Increased nitrogen （N） deposition will often lead to a decline in species richness in grassland ecosystems but the shifts in functional groups and plant traits are still poorly understood in China. A field experimen...Increased nitrogen （N） deposition will often lead to a decline in species richness in grassland ecosystems but the shifts in functional groups and plant traits are still poorly understood in China. A field experiment was conducted at Duolun, Inner Mongolia, China, to investigate the effects of N addition on a temperate steppe ecosystem. Six N levels （0, 3, 6, 12, 24, and 48 g N/（m2-a）） were added as three applications per year from 2005 to 2010. Enhanced N deposition, even as little as 3 g N/（m2.a） above ambient N deposition （1.2 g N/（m2.a））, led to a decline in species richness of the whole community. Increasing N addition can significantly stimulate aboveground biomass of perennial bunchgrasses （PB） but decrease perennial forbs （PF）, and induce a slight change in the biomass of shrubs and semi-shrubs （SS）. The biomass of annuals （AS） and perennial rhizome grasses （PR） accounts for only a small part of the total biomass. Species richness of PF decreased significantly with increasing N addition rate but there was a little change in the other functional groups. PB, as the dominant functional group, has a relatively higher height than others. Differences in the response of each functional group to N addition have site-specific and species-specific characteristics. We initially infer that N enrichment stimulated the growth of PB, which further suppressed the growth of other functional groups.展开更多
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
Aims With the global atmospheric nitrogen(N)deposition increasing,the effect of N deposition on terrestrial plant diversity has been widely studied.Some studies have reviewed the effects of N deposition on plant speci...Aims With the global atmospheric nitrogen(N)deposition increasing,the effect of N deposition on terrestrial plant diversity has been widely studied.Some studies have reviewed the effects of N deposition on plant species diversity;however,all studies addressed the effects of N deposition on plant community focused on species richness in specific ecosystem.There is a need for a systematic meta-analysis covering multiple dimensions of plant diversity in multiple climate zones and ecosystems types.Our goal was to quantify changes in species richness,evenness and uncertainty in plant communities in response to N addition across different environmental and experimental contexts.Methods We performed a meta-analysis of 623 experimental records published in English and Chinese journals to evaluate the response of terrestrial plant diversity to the experimental N addition in China.Three metrics were used to quantify the change in plant diversity:species richness(SR),evenness(Pielou index)uncertainty(Shannon index).Important Findings Results showed that(i)N addition negatively affected SR in temperate,Plateau zones and subtropical zone,but had no significant effect on Shannon index in subtropical zones;(ii)N addition decreased SR,Shannon index and Pielou index in grassland,and the negative effect of N addition on SR was stronger in forest than in grassland;(iii)N addition negatively affected plant diversity(SR,Shannon index and Pielou index)in the long term,whereas it did not affect plant diversity in the short term.Furthermore,the increase in N addition levels strengthened the negative effect of N deposition on plant diversity with long experiment duration;and(iv)the negative effect of ammonium nitrate(NH_(4)NO_(3))addition on SR was stronger than that of urea(CO(NH_(2))_(2))addition,but the negative effect of NH_(4)NO_(3) addition on Pielou index was weaker than that of CO(NH2)2 addition.Our results indicated that the effects of N addition on plant diversity varied depending on climate zones,ecosystem types,N addition lev展开更多
