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Strategy of fine root expansion of Phyllostachys pubescens population into evergreen broadleaved forest

毛竹种群向常绿阔叶林扩张的细根策略


为了探讨毛竹(Phyllostachys pubescens)种群向常绿阔叶林扩张的根系策略, 该文采用根钻法和内生长法, 在江西大岗山选取毛竹林与阔叶林的交错区——竹阔界面(bamboo-broad-leaved forest interface), 并垂直于界面连续设置毛竹林、毛竹与阔叶树的混交林(以下简称为竹阔混交林)、常绿阔叶林3种样地, 比较分析其细根的空间分布格局、比根长、根长密度、生长速率和周转率等指标。结果表明: 毛竹林细根生物量(1 201.60 g·m-2) >竹阔混交林(601.18 g·m-2) >常绿阔叶林(204.88 g·m-2); 在毛竹与阔叶树竞争的混交林中, 毛竹细根分布趋向于上层土壤(与毛竹林细根相比), 且其比根长也显著增加, 平均增幅高达123.42%, 总根长密度比阔叶树大2.1倍; 同时, 毛竹细根生长速率和周转率均高于阔叶树。这些结果说明毛竹可通过广布、精准、灵活、快速等细根竞争策略, 提高资源获取能力, 实现种群扩张。

Aims Roots, particularly fine roots, play an important role in interspecies competition. Our objective was to study the spatial distribution, morphological characteristics and growth rates of fine roots in both bamboo (Phyllostachys pubescens) and broad-leaved trees to better understand the mechanisms of expansion of bamboo into evergreen broad-leaved forest.
Methods We continuously sampled P. pubescens forest (PPF), bamboo-broad-leaved mixed forest (BMF) and evergreen broad-leaved forest (EBF) perpendicular to a bamboo-broad-leaved forest interface on Dagang Mountain, Jiangxi Province, China. The live fine root biomass, specific root length (SRL), root length density (RLD), fine root growth and turnover rates were comparatively analyzed by soil core and ingrowth methods.
Important findings Fine root biomass of PPF (1 201.60 g·m-2) was much larger than that of BMF (601.18 g·m-2) and EBF (204.88 g·m-2). Vertical stratification of bamboo fine roots in BMF was found to shift from lower to upper soil layers, SRL of bamboo significantly increased by 123.42% and average RLD of bamboo was 210.0% greater than that of broad-leaved trees. In addition, both growth and turnover rates of bamboo fine roots were faster than those of trees. Findings indicated that P. pubescens, with wide, precise, flexible and fast nutrient access and space-occupation abilities, would outcompete trees belowground, resulting in expansion of its population into evergreen broad-leaved forest.


