Functional traits of poplar leaves and fine roots responses to ozone pollution under soil nitrogen a

• 作 者: Pin Li Rongbin Yin Huimin Zhou Sheng Xu Zhaozhong Feng
• 机 构: Research Center for Urban Forestry,Key Laboratory for Forest Silviculture and Conservation of Minist
• 出 处: 环境科学学报（英文版）
• 发表日期: 2022年3期
• 关键词: Ozone pollution Nitrogen (N) input Fine roots Leaves Functional traits Chemical

Concurrent ground-level ozone (O3) 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 O3 have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosys-tems.How elevated O3 levels impact fine root biomass and biochemistry remains to be re-solved.This study was to assess poplar leaf and fine root biomass and biochemistry re-sponses to five different levels of O3 pollution,while additionally examining whether four levels of soil N supplementation were sufficient to alter the impact of O3 on these two organs.Elevated O3 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 con-trast,leaves contained more labile components,including nonstructural carbohydrates and N,as well as a higher N:P ratio.Elevated O3 significantly reduced labile components and in-creased biochemically-resistant components in leaves,whereas they had minimal impact on fine root biochemistry.This suggests that O3 pollution has the potential to delay leaf litter decomposition and associated nutrient cycling.N addition largely failed to affect the impact of elevated O3 levels on leaves or fine root chemistry,suggesting that soil N supplementation is not a suitable approach to combating the impact of O3 pollution on key functional traits of poplars.These results indicate that the significant differences in the responses of leaves and fine roots to O3 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.