Nitrogen deposition increases root production and turnover but slows root decomposition in Pinus elliottii plantations
Nitrogen deposition increases root production and turnover but slows root decomposition in Pinus elliottii plantations
复制标题
氮沉降增加了湿地松人工林的根系产量和周转率，但减缓了根系分解
DOI：
10.1111/nph.15066
复制
发表时间：
2018-06-01
期刊：
影响因子：
9.4
通讯作者：
Li, Shenggong
中科院分区：
文献类型：
--
作者：
Kou, Liang;Jiang, Lei;Li, Shenggong
木本植物的细根由多个根目组成，在功能上可分为吸收性细根（AFR，1、2目）和运输性细根（TFR，3-5目）。本研究通过4年的微型温室试验和两阶段的早、中、晚苗期试验，探讨了中国亚热带湿地松细根动态及其对氮素有效性增加的响应添加氮肥可提高AFR的产量、死亡率和周转率，但对TFR无显著影响。高速率的N持续抑制AFR分解，但影响TFR分解差异在早期（无影响）和晚期（负效应）阶段。氮素诱导的叶片和土壤磷浓度的降低是AFR产量增加的主要原因。AFR是湿地松的资源获取模块，当N不再限制湿地松的生长时，增加AFR的碳分配可能是湿地松获取磷的一种策略。我们的研究结果表明，AFR和TFR响应不同的N沉积，无论是在生产，死亡率，营业额和分解方面。
Fine roots of woody plants comprise multiple root orders, which can be functionally partitioned into two pools: absorptive fine roots (AFRs, orders 1, 2) and transport fine roots (TFRs, 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 AFRs and TFRs 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 AFRs but not TFRs. 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 AFRs was driven by N-induced decrease in foliar and soil phosphorus (P) concentrations. The decreased decomposition of AFRs might be due to the increased acid-unhydrolyzable residues in decomposing roots.AFRs are the resource-acquiring module, the increased carbon allocation to AFRs may represent a P-acquiring strategy when N no longer limits growth of P. elliottii. Our results suggest that AFRs and TFRs respond differently to N deposition, both in terms of production, mortality, and turnover and in terms of decomposition.