全 文 :植物生态学报 2013, 37 (3): 230–238 doi: 10.3724/SP.J.1258.2013.00023
Chinese Journal of Plant Ecology http://www.plant-ecology.com
——————————————————
收稿日期Received: 2012-09-24 接受日期Accepted: 2013-01-28
* 通讯作者Author for correspondence (E-mail: qingpeiyang@126.com)
毛竹种群向常绿阔叶林扩张的细根策略
刘 骏 杨清培* 宋庆妮 余定坤 杨光耀 祁红艳 施建敏
江西农业大学, 江西省竹子种质资源与利用重点实验室, 南昌 330045
摘 要 为了探讨毛竹(Phyllostachys pubescens)种群向常绿阔叶林扩张的根系策略, 该文采用根钻法和内生长法, 在江西大
岗山选取毛竹林与阔叶林的交错区——竹阔界面(bamboo-broad-leaved forest interface), 并垂直于界面连续设置毛竹林、毛竹
与阔叶树的混交林(以下简称为竹阔混交林)、常绿阔叶林3种样地, 比较分析其细根的空间分布格局、比根长、根长密度、生
长速率和周转率等指标。结果表明: 毛竹林细根生物量(1 201.60 g·m–2) >竹阔混交林(601.18 g·m–2) >常绿阔叶林(204.88
g·m–2); 在毛竹与阔叶树竞争的混交林中, 毛竹细根分布趋向于上层土壤(与毛竹林细根相比), 且其比根长也显著增加, 平均
增幅高达123.42%, 总根长密度比阔叶树大2.1倍; 同时, 毛竹细根生长速率和周转率均高于阔叶树。这些结果说明毛竹可通
过广布、精准、灵活、快速等细根竞争策略, 提高资源获取能力, 实现种群扩张。
关键词 大岗山, 常绿阔叶林, 毛竹种群扩张, 细根策略
Strategy of fine root expansion of Phyllostachys pubescens population into evergreen broad-
leaved forest
LIU Jun, YANG Qing-Pei*, SONG Qing-Ni, YU Ding-Kun, YANG Guang-Yao, QI Hong-Yan, and SHI Jian-Min
Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Utilization, Jiangxi Agricultural University, Nanchang 330045, China
Abstract
Aims Roots, particularly fine roots, play an important role in interspecies competition. Our objective was to
study the spatial distribution, morphological characteristics and growth rates of fine roots in both bamboo (Phyl-
lostachys pubescens) and broad-leaved trees to better understand the mechanisms of expansion of bamboo into
evergreen broad-leaved forest.
Methods We continuously sampled P. pubescens forest (PPF), bamboo-broad-leaved mixed forest (BMF) and
evergreen broad-leaved forest (EBF) perpendicular to a bamboo-broad-leaved forest interface on Dagang Moun-
tain, Jiangxi Province, China. The live fine root biomass, specific root length (SRL), root length density (RLD),
fine root growth and turnover rates were comparatively analyzed by soil core and ingrowth methods.
Important findings Fine root biomass of PPF (1 201.60 g·m–2) was much larger than that of BMF (601.18
g·m–2) and EBF (204.88 g·m–2). Vertical stratification of bamboo fine roots in BMF was found to shift from lower
to upper soil layers, SRL of bamboo significantly increased by 123.42% and average RLD of bamboo was 210.0%
greater than that of broad-leaved trees. In addition, both growth and turnover rates of bamboo fine roots were
faster than those of trees. Findings indicated that P. pubescens, with wide, precise, flexible and fast nutrient access
and space-occupation abilities, would outcompete trees belowground, resulting in expansion of its population into
evergreen broad-leaved forest.
Key words Dagang Mountain, evergreen broad-leaved forest, expansion of Phyllostachys pubescens population,
fine root strategy

毛竹(Phyllostachys pubescens)是一种高大的乔
木状竹类植物, 广泛分布于我国南方地区。日本和
欧美均有引种栽培(易同培等, 2008)。研究发现, 毛
竹依靠强大的地下茎(竹鞭)向其邻近的其他林分逐
渐扩张 , 形成大量的竹木混交林甚至毛竹纯林
(Isagi & Torii, 1998; 丁丽霞等, 2006)。竹林扩张导
致森林景观破坏(Isagi & Torii, 1998)、生物多样性减
少(Kiyoshi et al., 1996)、生态功能下降(李伟成等,
2006)等一系列问题, 引起了学者们的广泛关注(丁
丽霞等, 2006), 并初步发现快生长、高树冠(Kiyoshi
刘骏等: 毛竹种群向常绿阔叶林扩张的细根策略 231