Aims Global change factors(e.g.warming and nitrogen deposition)may influence biological invasions,but how these factors may influence the performance of invasive species and further mediate the interactions with nativ...Aims Global change factors(e.g.warming and nitrogen deposition)may influence biological invasions,but how these factors may influence the performance of invasive species and further mediate the interactions with native competitors remain still unknown.Methods Here,we conducted a 5-month greenhouse experiment to examine the effects of warming(using open-top chambers,+0.62°C)and N addition(adding NH4NO3 at a rate of 4.2 g m−2)on the performance of the native and invasive populations of an invasive species Plantago virginica in competition with a native Plantago asiatica.Important Findings Under warming treatment and its interaction with nitrogen addition treatment(W×N),invasive and native populations of P.virginica had different biomass allocation strategies to compete with native competitor P.asiatica.Native population of P.virginica(PV-Na)increased more below-ground biomass,whereas those from the invasive population(PV-In)increased more above-ground biomass.We also found that invasive species P.virginica had stronger responses to warming and N addition than the native species P.asiatica.The competitive ability of the invasive plants was significantly reduced by warming which indicated that the invasive plant were much stronger sensitivity to elevated temperature than native plant.Similarly,N addition and W×N reduced the competitive response of PV-In in below-ground biomass,but increased the competitive response of PV-Na in above-ground and total biomass when they grew with the P.asiatica.The results show that P.virginica have occurred differential biomass allocation strategies during its invasions and invasive population exhibit flexible competition ability to adapt to environmental changes(especially warming).These findings may potentially help to predict plant invasions and make management strategies in a world with changing climate.展开更多
Aims We aimed to evaluate the changes in water-use efficiency(WuE)in native tree species in forests of subtropical China,and determine how coexisting species would be responding to increases in atmospheric carbon diox...Aims We aimed to evaluate the changes in water-use efficiency(WuE)in native tree species in forests of subtropical China,and determine how coexisting species would be responding to increases in atmospheric carbon dioxide(CO_(2))concentrations and nitrogen(N)deposition.Methods We used model forest ecosystems in open-top chambers to study the effects of elevated CO_(2)(ca.700μmol mol−1)alone and together with N addition(NH4No3 applied at 100 kg N ha−1year−1)on WuE of four native tree species(Schima superba,Ormosia pin-nata,Castanopsis hystrix and Acmena acuminatissima)from 2006 to 2010.Important findingsour result indicated that all species increased their WuE when they were exposed to elevated CO_(2).although higher WuE was shown in faster-growing species(S.superba and O.pinnata)than that of slower-growing species(C.hystrix and Acmena acuminatissima),the increased extent of WuE induced by elevated CO_(2) was higher in the slower-growing species than that of the faster-growing species(P<0.01).the N treatment decreased WuE of S.superba,while the effects on other species were not significant.the interactions between elevated CO_(2) and N addition increased intrinsic WuE of S.superba significantly(P<0.001),however,it did not affect WuE of the other tree species significantly.We conclude that the responses of native tree species to elevated CO_(2) and N addition are different in subtropical China.the species-specific effects of elevated CO_(2) and N addition on WuE would have important implications on species composition in China’s subtropics in response to global change.展开更多
