报道了浙江种子植物1个新记录属——膜稃草属HymenachneP.Beauv.和5个新记录种——长圆楼梯草Elatostema oblongifolium Fu ex W.T.Wang、展穗膜稃草Hymenachne patens L.Liou、刚莠竹Microstegium ciliatum(Trin.)A.Camus、短叶黍Panic...报道了浙江种子植物1个新记录属——膜稃草属HymenachneP.Beauv.和5个新记录种——长圆楼梯草Elatostema oblongifolium Fu ex W.T.Wang、展穗膜稃草Hymenachne patens L.Liou、刚莠竹Microstegium ciliatum(Trin.)A.Camus、短叶黍Panicum brevifolium L.和中华笔草Pseudopogonatherum contortum(Brongn.)A.Camus var.sinense(Keng ex S.L.Chen)Keng et S.L.Chen,并简述了它们与同属相近类群的主要区别。展开更多
Aims Rising concentrations of atmospheric carbon dioxide([CO_(2)])may influence forest successional development and species composition of understory plant communities by altering biomass production of plant species o...Aims Rising concentrations of atmospheric carbon dioxide([CO_(2)])may influence forest successional development and species composition of understory plant communities by altering biomass production of plant species of functional groups.Here,we describe how elevated[CO_(2)](eCO_(2))affects aboveground biomass within the understory community of a temperate deciduous forest at the Oak Ridge National Laboratory sweetgum(Liquidambar styraciflua)free-air carbon dioxide enrichment(FACE)facility in eastern Tennessee,USA.We asked if(i)CO_(2)enrichment affected total understory biomass and(ii)whether total biomass responses could be explained by changes in understory species composition or changes in relative abundance of functional groups through time.Materials and methods The FACE experiment started in 1998 with three rings receiving ambient[CO_(2)](aCO_(2))and two rings receiving eCO_(2).From 2001 to 2003,we estimated species-specific,woody versus herbaceous and total aboveground biomass by harvesting four 130.5-m subplots within the established understory plant community in each FACE plot.In 2008,we estimated herbaceous biomass as previously but used allometric relationships to estimate woody biomass across two 535-m quadrats in each FACE plot.Important findings Across years,aboveground biomass of the understory community was on average 25%greater in eCO_(2)than in aCO_(2)plots.We could not detect differences in plant species composition between aCO_(2)and eCO_(2)treatments.However,we did observe shifts in the relative abundance of plant functional groups,which reflect important structural changes in the understory community.In 2001-03,little of the understory biomass was in woody species;herbaceous species made up 94%of the total understory biomass across[CO_(2)]treatments.Through time,woody species increased in importance,mostly in eCO_(2),and in 2008,the contribution of herbaceous species to total understory biomass was 61%in aCO_(2)and only 33%in eCO_(2)treatments.Our results suggest that rising atmospheric[CO_(2)]could accelerate successional development and have longer term impact on forest dynamics.展开更多
Aims in this study,we examine two common invasion biology hypotheses-biotic resistance and fluctuating resource availability-to explain the patterns of invasion of an invasive grass,Microstegium vimineum.Methods We us...Aims in this study,we examine two common invasion biology hypotheses-biotic resistance and fluctuating resource availability-to explain the patterns of invasion of an invasive grass,Microstegium vimineum.Methods We used 13-year-old deer exclosures in great smoky mountains National Park,USA,to examine how chronic disturbance by deer browsing affects available resources,plant diversity,and invasion in an understory plant community.using two replicate 1 m2 plots in each deer browsed and unbrowsed area,we recorded each plant species present,the abundance per species,and the fractional per-cent cover of vegetation by the cover classes:herbaceous,woody,and graminoid.For each sample plot,we also estimated overstory canopy cover,soil moisture,total soil carbon and nitrogen,and soil pH as a measure of abiotic differences between plots.Important Findings We found that plant community composition between chronically browsed and unbrowsed plots differed markedly.Plant diversity was 40%lower in browsed than in unbrowsed plots.at our sites,diver-sity explained 48%and woody plant cover 35%of the variation in M.vimineum abundance.in addition,we found 3.3 times less M.vimineum in the unbrowsed plots due to higher woody plant cover and plant diversity than in the browsed plots.a parsimonious explanation of these results indicate that disturbances such as herbivory may elicit multiple conditions,namely releasing available resources such as open space,light,and decreasing plant diversity,which may facilitate the proliferation of an invasive species.Finally,by testing two different hypotheses,this study addresses more recent calls to incorporate multiple hypotheses into research attempting to explain plant invasion.展开更多
文摘报道了浙江种子植物1个新记录属——膜稃草属HymenachneP.Beauv.和5个新记录种——长圆楼梯草Elatostema oblongifolium Fu ex W.T.Wang、展穗膜稃草Hymenachne patens L.Liou、刚莠竹Microstegium ciliatum(Trin.)A.Camus、短叶黍Panicum brevifolium L.和中华笔草Pseudopogonatherum contortum(Brongn.)A.Camus var.sinense(Keng ex S.L.Chen)Keng et S.L.Chen,并简述了它们与同属相近类群的主要区别。
基金US Department of Energy Office of Science,Biological and Environmental Research Program,Department of Ecology and Evolutionary Biology,University of Tennessee,Knoxville,Oak Ridge National Laboratory is managed by UT-Battelle,LLC,for the US Department of Energy under contract DE-AC05-00-OR22725.