doi: 10.3724/SP.J.1258.2013.00023
et al., 1996)等地上竞争优势是毛竹成功扩张的重要
原因, 然而对地下竞争的情况却知之甚少。
地下根系竞争是影响种群发展及群落动态的
主要因素(Chakraborty & Li, 2009; Lei et al., 2012),
如小黑麦(Triticosecale wittmack)与蚕豆(Vicia faba)
套作, 没有根系竞争时蚕豆为优势种, 而发生根系
竞争时, 小黑麦的生长却明显占优势(Sobkowicz,
2005)。在竞争过程中, 不同的植物会采取不同的根
系策略, 如在欧洲云杉(Picea abies)与欧洲水青冈
(Fagus sylvatica)混交、竞争时, 欧洲云杉会将细根
分布在土壤表层, 以接近较多的养分资源(Schmid
& Kazda, 2002), 而欧洲水青冈却将细根从表层转
向深层, 增加比根长(specific root length, SRL, 即单
位质量的细根总长)、比面积(SSA)来提高空间拓展
效率(Bolte & Villanueva, 2006); 而在胡桃(Juglans
regia) –小麦(Triticum aestivum)复合系统中, 胡桃细
根SRL却出现减小的现象(王来等, 2011); 另外, 在
加拿大寒带森林中, 美洲山杨(Populus tremuloides)
和北美白桦(Betula papyrifera)通过细根较快的生长
速度优先占领良好环境 , 实现与白云杉 (Picea
glauca)等针叶树的共存(Bauhus & Messier, 1999)。
由此可见 , 植物可以通过调节根系的空间分布
(Fransen et al., 1999; Zhou & Shangguan, 2006)、形
态结构 (Johnson & Biondini, 2001)和生长速率
(Kroons & Hutchings, 1995)等方式有效地开发资源,
在竞争中达到多种物种共存或取得优势, 从而维持
物种多样性或推动群落的发展。
毛竹种群向邻近阔叶林扩张, 在毛竹林与阔叶
林的交错区——竹阔界面 (bamboo-broad-leaved
forest interface)必然引起毛竹与阔叶树之间强烈的
地下竞争。那么, 在此竞争过程中, 毛竹根系是否
存在形态可塑与空间分化?如果存在, 那么, 毛竹
细根分布格局是否会发生变化?毛竹细根比根长
是否会改变?毛竹细根生长速率和周转率表现怎
样?为此, 本研究在江西大岗山选取典型的竹阔界
面样地, 沿毛竹水平扩张方向, 对毛竹林、毛竹与
阔叶树的混交林(以下简称为竹阔混交林)和常绿阔
叶林的细根(直径≤2 mm)生物量、SRL、根长密度
(root length density, RLD, 即单位面积的细根总长)、
生长速率(growth rate)和周转率(turnover rate)等指
标, 进行了比较分析, 以验证以下3个假设: 1)与毛
竹纯林相比, 在竹阔混交林中, 毛竹细根有向上层
土壤分布的趋势; 2)在与阔叶树竞争的情况下, 毛
竹细根会增加比根长; 3)与阔叶树相比, 毛竹细根
具有较快的生长速度和周转率。通过检验上述假设,
我们可以了解毛竹与阔叶树地下根系竞争的规律,
为毛竹种群扩张机制研究提供新的视角和理论参
考。
1 材料和方法
1.1 研究区概况
研究区位于江西省分宜县境内的大岗山国家
级森林生态系统定位研究站, 地理坐标为114°30′–
114°45′ E, 27°30–27°50′ N, 属于典型的中亚热带湿
润气候, 年平均气温为15.8–17.7 ℃, 极端最高气温
39.9 ℃, 极端最低气温–8.3 ℃, 年积温5 355 ℃, 年
降水量为1 591 mm, 无霜期为265天, 土壤为黄壤
或黄红壤, 地带性植被类型为常绿阔叶林。同时,
这里也是毛竹的适生区。研究发现毛竹林呈现不断
扩大的趋势, 逐渐向邻近的常绿阔叶林扩张, 形成
大量的竹阔混交林(杨清培等, 2011), 为我们的细根
策略研究提供了较理想的场地。
1.2 样地选择与根系采样
2010–2011年 , 选取典型的竹阔界面 , 海拔
280–320 m, 坡度20°–25°。沿毛竹林水平扩张方向
连续设置毛竹林、竹阔混交林、常绿阔叶林3种林
分样方, 样方大小为10 m × 20 m, 5次重复, 共计15
个样方。毛竹林是30年前自然扩张形成的毛竹纯林;
竹阔混交林是近10年毛竹向常绿阔叶林扩张形成
的混交林 ; 常绿阔叶林是以丝栗栲 (Castanopsis
fargesii)为优势种的次生林, 林龄40–50年, 主要伴
生种有苦槠 (Castanopsis sclerophylla)、小叶栎
(Quercus chenii)、黄牛奶树(Symplocos laurina)等,
其林分特征见表1。
按S型路线, 采用根钻法(内径为49 mm)测定生
物量(温达志等, 1999), 在每个样方各取6个采样点,
分层(0–20、20–40和40–60 cm)钻取土芯, 共4次(夏
季2010-07-03、秋季2010-10-02、冬季2011-01-03、
春季2011-04-05)。采用内生长法测定细根生长量
(Persson, 1983), 先用大土钻(内径为60 mm)取土芯,
除去根系, 制成无根土, 再按土壤剖面顺序填回原
土芯洞中, 培养细根生长。每个样方埋入36管无根
土, 并用铁丝圈作固定标记(2010-09-05)。此后每2
个月用小土钻(内径为49 mm)按上述层次取土芯样
232 植物生态学报 Chinese Journal of Plant Ecology 2013, 37 (3): 230–238