【目的】明确树种属性和养分添加对亚热带森林粗木质残体分解养分含量及化学计量的影响,为森林养分管理和碳循环提供理论依据。【方法】在浙江天童野外观测研究站森林选取6种典型树种粗木质残体,通过开展野外氮(N)磷(P)添加试验,设置对...【目的】明确树种属性和养分添加对亚热带森林粗木质残体分解养分含量及化学计量的影响,为森林养分管理和碳循环提供理论依据。【方法】在浙江天童野外观测研究站森林选取6种典型树种粗木质残体,通过开展野外氮(N)磷(P)添加试验,设置对照(CK,蒸馏水)、氮添加(N,100 kg hm^(-2)a^(-1))、磷添加(P,15 kg hm^(-2)a^(-1))和氮+磷添加(N+P,N100 kg hm^(-2)a^(-1)+P15 kg hm^(-2)a^(-1))4种处理,测定粗木质残体分解初期(3年)N、P养分含量和生态化学计量比,分析树种属性和外源养分添加对粗木质残体养分含量和化学计量比的影响。【结果】与初始养分含量相比,分解三年后,CK处理的被子树种N、P含量显著增加,C/N显著降低,裸子树种P含量显著降低(P<0.05)。与CK相比,P和N+P添加处理显著增加了裸子树种P含量,增加幅度分别为57.29%和53.79%;N+P添加处理显著降低了裸子树种碳(C)含量、C/N、C/P,降低幅度分别为24.0%、30.58%和44.91%(P<0.05)。N+P添加处理对被子树种养分含量及化学计量比无显著影响。主成分分析表明,N+P添加处理对裸子树种C、N、P含量及其化学计量比的影响大于被子树种,P元素是影响粗木质残体养分及化学计量特征的主要因素。分解三年后粗木质残体的养分含量和初始密度显著正相关,而与初始C含量显著负相关。【结论】总体而言,由于粗木质残体养分含量和物理性质的差异,被子和裸子树种粗木质残体养分含量和化学计量比对氮磷添加的响应存在明显差异,其中初始养分含量较低的裸子树种粗木质残体养分含量及化学计量比受氮磷添加的影响较大。因此,未来研究气候变化(如氮磷沉降)对森林养分库和有机碳分解影响时应考虑粗木质残体树种属性的差异。展开更多
We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation...We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation（ACp）,10-species-mixed plantation（Tp）,and 30-species-mixed plantation（THp） using the static chamber method in southern China.Four forest management treatments,including（1） understory removal（UR）;（2） C.alata addition（CA）;（3） understory removal and replacement with C.alata（UR＋CA）;and（4） control without any disturbances（CK）,were applied in the above four forest plantations with three replications for each treatment.The results showed that soil CO2 fluxes rates remained at a high level during the rainy season（from April to September）,followed by a rapid decrease after October reaching a minimum in February.Soil CO2 fluxes were significantly higher（P 〈 0.01） in EUp（132.6 mg/（m2.hr）） and ACp（139.8 mg/（m2.hr）） than in Tp（94.0 mg/（m2.hr）） and THp（102.9 mg/（m2.hr））.Soil CO2 fluxes in UR and CA were significantly higher（P 〈 0.01） among the four treatments,with values of 105.7,120.4,133.6 and 112.2 mg/（m2.hr） for UR＋CA,UR,CA and CK,respectively.Soil CO2 fluxes were positively correlated with soil temperature（P 〈 0.01）,soil moisture（P 〈 0.01）,NO3？-N（P 〈 0.05）,and litterfall（P 〈 0.01）,indicating that all these factors might be important controlling variables for soil CO2 fluxes.This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.展开更多
基金supported by the One Hundred Person Project of Chinese Academy of Sciencesthe National Natural Science Foundation of China (40771188,41071151)+1 种基金the Innovative Group Grants from NSFC (30821003)the Sino-German project (DFG Research Training Group,GK1070)
文摘Increased nitrogen （N） deposition will often lead to a decline in species richness in grassland ecosystems but the shifts in functional groups and plant traits are still poorly understood in China. A field experiment was conducted at Duolun, Inner Mongolia, China, to investigate the effects of N addition on a temperate steppe ecosystem. Six N levels （0, 3, 6, 12, 24, and 48 g N/（m2-a）） were added as three applications per year from 2005 to 2010. Enhanced N deposition, even as little as 3 g N/（m2.a） above ambient N deposition （1.2 g N/（m2.a））, led to a decline in species richness of the whole community. Increasing N addition can significantly stimulate aboveground biomass of perennial bunchgrasses （PB） but decrease perennial forbs （PF）, and induce a slight change in the biomass of shrubs and semi-shrubs （SS）. The biomass of annuals （AS） and perennial rhizome grasses （PR） accounts for only a small part of the total biomass. Species richness of PF decreased significantly with increasing N addition rate but there was a little change in the other functional groups. PB, as the dominant functional group, has a relatively higher height than others. Differences in the response of each functional group to N addition have site-specific and species-specific characteristics. We initially infer that N enrichment stimulated the growth of PB, which further suppressed the growth of other functional groups.
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This study was funded by National Key R&D Program of China(2018YFC0507203)the National Natural Science Foundation of China(41471049)the Natural Science Foundation of Zhejiang Province(LQ18C030001).