文摘Aims Rising concentrations of atmospheric carbon dioxide([CO_(2)])may influence forest successional development and species composition of understory plant communities by altering biomass production of plant species of functional groups.Here,we describe how elevated[CO_(2)](eCO_(2))affects aboveground biomass within the understory community of a temperate deciduous forest at the Oak Ridge National Laboratory sweetgum(Liquidambar styraciflua)free-air carbon dioxide enrichment(FACE)facility in eastern Tennessee,USA.We asked if(i)CO_(2)enrichment affected total understory biomass and(ii)whether total biomass responses could be explained by changes in understory species composition or changes in relative abundance of functional groups through time.Materials and methods The FACE experiment started in 1998 with three rings receiving ambient[CO_(2)](aCO_(2))and two rings receiving eCO_(2).From 2001 to 2003,we estimated species-specific,woody versus herbaceous and total aboveground biomass by harvesting four 130.5-m subplots within the established understory plant community in each FACE plot.In 2008,we estimated herbaceous biomass as previously but used allometric relationships to estimate woody biomass across two 535-m quadrats in each FACE plot.Important findings Across years,aboveground biomass of the understory community was on average 25%greater in eCO_(2)than in aCO_(2)plots.We could not detect differences in plant species composition between aCO_(2)and eCO_(2)treatments.However,we did observe shifts in the relative abundance of plant functional groups,which reflect important structural changes in the understory community.In 2001-03,little of the understory biomass was in woody species;herbaceous species made up 94%of the total understory biomass across[CO_(2)]treatments.Through time,woody species increased in importance,mostly in eCO_(2),and in 2008,the contribution of herbaceous species to total understory biomass was 61%in aCO_(2)and only 33%in eCO_(2)treatments.Our results suggest that rising atmospheric[CO_(2)]could accelerate successional development and have longer term impact on forest dynamics.
文摘Aims in this study,we examine two common invasion biology hypotheses-biotic resistance and fluctuating resource availability-to explain the patterns of invasion of an invasive grass,Microstegium vimineum.Methods We used 13-year-old deer exclosures in great smoky mountains National Park,USA,to examine how chronic disturbance by deer browsing affects available resources,plant diversity,and invasion in an understory plant community.using two replicate 1 m2 plots in each deer browsed and unbrowsed area,we recorded each plant species present,the abundance per species,and the fractional per-cent cover of vegetation by the cover classes:herbaceous,woody,and graminoid.For each sample plot,we also estimated overstory canopy cover,soil moisture,total soil carbon and nitrogen,and soil pH as a measure of abiotic differences between plots.Important Findings We found that plant community composition between chronically browsed and unbrowsed plots differed markedly.Plant diversity was 40%lower in browsed than in unbrowsed plots.at our sites,diver-sity explained 48%and woody plant cover 35%of the variation in M.vimineum abundance.in addition,we found 3.3 times less M.vimineum in the unbrowsed plots due to higher woody plant cover and plant diversity than in the browsed plots.a parsimonious explanation of these results indicate that disturbances such as herbivory may elicit multiple conditions,namely releasing available resources such as open space,light,and decreasing plant diversity,which may facilitate the proliferation of an invasive species.Finally,by testing two different hypotheses,this study addresses more recent calls to incorporate multiple hypotheses into research attempting to explain plant invasion.
