Aims Clonal plant species have the potential for high relative performance in heterogeneous environments,and this might increase the com-petitive ability and invasiveness of introduced clonal plant species.It was hypo...Aims Clonal plant species have the potential for high relative performance in heterogeneous environments,and this might increase the com-petitive ability and invasiveness of introduced clonal plant species.It was hypothesized that clonal species whose performance responds more to heterogeneity of a resource have higher competitive ability in habitats where this resource is more heterogeneous and that this relationship is stronger when other resources are less limiting.Methods To test these hypotheses,the perennial clonal herb Alternanthera philoxeroides,which is invasive in China,was grown alone or with each of four clonal perennial,co-occurring herbs native to China,i.e.Alternanthera sessilis,Cynodon dactylon,Hemarthria altissima and Wedelia chinensis.Plants were given homogeneous or het-erogeneous soil substrate crossed with low and high levels of soil moisture.Important Findings Effects of heterogeneity on the accumulation of mass and ramets and on competitive effect and response of A.philoxeroides differed between native species and interacted with effects of soil moisture.A.philoxeroides reduced the final total mass or ramet number of the native species except A.sessilis,and the negative competitive effects on H.altissima and C.dactylon were more pronounced in heterogeneous than in homogeneous soil.Competitive response of A.philoxeroides was more negative to A.sessilis than to the other native species.Across native species,the competitive response of A.philoxeroides was more negative in heterogeneous than in homo-geneous soils at low moisture level,but the reverse was true at high moisture level.Results do not consistently support either hypoth-esis,but do suggest that competitive ability can be partly explained by individual species traits such as size,and that some competi-tive effects and responses are emergent properties of interspecific interactions.展开更多
Aims Clonal growth is associated with invasiveness in introduced plant species,but few studies have compared invasive and noninvasive introduced clonal species to investigate which clonal traits may underlie invasiven...Aims Clonal growth is associated with invasiveness in introduced plant species,but few studies have compared invasive and noninvasive introduced clonal species to investigate which clonal traits may underlie invasiveness.To test the hypothesis that greater capacity to increase clonal growth via physiological integration of connected ramets increases invasiveness in clonal plants,we compared the effects of severing connections on accumulation of mass in the two species of the creeping,succulent,perennial,herbaceous genus Carpobrotus that have been introduced on sand dunes along the Pacific Coast of northern California,the highly invasive species Carpobrotus edulis and the co-occurring,noninvasive species Carpobrotus chilensis.Methods Pairs of ramets from four mixed populations of the species from California were grown in a common garden for 3 months with and without severing the stem connecting the ramets.To simulate the effect of clones on soils in natural populations,the older ramet was grown in sand amended with potting compost and the younger in sand alone.Important Findings Severance decreased net growth in mass by~60%in C.edulis and~100%in C.chilensis,due mainly to the negative effect of severance on the shoot mass of the younger ramet within a pair.Contrary to the hypothesis,this suggests that physiological integration increases growth more in the less invasive species.However,severance also decreased allocation of mass to roots in the older ramet and increased it in the younger ramet in a pair,and the effect on the younger ramet was about twice as great in C.edulis as in C.chilensis.This indicates that the more invasive species shows greater phenotypic plasticity in response to physiological integration,in particular greater capacity for division of labor.This could contribute to greater long-term growth and suggests that the division of labor may be a trait that underlies the association between clonal growth and invasiveness in plants.展开更多