文摘Aims With the global atmospheric nitrogen(N)deposition increasing,the effect of N deposition on terrestrial plant diversity has been widely studied.Some studies have reviewed the effects of N deposition on plant species diversity;however,all studies addressed the effects of N deposition on plant community focused on species richness in specific ecosystem.There is a need for a systematic meta-analysis covering multiple dimensions of plant diversity in multiple climate zones and ecosystems types.Our goal was to quantify changes in species richness,evenness and uncertainty in plant communities in response to N addition across different environmental and experimental contexts.Methods We performed a meta-analysis of 623 experimental records published in English and Chinese journals to evaluate the response of terrestrial plant diversity to the experimental N addition in China.Three metrics were used to quantify the change in plant diversity:species richness(SR),evenness(Pielou index)uncertainty(Shannon index).Important Findings Results showed that(i)N addition negatively affected SR in temperate,Plateau zones and subtropical zone,but had no significant effect on Shannon index in subtropical zones;(ii)N addition decreased SR,Shannon index and Pielou index in grassland,and the negative effect of N addition on SR was stronger in forest than in grassland;(iii)N addition negatively affected plant diversity(SR,Shannon index and Pielou index)in the long term,whereas it did not affect plant diversity in the short term.Furthermore,the increase in N addition levels strengthened the negative effect of N deposition on plant diversity with long experiment duration;and(iv)the negative effect of ammonium nitrate(NH_(4)NO_(3))addition on SR was stronger than that of urea(CO(NH_(2))_(2))addition,but the negative effect of NH_(4)NO_(3) addition on Pielou index was weaker than that of CO(NH2)2 addition.Our results indicated that the effects of N addition on plant diversity varied depending on climate zones,ecosystem types,N addition lev
基金supported by the National Key Research and Development Program of China(no.2017YFC1200105)Project of National Natural Science Foundation of China(no.31100298).
文摘Aims Global change factors(e.g.warming and nitrogen deposition)may influence biological invasions,but how these factors may influence the performance of invasive species and further mediate the interactions with native competitors remain still unknown.Methods Here,we conducted a 5-month greenhouse experiment to examine the effects of warming(using open-top chambers,+0.62°C)and N addition(adding NH4NO3 at a rate of 4.2 g m−2)on the performance of the native and invasive populations of an invasive species Plantago virginica in competition with a native Plantago asiatica.Important Findings Under warming treatment and its interaction with nitrogen addition treatment(W×N),invasive and native populations of P.virginica had different biomass allocation strategies to compete with native competitor P.asiatica.Native population of P.virginica(PV-Na)increased more below-ground biomass,whereas those from the invasive population(PV-In)increased more above-ground biomass.We also found that invasive species P.virginica had stronger responses to warming and N addition than the native species P.asiatica.The competitive ability of the invasive plants was significantly reduced by warming which indicated that the invasive plant were much stronger sensitivity to elevated temperature than native plant.Similarly,N addition and W×N reduced the competitive response of PV-In in below-ground biomass,but increased the competitive response of PV-Na in above-ground and total biomass when they grew with the P.asiatica.The results show that P.virginica have occurred differential biomass allocation strategies during its invasions and invasive population exhibit flexible competition ability to adapt to environmental changes(especially warming).These findings may potentially help to predict plant invasions and make management strategies in a world with changing climate.
基金South China Botanical Garden-Shanghai Institute of Plant Physiology&Ecology Joint Fund,Science and Technology Innovation Project of Guangdong Province Forestry(Grant No.2012KJCX019-02)the National Natural Science Foundation of China(Grant No.31370530).
文摘Aims We aimed to evaluate the changes in water-use efficiency(WuE)in native tree species in forests of subtropical China,and determine how coexisting species would be responding to increases in atmospheric carbon dioxide(CO_(2))concentrations and nitrogen(N)deposition.Methods We used model forest ecosystems in open-top chambers to study the effects of elevated CO_(2)(ca.700μmol mol−1)alone and together with N addition(NH4No3 applied at 100 kg N ha−1year−1)on WuE of four native tree species(Schima superba,Ormosia pin-nata,Castanopsis hystrix and Acmena acuminatissima)from 2006 to 2010.Important findingsour result indicated that all species increased their WuE when they were exposed to elevated CO_(2).although higher WuE was shown in faster-growing species(S.superba and O.pinnata)than that of slower-growing species(C.hystrix and Acmena acuminatissima),the increased extent of WuE induced by elevated CO_(2) was higher in the slower-growing species than that of the faster-growing species(P<0.01).the N treatment decreased WuE of S.superba,while the effects on other species were not significant.the interactions between elevated CO_(2) and N addition increased intrinsic WuE of S.superba significantly(P<0.001),however,it did not affect WuE of the other tree species significantly.We conclude that the responses of native tree species to elevated CO_(2) and N addition are different in subtropical China.the species-specific effects of elevated CO_(2) and N addition on WuE would have important implications on species composition in China’s subtropics in response to global change.
