Responses of fine roots and soil N availability to short-term nitrogen fertilization in a broad-leaved Korean pine mixed forest in northeastern China.
Responses of fine roots and soil N availability to short-term nitrogen fertilization in a broad-leaved Korean pine mixed forest in northeastern China.
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东北阔叶红松混交林细根和土壤氮素有效性对短期氮肥的响应
DOI：
10.1371/journal.pone.0031042
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Li MH
中科院分区：
文献类型：
--
作者：
Wang C;Han S;Zhou Y;Yan C;Cheng X;Zheng X;Li MH
了解土壤氮素有效性、细根质量、产量和周转速率对大气氮沉降的响应对于理解森林生态系统中细根的动态和功能至关重要。采用连续土芯和内生土芯的方法，在2010年生长季节对温带森林的细根生物量和坏死体、产量和周转率以及土壤硝态氮和氨氮与氮肥(50 kg N ha−1年−1)的关系进行了研究。与对照相比，施氮使土壤硝态氮增加16%(P<；0.001)，氨氮增加6%(P<；0.01)。0~20 cm土层细根生物量和坏死体质量分别比对照低13%(4.61vs.5.23mgha−1，P<；0.001)和34%(1.39mgha−1，1.86mgha−1，P<；0.001)。细根质量与土壤有效氮和硝态氮含量呈显著负相关，尤其是在0~10 cm土层。细根产量和周转率均随施氮量的增加而增加，说明在高氮素水平环境下，地下碳循环较快。虽然高氮供应被广泛认为可以促进地上生长速度，但本研究表明，高水平的氮供应可能会减少地下碳库的大小。因此，我们得出结论，高水平的大气氮沉降将刺激地下碳循环，导致地上和地下储存之间的碳平衡发生变化。本研究的意义表明，碳模型和预测需要考虑氮素沉积对地下系统的影响。
Knowledge of the responses of soil nitrogen (N) availability, fine root mass, production and turnover rates to atmospheric N deposition is crucial for understanding fine root dynamics and functioning in forest ecosystems. Fine root biomass and necromass, production and turnover rates, and soil nitrate-N and ammonium-N in relation to N fertilization (50 kg N ha−1 year−1) were investigated in a temperate forest over the growing season of 2010, using sequential soil cores and ingrowth cores methods. N fertilization increased soil nitrate-N by 16% (P<0.001) and ammonium-N by 6% (P<0.01) compared to control plots. Fine root biomass and necromass in 0–20 cm soil were 13% (4.61 vs. 5.23 Mg ha−1, P<0.001) and 34% (1.39 vs. 1.86 Mg ha−1, P<0.001) less in N fertilization plots than those in control plots. The fine root mass was significantly negatively correlated with soil N availability and nitrate-N contents, especially in 0–10 cm soil layer. Both fine root production and turnover rates increased with N fertilization, indicating a rapid underground carbon cycling in environment with high nitrogen levels. Although high N supply has been widely recognized to promote aboveground growth rates, the present study suggests that high levels of nitrogen supply may reduce the pool size of the underground carbon. Hence, we conclude that high levels of atmospheric N deposition will stimulate the belowground carbon cycling, leading to changes in the carbon balance between aboveground and underground storage. The implications of the present study suggest that carbon model and prediction need to take the effects of nitrogen deposition on underground system into account.
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