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Canopy processing of N deposition increases short‐term leaf N uptake and photosynthesis, but not long‐term N retention for aspen seedlings
Author(s) -
Wang Xin,
Wang Bin,
Wang Chengzhang,
Wang Zhenhua,
Li Jing,
Jia Zhou,
Yang Sen,
Li Ping,
Wu Yuntao,
Pan Shengnan,
Liu Lingli
Publication year - 2021
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.17041
Subject(s) - canopy , deposition (geology) , photosynthesis , growing season , environmental science , agronomy , biomass (ecology) , mesocosm , photosynthetic capacity , botany , nutrient , biology , ecology , paleontology , sediment
Summary 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 3‐yr mesocosm experiment by applying ( 15 NH 4 ) 2 SO 4 solution to aspen sapling canopies or directly to the soil. We found that 15 N‐NH 4 + 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 15 N 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.