文摘【目的】明确树种属性和养分添加对亚热带森林粗木质残体分解养分含量及化学计量的影响,为森林养分管理和碳循环提供理论依据。【方法】在浙江天童野外观测研究站森林选取6种典型树种粗木质残体,通过开展野外氮(N)磷(P)添加试验,设置对照(CK,蒸馏水)、氮添加(N,100 kg hm^(-2)a^(-1))、磷添加(P,15 kg hm^(-2)a^(-1))和氮+磷添加(N+P,N100 kg hm^(-2)a^(-1)+P15 kg hm^(-2)a^(-1))4种处理,测定粗木质残体分解初期(3年)N、P养分含量和生态化学计量比,分析树种属性和外源养分添加对粗木质残体养分含量和化学计量比的影响。【结果】与初始养分含量相比,分解三年后,CK处理的被子树种N、P含量显著增加,C/N显著降低,裸子树种P含量显著降低(P<0.05)。与CK相比,P和N+P添加处理显著增加了裸子树种P含量,增加幅度分别为57.29%和53.79%;N+P添加处理显著降低了裸子树种碳(C)含量、C/N、C/P,降低幅度分别为24.0%、30.58%和44.91%(P<0.05)。N+P添加处理对被子树种养分含量及化学计量比无显著影响。主成分分析表明,N+P添加处理对裸子树种C、N、P含量及其化学计量比的影响大于被子树种,P元素是影响粗木质残体养分及化学计量特征的主要因素。分解三年后粗木质残体的养分含量和初始密度显著正相关,而与初始C含量显著负相关。【结论】总体而言,由于粗木质残体养分含量和物理性质的差异,被子和裸子树种粗木质残体养分含量和化学计量比对氮磷添加的响应存在明显差异,其中初始养分含量较低的裸子树种粗木质残体养分含量及化学计量比受氮磷添加的影响较大。因此,未来研究气候变化(如氮磷沉降)对森林养分库和有机碳分解影响时应考虑粗木质残体树种属性的差异。
基金supported by the National Natural Science Foundation of China (No. 30630015,30771704)
文摘We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation（ACp）,10-species-mixed plantation（Tp）,and 30-species-mixed plantation（THp） using the static chamber method in southern China.Four forest management treatments,including（1） understory removal（UR）;（2） C.alata addition（CA）;（3） understory removal and replacement with C.alata（UR＋CA）;and（4） control without any disturbances（CK）,were applied in the above four forest plantations with three replications for each treatment.The results showed that soil CO2 fluxes rates remained at a high level during the rainy season（from April to September）,followed by a rapid decrease after October reaching a minimum in February.Soil CO2 fluxes were significantly higher（P 〈 0.01） in EUp（132.6 mg/（m2.hr）） and ACp（139.8 mg/（m2.hr）） than in Tp（94.0 mg/（m2.hr）） and THp（102.9 mg/（m2.hr））.Soil CO2 fluxes in UR and CA were significantly higher（P 〈 0.01） among the four treatments,with values of 105.7,120.4,133.6 and 112.2 mg/（m2.hr） for UR＋CA,UR,CA and CK,respectively.Soil CO2 fluxes were positively correlated with soil temperature（P 〈 0.01）,soil moisture（P 〈 0.01）,NO3？-N（P 〈 0.05）,and litterfall（P 〈 0.01）,indicating that all these factors might be important controlling variables for soil CO2 fluxes.This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.
