湖南会同5个亚热带树种的细根构型及功能特征分析

doi:10.3773/j.issn.1005-264x.2010.08.006

摘要/Abstract

摘要：

细根(直径< 2 mm)具有复杂的分枝系统, 不同树种间的细根在空间分布、形态和大小上有较大差异, 研究不同树种的细根构型及不同根序的养分特征, 对认识不同树种的细根形态和化学成分的变异格局, 及其对树种地下生态位分离(niche segregation)、共存和森林生态系统功能过程的影响有着重要意义。在湖南会同林区选择青冈(Cyclobalanopsis glauca)、枫香(Liquidanbar formosana)、拟赤杨(Alniphyllum fortunei)、杉木(Cunninghamia lanceolata)、马尾松(Pinus massoniana)等5个亚热带树种, 用挖掘法采集完整的细根根系, 按照Pregitzer细根分级方法对细根分级, 用Win-RHIZO根系测定系统对细根构型的参数进行测定, 同时测定各级根系的C、N含量, 以探讨各树种各级细根的功能特征, 揭示不同树种细根构型与养分策略之间的关系。结果表明: 5个亚热带树种细根1级根比根长、比表面积最高, 直径最细; 3级根比根长、比表面积最低, 直径最粗。不同树种之间细根形态特征和构型也表现出差异性: 枫香的1级根序比根长最大, 为31.45 m·g^-1, 杉木的最小, 为16.34 m·g^-1, 枫香和杉木之间差异显著。马尾松的1、2级根序的比表面积最大, 杉木的1级根序的比表面积最小, 青冈2级根序的比表面积最小, 3级根序比表面积杉木最大, 青冈最小。不同树种之间的细根直径差异达到极显著水平, 各根序的平均直径以杉木的最大, 拟赤杨的最小。5个树种细根根尖密度大小顺序为马尾松>青冈>枫香>杉木>拟赤杨, 各树种细根分叉数以拟赤杨和马尾松的较高, 杉木最低。除杉木和枫香外, 5个树种细根C含量均呈现出随着根序上升而增加的趋势, C/N比也随根序的上升而增加, 而细根N含量呈现出随着根序上升而明显下降的趋势。细根平均C含量以杉木的最高, 拟赤杨的最低, 马尾松、青冈与枫香之间的差异不显著。细根平均N含量以拟赤杨的最高, 马尾松的最低。C/N比以马尾松的最高, 拟赤杨的最低。5个树种中, 马尾松的外生菌根有很强的拓展能力, 因此能显著地增强植物根系的养分、水分吸收能力, 即使在贫瘠和干旱的土壤环境中, 也能有效地利用有限的养分和水分, 促进个体生长。而杉木细根吸收养分和水分的效率及能力最小。

关键词: 拟赤杨, 碳氮比, 杉木, 青冈, 细根, 枫香, 马尾松, 比表面积, 比根长, 中国亚热带地区

Abstract:

Aims Our objectives were to examine: 1) fine root architecture among five subtropical tree species in southern China; 2) nutrient concentrations across different branch orders and 3) the relationship between root architecture and nutrient exploration strategy.

Methods Intact fine root segments of Cyclobalanopsis glauca, Liquidambar formosana, Alniphyllum fortunei, Cunninghamia lanceolata and Pinus massoniana were collected by excavation in Huitong County, Hunan Province, China. Individual roots were dissected according to the branching order, starting from the distal end of the root system that was numbered as the first order and then increasing sequentially with each branch from the first order to higher order roots. Following dissection, fine root samples were scanned by the Win-RHIZO system to analyze specific root length (SRL), specific root surface area (SRA), diameter, tips and forks. Fine root samples were then oven-dried at 85 °C to a constant weight to determine weight. The contents of C and N in a given order were determined using the wet combustion and the semimicro-Kjeldahl methods, respectively.

Important findings The SRL and SRA decreased and root diameter increased from the first to third order roots for all species. Significant differences among species were also observed for fine root morphology and architecture; the highest SRL (31.45 m·g^-1) of the first order roots was observed for L. formosana and the lowest SRL (16.34 m·g^-1) was observed for Cunninghamia lanceolata. The highest SRA was found in the first and the second order roots of P. massoniana; the first order roots of Cunninghamia lanceolata and the second order roots of Cyclobalanopsis glauca had the lowest The SRA. Cunninghamia lanceolata had the largest fine root diameter, and A. fortunei had the smallest. No significant differences were found for the number of fine root tips, but there were large differences for number of forks among species. Apart from Cunninghamia lanceolata and L. formosana, C content in fine roots has been observed to significantly increase as root order increased. The C/N ratio increased from low to high root order, and N content decreased. C content was highest in Cunninghamia lanceolata and lowest in A. fortunei. No significant differences were found among the other species. N content was highest in A. fortunei and lowest in P. massoniana. The C/N ratio was highest in P. massoniana and lowest in A. fortunei.

