群落净生产力(Net Community Production,NCP)代表了总初级生产力与群落呼吸的差值,是衡量生物活动对上层海洋碳循环影响的重要指标。O_(2)/Ar比值消除了物理过程对海水中溶解氧(O_(2))饱和度的影响,因此基于生物氧饱和度(ΔO_(2)/Ar)...群落净生产力(Net Community Production,NCP)代表了总初级生产力与群落呼吸的差值,是衡量生物活动对上层海洋碳循环影响的重要指标。O_(2)/Ar比值消除了物理过程对海水中溶解氧(O_(2))饱和度的影响,因此基于生物氧饱和度(ΔO_(2)/Ar)可以估算海洋混合层群落净生产力。本研究于2015年10月,首次利用膜进样质谱法走航获取了黄东海表层海水中高分辨率O_(2)/Ar数据,并估算了其NCP,探讨了其分布特征及影响因素。本航次观测到的Δ(O_(2)/Ar)范围为-30.21%~44.38%,平均值为(0.32±8.29)%,低值主要出现在长江口北侧,而长江口(11.75±13.75)%和浙闽沿岸(5.42±5.21)%的Δ(O_(2)/Ar)明显高于南黄海(-2.62±5.96)%和东海陆架区(-0.79±5.02)%。南黄海和东海陆架区平均NCP为(-9.24±23.15)和(-4.04±18.68)mmol·m^(-2)·d^(-1),总体表现为异养状态,而长江口和浙闽近岸NCP均值分别为(24.49±35.74)和(10.85±12.17)mmol·m^(-2)·d^(-1)。东、黄海NCP的空间分布格局主要受到陆源输入和水团混合的影响,营养盐和光照也是秋季影响NCP分布的重要因素。本研究有助于深入认识高度动态的东、黄海碳循环过程及控制机制。展开更多
Aims Seasonal variations in species richness,aboveground net primary productivity(ANPP)and stability under resource enrichment are frequently ignored.This study explores how the impacts of resource enrichment on speci...Aims Seasonal variations in species richness,aboveground net primary productivity(ANPP)and stability under resource enrichment are frequently ignored.This study explores how the impacts of resource enrichment on species richness,ANPP and stability vary among seasons in semi-arid grasslands.Methods We conducted a 3-year experiment in an Inner Mongolia grassland to determine the effects of resource input(water[W],nitrogen[N])on species richness,community ANPP and stability using seasonal sampling during the growing season(2013–2015).Structural equation modeling(SEM)was used to examine the relative importance of resource input on community stability via mechanistic pathways in each month and the whole growing season.Important Findings Resource inputs did not affect community ANPP in May and June,while N and/or NW enhanced ANPP in July and August.Resource inputs generally did not affect species richness,asynchrony or community stability in most of the time.Positive responses of perennial bunchgrasses(PB)to N and/or NW treatments contributed to the increased community ANPP in July and August.Species asynchrony may be the major mechanism contributing to community stability in May and June and the entire growing season,and PB stability is potentially the primary factor controlling community stability in July and August under resource enrichment.Our results indicate that season and resource availability could interact to regulate species richness,community ANPP and stability in semi-arid grasslands.These findings have important implications for management practices in semi-arid grasslands in order to mitigate the impact of land use and global change.展开更多
Aims Water and nitrogen(N)are two key resources in dryland ecosystems,but they may have complex interactive effects on the community structure and ecosystem functions.How future precipitation(rainfall vs snowfall)chan...Aims Water and nitrogen(N)are two key resources in dryland ecosystems,but they may have complex interactive effects on the community structure and ecosystem functions.How future precipitation(rainfall vs snowfall)change will impact aboveground net primary production(ANPP)is far from clear,especially when combined with increasing N availability.Methods In this study,we investigated changes in community productivity,abundance and aboveground biomass of two dominant plant functional groups(PFGs),i.e.perennial rhizome grasses(PR)and perennial bunchgrasses(PB)under the impacts of increased precipitation(rainfall vs snowfall)combined with N addition in a semiarid temperate steppe.Important Findings Summer rainfall augmentation marginally increased community ANPP,whereas it significantly increased the abundance and aboveground biomass of PR,but not those of PB.Summer rainfall addition increased the fraction of PR biomass(fPR)while decreased that of PB(fPB).Spring snow addition had no effect on aboveground biomass of either compositional PFG although it marginally increased community ANPP.Nitrogen addition significantly increased community ANPP with greater increase in PR under summer rainfall addition,indicating strong interactive effects on community ANPP largely by enhancing PR biomass.We also found a nonlinear increase in the positive effect of nitrogen addition on productivity with the increased precipitation amount.These findings indicate an amplified impact of precipitation increase on grassland productivity under the accelerated atmospheric N deposition in the future.展开更多
