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题名: 高山杜鹃叶属性及化学计量特征时空变化研究
作者: 王萌
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 刘国华
关键词: leaf traits, stoichiometry, altitude, leaf age, alpine ; 叶属性,化学计量学,海拔,叶龄,高山
其他题名: Spatial and temporal variations of leaf traits and stoichiometric characteristics of an alpine rhododendron
学位专业: 生态学
中文摘要:        植物叶片的形态及化学计量特征同时受植物内在相对稳定的可遗传特性以及具体外部环境因子的影响。以往针对植物叶片叶属性及化学计量特征的研究更多的集中在以特定年龄叶片为对象,研究外界环境对其的影响及其与环境因子间的关系,缺乏将不同生长发育阶段的叶片视作一个整体,对植物本身叶片年龄造成的叶属性和化学计量特征的变化的研究,以及外部环境和不同生长阶段对叶属性及化学计量特征的共同影响的研究。
      凝毛杜鹃(Rhododendron agglutinatum)是一种在中国西南部高山地区的林线位置及以上广泛分布的高大常绿灌木。本实验以凝毛杜鹃为研究对象,在四川省米亚罗林区,选择一条含该物种完整海拔分布带的典型山坡,从3700 米至4150 米沿海拔梯度连续设置10 组样地,在生长季和冬季分别测量凝毛杜鹃不同年龄叶片(生长季时为新生叶、成熟叶及衰老叶;冬季为新生叶和成熟叶)的形态学特征(包括叶干物质含量,比叶重和单叶面积),碳元素含量以及营养元素含量(氮,磷),同时计算化学元素计量关系(碳氮比,碳磷比和氮磷比)。本研究得到以下主要结论:
      1. 生长季时期,叶片年龄和海拔变化对凝毛杜鹃的叶属性及化学计量特征均产生影响。单叶面积随叶片年龄的增大而增大;成熟叶片的干物质含量、比叶重、单位质量碳含量和单位面积碳含量均高于新生叶和衰老叶;养分元素(氮,磷)的含量随叶片年龄的增大而减少;单叶面积、碳氮比,碳磷比随叶片年龄的增大而增大;新生叶的氮磷比最低。
      新生叶的叶属性及化学计量特征均受海拔梯度变化的影响。测量的三种叶形态属性特征均随海拔升高而减小;元素含量方面,单位质量和单位面积碳含量随海拔升高而降低;单位质量养分含量和单位面积养分含量均随海拔升高而增加。化学计量关系均表现为随海拔升高而减小。
      成熟叶测定的叶属性中,比叶重随海拔升高而增加,表现出和新生叶比叶重相反的海拔变化趋势;干物质含量和单叶面积没有明显的海拔变化规律。成熟叶的单位质量和面积养分含量随海拔升高而增加,与新生叶的趋势一致;单位面积碳含量随海拔升高而增加,而单位质量碳含量无明显海拔变化规律。成熟叶的化学计量关系中,碳氮比和碳磷比随海拔升高而减小,与新生叶中的趋势一致,而氮磷比无明显变化规律。
      衰老叶中只有单位面积磷含量和氮磷比表现出了与海拔间的相关关系,其他叶属性、元素含量及化学计量关系与海拔变化无明显相关。单位面积磷含量随海拔升高而减小,与其在新生叶和成熟叶中随海拔变化的规律相反,氮磷比随海拔高度的增加而升高。
      氮元素可能是该地区凝毛杜鹃生长的主要限制元素。同时,随着叶片年龄的增加,叶属性及化学计量特征受海拔的影响下降,显示了在气候变化背景下,新叶具有更高的敏感性和适应性。
      2. 冬季时,三种测定的叶结构属性及碳元素含量在新生叶和成熟叶之间不存在显著的年龄差异,新生叶较成熟叶具有更高的营养元素含量和更低的C/N、C/P 比值,新生叶的N/P 整体上低于其在成熟叶中的水平,但差异未达到显著水平;
      三种测定的叶结构属性无明显的海拔变化规律,碳元素含量、氮元素含量在新生叶中表现为随海拔升高而增加,新生叶中磷元素含量及成熟叶中三种测定的元素含量均没有表现出明显的海拔变化规律;化学计量比的海拔变化规律仅出现在新生叶中与氮元素含量相关的关系中,具体表现为新生叶C/N 比值随海拔升高而下降、N/P 随海拔升高而增大。
英文摘要:       Leaf morphological and stoichiometric characteristics are considered to representing both plant's interior inheritable characters and adaptations to specific exterior environments. Previous studies have focused on the environmental effects rather than effects of interior process or the co-effects on leaf traits. Rhododendron agglutinatum, an evergreen alpine shrub species, occupies a wide range of habitats above timberline in the Miyaluo Natural Forest Reserve, southwestern China. Along an altitudinal gradient ranging from 3700 to 4150 m, we measured leaf morphological characters (LDMC, LMA, and OLA), carbon (C) and nutrient (N, P) contents in leaves of different age groups (juvenile leaves, mature leaves and senescent leaves in growing season; juvenile leaves and mature leaves in winter)in growing season and winter. We also calculated the stoichiometric relationships among carbon and
nutrients (C/N, C/P and N/P).Results of this study are shown as follows.
1. The results of study in growing season showed that both age and altitude affected the leaf morphological and stoichiometric properties of R. agglutinatum. Mature leaves possessed the highest LDMC, LMA and C contents both on a dry mass basis and on a unit area basis. Younger leaves possessed higher contents of nutrients. OLA as well as ratios between carbon and nutrients (C/N, C/P) increased with ages.
      Juvenile leaves possessed lowest ratio between nitrogen and phosphorus. In juvenile leaves, nutrients increased with increasing altitude, whereas other traits decreased with increasing altitude. In mature leaves, nutrients and their ratios with carbon showed consistent trends with juvenile leaves along increasing altitude, whereas LMA and carbon on a unit area basis showed opposite trends with juvenile leaves along increasing altitude. Other traits were uncorrelated with altitude. In senescent leaves, only content of phosphorus on a unit area basis and N/P were found linearly correlated with altitude.
      Our results in growing season demonstrated a clear pattern of nutrient distribution with aging process in leaves and indicated that a high possibility of N limitation in this region. We also concluded that younger leaves could be more sensitive to climate changes due to a greater altitudinal influence on the leaf traits in younger leaves than those in elder leaves.
      2. In winter, LDMC, LMA, OLA and carbon contents didn’t show significant differences between juvenile and mature leaves. Nutrient concentrations in juvenile leaves were significantly higher than those in mature leaves, but the C/N and C/P ratios of juvenile leaves were significantly smaller than those of mature leaves.
      N/P ratio of juvenile leaves though not significantly, were smaller than that of mature leaves. None of LDMC, LMA or OLA were correlated with altitude, neither in juvenile
leaves nor mature leaves. Only carbon content and nitrogen content in juvenile leaves increased with increasing altitude, while other tested element contents were uncorrelated with altitude.
      C/N ratio of juvenile leaves was decreased with increasing altitude, N/P ratio of juvenile leaves increased with increasing altitude. Other stoichiometric ratios in juvenile or mature leaves showed no trends with altitudinal elevation
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36976
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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Recommended Citation:
王萌. 高山杜鹃叶属性及化学计量特征时空变化研究[D]. 北京. 中国科学院研究生院. 2016.
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