赤杨对辽东落叶松人工林土壤氨基糖积累的影响

微生物残留物是土壤稳定性碳库的重要组成部分,然而其对固氮树种的响应还不清楚。以辽东山区日本落叶松(Larix kaempferi)人工纯林和落叶松-赤杨混交林为研究对象,以氨基糖作为微生物残留物的生物标识物,研究了赤杨对落叶松人工林根际和非根际土壤氨基糖积累的影响。结果表明,混交林中落叶松根际和非根际各氨基糖单体含量均显著高于纯林,说明赤杨引入有利于土壤微生物残留物的积累。其中,混交林落叶松根际及非根际土壤氨基糖葡萄糖含量分别比纯林高出99.5%(P0.01)和154%(P0.01);胞壁酸含量分别比纯林高出66.1%(P0.01)和132.3%(P0.01)。赤杨引入对氨基葡萄糖/胞壁酸比值的影响不显著,但显著增加氨基糖对土壤有机碳的贡献。冗余度分析表明全氮是驱动土壤中氨基糖发生变化的主要因子。表明赤杨引入显著提高微生物固持的土壤碳库和有机碳稳定性,这对落叶松人工林合理经营具有重要意义。

Effects of N-fixing tree species (Alnus sibirica) on amino sugars in the soils of a Larix kaempferi plantation in eastern Liaoning Province, China

Microbial residues are an important component of soil stable carbon (C) pools. However, their response to N-fixing tree species is still unclear. The present study investigated the effects of alder (Alnus sibirica) on microbial residues (as indicated by amino sugars) in the rhizosphere and non-rhizosphere soils of a larch (Larix kaempferi) plantation in eastern Liaoning Province, China. The contents of individual amino sugars significantly increased in the larch rhizosphere and non-rhizosphere soils in the mixed plantation relative to the pure plantation, indicating that alder benefits microbial residue accumulation. Specifically, the glucosamine (GluN) contents were 99.5% (P<0.01) and 154% (P<0.01) higher in the larch rhizosphere and non-rhizosphere soils in the mixed plantation than in the pure plantation, respectively, while the muramic acid (MurN) contents in the rhizosphere and non-rhizosphere soils were 66.1% (P<0.01) and 132.3% (P<0.01) higher in the mixed plantation than in the pure plantation, respectively. We found that alder had no effect on the GluN/MurN ratio, but significantly enriched the amino sugar proportion of soil organic C. Redundancy analysis revealed that total nitrogen was the dominant factor driving changes in amino sugars. This study indicates that alder would significantly stimulate the microbial fixation of C and the stability of soil organic C, which means that it plays a vital role in managing larch plantations.