文摘群落净生产力(Net Community Production,NCP)代表了总初级生产力与群落呼吸的差值,是衡量生物活动对上层海洋碳循环影响的重要指标。O_(2)/Ar比值消除了物理过程对海水中溶解氧(O_(2))饱和度的影响,因此基于生物氧饱和度(ΔO_(2)/Ar)可以估算海洋混合层群落净生产力。本研究于2015年10月,首次利用膜进样质谱法走航获取了黄东海表层海水中高分辨率O_(2)/Ar数据,并估算了其NCP,探讨了其分布特征及影响因素。本航次观测到的Δ(O_(2)/Ar)范围为-30.21%~44.38%,平均值为(0.32±8.29)%,低值主要出现在长江口北侧,而长江口(11.75±13.75)%和浙闽沿岸(5.42±5.21)%的Δ(O_(2)/Ar)明显高于南黄海(-2.62±5.96)%和东海陆架区(-0.79±5.02)%。南黄海和东海陆架区平均NCP为(-9.24±23.15)和(-4.04±18.68)mmol·m^(-2)·d^(-1),总体表现为异养状态,而长江口和浙闽近岸NCP均值分别为(24.49±35.74)和(10.85±12.17)mmol·m^(-2)·d^(-1)。东、黄海NCP的空间分布格局主要受到陆源输入和水团混合的影响,营养盐和光照也是秋季影响NCP分布的重要因素。本研究有助于深入认识高度动态的东、黄海碳循环过程及控制机制。
基金This work was supported by the National Natural Science Foundation of China(31630010 and 31320103916).
文摘Aims Seasonal variations in species richness,aboveground net primary productivity(ANPP)and stability under resource enrichment are frequently ignored.This study explores how the impacts of resource enrichment on species richness,ANPP and stability vary among seasons in semi-arid grasslands.Methods We conducted a 3-year experiment in an Inner Mongolia grassland to determine the effects of resource input(water[W],nitrogen[N])on species richness,community ANPP and stability using seasonal sampling during the growing season(2013–2015).Structural equation modeling(SEM)was used to examine the relative importance of resource input on community stability via mechanistic pathways in each month and the whole growing season.Important Findings Resource inputs did not affect community ANPP in May and June,while N and/or NW enhanced ANPP in July and August.Resource inputs generally did not affect species richness,asynchrony or community stability in most of the time.Positive responses of perennial bunchgrasses(PB)to N and/or NW treatments contributed to the increased community ANPP in July and August.Species asynchrony may be the major mechanism contributing to community stability in May and June and the entire growing season,and PB stability is potentially the primary factor controlling community stability in July and August under resource enrichment.Our results indicate that season and resource availability could interact to regulate species richness,community ANPP and stability in semi-arid grasslands.These findings have important implications for management practices in semi-arid grasslands in order to mitigate the impact of land use and global change.
基金X.Z.was supported by Youth Program of the National Natural Science Foundation of China(31800381)This study was financially supported by projects from the National Natural Science Foundation of China(32071562)a Strategic Priority Research Programon Soil and Microbes of the Chinese Academy of Sciences(XDB15010401).
文摘Aims Water and nitrogen(N)are two key resources in dryland ecosystems,but they may have complex interactive effects on the community structure and ecosystem functions.How future precipitation(rainfall vs snowfall)change will impact aboveground net primary production(ANPP)is far from clear,especially when combined with increasing N availability.Methods In this study,we investigated changes in community productivity,abundance and aboveground biomass of two dominant plant functional groups(PFGs),i.e.perennial rhizome grasses(PR)and perennial bunchgrasses(PB)under the impacts of increased precipitation(rainfall vs snowfall)combined with N addition in a semiarid temperate steppe.Important Findings Summer rainfall augmentation marginally increased community ANPP,whereas it significantly increased the abundance and aboveground biomass of PR,but not those of PB.Summer rainfall addition increased the fraction of PR biomass(fPR)while decreased that of PB(fPB).Spring snow addition had no effect on aboveground biomass of either compositional PFG although it marginally increased community ANPP.Nitrogen addition significantly increased community ANPP with greater increase in PR under summer rainfall addition,indicating strong interactive effects on community ANPP largely by enhancing PR biomass.We also found a nonlinear increase in the positive effect of nitrogen addition on productivity with the increased precipitation amount.These findings indicate an amplified impact of precipitation increase on grassland productivity under the accelerated atmospheric N deposition in the future.
