• 论文与研究报告 •

### 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

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

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.