Water and nitrogen (N) inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influen...Water and nitrogen (N) inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influencing biodiversity and ecosystem function.Snowfall is a form of precipitation in winter,and snow melting can recharge soil water and result in a flourish of ephemerals during springtime in the Gurbantunggut Desert,China.A bi-factor experiment was designed and deployed during the snow-covering season from 2009 to 2010.The experiment aimed to explore the effects of different snow-covering depths and N addition levels on ephemerals.Findings indicated that deeper snow cover led to the increases in water content in topsoil as well as density and coverage of ephemeral plants in the same N treatment; by contrast,N addition sharply decreased the density of ephemerals in the same snow treatment.Meanwhile,N addition exhibited a different effect on the growth of ephemeral plants:in the 50% snow treatment,N addition limited the growth of ephemeral plants,showing that the height and the aboveground biomass of the ephemeral plants were lower than in those without N addition; while with the increases in snow depth (100% and 150% snow treatments),N addition benefited the growth of the dominant individual plants.Species richness was not significantly affected by snow in the same N treatment.However,N addition significantly decreased the species richness in the same snow-covering depth.The primary productivity of ephemerals in the N addition increased with the increase of snow depth.These variations indicated that the effect of N on the growth of ephemerals was restricted by water supply.With plenty of water (100% and 150% snow treatments),N addition contributed to the growth of ephemeral plants; while with less water (50% snow treatment),N addition restricted the growth of ephemeral plants.展开更多
Rapid spread and growth of plants that are poisonous to animals produce large amounts of plant litter in degraded grasslands.Nitrogen(N)input may promote the growth of these poisonous plants and alter the rhizosphere ...Rapid spread and growth of plants that are poisonous to animals produce large amounts of plant litter in degraded grasslands.Nitrogen(N)input may promote the growth of these poisonous plants and alter the rhizosphere microbes and arbuscular mycorrhizal fungi(AMF)in particular.However,it is unclear how poisonous plant litter affects the growth of palatable plants and their associated AMF in the rhizosphere and whether and how N deposition may mediate these effects.A greenhouse experiment was performed to test the combined effects of litter addition of a poisonous plant,Stellera chamaejasme,and N addition on the growth of a dominant grass,Leymus chinensis,AMF characteristics and soil properties.Litter addition significantly increased the ramet number and aboveground biomass of L.chinensis and soil available phosphorus(AP)concentration and decreased the spore density of AMF.However,the interaction of both treatments had no significant effects on traits of L.chinensis and AMF properties.Stellera chamaejasme liter positively affected L.chinensis by increasing AP and negatively affected AMF by combining balanced changes in soil nutrients and litter-induced allelopathic compositions.High N addition may alleviate soil N limitation and inhibit litter decomposition,thus overriding the litter's effects on L.chinensis and AMF.These findings imply that it is necessary to objectively and comprehensively evaluate the ecological functions of poisonous plants beyond their harmful effects on livestock.Simultaneously,N deposition should be an indispensable factor in predicting the relationships between poisonous plants and edible plants indegraded grasslands.展开更多
基金funded by the National Basic Research Program of China(2009CB825102)the National Basic Research Program of China(2009CB421102E)+1 种基金the International Science & Technology Cooperation Program of China(2010DFA92720)the Natural Science Foundation of China(4117049)
文摘Water and nitrogen (N) inputs are considered as the two main limiting factors affecting plant growth.Changes in these inputs are expected to alter the structure and composition of the plant community,thereby influencing biodiversity and ecosystem function.Snowfall is a form of precipitation in winter,and snow melting can recharge soil water and result in a flourish of ephemerals during springtime in the Gurbantunggut Desert,China.A bi-factor experiment was designed and deployed during the snow-covering season from 2009 to 2010.The experiment aimed to explore the effects of different snow-covering depths and N addition levels on ephemerals.Findings indicated that deeper snow cover led to the increases in water content in topsoil as well as density and coverage of ephemeral plants in the same N treatment; by contrast,N addition sharply decreased the density of ephemerals in the same snow treatment.Meanwhile,N addition exhibited a different effect on the growth of ephemeral plants:in the 50% snow treatment,N addition limited the growth of ephemeral plants,showing that the height and the aboveground biomass of the ephemeral plants were lower than in those without N addition; while with the increases in snow depth (100% and 150% snow treatments),N addition benefited the growth of the dominant individual plants.Species richness was not significantly affected by snow in the same N treatment.However,N addition significantly decreased the species richness in the same snow-covering depth.The primary productivity of ephemerals in the N addition increased with the increase of snow depth.These variations indicated that the effect of N on the growth of ephemerals was restricted by water supply.With plenty of water (100% and 150% snow treatments),N addition contributed to the growth of ephemeral plants; while with less water (50% snow treatment),N addition restricted the growth of ephemeral plants.
基金National Natural Science Foundation of China(31570452,31670524).
文摘Rapid spread and growth of plants that are poisonous to animals produce large amounts of plant litter in degraded grasslands.Nitrogen(N)input may promote the growth of these poisonous plants and alter the rhizosphere microbes and arbuscular mycorrhizal fungi(AMF)in particular.However,it is unclear how poisonous plant litter affects the growth of palatable plants and their associated AMF in the rhizosphere and whether and how N deposition may mediate these effects.A greenhouse experiment was performed to test the combined effects of litter addition of a poisonous plant,Stellera chamaejasme,and N addition on the growth of a dominant grass,Leymus chinensis,AMF characteristics and soil properties.Litter addition significantly increased the ramet number and aboveground biomass of L.chinensis and soil available phosphorus(AP)concentration and decreased the spore density of AMF.However,the interaction of both treatments had no significant effects on traits of L.chinensis and AMF properties.Stellera chamaejasme liter positively affected L.chinensis by increasing AP and negatively affected AMF by combining balanced changes in soil nutrients and litter-induced allelopathic compositions.High N addition may alleviate soil N limitation and inhibit litter decomposition,thus overriding the litter's effects on L.chinensis and AMF.These findings imply that it is necessary to objectively and comprehensively evaluate the ecological functions of poisonous plants beyond their harmful effects on livestock.Simultaneously,N deposition should be an indispensable factor in predicting the relationships between poisonous plants and edible plants indegraded grasslands.