Mature conifers assimilate nitrate as efficiently as ammonium from soils in four forest plantations

第一作者：Xulun Zhou

第一单位：中科院应用生态学研究所

通讯作者：Yunting Fang

 Abstract 

已有研究：Conifers are considered to prefer to take up ammonium (NH₄⁺) over nitrate (NO3-).

存在问题：However, this conclusion is mainly based on hydroponic experiments that separate roots from soils.

提出新的问题：It remains unclear to what extent mature conifers can use nitrate compared to ammonium under field conditions where both roots and soil microbes compete for nitrogen (N).

主要研究：We conducted an in situ whole mature tree nitrogen‐15 (15N) labeling experiment (15NH4+ vs 15NO3-) over 15 d to quantify ammonium and nitrate uptake and assimilation rates in four 40‐yr‐old monoculture coniferous plantations (Pinus koraiensis, Pinus sylvestris, Picea koraiensis and Larix olgensis, respectively).

结果1-整株树15NO3-占比：For the whole tree, 15NO3- contributed 39% to 90% to total 15N tracer uptake among four plantations during the study period. 

结果2-第三天15NO3-占比：At day 3, the 15NO3-accounted for 77%, 64%, 62% and 59% by Larix olgensis, Pinus koraiensis, Pinus sylvestris and Picea koraiensis, respectively.

结论：Our study indicates that mature coniferous trees assimilated nitrate as efficiently as ammonium from soils even at low soil nitrate concentration, in contrast to the results from hydroponic experiments showing that ammonium uptake dominated over nitrate. This implies that mature conifers can adapt to increasing availability of nitrate in soil, for example, under the context of globalization of N deposition and global warming.

 通讯作者 

doi: https://doi.org/10.1111/nph.17110

Journal: New Phytologist

Published online: Dec 17, 2020