www.plant-ecology.com
表1 试验地竹阔界面3种林分特征(平均值±标准误差)
Table 1 Characteristics of three forest stands at bamboo-broad-leaved forest interface in experimental area (mean ± SE)
林分
Stand
植物高度
Plant hight (m)
胸径
DBH (cm)
密度
Density (ind.·hm–2)
毛竹林 PPF 13.83 ± 1.72 10.07 ± 1.76 5 100
12.66 ± 1.53 9.45 ± 1.27 2 100 竹阔混交林 BMF
14.37 ± 2.72 16.30 ± 13.43 1 800
常绿阔叶林 EBF 14.95 ± 2.74 17.76 ± 9.35 1 078
BMF, bamboo and broad-leaved mixed forest; DBH, diameter at breast height; EBF, evergreen broad-leaved forest; PPF, Phyllostachys pubescens
forest.


品1次(每个样方6管), 共取6次(最后1次取样时间为
2011-09-05)。将所取土芯样品装入保鲜袋, 并带回
实验室, 放置于4 ℃冰箱内保存, 2周之内完成根系
样品相关处理。
1.3 根系样品处理与测定
土芯样品经过自来水浸泡、冲洗、过筛, 根据
外形、颜色和弹性挑选出直径小于2 mm的活根, 并
将竹阔混交林中的毛竹细根和阔叶树细根分开。将
所有样品置于65 ℃烘箱烘干至恒重(48 h)。生物量、
比根长、细根周转率的测量方法见参考文献
(Johnson et al., 2001; 梅莉等, 2006), 相关公式如
下。
B = W / [π × (0.049 / 2)2] (1)
SRL = L / W (2)
RLD = B × SRL (3)
T = P / Bave (4)
公式(1–4)中, B为细根生物量(g·m–2), W为土柱细根
质量(g), 0.049为根钻内径(m), L为土柱细根总长度
(m), T为细根周转率(times·a–1), P为细根年生长量,
即最后1次取样所得细根生长量(g·m–2·a–1), Bave为细
根年平均生物量, 即4个季节细根生物量的平均值
(g·m–2)。
1.4 数据分析
每次实验, 每个样方各指标均可获得6个数据,
将这6个数据的平均值作为1个重复, 因每个林分有
5个样方, 于是每个林分各指标均可获得5个重复。
采用general linear model (GLM)单变量多因素
方差分析判断不同林分、不同季节、不同土层间细
根生物量以及相同土层中不同林分细根RLD的差异
显著性。若差异达显著水平(p < 0.05), 则采用最小
显著差数法(least significant difference, LSD)对它们
的均值进行多重比较。采用单因素方差分析
(one-way ANOVA)判断毛竹与阔叶树细根在不同林
分中垂直分布格局和比根长的显著性; 采用配对t
检验对毛竹和阔叶树细根生长量进行显著性差异
分析。在上述检验前, 均需采用Levene’s test方差齐
性检验对方差齐性进行检验, 未通过检验者, 对数
据进行对数、平方根或倒数等转换, 将数据转换成
齐性数据后再进行分析, 如果方差仍不具有齐性,
则采用Kruskal-Wallis H(K)检验差异显著性。
数据整理、制图由Excel 2010实现; GLM单变量
多因素方差分析、one-way ANOVA、配对t检验、
Levene’s test方差齐性检验由SPSS 19.0完成。
2 结果和分析
2.1 细根生物量及其空间分布
竹阔界面毛竹林、竹阔混交林、常绿阔叶林细
根生物量存在显著差异(F = 165.81, p < 0.001, 表2),
细根生物量在3个土壤层次(0–20、20–40和40–60
cm)均表现为: 毛竹林 > 竹阔混交林 > 常绿阔叶
林(图1)。3个土层中, 毛竹林细根生物量分别为
631.91、382.43、187.26 g·m–2; 竹阔混交林居中, 分
别为368.57、161.22、71.39 g·m–2, 常绿阔叶林最低,
分别为135.64、44.88、24.36 g·m–2 (图1)。在0–60 cm
土层中, 这3种林分依次为1 201.60 g·m–2、601.18
g·m–2、204.88 g·m–2。生物量的大小可反映细根的分
布范围和对土壤资源的竞争能力(Heinsoo et al.,
2009)。毛竹生物量较高, 说明它具有较强的养分资
源垄断能力。
随着毛竹向常绿阔叶林的扩张, 毛竹与阔叶树
的竞争引起毛竹细根生物量的空间分布格局发生
明显变化(图2)。在竹阔混交林中, 毛竹细根在0–20
cm土层的比例显著增加(F = 8.11, p = 0.036 < 0.05),
由毛竹林中的52.59%增加到61.65%, 而在20–40 cm
和40–60 cm土层中的比例却大大下降 , 分别由
31.83%和15.58%减小到27.12%和11.23% (F20–40 =
刘骏等: 毛竹种群向常绿阔叶林扩张的细根策略 233

