毛竹林扩张对周边森林群落菌根系统的影响

doi:10.17521/cjpe.2015.0036

摘要/Abstract

摘要：

毛竹(Phyllostachys heterocycla ‘Pubescens’)凭借其独特的生长特性极易扩张进入周边的常绿或针阔混交森林群落并取而代之。菌根减弱假说对毛竹林扩张导致周边林分枯亡并抑制林下幼苗更新的机制进行了解释, 即毛竹林的成功扩张是由于毛竹蔓延引起森林群落的菌根系统紊乱, 使宿主植物与菌根真菌的共生关系受到干扰, 进而影响了宿主植物的分布与更新。该研究以浙江省西天目山国家自然保护区为研究区域, 对菌根减弱假说进行了检验。通过在毛竹-针阔混交林交接区沿毛竹扩张方向设置毛竹纯林、竹-林过渡带、针阔混交林3种类型的样带, 选取在针阔混交林、竹-林过渡带同时存在的6种优势乔灌树种——杉木(Cunninghamia lanceolata)、枫香树(Liquidambar formosana)、青冈(Cyclobalanopsis glauca)、柳杉(Cryptomeria fortunei)、江浙山胡椒(Lindera chienii)、毛柄连蕊茶(Camellia fraterna), 测定这6个树种在两样带中的菌根侵染频率和强度, 检测在毛竹林扩张中周边森林群落菌根的响应, 同时对比了毛竹在毛竹纯林和竹-林过渡带菌根感染率和强度的变化, 检验该假设。实验结果表明: 1)针阔混交林和竹-林过渡带的主要树种菌根都具有较高的菌根侵染频率(> 95%), 且不同林分间林木的侵染频率无显著差异(p > 0.1); 2)在竹-林过渡带杉木和江浙山胡椒的丛枝菌根侵染强度较针阔混交林明显增加(p < 0.1); 3)毛竹的丛枝菌根侵染频率和强度远低于其他针阔树种, 且在扩张前后没有显著变化(p > 0.1)。实验结果否定菌根减弱假说。

关键词: 毛竹, 毛竹林扩张, 针阔混交林, 丛枝菌根, 外生菌根

Abstract: Aims

Phyllostachys heterocycla ‘Pubescens’, through its unique growth feature, is easy to encroach on, and replace surrounding evergreen broad-leaved forests or coniferous and broad-leaved mixed forests rapidly. The expansion leads to coniferous and broadleaved tree species withering and dying gradually, and inhibits the forest regeneration. Mycorrhizal weakening hypothesis suggests that expansion of P. heterocycla ‘Pubescens’ would interrupt the original mycorrhizal associations and causes the subsequence dieback of the forests. This study was to investigate the changes of mycorrhiza along a bamboo forest, bamboo-forest transition, mixed forest transect to examine the hypothesis.

Methods

A transect, perpendicular to the bamboo expansion direction, went through P. heterocycla ‘Pubescens’ forest (PPF), bamboo-forest transition (BFT), coniferous and broad-leaved mixed forest (CBF), and were sampled in the Tianmu Mountain National Reserve, Zhejiang Province. Six dominant tree and shrub species (Cunninghamia lanceolata, Liquidambar formosana, Cyclobalanopsis glauca, Cryptomeria fortune, Lindera chienii, Camellia fraterna) existing in both CBF and BFT, were chosen for collecting their root tips for measuring the frequency and intensity of arbuscular mycorrizal (AM) colonization for AM species, and frequency of ectomycorrhizal (EM) colonization for EM species. The AM colonization frequency and intensity of P. heterocycla ‘Pubescens’ in PPF and BFT were also measured and compared.

