为探究胡杨异形叶随树冠高度变化的空间分布规律,以甘肃河西走廊金塔县的人工胡杨林植株为研究对象,调查树冠不同分层间胡杨各异形叶出现频率。结果表明:条形叶与披针形叶频率在树冠底部最高,锯齿卵形叶出现频率在树冠中部达到最大,锯齿阔卵形叶与锯齿扇形叶多出现于树冠上部。其中,条形叶频率、锯齿卵形叶频率与锯齿扇形叶频率在树冠各分层间叶形存在显著差异。随着树冠高度的增加,条形叶出现频率逐渐减少,披针形叶出现频率无明显变化,而锯齿卵形叶、锯齿阔卵形叶和锯齿扇形叶的出现频率逐渐增大;各异形叶在树冠垂直空间分布上表现出一定的消长规律。本研究结果揭示了胡杨异形叶在树冠层的分布规律,有助于深入了解胡杨异形叶对生存环境的适应性变化。 In order to explore the vertical spatial distribution law of the heteromorphic leaves in the canopy of Populus euphratica, the occurrence frequencies of heteromorphic leaves among different layers of the canopy were investigated by taking the artificial P. euphratica forest in Jinta County. The results showed that the frequencies of linear and lanceolate leaves were the highest at the bottom of the crown, the frequency of dentate ovate leaves was the highest in the middle of the crown, and the frequency of dentate broad-ovate leaves and dentate fan-shaped leaves was the highest in the upper part of the crown. Among heteromorphic leaves, the frequencies of linear leaves, dentate ovate leaves and dentate fan-shaped leaves were significantly different among the tree crown layers. The different heteromorphic leaves showed different trends with the increasing the tree crown height, the frequency of linear leaves gradually decreased, the frequencies of dentate ovate leaves, dentate broad-ovate leaves and dentate fan-shaped leaves significantly increased, while the frequency of lanceolate leaves were not significant changes. The relationships of each frequency of heteromorphic leaves in the vertical spatial distribution in the canopy showed a trade-off pattern. These results reveal the distribution pattern of heteromorphic leaves in the canopy layer of P. euphratica, which helps to understand the adaptive changes of heteromorphic leaf distribution to the survival environment.
为探究胡杨异形叶随树冠高度变化的空间分布规律,以甘肃河西走廊金塔县的人工胡杨林植株为研究对象,调查树冠不同分层间胡杨各异形叶出现频率。结果表明:条形叶与披针形叶频率在树冠底部最高,锯齿卵形叶出现频率在树冠中部达到最大,锯齿阔卵形叶与锯齿扇形叶多出现于树冠上部。其中,条形叶频率、锯齿卵形叶频率与锯齿扇形叶频率在树冠各分层间叶形存在显著差异。随着树冠高度的增加,条形叶出现频率逐渐减少,披针形叶出现频率无明显变化,而锯齿卵形叶、锯齿阔卵形叶和锯齿扇形叶的出现频率逐渐增大;各异形叶在树冠垂直空间分布上表现出一定的消长规律。本研究结果揭示了胡杨异形叶在树冠层的分布规律,有助于深入了解胡杨异形叶对生存环境的适应性变化。
胡杨,异形叶,出现频率,树冠,垂直分布
Dou Zhang, Xiaowei Zhang, Li Wang *
Forestry College of Gansu Agricultural University, Lanzhou Gansu
Received: Apr. 15th, 2022; accepted: May 11th, 2022; published: May 23rd, 2022
In order to explore the vertical spatial distribution law of the heteromorphic leaves in the canopy of Populus euphratica, the occurrence frequencies of heteromorphic leaves among different layers of the canopy were investigated by taking the artificial P. euphratica forest in Jinta County. The results showed that the frequencies of linear and lanceolate leaves were the highest at the bottom of the crown, the frequency of dentate ovate leaves was the highest in the middle of the crown, and the frequency of dentate broad-ovate leaves and dentate fan-shaped leaves was the highest in the upper part of the crown. Among heteromorphic leaves, the frequencies of linear leaves, dentate ovate leaves and dentate fan-shaped leaves were significantly different among the tree crown layers. The different heteromorphic leaves showed different trends with the increasing the tree crown height, the frequency of linear leaves gradually decreased, the frequencies of dentate ovate leaves, dentate broad-ovate leaves and dentate fan-shaped leaves significantly increased, while the frequency of lanceolate leaves were not significant changes. The relationships of each frequency of heteromorphic leaves in the vertical spatial distribution in the canopy showed a trade-off pattern. These results reveal the distribution pattern of heteromorphic leaves in the canopy layer of P. euphratica, which helps to understand the adaptive changes of heteromorphic leaf distribution to the survival environment.