doi: 10.3724/SP.J.1258.2013.00023
表2 试验地竹阔界面不同林分细根生物量的方差分析
Table 2 Analysis of variance (ANOVA) of fine root biomass in different forest stands at bamboo-broad-leaved forest interface in
experimental area
因子 Factor df MS F p
林分 Stand 2 11.139 165.811 <0.001***
季节 Season 3 0.009 0.141 0.935
土壤层次 Soil layer 2 7.731 115.083 <0.001***
林分×季节 Stand × season 6 0.096 1.425 0.209
林分×土壤层次 Stand × soil layer 4 0.156 2.315 0.060
季节×土壤层次 Season × soil layer
林分×季节×层次 Stand × season × soil layer
误差 Error
6
12
144
0.072
0.033
0.067
1.077
0.496
0.379
0.915
***, p < 0.001.



图1 试验地垂直于竹阔界面的3种林分3个土壤层次(0–20,
20–40, 40–60 cm)中细根生物量比较(平均值±标准误差)。不
同字母表示同一土壤层次林分间细根生物量差异显著(p <
0.05, 最小显著差数法)。
Fig. 1 Comparison of fine root biomass in three soil layers
(0–20, 20–40, 40–60 cm) of three forest stands perpendicular to
bamboo-broad-leaved forest interface in experimental area
(mean ± SE). Different letters indicate significant difference
among fine root biomass in the same soil layers at different
forest stands (p < 0.05, least significant difference, LSD). BMF,
bamboo and broad-leaved mixed forest; EBF, evergreen
broad-leaved forest; PPF, Phyllostachys pubescens forest.


