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林业科学 ›› 2020, Vol. 56 ›› Issue (2): 1-11.doi: 10.11707/j.1001-7488.20200201

• 论文与研究报告 • 上一篇    下一篇

异质性供氮环境下杉木、马尾松、木荷氮素吸收偏好及其根系觅氮策略

闫小莉1,胡文佳1,马远帆1,霍昱帆1,王拓2,马祥庆1,*   

  1. 1. 福建农林大学林学院 福州 350002
    2. 东北师范大学 长春 130042
  • 收稿日期:2019-01-20 出版日期:2020-02-25 发布日期:2020-03-17
  • 通讯作者: 马祥庆
  • 基金资助:
    国家自然科学基金项目(31700557)

Nitrogen Uptake Preference of Cunninghamia lanceolata, Pinus massoniana, and Schima superba under Heterogeneous Nitrogen Supply Environment and their Root Foraging Strategies

Xiaoli Yan1,Wenjia Hu1,Yuanfan Ma1,yufan Huo1,Tuo Wang2,Xiangqing Ma1,*   

  1. 1. College of Forestry, Fujian Agriculture and Forestry University Fuzhou 350002
    2. Northeast Normal University Changchun 130042
  • Received:2019-01-20 Online:2020-02-25 Published:2020-03-17
  • Contact: Xiangqing Ma

摘要:

目的: 林木可吸收利用土壤中的NH4+-N和NO3--N存在很大的空间异质性,不同树种具有不同的N素吸收偏好和根系觅N策略。研究亚热带主要针叶树种杉木、马尾松和阔叶树种木荷的N素吸收偏好及异质N环境中的根系形态特征和苗木生长,为揭示3个树种的N素营养性状遗传特性提供参考,对营造针阔混交林、提高林地N素利用效率和生产力具有重要理论价值。方法: 以杉木、马尾松和木荷幼苗为研究对象,采用自主研发的异质养分环境根箱培养系统,构建不同N素形态(NH4+-N和NO3--N)和浓度配比的4个供N处理(NH4+:NO3-为10:0和0:10的高异质性、8:2和2:8的中异质性、6:4和4:6的低异质性、5:5和5:5的同质性),分析3个树种根系生长与形态特征、苗木生长和生物量。结果: 1)异质性供N处理下,杉木在NO3--N斑块中的根长、根表面积和根生物量均显著大于NH4+-N斑块中的值,而马尾松和木荷则是NH4+-N斑块中的值大于NO3--N斑块中的值;杉木根系平均直径NO3--N斑块中的小于NH4+-N斑块中的值,而马尾松和木荷根系平均直径为NO3--N大于NH4+-N斑块中的值,3个树种根系特征参数在同质供N处理下的2个斑块间无显著差异。总根长、根表面积和根生物量均表现为:同质<低异质<中异质<高异质,高异质性供N处理下根系生物量比其他3个处理分别高7.96%~20.15%、3.47%~19.07%、4.49%~9.08%。2)3个树种苗高、地径、总生物量表现为:低异质>同质>中异质>高异质,生物量在低异质性供N处理下比其他3个处理分别高5.40%~33.67%、7.61%~31.24%和11.32%~36.61%,根冠比在高异质供N处理下相比同质供N处理下的提高58.47%~92.68%。结论: 在同质供N的理想环境中,杉木、马尾松和木荷的根系生长无显著的N素吸收偏好性。但在NO3--N和NH4+-N的异质性供N环境下,杉木偏向于在NO3--N的斑块中生长更多更细长的根系,而马尾松和木荷则偏向于在NH4+-N斑块中生长更多更细长的根系。3个树种根长、表面积和生物量随着异质供N性的程度提高而增大,但根系平均直径越小,且N异质性程度越大越不利于苗木生长和生物量的累积。

关键词: 根系形态, 氮素吸收偏好, 觅氮策略, 杉木, 马尾松, 木荷

Abstract:

Objective: NH4+-N and NO3--N are the main inorganic N forms absorbed and utilized by trees. As distribution of absorbable N forms in soil is subject to great spatial heterogeneity, different tree species tend to develop different preferences for nutrients and absorption strategies. This study investigated the preference behavior of N, root morphological traits, and seedlings growth in Cunninghamia lanceolata, Pinus massoniana, and Schima superba under N heterogeneous environments. The results should reveal the mechanisms of nutrient preference and N foraging strategy in response to N heterogeneous environment, and provide a scientific theoretical basis for different tree species configuration of the mixed broadleaf-conifer forest plantations. It may also contribute to silviculture practice to improve the N use efficiency and productivity of the plantations. Method: In this study, four N treatments with different N forms (NH4+-N and NO3--N) and proportion were constructed with the self-designed root box culture system. The NH4+:NO3- was 10:0 and 0:10 for the high hetero-N, 8:2 and 2:8 for the medium hetero-N, 6:4 and 4:6 for the low hetero-N, and 5:5 for the homo-N, respectively. The seedlings of C. lanceolata, P. massoniana and S. superba were subjected to the four N treatments in order to investigate the root growth and morphological traits, and seedlings growth after 180 days treatment. Results: (1) under the heterogeneous N supply treatments, the root length, surface area and biomass of C. lanceolata in NO3--N patches were greater than in the NH4+-N patches, but the root length, surface area and biomass of P. massonina and S. superba in NH4+-N patches were greater than in the NO3--N patches. There was no significant difference in root morphological traits between NO3--N and NH4+-N nutrient patches under the homogeneous N supply. The total root length, surface area and biomass of the three species were as the follow:homogeneity < low heterogeneity < medium heterogeneity < high heterogeneity. For example, the root biomass under the treatment of high heterogeneity was 7.96%-20.15%, 3.47%-19.07%, and 4.49%-9.08% higher than that with the other three treatments, respectively. (2) The height, diameter and total biomass of the three tree species were as the follow:low heterogeneity > homogeneity > medium heterogeneity > high heterogeneity. For example, the biomass under the treatment of low heterogeneity was 5.40%-33.67%, 7.61%-31.24%, and 11.32%-36.61% higher than that of the other three treatments, respectively. The root to shoot ratio of the three species under the high heterogeneity treatment increased by 58.47%-92.68% compared with the treatment of homogeneous N supply Conclusion: Under the heterogeneous N supply, C. lanceolata tends to grow more and slender roots in NO3--N patches, but P. massoniana and S. superba tends to grow more and slender roots in NH4+-N patches. The root length, surface area and biomass of the three tree species increased with the increase of heterogeneity, but the average diameter was smaller. The height, diameter and biomass of the three tree species were greatest in the environment of lower heterogeneity and homogeneous N supply. It is concluded that the C. lanceolata prefers to absorb and utilize NO3--N, while P. massoniana and S. superba prefer to absorb and utilize the NH4+-N under the environment of heterogeneous N supply.

Key words: root morphology, nitrogen uptake preference, foraging strategy for nitrogen, Cunninghamia lanceolata, Pinus massoniana, Schima superba

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