植物生态学报 ›› 2020, Vol. 44 ›› Issue (3): 214-227.DOI: 10.17521/cjpe.2019.0299

• 研究论文 • 上一篇    下一篇

亚热带不同树种凋落叶分解对氮添加的响应

陈思路1,2,蔡劲松4,林成芳1,2,3,*(),宋豪威1,2,杨玉盛1,2,3   

  1. 1福建师范大学地理科学学院, 福州 350007
    2湿润亚热带山地生态国家重点实验室培育基地, 福州 350007
    3福建三明森林生态系统与全球变化研究站, 福建三明 365000
    4福建省三明市郊国有林场, 福建三明 365000
  • 收稿日期:2019-11-04 接受日期:2020-02-06 出版日期:2020-03-20 发布日期:2020-04-30
  • 通讯作者: 林成芳
  • 基金资助:
    国家自然科学基金(31770663);福建省自然科学基金(2018J01718)

Response of leaf litter decomposition of different tree species to nitrogen addition in a subtropical forest

CHEN Si-Lu1,2,CAI Jin-Song4,LIN Cheng-Fang1,2,3,*(),SONG Hao-Wei1,2,YANG Yu-Sheng1,2,3   

  1. 1School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
    2State Key Laboratory of Humid Subtropical Mountain Ecology, Fuzhou, 350007, China
    3Sanming Research Station of Forest Ecosystem and Global Change, Sanming, Fujian 365000, China
    4State-owned Forest Farm in the Suburbs of Sanming, Fujian Province, Sanming, Fujian 365000, China
  • Received:2019-11-04 Accepted:2020-02-06 Online:2020-03-20 Published:2020-04-30
  • Contact: Cheng-Fang LIN
  • Supported by:
    National Natural Science Foundation of China(31770663);Natural Science Foundation of Fujian(2018J01718)

摘要:

为探究不同质量凋落物对氮(N)沉降的响应, 该研究采用尼龙网袋分解法, 在亚热带福建三明格氏栲(Castanopsis kawakamii)自然保护区的米槠(Castanopsis carlesii)天然林, 选取4种本区常见的具有不同初始化学性质的树种凋落叶进行模拟N沉降(N添加)分解实验(施N水平为对照0和50 kg·hm -2·a -1)。研究结果表明: 在2年的分解期内, 对照处理的各树种凋落叶的分解速率依次为观光木(Michelia odora, 0.557 a -1)、米槠(0.440 a -1)、台湾相思(Acacia confusa, 0.357 a -1)、杉木(Cunninghamia lanceolata, 0.354 a -1); N添加处理凋落叶分解速率依次为观光木(0.447 a -1)、米槠(0.354 a -1)、杉木(0.291 a -1)、台湾相思(0.230 a -1), 除杉木凋落叶外, N添加显著降低了其他3种凋落叶分解速率。N添加不仅使4种树木凋落叶分解过程中的N释放减慢, 同时还抑制凋落叶化学组成中木质素和纤维素的降解; N添加在凋落叶分解过程中总体上提高β-葡萄糖苷酶(βG)和酸性磷酸酶活性, 对纤维素水解酶的活性影响不一致, 而降低β-N-乙酰氨基葡萄糖苷酶活性和酚氧化酶活性。凋落叶分解速率与凋落叶中的碳获取酶(βG)活性以及其化学组分中的可萃取物含量极显著正相关, 与初始碳浓度、纤维素和木质素含量极显著负相关, 与初始N含量没有显著相关性。凋落物类型和N添加的交互作用虽未影响干质量损失速率, 但对木质素和纤维素的降解具有显著效应。综上所述, 化学组分比初始N含量能更好地预测凋落叶分解速率, 而N添加主要通过抑制分解木质素的氧化酶(如PHO)来降低凋落叶分解速率。

关键词: 凋落叶分解, 氮沉降, 酶活性, 亚热带森林

Abstract:

Aims Litter decomposition plays a vital role in nutrient recycling of forest ecosystems. The decomposition rate of leaves can vary among tree species with different substrate quality and environmental conditions, such as the supply of exogenous nitrogen (N). However, the effects of exogenous N on leaf litter decomposition of different tree species in subtropical forests with high nitrogen deposition background remain poorly understood. Thus this study was designed to address the effect of N addition on litter decomposition of different tree species in a subtropical forest ecosystem.
Methods Leaf litters of four common tree species with contrasting substrate quality were collected and decomposed in fertilized (50 kg N·hm -2·a -1) and control (0 kg N·hm -2·a -1) plots for up to two years by using the nylon bag method, in Sanming Castanopsis kawakamii nature reserve of Fujian Province.
Important findings The litter decomposition rate in control plots ranked as follows: Michelia odora (0.557 a -1), Castanopsis carlesii (0.440 a -1), Acacia confusa (0.357 a -1), Cunninghamia lanceolata (0.354 a -1), while the decomposition rate in N addition plots ranked as follows: Michelia odora (0.447 a -1), Castanopsis carlesii (0.354 a -1), Cunninghamia lanceolata (0.291 a -1), Acacia confusa (0.230 a -1). Overall, N addition significantly increased the litter mass remaining of Michelia odora, Acacia confusa and Castanopsis carlesii, but not Cunninghamia lanceolata. N addition not only slowed down the release of N, but also retarded the degradation of lignin and cellulose in the decomposition process. Moreover, N addition increased the activities of β-glucosidase (βG) and acid phosphatase, had species-specific effects on the activity of cellulose hydrolase, and decreased the activity of β-N-acetylglucosaminidase and phenoloxidase (PHO). The litter mass loss rate was positively correlated with the activities of carbon acquiring enzyme (βG) in litter layer and the extractives, negatively correlated with carbon concentration, cellulose and lignin, but did not correlate significantly with the initial N concentration. Further analysis found an interactive effect of litter type and N addition on the degradation of cellulose and lignin, but not on dry mass loss. Overall, our results demonstrated that litter chemical components may be better parameters to predict the decomposition rate of leaf litters than the initial nutrient concentrations, and N addition could decrease leaf litter decomposition by inhibiting oxidase (e.g. PHO). We call for further experiments to involve more species and longer time for revealing the response of leaf litter decomposition and its extracellular enzyme activity to N addition.

Key words: leaf litter decomposition, nitrogen deposition, enzyme activities, subtropical forest