Chin J Plant Ecol ›› 2024, Vol. 48 ›› Issue (1): 103-112.DOI: 10.17521/cjpe.2023.0069

• Research Articles • Previous Articles     Next Articles

Effects of nitrogen addition on the morphological and chemical traits of fine roots with different orders of Castanopsis hystrix

SHU Wei-Wei1,2, YANG Kun1,2, MA Jun-Xu1,2, MIN Hui-Lin1,2, CHEN Lin1,2, LIU Shi-Ling1,2, HUANG Ri-Yi1, MING An-Gang1,2, MING Cai-Dao1, TIAN Zu-Wei1,*()   

  1. 1Experimental Center of Tropical Forestry, Chinese Academy of Forestry, Pingxiang, Guangxi 532600, China
    2Guangxi Youyiguan Forest Ecosystem National Observation and Research Station, Pingxiang, Guangxi 532600, China
  • Received:2023-03-10 Accepted:2023-08-03 Online:2024-01-20 Published:2023-08-31
  • Supported by:
    Natural Science Foundation of Guangxi Zhuangzu Autonomous Region(2023GXNSFBA026143)

Abstract:

Aims As an important organ for plant nutrient acquisition and energy transport, fine roots are the most active and sensitive part of the root system. Their functional traits change along the environmental gradient, which can reflect plant resource acquisition strategies and adaptability to environmental changes. The purpose of this study was to analyze the effects of different nitrogen (N) addition levels on the morphological and chemical traits of the fine roots of Castanopsis hystrix, explore the plasticity of the fine roots of the species to short-term N addition, and provide theoretical support for clarifying and predicting the changes of root physiological function under global climate change.

Methods In January 2020, four treatments with different N addition levels were set up in the C. hystrix plantation, which were the control (CK, 0 kg·hm-2·a-1), low N treatment (LN, 50 kg·hm-2·a-1), medium N treatment (MN, 100 kg·hm-2·a-1) and high N treatment (HN, 150 kg·hm-2·a-1), with three replicates per treatment. Fine roots of C. hystrix were dug out by the excavation method, and traits of the 1st to 5th order fine roots in different N addition treatments were determined, including specific root length, specific root area, root tissue density, average root diameter and stoichiometry.

Important findings The results showed that, compared with the CK treatment, MN and HN treatments significantly reduced soil pH, HN treatment significantly increased soil NO3--N and total phosphorus contents. Nitrogen addition significantly increased the content of carbon (C) in the 1st order fine root. HN treatment significantly increased the C content of the 2nd order fine root. MN and HN treatments significantly increased the N content of the 1st and 2nd order fine root, and significantly decreased the C:N of the 2nd order fine root. There were no significant differences in specific root length, specific root surface area, root tissue density and average root diameter of fine roots under different N addition levels. Taken together, these results showed that short-term N addition mainly affected the element content and stoichiometric ratio of fine roots, but had no significant effect on the morphological traits of fine roots in the C. hystrix plantation. This finding will help to understand the response of forest nutrient cycling and C sequestration to global environmental changes in the southern subtropical region.

Key words: root order, nitrogen addition, fine root, morphological trait, plastic