Data from: Fate of atmospherically deposited NH4+ and NO3- in two temperate forests in China: temporal pattern and redistribution
Li, Shanlong et al. (2019), Data from: Fate of atmospherically deposited NH4+ and NO3- in two temperate forests in China: temporal pattern and redistribution, Dryad, Dataset, https://doi.org/10.5061/dryad.t3k2t2j
The impacts of anthropogenic nitrogen (N) deposition on forest ecosystems depend in large part on its fate. However, our understanding of the fates of different forms of deposited N as well as the redistribution over time within different ecosystems is limited. In this study we used the 15N-tracer method to investigate both the short-term (1 week to 3 months) and long-term (1 to 3 years) fates of deposited NH4+ or NO3- by following the recovery of the 15N in different ecosystem compartments in a larch plantation forest and a mixed forest located in northeastern China. The results showed similar total ecosystem retention for deposited NH4+ and NO3-, but their distribution within the ecosystems (plants vs soil) differed distinctly particularly in the short-term, with higher 15NO3- recoveries in plants (while lower recoveries in organic layer) than found for 15NH4+. The different short-term fate was likely related to the higher mobility of 15NO3- than 15NH4+ in soils instead of plant uptake preferences for NO3- over NH4+. In the long-term, differences between N forms became less prevalent but higher recoveries in trees (particularly in the larch forest) of 15NO3- than 15NH4+ tracer persisted, suggesting that incoming NO3- may contribute more to plant biomass increment and forest carbon sequestration than incoming NH4+. Differences between the two forests in recoveries were largely driven by a higher 15N recovery in the organic layer (both N forms) and in trees (for 15NO3-) in the larch forest compared to the mixed forest. This was due to a more abundant organic layer and possibly higher tree N demand in the larch forest than in the mixed forest. Leachate 15N loss was minor (<1% of the added 15N) for both N forms and in both forests. Total 15N recovery averaged 78% in the short-term and decreased to 55% in the long-term but with increasing amount of 15N label (re)-redistributed into slow turn-over pools (e.g., trees and mineral soil). The different retention dynamics of deposited NH4+ and NO3- may have implications in environmental policy related to the anthropogenic emissions of the two N forms.
National Science Foundation, Award: No