Aims Theories based on resource additions indicate that plant species richness is mainly determined by the number of limiting resources.However,the individual effects of various limiting resources on species richness ...Aims Theories based on resource additions indicate that plant species richness is mainly determined by the number of limiting resources.However,the individual effects of various limiting resources on species richness and aboveground net primary productivity(ANPP)are less well understood.Here,we analyzed potential linkages between additions of limiting resources,species loss and ANPP increase and further explored the underlying mechanisms.Methods Resources(N,P,K and water)were added in a completely randomized block design to alpine meadow plots in the Qinghai-Tibetan Plateau.Plant aboveground biomass,species composition,mean plant height and light availability were measured in each plot.Regression and analysis of variance were used to analyze the responses of these measures to the different resource-addition treatments.Important Findings Species richness decreased with increasing number of added limiting resources,suggesting that plant diversity was apparently determined by the number of limiting resources.Nitrogen was the most important limiting resource affecting species richness,whereas Pand K alone had negligible effects.The largest reduction in species richness occurred when all three elements were added in combination.Water played a different role compared with the other limiting resources.Species richness increased when water was added to the treatments with N and P or with N,P and K.The decreases in species richness after resource additions were paralleled by increases in ANPP and decreases in light penetration into the plant canopy,suggesting that increased light competitionwas responsible for the negative effects of resource additions on plant species richness.展开更多
Aims The prediction that facilitation is the dominant interaction in physically stressful conditions has been supported by many but not all field studies.In the present paper,we tested the effects of the identity of s...Aims The prediction that facilitation is the dominant interaction in physically stressful conditions has been supported by many but not all field studies.In the present paper,we tested the effects of the identity of species,the local environmental conditions and the currencies of performance measurement on such variation.Methods Using contrasting two plots,six species,and up to five multiple traits,we comprehensively explored the effects of the above factors on the assessment of plant interactions in an alpine meadow of the QingHai Tibetan Plateau.Additionally,we attempted to figure out the possible mechanisms underlying the responses observed.The data were analysed by both standard ANOVAs and multivariate statistics.Important findings Our results demonstrated that the response to the removal of neighbours was both species and trait specific,and the effect of the ocal environmental conditions was dependent on the species involved.The contrast between plots had crucial influence on the net interactions of Kobresia macrantha,but little effect on Elymus nutans.Regarding the abiotic conditions,neighbours had significant impact on soil temperature,moist and solar radiation.The results contribute to advance our knowledge on the potential underlying factors influencing the assessment of facilitation.展开更多
基金National Natural Science Foundation of China(30970465)Research Station of Alpine Meadow and Wetland Ecosystems of Lanzhou University.
文摘Aims Theories based on resource additions indicate that plant species richness is mainly determined by the number of limiting resources.However,the individual effects of various limiting resources on species richness and aboveground net primary productivity(ANPP)are less well understood.Here,we analyzed potential linkages between additions of limiting resources,species loss and ANPP increase and further explored the underlying mechanisms.Methods Resources(N,P,K and water)were added in a completely randomized block design to alpine meadow plots in the Qinghai-Tibetan Plateau.Plant aboveground biomass,species composition,mean plant height and light availability were measured in each plot.Regression and analysis of variance were used to analyze the responses of these measures to the different resource-addition treatments.Important Findings Species richness decreased with increasing number of added limiting resources,suggesting that plant diversity was apparently determined by the number of limiting resources.Nitrogen was the most important limiting resource affecting species richness,whereas Pand K alone had negligible effects.The largest reduction in species richness occurred when all three elements were added in combination.Water played a different role compared with the other limiting resources.Species richness increased when water was added to the treatments with N and P or with N,P and K.The decreases in species richness after resource additions were paralleled by increases in ANPP and decreases in light penetration into the plant canopy,suggesting that increased light competitionwas responsible for the negative effects of resource additions on plant species richness.
基金National Natural Science Foundation of China(30770360)Research Fund for the Doctoral Program of Higher Education of China(20070730051 to S.X.).
文摘Aims The prediction that facilitation is the dominant interaction in physically stressful conditions has been supported by many but not all field studies.In the present paper,we tested the effects of the identity of species,the local environmental conditions and the currencies of performance measurement on such variation.Methods Using contrasting two plots,six species,and up to five multiple traits,we comprehensively explored the effects of the above factors on the assessment of plant interactions in an alpine meadow of the QingHai Tibetan Plateau.Additionally,we attempted to figure out the possible mechanisms underlying the responses observed.The data were analysed by both standard ANOVAs and multivariate statistics.Important findings Our results demonstrated that the response to the removal of neighbours was both species and trait specific,and the effect of the ocal environmental conditions was dependent on the species involved.The contrast between plots had crucial influence on the net interactions of Kobresia macrantha,but little effect on Elymus nutans.Regarding the abiotic conditions,neighbours had significant impact on soil temperature,moist and solar radiation.The results contribute to advance our knowledge on the potential underlying factors influencing the assessment of facilitation.