Important findings

1) Before and during the encroachment of P. heterocycla ‘Pubescens’, frequency of the mycorrhizal fungi root colonization of the six tree species were very high (>95%), and there was no significant difference between CBF and BFT (p > 0.1); 2) In BFT, intensity of the AM fungi root colonization of Cunninghamia lanceolata and Liquidambar formosana increased significantly than those in CBF (p < 0.1); 3) The frequency and intensity of the AM fungi root colonization of P. heterocycla ‘Pubescens’ were much lower than any other tree species, with no significant change during the expansion. The findings reject the mycorrhizal weakening hypothesis i.e., P. heterocycla ‘Pubescens’ realizing its population expansion and replacing surrounding forests IS NOT caused by destructing mycorrhizal associations of adjacent forests.

Key words: Phyllostachys heterocycla ‘Pubescens’, expansion of Phyllostachys heterocycla ‘Pubescens’ forest, coniferous and broad-leaved mixed forest, arbuscular mycorrhiza, ectomycorrhiza

潘璐, 牟溥, 白尚斌, 古牧. 毛竹林扩张对周边森林群落菌根系统的影响. 植物生态学报, 2015, 39(4): 371-382. DOI: 10.17521/cjpe.2015.0036

PAN Lu,MOU Pu,BAI Shang-Bin,GU Mu. Impact of Phyllostachys heterocycla ‘Pubescens’ expansion on mycorrhizal associations of the adjacent forests. Chinese Journal of Plant Ecology, 2015, 39(4): 371-382. DOI: 10.17521/cjpe.2015.0036

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2015.0036

https://www.plant-ecology.com/CN/Y2015/V39/I4/371

图/表 9

图1 试验地样带布设示意图。从毛竹纯林到针阔混交林, 海拔逐渐升高。

Fig. 1 Diagram of belt transects in the experimental area. The altitude gradually increased from PPF to CBF. BFT, bamboo-forest transition; CBF, coniferous and broad-leaved mixed forest; PPF, Phyllostachys heterocycla ‘Pubescens’ forest.

图2 丛枝菌根形态(墨水染色)。A, 杉木侵染根尖段。B, 杉木菌根内菌丝(箭头所示)。C, 杉木菌根丛枝结构(箭头所示)。D, 毛柄连蕊茶侵染根尖段。E, 毛柄连蕊茶菌根丛枝结构(箭头所示)。F, 毛柄连蕊茶菌根孢子(箭头所示)。G, 江浙山胡椒侵染根尖段。H, 江浙山胡椒菌根孢子(箭头所示)。I, 江浙山胡椒丛枝结构(箭头所示)。

Fig. 2 Morphology of arbuscular mycorrhiza, stained with ink. A, An infected root tip of Cunninghamia lanceolata. B, Arrow indicates intraradical hyphae in a root of Cunninghamia lanceolata. C, Arrow indicates arbuscules in a root of Cunninghamia lanceolata. D, A infected root tip of Camellia fraterna. E, Arrow indicates arbuscules in a root of Camellia fraterna. F, Arrow indicates a fungal spore in a root of Camellia fraterna. G, An infected root tip of Lindera chienii. H, Arrow indicates two fungal spores in a root of Lindera chienii. I, Arrow indicates arbuscules in a root of Lindera chienii.

图3 枫香树(A-C)、柳杉(D-F)、青冈(G-I)外生菌根形态。

Fig. 3 Morphology of ectomycorrhiza in Liquidambar formosana (A-C), Cryptomeria fortunei (D-F), and Cyclobalanopsis glauca (G-I).

图4 试验地3种林分的土壤pH值(A)、含水量(B)、铵态氮(C)、硝态氮(D)、总有效氮(E)对比(平均值±标准误差)。BFT, 竹-林过渡带; CBF, 针阔混交林; PPF, 毛竹纯林。不同小写字母表示同一林型中离毛竹根远近距离的土壤养分指标差异显著(p < 0.1)。

Fig. 4 Comparison of soil pH value (A), soil water content (B), NH4+-N (C), NO3--N (D), total available N (NH4+-N + NO3--N) (E) contents in three stands in the study site (mean ± SE). BFT, bamboo-forest transition; CBF, coniferous and broad-leaved mixed forest; PPF, Phyllostachys heterocycla ‘Pubescens’ forest. Different lowercase letters denote significant difference among soil nutrients due to the different distance to bamboo roots in the same forest stand (p < 0.1).