Key words: Alniphyllum fortunei, C/N ratio, Cunninghamia lanceolata, Cyclobalanopsis glauca, fine roots, Liquidanbar formosana, Pinus massoniana, specific root surface area (SRA), specific root length (SRL), subtropical area in China

刘佳, 项文化, 徐晓, 陈瑞, 田大伦, 彭长辉, 方晰. 湖南会同5个亚热带树种的细根构型及功能特征分析. 植物生态学报, 2010, 34(8): 938-945. DOI: 10.3773/j.issn.1005-264x.2010.08.006

LIU Jia, XIANG Wen-Hua, XU Xiao, CHEN Rui, TIAN Da-Lun, PENG Chang-Hui, FANG Xi. Analysis of architecture and functions of fine roots of five subtropical tree species in Huitong, Hunan Province, China. Chinese Journal of Plant Ecology, 2010, 34(8): 938-945. DOI: 10.3773/j.issn.1005-264x.2010.08.006

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链接本文: https://www.plant-ecology.com/CN/10.3773/j.issn.1005-264x.2010.08.006

https://www.plant-ecology.com/CN/Y2010/V34/I8/938

图/表 5

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变异来源 Source of variation	比根长 SRL	比表面积SRA	细根直径 Fine root diameter	C含量 C content	N含量 N content	C/N比 C/N ratio
树种×根序 Tree species × Root order	0.007 8**	0.074 7	0.007 5**	0.027 2*	< 0.000 1**	< 0.000 1**
树种 Tree species	0.050 1	0.056 2	0.000 2**	< 0.000 1**	0.023 4**	< 0.000 1**
根序 Root order	< 0.000 1*	< 0.000 1**	< 0.000 1**	< 0.000 1**	< 0.000 1**	< 0.000 1**

变异来源 Source of variation	比根长 SRL	比表面积SRA	细根直径 Fine root diameter	C含量 C content	N含量 N content	C/N比 C/N ratio
树种×根序 Tree species × Root order	0.007 8**	0.074 7	0.007 5**	0.027 2*	< 0.000 1**	< 0.000 1**
树种 Tree species	0.050 1	0.056 2	0.000 2**	< 0.000 1**	0.023 4**	< 0.000 1**
根序 Root order	< 0.000 1*	< 0.000 1**	< 0.000 1**	< 0.000 1**	< 0.000 1**	< 0.000 1**

树种 Tree species	比根长 SRL (m·g^-1)			比表面积 SRA (cm²·g^-1)			根尖密度 Tip density (No.·cm^-1)	分叉 Forks (No.·cm^-1)
树种 Tree species	1	2	3	1	2	3	根尖密度 Tip density (No.·cm^-1)	分叉 Forks (No.·cm^-1)
马尾松 Pinus massoniana	23.53^ab (10.06)	11.73^a (4.34)	4.00^ab (0.72)	272.95^a (80.27)	184.08^a (40.16)	102.36^ab (26.7)	2.99^a (0.29)	5.09^a (1.11)
枫香 Liquidanbar formosana	31.45^a (11.67)	9.42^a (2.97)	3.71^ab (0.69)	271.72^a (75.45)	142.28^a (27.33)	84.73^ab (21.6)	2.85^a (0.21)	3.09^b (1.52)
拟赤杨 Alniphyllum fortunei	28.26^ab (12.89)	11.56^a (5.59)	4.13^ab (0.69)	247.20^a (76.57)	146.68^a (34.33)	82.86^ab (34.38)	2.38^a (0.27)	5.16^a (1.20)
青冈 Cyclobalanopsis glauca	23.40^ab (8.21)	8.67^a (10.56)	2.17^b (0.72)	228.85^a (78.60)	139.92^a (91.43)	61.57^b (14.43)	2.92^a (0.23)	3.95^ab (1.34)
杉木 Cunninghamia lanceolata	16.34b (10.07)	9.38a (3.57)	5.20a (0.72)	226.79a (37.25)	166.35a (41.75)	139.76a (90.48)	2.57a (0.22)	2.46b (0.77)

树种 Tree species	比根长 SRL (m·g^-1)			比表面积 SRA (cm²·g^-1)			根尖密度 Tip density (No.·cm^-1)	分叉 Forks (No.·cm^-1)
树种 Tree species	1	2	3	1	2	3	根尖密度 Tip density (No.·cm^-1)	分叉 Forks (No.·cm^-1)
马尾松 Pinus massoniana	23.53^ab (10.06)	11.73^a (4.34)	4.00^ab (0.72)	272.95^a (80.27)	184.08^a (40.16)	102.36^ab (26.7)	2.99^a (0.29)	5.09^a (1.11)
枫香 Liquidanbar formosana	31.45^a (11.67)	9.42^a (2.97)	3.71^ab (0.69)	271.72^a (75.45)	142.28^a (27.33)	84.73^ab (21.6)	2.85^a (0.21)	3.09^b (1.52)
拟赤杨 Alniphyllum fortunei	28.26^ab (12.89)	11.56^a (5.59)	4.13^ab (0.69)	247.20^a (76.57)	146.68^a (34.33)	82.86^ab (34.38)	2.38^a (0.27)	5.16^a (1.20)
青冈 Cyclobalanopsis glauca	23.40^ab (8.21)	8.67^a (10.56)	2.17^b (0.72)	228.85^a (78.60)	139.92^a (91.43)	61.57^b (14.43)	2.92^a (0.23)	3.95^ab (1.34)
杉木 Cunninghamia lanceolata	16.34b (10.07)	9.38a (3.57)	5.20a (0.72)	226.79a (37.25)	166.35a (41.75)	139.76a (90.48)	2.57a (0.22)	2.46b (0.77)