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生态学杂志 ›› 2022, Vol. 41 ›› Issue (2): 218-226.doi: 10.13292/j.1000-4890.202202.004

• 研究报告 • 上一篇    下一篇

亚热带丛枝菌根与外生菌根森林对土壤氮循环的影响

陈亮*,蔡咏欣,雷惠敏,齐晓旭,林俊均,廖伟,黄子玄   

  1. (中南林业科技大学生命科学与技术学院, 长沙 410004)
  • 出版日期:2022-02-10 发布日期:2022-08-10

Comparison of soil nitrogen cycling between arbuscular mycorrhizal and ectomycorrhizal forests in a subtropical region.

CHEN Liang*, CAI Yong-xin, LEI Hui-min, QI Xiao-xu, LIN Jun-jun, LIAO Wei, HUANG Zi-xuan#br#     

  1. (Faculty of Life Science and Technology, Central South University of Forestry and Technology, Changsha 410004, China).
  • Online:2022-02-10 Published:2022-08-10

摘要: 菌根真菌能促进植物获取氮素从而调节土壤氮循环过程,但不同类型菌根影响土壤氮循环的特征尚待更多研究。本试验选择中国亚热带典型次生林植被,设置丛枝菌根(AM)和外生菌根(ECM)树种优势样地,对比分析两种菌根类型森林土壤氮状态的差异,以探究菌根类型影响土壤氮循环的可能作用机制。结果表明,AM与ECM森林的土壤总氮和铵态氮(NH4+-N)含量均无显著差异(P>0.05),但AM森林土壤可溶性有机氮和硝态氮(NO3--N)含量都显著高于ECM森林土壤(P<0.001),其中AM森林表层有机和下层矿质土的NO3--N分别是ECM森林的2.2和2.3倍。AM森林土壤NO3-/NH4+>1,而ECM的NO3-/NH4+<1,表明AM森林土壤可利用氮饱和而ECM不足。氮转化速率测定表明,AM森林有机土层的净氮硝化速率是ECM的3.2倍,且与硝态氮含量呈显著正相关(P<0.01)。AM森林的叶凋落物质量、土壤pH和含水量都显著高于ECM森林,是导致其土壤氮循环相对快速的主要原因。本研究发现,AM森林土壤硝态氮淋失风险高于ECM森林,证实了“菌根养分经济理论”同样适用于亚热带森林,这对于全球变化下该区域森林土壤氮循环模型预测与发展,以及科学指导森林植被恢复具有理论意义。

关键词: 菌根养分经济, 无机氮, 净氮转化速率

Abstract: Mycorrhizae can enhance plant nitrogen (N) acquisition and affect soil N cycling. Because tree species differ in mycorrhizae types they associated with, stand-scale soil N cycling could be influenced by tree species composition via their association with different types of mycorrhizae. We investigated the effects of arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) forests on soil N cycling in subtropical forests. Total soil N and ammonium (NH4+-N) contents did not differ between AM and ECM forests, whereas dissolved organic N (DON) and nitrate (NO3--N) were significantly higher in AM than in ECM forests (P<0.001). In particular, soil NO3--N was more than twice as high in AM as in ECM forests in both the organic horizon and mineral horizon. Soil NO3-∶NH4+ ratio was greater than 1 in AM forest soil but less than 1 in ECM forest soil, indicating that plant-available N was abundant in AM forest soil. Soil net nitrification was 2.2 times higher in the AM forest than in the ECM forest and positively correlated with soil NO3--N content. The relatively fast soil N cycling in AM forests was attributed to the higher aboveground litter quality, soil pH, and water contents. We found that more nitrate was leached in AM forests than ECM stands, suggesting that the “mycorrhizal-associated nutrient economy” framework can also apply to subtropical forests. These results will improve our prediction of soil N cycling, aid the development of soil N cycling models under global change, and facilitate forest restoration in this subtropical region.

Key words: mycorrhizal-associated nutrient economy, inorganic nitrogen, net nitrogen transformation rate.