Keywords:Populus euphratica, Heteromorphic Leaves, The Occurrence Frequency, Canopy, The Vertical Spatial Distribution
Copyright © 2022 by author(s) and Hans Publishers Inc.
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胡杨(populus euphratica)为杨柳科(Salicaceae)杨属(Populus)落叶乔木,是我国西北干旱区荒漠河岸林的主要建群树种 [
胡杨异形叶是其个体发育过程中对环境变化的生态适应性表现 [
本研究在甘肃省酒泉市金塔县沙漠胡杨林景区的人工胡杨林内进行。金塔县地处黑河流域中下游,河西走廊中部北侧,巴丹吉林沙漠边缘。由于深居西北内陆,金塔县气候干燥,降水量少,蒸发量大,冬季寒冷,夏季酷热,日均温差、年均温差较大,光热资源丰富,属典型的温带大陆性气候。年均温8℃,年均降水量50 mm左右,年均蒸发量超过2500 mm。天然植被主要以耐盐碱、干旱的梭梭、柽柳、胡杨等为主 [
为了系统研究异形叶的空间分布,根据叶片的长宽比及叶缘形状 [
图1. 异形叶划分
图2. 各分层实际高度
于2019年8月胡杨叶片发育成熟时期,对于已编号的胡杨个体,由活枝下高开始,自下而上,每间隔1 m为一个研究层直至树冠顶部,并利用测高仪测量得到每层的实际高度(图2)。每个研究层从东、南、西、北四个方向各剪取一根长度相同的枝条,将各枝条上所有叶片混合后,根据图1所示异形叶类型将叶片进行分类,调查统计每一研究层各类异形叶出现的数量,并计算各异形叶在第一研究层出现的频率。具体计算公式如下:
f a b = n a b ÷ N a × 100 %
式中:fab为第a层b类异形叶出现的频率;nab为第a层b类异形叶出现的数量;Na为第a层测量的异形叶片总数。
使用Excel对所测数据进行统计,采用SPSS 20.0软件对不同研究层间各类异形叶频率进行方差分析和Pearson相关性分析,使用Origin 2021软件对不同高度下的各类异性叶频率进行一般线型回归分析并作图。
由图3可知,条形叶、披针形叶、锯齿卵形叶和锯齿阔卵形叶分布于树冠整个垂直空间。而锯齿扇形叶除第二分层中存在很低的出现频率外,主要出现第五、六、七分层,以在树冠上部为主。条形叶出现频率在各分层间存在显著差异,其频率在64.6%到23.4%之间变化,其中最低值出现在第六分层,最高值出现在第一分层;披针形叶出现频率在各分层间不存在显著差异,各分层出现频率在30%左右波动;卵形叶出现频率范围为7.9% (第一分层)~28.8% (第四分层),且在各分层间存在显著差异;锯齿卵形叶在各分层出现频率的平均值为19.0%,其中最值出现在第六分层,最低值出出在第一分层。但其出现频率在各分层间不存在显著差异;锯齿扇形叶出现频率在各分层间存在显著差异,且其频率在第三分层最低,值仅为0.3%,在第七分层最高,值为最低值的27倍(表1,图3)。
图3. 不同层次间异形叶频率变化
条形叶 | 披针形叶 | 锯齿卵形叶 | 锯齿卵圆形叶 | 锯齿扇形叶 | |
---|---|---|---|---|---|
自由度 | 6 | 6 | 6 | 6 | 6 |
F值 | 2.93 | 0.71 | 3.00 | 1.95 | 25.80 |
显著性 | 0.01 | 0.65 | 0.01 | 0.08 | <0.01 |
表1. 不同层次间各类异性叶频率差异