0.57, p = 0.477 > 0.05; F40–60 = 8.42, p = 0.027 < 0.05,
图2A)。相反, 阔叶树细根生物量在0–20 cm土层中
的比例由66.33%下降至60.57% (F = 0.42, p = 0.539
> 0.05), 而20–40 cm和40–60 cm土层中的比例相应
增加(图2B)。这说明在毛竹与阔叶树的竞争过程中,
毛竹细根有向营养物质丰富的上层土壤分布的趋
势。
2.2 细根比根长
在毛竹与阔叶树的竞争中, 毛竹的细根SRL都
表现出明显的形态可塑性(图3)。在0–20 cm、20–40
cm和40–60 cm 3个土层中, 毛竹细根SRL分别由毛
竹林中的3.82、4.48、6.24 m·g–1增加至竹阔混交林
中的8.01、9.47、15.55 m·g–1 (F0–20 = 5.34, p = 0.025 <
0.05; F20–40 = 4.53; p = 0.038 < 0.05; F40–60 = 13.54; p
= 0.001 < 0.01), 平均增幅达到123.42% (图3A)。阔
叶树细根SRL也分别由常绿阔叶林中的13.14、
14.63、18.97 m·g–1变为竹阔混交林的12.67、16.39、
24.13 m·g–1 (F0–20 = 0.20, p = 0.66 > 0.05; F20–40 =
0.44, p = 0.512 > 0.05; F40–60 = 0.006, p = 0.937 >
0.05), 但平均增幅仅为11.88% (图3B)。SRL反映了
植物对养分与水分的吸收能力, SRL越大, 吸收能力
越强(Metcalfe et al., 2008)。毛竹的SRL增幅远大于
阔叶树, 说明毛竹细根形态可塑性更高、适应性更
强(Pregitzer et al., 1998)。
2.3 根长密度
毛竹与阔叶树的竞争导致其混交林表层细根
RLD明显增加(图4)。毛竹林的RLD为5 239.80 m·m–2
(0–60 cm土层合计), 其中0–20 cm、20–40 cm和
40–60 cm土层的RLD分别为2 440.37、1 643.43和
1 156.00 m·m–2; 常绿阔叶林的 RLD为 2 928.94
m·m–2 (0–60 cm土层合计), 相应土层的RLD分别为
1 801.18、663.97和463.79 m·m–2。竹阔混交林表层
细根的RLD明显高于毛竹林与常绿阔叶林, 总计为
4 613.20 m·m–2, 在0–20 cm、20–40 cm和40–60 cm 3
个土层的RLD分别为2 545.20、1 327.31和740.34
m·m–2 (图4)。同时, 在竹阔混交林中, 毛竹细根的
RLD显著高于阔叶树 , 前者是后者的2.1倍 (F =
16.42, p = 0.004 < 0.01) (图5), 这说明毛竹细根具有
较好的土壤空间拓展能力(Bolte & Villanueva, 2006;
史建伟等, 2011)。
234 植物生态学报 Chinese Journal of Plant Ecology 2013, 37 (3): 230–238

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图2 试验地竹阔竞争引起毛竹(A)与阔叶树(B)细根生物量垂直空间分布格局变化(平均值±标准误差)。不同小写字母表示同
一土层中毛竹或阔叶树在竞争前后细根生物量比例差异显著(p < 0.05, 方差分析)。
Fig. 2 Variation in vertical distribution pattern of fine root biomass of Phyllostachys pubescens (A) and broad-leaved trees (B)
when they competed in experimental area (mean ± SE). Different lowercase letters indicate significant difference of proportion of
fine root biomass of Phyllostachys pubescens or broad-leaved trees at the same soil layer between pre- and in-competition periods (p
< 0.05, analysis of variance).



图3 试验地竹阔竞争引起毛竹(A)与阔叶树(B)细根比根长变化(平均值±标准误差)。不同小写字母表示同一土层中毛竹或阔
叶树在竞争前后细根比根长差异显著(p < 0.05, 方差分析)。
Fig. 3 Variation in specific root length (SRL) of Phyllostachys pubescens (A) and broad-leaved trees (B) when they competed in
experimental area (mean ± SE). Different lowercase letters indicate significant difference of SRL of P. pubescens or broad-leaved
trees at the same soil layer between pre- and in-competition periods (p < 0.05, analysis of variance).


2.4 细根年生长量与周转率
毛竹林细根年生长量明显高于常绿阔叶林(图
6)。毛竹细根年生长量为946.72 g·m–2, 常绿阔叶林
为130.93 g·m–2, 前者是后者的7.2倍。快速的细根生
长, 使毛竹在空间占领速度和范围方面获得优势
(Bolte & Villanueva, 2006)。另外, 毛竹细根周转率
也稍高于阔叶树(图7)。毛竹细根周转速率为0.79
times·a–1, 阔叶树为0.64 times·a–1 (F = 0.72, p =
0.416 > 0.05)。较快的细根周转, 可以产生更多的新
根替代旧根, 保证植物对水分和养分的吸收效率
(裴智琴等, 2011)。可见, 快速的细根生长与周转,
使毛竹具有较强的养分与水分吸收能力。
3 结论和讨论
3.1 生物量及其空间分化策略
生物量表征着根系的广布性(Wijesinghe et al.,
2001), 也反映了植物对土壤资源的竞争能力(王庆
成和程云环, 2004)。毛竹细根生物量远高于常绿阔
叶林(5.86倍), 说明毛竹细根具有较高的广布性(王
庆成和程云环, 2004)。
同时, 种间竞争常引起细根垂直分布发生变
化 , 如刘桂华和李宏开 ( 2 0 0 2 )在毛竹和檫树
(Sassafras tsumu)混交生长时发现毛竹鞭根有向上
层集中的现象, Schmid和Kazda (2002)发现在欧洲
刘骏等: 毛竹种群向常绿阔叶林扩张的细根策略 235