Aims Many wetlands are polluted with both nutrients and toxic metals and vegetated largely by clonal plants.We hypothesized that eutrophication and clonal integration can increase phytoremediation of toxic metal pollu...Aims Many wetlands are polluted with both nutrients and toxic metals and vegetated largely by clonal plants.We hypothesized that eutrophication and clonal integration can increase phytoremediation of toxic metal pollution by increasing plant growth,even under the stress imposed by toxicity.Methods To test this hypothesis,single ramets of the common,widespread,floating,stoloniferous plant Pistia stratiotes L.,were grown for 42 days at two levels of nutrient availability with and without 0.6 mg L^(-1) cadmium.Ramets were either severed from their vegetative offspring to prevent clonal integration or left connected,and severed offspring were either removed to eliminate intraclonal competition or left in place.Important Findings Plants subjected to cadmium addition accumulated almost twice as much dry mass if given the higher nutrient level,due mainly to a doubling of the number of clonal offspring.Severance had little effect on the final mass of the parent plus offspring ramets.Removing offspring following severance had no effect on the final mass of the parental ramet in the presence of added cadmium,but it did increase the final mass of the parent in the absence of cadmium.These results support the hypothesis that eutrophication can increase remediation of toxic metal pollution by aquatic macrophytes but provided no evidence that clonal integration can affect remediation.Species such as P.stratiotes may help remediate co-pollution of wetlands with toxic metals and nutrients,and fragmentation of clones may not affect their remediation capacity.展开更多
Aims Fruit color polymorphisms are widespread in plants,but what maintains them is largely unclear.One hypothesis is that some morphs are preferred by dispersers while others have higher pre-or postdispersal fitness.T...Aims Fruit color polymorphisms are widespread in plants,but what maintains them is largely unclear.One hypothesis is that some morphs are preferred by dispersers while others have higher pre-or postdispersal fitness.This leads to the prediction that fruit color morphs will differ in pre-or postdispersal fitness.Methods We compared genetic and clonal diversity,mating system,morphological traits that might be associated with resistance to freezing,and germination,survival and seed production of progeny of the red and white fruit morphs in a population of a diploid,wild strawberry,Fragaria pentaphylla,from south-central China.Important Findings The red morph was much more abundant than the white but did not show higher genetic diversity as measured by observed and effective numbers of alleles,Shannon information index,or expected or observed heterozygosities.AMOVA showed that most of the genetic variation in the population was within rather than between morphs.Morphs did not differ in mating system parameters,and no significant biparental inbreeding was found in either morph.Gene flow between two morphs was high(N_(m)=6.89).Seeds of the red morph germinated about 2 days earlier and had a 40%higher rate of germination than those of the white morph,but survival of seedlings and seed production by surviving offspring did not differ between morphs.The whole postdispersal fitness of the red morph was about two times higher than that of the white morph.Red morphs had hairier petioles but not more surface wax on leaves.Overall,results showed partial evidence for difference in pre-and postdispersal fitness between fruit color morphs in F.pentaphylla.Differences in fitness independent of dispersal may thus partially account for fruit color polymorphism in all cases.展开更多
Soil nutrient heterogeneity is common in nature,but few studies have tested the effects of soil nutrient heterogeneity on plant productivity in natural communities.Such effects are of particular interest in habitats w...Soil nutrient heterogeneity is common in nature,but few studies have tested the effects of soil nutrient heterogeneity on plant productivity in natural communities.Such effects are of particular interest in habitats where heterogeneity may be increasing due to global warming,as in high-elevation grassland on the Qinghai-Tibetan Plateau.In a three-year study,we added N,P and K to 2 m×2 m plots in grassland to establish five homogeneous and six heterogeneous treatments that varied in patch size,patch contrast(difference in nutrient levels between patches),and number of patch types(with different nutrient levels).We measured aboveground biomass of grasses,other graminoids,legumes and forbs.Biomass of grasses was higher(over 300 g m^(-2))and that of legumes was lower(about 25 g m^(-2))at higher nutrient availability in homogeneous treatments.Within heterogeneous plots,grasses similarly had about 25%higher biomass and legumes had about 60%lower biomass in patches with higher nutrients,mainly at the larger patch size and sometimes more so when patch contrast was greater.Accounting for 47%-61%of the total aboveground biomass,grasses showed a roughly similar pattern to that of the whole community.An increase in soil nutrient heterogeneity is unlikely to affect plant aboveground biomass in this grassland,although it can increase biomass of grasses and decrease that of legumes.Soil nutrient heterogeneity might partly mitigate these effects if large patches without elevated nutrients persist.展开更多
基金This research was supported by the Fundamental Research Funds for the Central Universities(TD-JC-2013-1)the National Natural Science Foundation of China(31570413,31500331).
