Canopy processing of N deposition increases short-term leaf N uptake and photosynthesis, but not long-term N retention for aspen seedlings

作  者:Wang X, Wang B, Wang CZ, Wang ZH, Li J, Jia Z, Yang S, Li P, Wu YT, Pan SN, Liu LL*
影响因子:8.512
刊物名称:New Phytologist
出版年份:2020
卷:  期:  页码:DOI: 10.1111/nph.17041

论文摘要:

  • Forest canopies can retain nitrogen (N) from atmospheric deposition. However, most empirical and modeling studies do not consider the processing of the N deposited in the canopy.
  • To assess whether N deposition through canopy will alter the plant’s N uptake and retention, we conducted a 3yr mesocosm experiment by applying (15NH4)2SO4 solution to aspen sapling canopies or directly to the soil.
  • We found that 15NNH4+ applied to the canopy was directly taken up by leaves. Compared with the soil N application, the canopy N application resulted in higher photosynthesis but lower N retention of the plant–soil system in the first growing season. Plant biomass, N concentration, and leaf N resorption were not significantly different between the canopy and soil N applications. The partitioning of retained 15N among plant components and soil layers was similar between the two treatments 3 yr after the N application.
  • Our findings indicated that the canopy N processing could alter leaf N supply and photosynthesis in the short term but not N retention in the long term. Under natural conditions, the chronic N deposition could continuously refill the canopy N pool, causing a sustained increase in canopy carbon uptake. Canopy N processing needs to be considered for accurately predicting the impact of N deposition.
全文链接:https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.17041