doi: 10.3724/SP.J.1258.2013.00023


图4 试验地竹阔界面3种林分细根根长密度在不同土壤层
次(0–20, 20–40, 40–60 cm)中的比较(平均值±标准误差)。不
同字母表示同一土层中3种林分细根根长密度差异显著(p <
0.05, 最小显著差数法)。
Fig. 4 Comparison of root length density (RLD) in three soil
layers (0–20, 20–40, 40–60 cm) of the three forest stands at
bamboo-broad-leaved forest interface in the experimental area
(mean ± SE). Different letters indicate significant difference
among fine root RLD in the same soil layer at different forest
stands (p < 0.05, least significant difference, LSD). BMF,
bamboo and broad-leaved mixed forest; EBF, evergreen
broad-leaved forest; PPF, Phyllostachys pubescens forest.




图5 试验地竹阔混交林中毛竹、阔叶树细根根长密度比较
(平均值±标准误差)。不同字母表示同一土层中毛竹与阔叶
树细根根长密度差异显著(p < 0.05, 方差分析)。
Fig. 5 Comparison of root length density (RLD) of Phyll-
ostachys pubescens and broad-leaved trees in bamboo and
broad-leaved mixed forest in the experimental area (mean
± SE). Different letters indicate significant difference of fine
root RLD between P. pubescens and broad-leaved trees in the
same soil layer (p < 0.05, analysis of variance). FBM, fine root
of broad-leaved trees; FPM, fine root of P. pubescens.


云杉与欧洲水青冈混交竞争时, 会将细根向表层土
壤分布, 但郑郁善和王舒凤(2000)发现毛竹和杉木
混交使得毛竹鞭根向下层转移, 说明根系竞争策略
与其竞争物种密切相关。一般认为根系趋向营养丰



图6 试验地毛竹和阔叶树细根年生长动态比较(平均值±标
准误差)。
Fig. 6 Comparison of annual production dynamics of fine
root between Phyllostachys pubescens and broad-leaved trees
in experimental area (mean ± SE). FBM, fine root of broad-
leaved trees; FPM, fine root of P. pubescens.



图7 试验地毛竹和阔叶树细根周转率比较(平均值±标准误
差)。相同字母表示毛竹和阔叶树细根周转率差异不显著(p >
0.05, 方差分析)。
Fig. 7 Comparison of turnover rate of fine root between
Phyllostachys pubescens and broad-leaved trees in experimen-
tal area (mean ± SE). Same letters indicate no significant dif-
ference of turnover rate of fine root between P. pubescens and
broad-leaved trees (p > 0.05, analysis of variance). EBF, ever-
green broad-leaved forest; PPF, Phyllostachys pubescens forest.


富腐殖质层分布代表了觅食精确性(Campbell et al.,
1991), 是根系竞争力的重要体现(Schmid & Kazda,
2002)。本研究发现, 随着毛竹向常绿阔叶林扩张,
毛竹细根在0–20 cm土层的分布比例由毛竹林中的
52.59%增加至竹阔混交林中的61.65% (p < 0.05),
而阔叶树却由66.33%下降至60.57% (p > 0.05)。可
见, 毛竹在与阔叶树竞争的过程中, 会调整其细根
的空间分布格局, 将更多的细根分配到营养丰富的
表层土壤, 支持我们的第一个假设, 这也体现了毛
竹细根具有较高的觅食精确性。
236 植物生态学报 Chinese Journal of Plant Ecology 2013, 37 (3): 230–238

