区域尺度上麻栎叶片氮磷化学计量特征变异机制及其内稳性

Stoichiometric variation and homeostasis at regional scale are the topic of plant stoichiometry. While, it is less study on genetic and environmental controls on leaf stoichiometry at species level, and stoichiometric homeostasis is not validated for a given species. According to our previously studies, leaf and soil nitrogen (N) and phosphorus (P) concentrations and geographic and climatic variables would be collected from 36 Quercus acutissima populations across China, and the effect of environmental variables on variation patterns of leaf N, P stoichiometry would be clarified. Meanwhile, leaf and soil N, P concentrations and geographic and climatic variables would be obtained from 4 Quercus acutissima provenances trials with 36 provenances, intraspecific genetic (provenance) and environmental variations of leaf N and P stoichiometry would be presented, and the effect of provenance and environment on leaf stoichiometry would be quantified. At last, stoichiometric homeostasis would be assessed at regional scale and intraspecific genetics level by homeostasis index and Eberhat-Russell models, respectively. This study would clarify the variation and homeostasis mechanism of leaf stoichiometry at species level based on provenance trials in forest breeding, which contributes to validate stoichiometric homeostasis and provide new idea and methodology for plant stoichiometry.

区域尺度上化学计量特征变异机制及其内稳性是植物化学计量学研究的热点和难点问题。物种水平上，叶片化学计量特征变异的遗传和环境机制研究较少，叶片化学计量学内稳性也一直未有定论。在已有基础上，本项目以36个麻栎地理种群和4处种源试验林为对象，基于地理种群研究麻栎叶片氮、磷化学计量特征及其与环境因子的关系，阐明区域尺度上化学计量特征的变化规律和模式，并揭示各环境因子的影响机制；基于种源试验林研究麻栎叶片氮、磷化学计量特征及其立地环境，分析化学计量特征的种源和区域变化规律，并量化其种内遗传（种源）和立地环境的影响机制；采用内稳性指数、Eberhat和Russell模式分别评价区域尺度和种内遗传水平上叶片化学计量学内稳性。本研究基于林木育种学方法解决化学计量学问题，在物种水平上揭示化学计量特征的变异规律、变异机制和内稳性，验证植物化学计量学内稳性理论，为植物化学计量学研究提供新思路和新方法。

项目实施以来，团队很好的完成了项目任务书中各项研究内容，主要取得了以下结论。.一是阐明了麻栎林生态化学计量与养分循环的纬度格局及其影响机制。麻栎器官氮（N）含量随纬度的增加呈先降低后升高的变化趋势，叶片和转运细根磷（P）含量则随纬度增加呈现升高的趋势；叶片、细根N:P先降低后升高。N回收效率随纬度增加而升高；N转移因子（Ⅱ）、P回收效率、P富集因子均随纬度增加呈先升高后降低的变化趋势；P转移因子（Ⅰ）随纬度增加表现出先降低后升高的趋势。年均温度、年均降水量等环境因子是影响麻栎N、P化学计量性状变异的主导因素。.二是揭示了麻栎叶片碳（C）、氮、磷化学计量变异的环境和遗传机制。结合林木育种方法，以3个麻栎种源试验林为研究对象，揭示了地点（环境）显著影响叶片C、N、P、C:N、C:P、N:P，解释量占总变异量的13.2%~66.7%，而种源（遗传）的影响并不显著，化学计量特征在地点间稳定的相关系数反映出叶片化学计量特征的特定耦合比例不受环境的影响，支持化学计量学的内稳性理论。.三是阐明了麻栎种源林叶片N、P化学计量特征与叶片形态和个体大小的协同变化关系。发现叶片N和P的化学计量与叶片形状、个体大小显著相关，说明叶片N和P的化学计量影响叶片和树干的表型形态表现。叶片N、P化学计量学与叶片形状关系的SMA斜率为|0.12| ~ |1.00|，与个体大小关系的SMA斜率为|0.95| ~ |2.66|，表明非功能组织（干）比功能组织（叶）更容易受到叶片营养的影响，而叶片化学计量学在非功能组织（干）的构建中更为重要。叶片N:P与树高和胸径均表现出显著的协同变化关系，说明叶片N:P和个体大小对环境变化表现出相似的塑性响应。