Concurrent ground-level ozone(O_(3))pollution and anthropogenic nitrogen(N)deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnov...Concurrent ground-level ozone(O_(3))pollution and anthropogenic nitrogen(N)deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnover organs to O_(3) have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosystems.How elevated O_(3) levels impact fine root biomass and biochemistry remains to be resolved.This study was to assess poplar leaf and fine root biomass and biochemistry responses to five different levels of O_(3) pollution,while additionally examining whether four levels of soil N supplementation were sufficient to alter the impact of O_(3) on these two organs.Elevated O_(3) resulted in a more substantial reduction in fine root biomass than leafbiomass;relative to leaves,more biochemically-resistant components were present within fine root litter,which contained high concentrations of lignin,condensed tannins,and elevated C:N and lignin:N ratios that were associated with slower rates of litter decomposition.In contrast,leaves contained more labile components,including nonstructural carbohydrates and N,as well as a higher N:P ratio.Elevated O_(3) significantly reduced labile components and increased biochemically-resistant components in leaves,whereas they had minimal impact on fine root biochemistry.This suggests that O_(3) pollution has the potential to delay leaf litter decomposition and associated nutrient cycling.N addition largely failed to affect the impact of elevated O_(3) levels on leaves or fine root chemistry,suggesting that soil N supplementation is not a suitable approach to combating the impact of O_(3) pollution on key functional traits of poplars.These results indicate that the significant differences in the responses of leaves and fine roots to O_(3) pollution will result in marked changes in the relative belowground roles of these two litter sources within forest ecosystems,and such changes will independently of nitrogen load.展开更多
基金supported by the National Natural Science Foundation of China (Nos.31870458,41675153)the National Key Research and Development Program of China(No.2017YFE0127700).
文摘Concurrent ground-level ozone(O_(3))pollution and anthropogenic nitrogen(N)deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnover organs to O_(3) have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosystems.How elevated O_(3) levels impact fine root biomass and biochemistry remains to be resolved.This study was to assess poplar leaf and fine root biomass and biochemistry responses to five different levels of O_(3) pollution,while additionally examining whether four levels of soil N supplementation were sufficient to alter the impact of O_(3) on these two organs.Elevated O_(3) resulted in a more substantial reduction in fine root biomass than leafbiomass;relative to leaves,more biochemically-resistant components were present within fine root litter,which contained high concentrations of lignin,condensed tannins,and elevated C:N and lignin:N ratios that were associated with slower rates of litter decomposition.In contrast,leaves contained more labile components,including nonstructural carbohydrates and N,as well as a higher N:P ratio.Elevated O_(3) significantly reduced labile components and increased biochemically-resistant components in leaves,whereas they had minimal impact on fine root biochemistry.This suggests that O_(3) pollution has the potential to delay leaf litter decomposition and associated nutrient cycling.N addition largely failed to affect the impact of elevated O_(3) levels on leaves or fine root chemistry,suggesting that soil N supplementation is not a suitable approach to combating the impact of O_(3) pollution on key functional traits of poplars.These results indicate that the significant differences in the responses of leaves and fine roots to O_(3) pollution will result in marked changes in the relative belowground roles of these two litter sources within forest ecosystems,and such changes will independently of nitrogen load.
