濒危种观光木小枝生物量分配与功能性状的纬度变异规律及其影响因素

为了探讨观光木当年生枝条生物量的分配规律和叶片功能性状的变化规律及其影响因素，该研究以濒危物种观光木(Michelia odora)为对象，测定了广西地区5个不同纬度上观光木当年生小枝及叶片功能性状。结果表明：(1)随着纬度的增加小枝总重和总叶重总体呈异速生长关系，其生物量更多趋于对小枝的构建。(2)观光木叶功能性状呈现一定规律，即从南向北随纬度的增加，其叶面积、叶重呈逐渐降低的趋势，叶厚度、叶干物质含量、气孔长、气孔大小、气孔密度呈逐渐上升的趋势，比叶面积、叶含水率、气孔宽先增大后减小，总体呈逐渐减低的趋势，叶组织密度先减小后增大，反映观光木可通过叶片形态可塑性以应对地理环境的变化。(3)比叶面积与叶含水率呈显著正相关，而与叶鲜重、叶干物质含量、气孔密度呈显著负相关；叶干物质含量与叶含水率呈显著负相关，说明观光木可以通过叶片性状组合的调整和平衡从而响应环境变化。(4)CCA分析显示，坡度是影响观光木功能性状的最显著变量，年平均温度对观光木功能性状也具有显著影响，年均降水量和相对湿度对植物功能性状具有一定强度的影响，但不起显著作用。该研究结果有助于理解观光木对环境的适应特征，其对纬度变...

Latitudinal variation of branchlet biomass allocation and functional traits of endangered species Michelia odora and its influencing factors

In this study, the functional traits of annual branchlets and leaves of Michelia odora, an endangered species, were sampled and measured along five different latitude gradients in Guangxi. The variation of biomass distribution and leaf functional traits along the latitude gradient were discussed. The results were as follows:(1)The total branchlet weight and total leaf weight tended to allometric growth relationship with the increase of latitude, and its biomass tended to the construction of branchlets.(2)The functional traits of the leaves showed a certain rule, i. e. increased with latitude from south to north, and its leaf area and leaf mass decrease of with the increasing latitude; leaf thickness, leaf dry matter content, stomatal length, stomatal area, stomatal density showed a trend of gradual increase; specific leaf area, leaf water content and stomatal width increased at first and then decreased, and overall showed a trend of gradual decrease, leaf tissue density decreased and then increased, which indicates that M. odora can respond to changes in the geographical environment through the plasticity of the leaf shape.(3)Specific leaf area was significantly positively correlated with leaf moisture content, but negatively correlated with leaf fresh weight, leaf dry matter content, and stomatal density. There was a significantly negative correlation between leaf dry matter content and leaf water content, which means that M. odora can respond to the change of geographical environment by adjusting and balancing the character combination of leaves.(4)CCA analysis showed that slope was the most significant variable affecting the functional traits of M. odora, the mean annual temperature also had a significant impact on the functional traits of M. odora, the mean annual precipitation, and relative humidity had a certain intensity effect on plant functional traits, but not significant. All the results are helpful to understand the adaptation characteristics of M. odora to the environment, and its response mechanism to latitude variation is of great significance.