in the seed bank community.Our study also suggests that control measures that result in disturbance of areas colonized by G.tinctoria could promote the germination of undesirable weeds.展开更多
Aims Gunnera tinctoria is an unusual N-fixing plant species that has become invasive worldwide,generally in environments with a low evaporative demand and/or high rainfall.Amongst the many mechanisms that may explain ...Aims Gunnera tinctoria is an unusual N-fixing plant species that has become invasive worldwide,generally in environments with a low evaporative demand and/or high rainfall.Amongst the many mechanisms that may explain its success as an introduced species,a contrasting phenology could be important but this may depend on an ability to grow and utilize nutrients under sub-optimal conditions.We examined whether G.tinctoria has an advantage in terms of a contrasting phenology and N-fixing capability,in comparisons with Juncus effusus,the native species most impacted by G.tinctoria invasions.Methods We made phenological assessments on a weekly or bi-weekly basis on long-established populations on Achill Island,Ireland,during 2016-2017.Data on leaf and inflorescence number,total leaf area,light interception and above-ground biomass were collected alongside measurements of soil temperature,moisture and oxidation-reduction potential.The significance of N-fixing ability for supporting seasonal growth was assessed usingδ15N isotopic assessments,together with in situ acetylene reduction measurements.Important Findings The timing of the initiation of growth of G.tinctoria and J.effusus varied between 2016 and 2017,with the earlier emergence and expansion of leaves of G.tinctoria,and the largest above-ground biomass associated with higher water availability.The early growth of G.tinctoria was dependent on preformed structures,with maximum canopy development occurring in late May,prior to that of J.effusus.Whilst N-fixation was observed in March,this made a more significant contribution to growth during the later stages of canopy development.Based onδ15N isotopic analyses,early growth was predominantly associated with N-remobilization from the rhizomes,whilst seedlings were largely reliant on N-fixation.This emphasizes the importance of nutrient mobilization for early growth and shows that the importance of an N-fixing capability may vary developmentally,as well as during different stages of the invasion process.展开更多
基金Environmental Protection Agency Ireland,under the National Development Plan 2000–2006.
文摘Aims In recent years,there has been an increasing interest in the impact of invasive alien plant species on the soil seed bank.Soil seed banks play an important role in determining the composition and dynamics of the vegetation through time.Therefore,an ability to form a persistent seed bank and/or a capacity to alter the structure of the seed bank of invaded communities could be important factors in determining the success of many alien plant species.In this study,we report on a detailed assessment of the characteristics of the seed bank community associated with the herbaceous plant invader,Gunnera tinctoria,a newly emerging and potentially globally significant invasive plant species.This species,native to South America,is invasive in a range of wet habitats in Europe,Australasia and the USA.Methods A comprehensive assessment of the seed bank of invaded and comparable uninvaded areas was made at two points in time(May and October),at three sites in western Ireland.The seedling emergence approach was used to assess the structure(diversity,dominance and abundance)of the soil seed bank.Differences between invaded and uninvaded seed bank communities were investigated at the spatial scales of site,plot and depth.Important Findings Gunnera tinctoria formed a large persistent seed bank at the study sites.Approximately 30000 seedlings per square metre emerged from soils collected from invaded areas,of which 30%were found in deep soil layers.Seedlings of this invader represented 53–86%of the total number of seedlings associated with invaded areas.Both the transient and the more persistent component of the seed bank of invaded communities were significantly less diverse and abundant than those of uninvaded areas,and were characterized by higher dominance,even when seedlings of the invader were not included in the analysis.The seed bank of invaded areas was largely composed of seeds of agricultural weeds in addition to those of the invader.These results suggest that G.tinctoria has the capacity to profoundly alter the seed bank of invaded communities.These results have direct relevance for the development of control and management strategies,for this and other comparable invasive species,which should account for both quantitative and qualitative alterations in the seed bank community.Our study also suggests that control measures that result in disturbance of areas colonized by G.tinctoria could promote the germination of undesirable weeds.
基金supported by the Brazilian National Council for Scientific and Technological Development(CNPq).M.C.M.received the grant number 205031/2014-5.A.B.G.and L.G.S.were supported by grants from the Spanish Ministerio de Economía y Competitividad(BES-2013-062945 and CTM2015-64728-C2-1-R,respectively).
文摘Aims Gunnera tinctoria is an unusual N-fixing plant species that has become invasive worldwide,generally in environments with a low evaporative demand and/or high rainfall.Amongst the many mechanisms that may explain its success as an introduced species,a contrasting phenology could be important but this may depend on an ability to grow and utilize nutrients under sub-optimal conditions.We examined whether G.tinctoria has an advantage in terms of a contrasting phenology and N-fixing capability,in comparisons with Juncus effusus,the native species most impacted by G.tinctoria invasions.Methods We made phenological assessments on a weekly or bi-weekly basis on long-established populations on Achill Island,Ireland,during 2016-2017.Data on leaf and inflorescence number,total leaf area,light interception and above-ground biomass were collected alongside measurements of soil temperature,moisture and oxidation-reduction potential.The significance of N-fixing ability for supporting seasonal growth was assessed usingδ15N isotopic assessments,together with in situ acetylene reduction measurements.Important Findings The timing of the initiation of growth of G.tinctoria and J.effusus varied between 2016 and 2017,with the earlier emergence and expansion of leaves of G.tinctoria,and the largest above-ground biomass associated with higher water availability.The early growth of G.tinctoria was dependent on preformed structures,with maximum canopy development occurring in late May,prior to that of J.effusus.Whilst N-fixation was observed in March,this made a more significant contribution to growth during the later stages of canopy development.Based onδ15N isotopic analyses,early growth was predominantly associated with N-remobilization from the rhizomes,whilst seedlings were largely reliant on N-fixation.This emphasizes the importance of nutrient mobilization for early growth and shows that the importance of an N-fixing capability may vary developmentally,as well as during different stages of the invasion process.
