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
Tall clonal grasses commonly display competitive advantages with nitrogen(N)enrichment.However,it is currently unknown whether the height is derived from the vegetative or reproductive module.Moreover,it is unclear wh...Tall clonal grasses commonly display competitive advantages with nitrogen(N)enrichment.However,it is currently unknown whether the height is derived from the vegetative or reproductive module.Moreover,it is unclear whether the height of the vegetative or reproductive system regulates the probability of extinction and colonization,and determines species diversity.In this study,the impacts on clonal grasses were studied in a field experiment employing two frequencies(twice a year vs.monthly)crossing with nine N addition rates in a temperate grassland,China.We found that the N addition decreased species frequency and increased extinction probability,but did not change the species colonization probability.A low frequency of N addition decreased species frequency and colonization probability,but increased extinction probability.Moreover,we found that species reproductive height was the best index to predict the extinction probability of clonal grasses in N-enriched conditions.The low frequency of N addition may overestimate the negative effect from N deposition on clonal grass diversity,suggesting that a higher frequency of N addition is more suitable in assessing the ecological effects of N deposition.Overall,this study illustrates that reproductive height was associated with the clonal species extinction probability under N-enriched environment.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supported by a grant from the National Natural Science Foundation of China(grant no.32071603 and 32122055)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA26020101)。
文摘Tall clonal grasses commonly display competitive advantages with nitrogen(N)enrichment.However,it is currently unknown whether the height is derived from the vegetative or reproductive module.Moreover,it is unclear whether the height of the vegetative or reproductive system regulates the probability of extinction and colonization,and determines species diversity.In this study,the impacts on clonal grasses were studied in a field experiment employing two frequencies(twice a year vs.monthly)crossing with nine N addition rates in a temperate grassland,China.We found that the N addition decreased species frequency and increased extinction probability,but did not change the species colonization probability.A low frequency of N addition decreased species frequency and colonization probability,but increased extinction probability.Moreover,we found that species reproductive height was the best index to predict the extinction probability of clonal grasses in N-enriched conditions.The low frequency of N addition may overestimate the negative effect from N deposition on clonal grass diversity,suggesting that a higher frequency of N addition is more suitable in assessing the ecological effects of N deposition.Overall,this study illustrates that reproductive height was associated with the clonal species extinction probability under N-enriched environment.