www.plant-ecology.com
尽管Campbell等(1991)认为根系广布性和觅食
精确性之间是负相关的, 但是通过本研究发现, 毛
竹既具有较宽的细根广布性, 又具有较高的觅食精
确性 , 这与Einsmann等 (1999)对大叶假含羞草
(Chamaecrista nictitans)等6种草本植物研究的结果
相一致。
3.2 形态可塑性策略
SRL不但是表征细根形态的一个重要参数
(Ostonen et al., 2007), 而且是衡量根系竞争策略的
重要指标(Casper & Jackson, 1997)。
虽然有人认为SRL的减小能使植物适应竞争压
力, 如王来等(2011)发现, 胡桃–小麦农林复合系统
中小麦就会增加细根直径 , 减小SRL。Zamora等
(2007)也发现, 在陆地棉(Gossypium hirsutum)与美
国山核桃(Carya illinoensis)的竞争中有显著减小
SRL的现象, 但是大多数研究学者认为SRL的增大
有利于增强细根竞争力(Davis et al., 2004), 如Curt
和 Prévosto (2003)研究发现, 欧洲水青冈在与欧洲
赤松(Pinus sylvestris)、垂枝桦(Betula pendula)的根
系竞争中, SRL增大; 强烈竞争环境中, 赤松(Pinus
densiflora)细根的SRL也显著增加(Fujii & Kasuya,
2008)。本研究发现, 随着毛竹种群扩张, 毛竹与阔
叶树的地下竞争加剧, 虽然二者的SRL都明显增加,
但毛竹林的增幅更明显(123.42%), 支持我们的第
二个假设。可见, 毛竹细根形态可塑性比阔叶树要
强, 说明增加细根的SRL也是提高毛竹竞争力的重
要方式。
同样, RLD用来表示植物对空间与养分资源的
分享比例, 反映着植物竞争能力的大小(Livesley et
al., 2000)。毛竹林细根RLD远高于常绿阔叶林, 且
在竹阔混交林中, 毛竹细根RLD显著高于阔叶树
(高2.1倍), 说明毛竹林细根竞争能力大于阔叶树。
这是毛竹成功扩张的又一细根策略。
3.3 细根生长与周转策略
生长量也代表细根对土壤资源的竞争能力
(Gersani et al., 2001)。Lei等(2012)发现, 为了争夺土
壤资源和生存空间, 花旗松(Pseudotsuga menziesii)
和欧洲云杉在混交栽培时, 其细根生长量均高于纯
林栽培; Brassard等(2011)发现Populus tremuloides、
云杉(Picea spp.)、Abies balsamea也具有相同的竞争
效应。本研究中, 毛竹林细根增殖能力较强, 年生
长量是常绿阔叶林的7.2倍, 因为毛竹林每年都有
大量鞭根与竹根分别从新鞭和竹蔸上长出(熊国辉
等, 2007), 在毛竹扩张过程中, 它能以较快的速度
抢占较大的空间资源。细根周转率也是种间地下竞
争的重要策略(裴智琴等, 2011)。根系周转率高, 会
使衰老细根以较快的速度被新生细根替代, 从而能
持续获取土壤资源(Eissenstat et al., 2000)。本研究
中, 毛竹细根周转速率快于常绿阔叶林, 较快的周
转速率保证了毛竹获取养分资源的能力, 从而为毛
竹扩张奠定了基础。可见, 以上结果支持我们的第
三个假设。
总之, 毛竹可通过广布、精准、灵活、快速等
细根竞争策略, 提高资源获取能力, 实现种群扩
张。当然, 种间竞争是一个复杂的生态问题, 地上
和地下的关系(Palacio & Montserrat-Martí, 2007)、植
物和微生物的关系(Kalliokoski et al., 2010)、土壤营
养状况(Hodge, 2004)等因素都会影响到植物种间竞
争。本实验从野外群落水平研究了毛竹与阔叶树间
的根系竞争关系, 要想真正弄清二者的关系及其内
在的机理, 还有待于下一步的控制实验。
基金项目 国家自然科学基金(31260120和3117-
0306)和江西省自然科学基金(20122BAB204019)。
致谢 感谢大岗山国家级森林生态实验站提供研
究平台。
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