文摘Aims Clonal plant species have the potential for high relative performance in heterogeneous environments,and this might increase the com-petitive ability and invasiveness of introduced clonal plant species.It was hypothesized that clonal species whose performance responds more to heterogeneity of a resource have higher competitive ability in habitats where this resource is more heterogeneous and that this relationship is stronger when other resources are less limiting.Methods To test these hypotheses,the perennial clonal herb Alternanthera philoxeroides,which is invasive in China,was grown alone or with each of four clonal perennial,co-occurring herbs native to China,i.e.Alternanthera sessilis,Cynodon dactylon,Hemarthria altissima and Wedelia chinensis.Plants were given homogeneous or het-erogeneous soil substrate crossed with low and high levels of soil moisture.Important Findings Effects of heterogeneity on the accumulation of mass and ramets and on competitive effect and response of A.philoxeroides differed between native species and interacted with effects of soil moisture.A.philoxeroides reduced the final total mass or ramet number of the native species except A.sessilis,and the negative competitive effects on H.altissima and C.dactylon were more pronounced in heterogeneous than in homogeneous soil.Competitive response of A.philoxeroides was more negative to A.sessilis than to the other native species.Across native species,the competitive response of A.philoxeroides was more negative in heterogeneous than in homo-geneous soils at low moisture level,but the reverse was true at high moisture level.Results do not consistently support either hypoth-esis,but do suggest that competitive ability can be partly explained by individual species traits such as size,and that some competi-tive effects and responses are emergent properties of interspecific interactions.
基金This work was supported by the Spanish Ministry of Economy and Competitiveness(Grant CGL2013-44519-R to S.R.R.).
文摘Aims Clonal growth is associated with invasiveness in introduced plant species,but few studies have compared invasive and noninvasive introduced clonal species to investigate which clonal traits may underlie invasiveness.To test the hypothesis that greater capacity to increase clonal growth via physiological integration of connected ramets increases invasiveness in clonal plants,we compared the effects of severing connections on accumulation of mass in the two species of the creeping,succulent,perennial,herbaceous genus Carpobrotus that have been introduced on sand dunes along the Pacific Coast of northern California,the highly invasive species Carpobrotus edulis and the co-occurring,noninvasive species Carpobrotus chilensis.Methods Pairs of ramets from four mixed populations of the species from California were grown in a common garden for 3 months with and without severing the stem connecting the ramets.To simulate the effect of clones on soils in natural populations,the older ramet was grown in sand amended with potting compost and the younger in sand alone.Important Findings Severance decreased net growth in mass by~60%in C.edulis and~100%in C.chilensis,due mainly to the negative effect of severance on the shoot mass of the younger ramet within a pair.Contrary to the hypothesis,this suggests that physiological integration increases growth more in the less invasive species.However,severance also decreased allocation of mass to roots in the older ramet and increased it in the younger ramet in a pair,and the effect on the younger ramet was about twice as great in C.edulis as in C.chilensis.This indicates that the more invasive species shows greater phenotypic plasticity in response to physiological integration,in particular greater capacity for division of labor.This could contribute to greater long-term growth and suggests that the division of labor may be a trait that underlies the association between clonal growth and invasiveness in plants.
基金supported by the National Natural Science Foundation of China(31761123001,31870610)the Joint Fund of the Zhejiang Provincial Natural Science Foundation(LTZ20C030001)the Ten Thousand Talent Program of Zhejiang Province(2018R52016).