同一分层中各叶形出现频率随分层不同而不同。第一分层中,条形叶出现频率最高,其余依次为披针形叶、卵形叶和锯齿卵形叶。第二分层中,各叶形出现频率从高到低依次为条形叶、披针形叶、卵形叶、锯齿卵形叶和锯齿扇形叶(0.3%)。第三分层中,出现频率最高的叶形为披针形叶,其值为39.6%,其次为条形叶38.0%和卵形叶(12.5%),锯齿卵形叶出现频率最低,其值为10.0%。第四分层中,各叶形出现频率在32.1%到12.7%之间变化,其中,条形叶出现频率最高,锯齿卵形叶最低。第五、六、七分层中,披针形叶出现频率最高,锯齿扇形叶出现频率最低,其余叶形位于二者中间。
各叶形在各分层出现频率与高度的回归分析表明(见图4),条形叶在各分层出现频率与各分层高度间存在呈极显著负相关,说明条形叶出现频率随树冠高度增加呈减小趋势。卵形叶、锯齿卵形叶和锯齿扇形叶出现频率与各分层高度间存在显著正相关,表明随树冠高度增加,卵形叶、锯齿卵形叶和锯齿扇形叶出现频率呈上升趋势。披针形叶出现频率与各分层高度间无显著性相关。
图4. 各异形叶在不同高度间的变化规律
各形叶出现频率之间的相关性分析表明,条形叶出现频率与披针形叶、卵形叶、锯齿卵形叶和锯齿扇形叶出现频率间呈显著负相关关系。披针形叶出现频率与卵形叶间呈显著负相关关系,与锯齿阔卵形叶、锯齿扇形叶出现频率间不存在显著相关关系。锯齿卵形叶出现频率与锯齿阔卵形叶出现频率间存在正相关关系,与锯齿阔卵形叶出现频率间不存在显著相关性。锯齿阔卵形叶出现频率则与锯齿扇形叶出现频率间无显著相关性(表2)。
条形叶 | 披针形叶 | 锯齿卵形叶 | 锯齿阔卵形叶 | 锯齿扇形叶 | |
---|---|---|---|---|---|
条形叶 | 1 | ||||
披针形叶 | −0.46** | ||||
锯齿卵形叶 | −0.66** | −0.23* | |||
锯齿阔卵形叶 | −0.59** | −0.17 | 0.41** | 1 | |
锯齿扇形叶 | −0.23* | 0.02 | 0.12 | 0.14 | 1 |
表2. 各异形叶频率间的相关分析
**在0.01级别(双尾),相关性显著。*在0.05级别(双尾),相关性显著。
异形叶的产生是植物长期进化过程中,自身基因调控与环境相结合的产物,是一种对生存环境条件适应的表现 [
异形叶在树冠层分布频率的差异,通常受光照 [
大量对胡杨异形叶的研究表明,随胡杨胸径的增大,各异形叶呈现依次发育出现的规律,最终锯齿扇形叶、锯齿卵形叶将占据绝大部分树冠 [
本研究量化分析了胡杨各异形叶在树冠层的分布,结果表明各叶形在树冠不同分层间出现频率存在差异。其中,条形叶与披针形叶频率在树冠底部最高,锯齿卵形叶出现频率在树冠中部达到最大,锯齿卵形叶与锯齿扇形叶多出现于树冠上部。条形叶与披针形叶出现频率高于其余叶形出现频率。且随着树冠高度增加,各异形叶在树冠空间分布上呈现出一定的消长规律,表现为条形叶出现频率逐渐减小,锯齿卵形叶、锯齿阔卵形叶和锯齿扇形叶的出现频率逐渐增大,而披针形叶出现频率无明显变化。异形叶作为胡杨适应环境的特征和策略,其随树高变化的规律还受生长发育的影响,受人工林的生长发育同步性较高的限制,后续还需进一步补充和探索个体发育对各异形叶随树高变化的分布频率的影响。
本文得到甘肃省青年科技基金项目(18JR3RA188)和甘肃农业大学科技创新基金—公招博士科研启动基金项目(2017RCZX-23)资助。
张 斗,张晓玮,王 立. 胡杨异形叶沿树冠垂直空间分布规律研究Study on the Vertical Spatial Distribution of the Heteromorphic Leaves along the Canopy of Populus euphratica[J]. 植物学研究, 2022, 11(03): 306-313. https://doi.org/10.12677/BR.2022.113036