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Nitrogen deposition increases root production and turnover but slows root decomposition in Pinus elliottii plantations
Author(s) -
Kou Liang,
Jiang Lei,
Fu Xiaoli,
Dai Xiaoqin,
Wang Huimin,
Li Shenggong
Publication year - 2018
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.15066
Subject(s) - decomposition , pinus <genus> , deposition (geology) , nitrogen , nutrient , phosphorus , agronomy , chemistry , botany , biology , ecology , paleontology , organic chemistry , sediment
Summary Fine roots of woody plants comprise multiple root orders, which can be functionally partitioned into two pools: absorptive fine roots ( AFR s, orders 1, 2) and transport fine roots ( TFR s, orders 3–5). However, the function‐based fine‐root dynamics and especially their responses to increased nitrogen (N) availability remain unclear. We explored dynamic responses of both AFR s and TFR s of Pinus elliottii to N addition in subtropical China based on a 4‐yr minirhizotron experiment and a two‐stage – early (0.5 yr) vs late (4 yr) – decomposition experiment. N addition increased the production, mortality, and turnover of AFR s but not TFR s. High rates of N persistently inhibited AFR decomposition but affected TFR decomposition differentially at the early (no effect) and late (negative effect) stages. The increased production of AFR s was driven by N‐induced decrease in foliar and soil phosphorus (P) concentrations. The decreased decomposition of AFR s might be due to the increased acid‐unhydrolyzable residues in decomposing roots. AFR s are the resource‐acquiring module, the increased carbon allocation to AFR s may represent a P‐acquiring strategy when N no longer limits growth of P. elliottii . Our results suggest that AFR s and TFR s respond differently to N deposition, both in terms of production, mortality, and turnover and in terms of decomposition.