表1 浙江天目山禅源寺附近林区研究林地3种森林类型的土壤有效氮含量(平均值±标准误差)

Table 1 Available nitrogen contents in soil of three forest stands in experimental area near Chanyuan Temple, Tianmu Mountain, Zhejiang Province, China (mean ± SE)

样地类型 Stand type	n	土壤有效氮含量 Soil available N content (mg·kg^-1)
样地类型 Stand type	n	铵态氮 NH₄⁺-N (mg·kg^-1)	硝态氮¹⁾ NO₃^--N (mg·kg^-1)¹⁾	铵态氮+硝态氮 NH₄⁺-N + NO₃^--N (mg·kg^-1)
毛竹纯林 Phyllostachys heterocycla ‘Pubescens’ forest	10	0.026 8 ± 0.002 0^a	0.002 1 ± 0.000 3^b	0.029 0 ± 0.002 1^a
竹-林过渡带 Bamboo-forest transition	10	0.024 1 ± 0.002 2^ab	0.005 2 ± 0.000 6^a	0.029 3 ± 0.002 3^a
针阔混交林 Coniferous and broad-leaved mixed forest	5	0.197 0 ± 0.000 5^b	0.003 7 ± 0.000 2^a	0.023 4 ± 0.000 4^a

图5 试验地丛枝菌根树种杉木、毛柄连蕊茶、江浙山胡椒在毛竹-针阔混交林竞争界面两侧的菌根侵染频率和强度对比(平均值±标准误差)。BFT, 竹-林过渡带; CBF, 针阔混交林。不同小写字母表示不同样带的差异显著(p < 0.1)。

Fig. 5 Comparison of frequency and intensity of the arbuscular mycorrhizal fungi root colonization of Cunninghamia lanceolata (A), Camellia fraternal (B), Lindera chienii (C) at two sides of bamboo and broad-leaved forest interface in the study site (mean ± SE). BFT, bamboo-forest transition; CBF, coniferous and broad-leaved mixed forest. Different lowercase letters denote significant difference among different forest stands (p < 0.1).

图6 试验地外生菌根树种枫香树、柳杉、青冈在竹-针阔竞争界面两侧的菌根侵染频率对比(平均值±标准误差)。BFT, 竹-林过渡带; CBF, 针阔混交林。相同小写字母表示同一树种在不同样带的侵染频率差异不显著(p < 0.1)。

Fig. 6 Comparison of frequency of the ectomycorrhizal fungi root colonization in Liquidambar formosana, Cryptomeria fortune, Cyclobalanopsis glauca at two sides of bamboo and broad-leaved forest interface in the study site (mean ± SE). BFT, bamboo-forest transition; CBF, coniferous and broad- leaved mixed forest. Same lowercase letter denotes insignificant difference between the same species in different stands (p < 0.1).

图7 试验地毛竹在竹-林过渡带、毛竹纯林的菌根侵染频率和强度对比(平均值±标准误差)。BFT, 竹-林过渡带; PPF, 毛竹纯林。相同小写字母表示同一树种在不同样带的侵染频率差异不显著(p < 0.1)。

Fig. 7 Comparison of frequency and intensity of the arbuscular mycorrhizal fungi root colonization of Phyllostachys heterocycla ‘Pubescens’ at coniferous and broad-leaved mixed forest and coniferous and broad-leaved mixed forest in the study site (mean ± SE). BFT, bamboo-forest transition; PPF, Phyllostachys heterocycla ‘Pubescens’ forest. Same lowercase letter denotes insignificant difference between the same species in different stands (p < 0.1).

图8 毛竹丛枝菌根形态(墨水染色)。A, 箭头所示为胞内的丛枝结构。B, 箭头所示为根内孢子。

Fig. 8 Morphology of arbuscular mycorrhiza of Phyllostachys heterocycla ‘Pubescens’ stained with ink. A, Arrow indicates arbuscules in the root cells. B, Arrow indicates a fungal spore in a bamboo root.

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