文摘Aims Many wetlands are polluted with both nutrients and toxic metals and vegetated largely by clonal plants.We hypothesized that eutrophication and clonal integration can increase phytoremediation of toxic metal pollution by increasing plant growth,even under the stress imposed by toxicity.Methods To test this hypothesis,single ramets of the common,widespread,floating,stoloniferous plant Pistia stratiotes L.,were grown for 42 days at two levels of nutrient availability with and without 0.6 mg L^(-1) cadmium.Ramets were either severed from their vegetative offspring to prevent clonal integration or left connected,and severed offspring were either removed to eliminate intraclonal competition or left in place.Important Findings Plants subjected to cadmium addition accumulated almost twice as much dry mass if given the higher nutrient level,due mainly to a doubling of the number of clonal offspring.Severance had little effect on the final mass of the parent plus offspring ramets.Removing offspring following severance had no effect on the final mass of the parental ramet in the presence of added cadmium,but it did increase the final mass of the parent in the absence of cadmium.These results support the hypothesis that eutrophication can increase remediation of toxic metal pollution by aquatic macrophytes but provided no evidence that clonal integration can affect remediation.Species such as P.stratiotes may help remediate co-pollution of wetlands with toxic metals and nutrients,and fragmentation of clones may not affect their remediation capacity.
基金Funding Spanish Ministry of Economy and Competitiveness(Grant CGL2013-44519-R,co-financed by the European Regional Development Fund,to S.R.R.)and CSIRO Julius Career Award(to B.L.W.).
基金supported by the National Natural Science Foundation of China(31261120580).
文摘Aims Fruit color polymorphisms are widespread in plants,but what maintains them is largely unclear.One hypothesis is that some morphs are preferred by dispersers while others have higher pre-or postdispersal fitness.This leads to the prediction that fruit color morphs will differ in pre-or postdispersal fitness.Methods We compared genetic and clonal diversity,mating system,morphological traits that might be associated with resistance to freezing,and germination,survival and seed production of progeny of the red and white fruit morphs in a population of a diploid,wild strawberry,Fragaria pentaphylla,from south-central China.Important Findings The red morph was much more abundant than the white but did not show higher genetic diversity as measured by observed and effective numbers of alleles,Shannon information index,or expected or observed heterozygosities.AMOVA showed that most of the genetic variation in the population was within rather than between morphs.Morphs did not differ in mating system parameters,and no significant biparental inbreeding was found in either morph.Gene flow between two morphs was high(N_(m)=6.89).Seeds of the red morph germinated about 2 days earlier and had a 40%higher rate of germination than those of the white morph,but survival of seedlings and seed production by surviving offspring did not differ between morphs.The whole postdispersal fitness of the red morph was about two times higher than that of the white morph.Red morphs had hairier petioles but not more surface wax on leaves.Overall,results showed partial evidence for difference in pre-and postdispersal fitness between fruit color morphs in F.pentaphylla.Differences in fitness independent of dispersal may thus partially account for fruit color polymorphism in all cases.
基金supported by the National Natural Science Foundation of China(grants 32301322,32371664,and 32101261)。
文摘Soil nutrient heterogeneity is common in nature,but few studies have tested the effects of soil nutrient heterogeneity on plant productivity in natural communities.Such effects are of particular interest in habitats where heterogeneity may be increasing due to global warming,as in high-elevation grassland on the Qinghai-Tibetan Plateau.In a three-year study,we added N,P and K to 2 m×2 m plots in grassland to establish five homogeneous and six heterogeneous treatments that varied in patch size,patch contrast(difference in nutrient levels between patches),and number of patch types(with different nutrient levels).We measured aboveground biomass of grasses,other graminoids,legumes and forbs.Biomass of grasses was higher(over 300 g m^(-2))and that of legumes was lower(about 25 g m^(-2))at higher nutrient availability in homogeneous treatments.Within heterogeneous plots,grasses similarly had about 25%higher biomass and legumes had about 60%lower biomass in patches with higher nutrients,mainly at the larger patch size and sometimes more so when patch contrast was greater.Accounting for 47%-61%of the total aboveground biomass,grasses showed a roughly similar pattern to that of the whole community.An increase in soil nutrient heterogeneity is unlikely to affect plant aboveground biomass in this grassland,although it can increase biomass of grasses and decrease that of legumes.Soil nutrient heterogeneity might partly mitigate these effects if large patches without elevated nutrients persist.
