Long-Term Research Station of Alpine Forest Ecosystems, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology and Forestry, Sichuan Agricultural University, Chengdu, 611130, China.
Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang, 621000, China.
Sci Rep. 2019 Feb 14;9(1):2052. doi: 10.1038/s41598-018-38431-4.
Repeated freeze-thaw cycles (FTCs) can alter the relationships between plant litter and soil nitrogen (N) mineralization in subalpine ecosystems, but little information is available about the underlying mechanisms. Therefore, a controlled soil incubation experiment was carried out to study the effects of litter removal on soil N mineralization during FTCs, and the results indicated that FTCs promoted soil N mineralization more than the continuously frozen or nonfrozen condition did. Litter removal promoted soil ammonium N (NH-N) and dissolved organic N (DON) as well as the cumulative N mineralization (CNM) and ammonification, but it reduced the soil microbial biomass N (MBN) in the early stage of FTCs. With an increasing number of FTCs, litter removal significantly reduced the CNM but increased the soil MBN. The modified first-order kinetics model was verified under incubation conditions and predicted a lower soil N mineralization rate in FTCs with litter removal. In addition, the dominant factor impacting soil N mineralization was soil NO-N, and soil MBN had a greater influence on soil N mineralization when litter remained than when it was removed. These results further clarify the mechanism driving the effect of plant residues on soil N cycling.
反复的冻融循环（FTCs）会改变亚高山生态系统中植物凋落物与土壤氮（N）矿化之间的关系，但关于其潜在机制的信息却很少。因此，进行了一项控制土壤培养实验，以研究 FTCs 期间凋落物去除对土壤 N 矿化的影响，结果表明 FTCs 比连续冻结或非冻结条件更能促进土壤 N 矿化。凋落物去除促进了土壤铵态氮（NH-N）和溶解有机氮（DON）以及累积氮矿化（CNM）和氨化作用，但在 FTCs 的早期会降低土壤微生物生物量氮（MBN）。随着 FTCs 的增加，凋落物去除显著降低了 CNM，但增加了土壤 MBN。在培养条件下验证了修正的一级动力学模型，并预测在 FTCs 中去除凋落物会降低土壤 N 矿化率。此外，土壤 NO-N 是影响土壤 N 矿化的主要因素，当凋落物存在时，土壤 MBN 对土壤 N 矿化的影响大于凋落物去除时。这些结果进一步阐明了植物残体对土壤 N 循环影响的作用机制。
