新疆准噶尔荒漠植物叶片功能性状的进化和环境驱动机制初探

Leaf functional trait variation and its relationship with plant phylogenic background and the climate in Xinjiang Junggar Basin, NW China

植物功能性状是由遗传因素和环境条件共同决定的。剖析各因素对植物性状变异的相对影响,对揭示植物对环境变化的响应和适应规律至关重要。作者以干旱区植物为研究对象,定量化分析了植物叶片功能性状变异及其与环境梯度的关系。研究区域位于中国新疆准噶尔盆地及其周边区域。在30个样地中,观测了110种植物的叶比重、叶片单位质量氮含量和单位面积氮含量以及叶片干物质含量,通过插值法获得每个样地的生物气候数据。结果表明:物种水平上叶片性状(性状值为每个物种的实际观测值)的变异在很大程度上由植物进化背景所决定,气候因子和功能群的作用次之;在群落尺度上(性状值为每个样地的权重和),叶比重与气候干旱程度呈正相关,单位质量氮含量在水热组合最优的区域出现最大值,而叶片干物质含量和单位面积氮含量与气候因子的相关性较小。叶比重是群落尺度上探讨叶片功能性状与环境梯度关系的一个合适的指标。此外,在研究植物性状-环境关系过程中,尽可能观测多个植物功能性状是必要的。但是,只有排除植物系统背景的影响,关于植物性状-环境关系的研究结论才可能接近真实情况。将来应该加强同一种内不同种群间的叶片性状的采样和分析工作。

To quantitatively characterize leaf trait variation and the manner that plants adapt to extremely dry climates, we measured four leaf functional traits, i.e., leaf mass per area（LMA）, mass-and area-based leaf nitrogen concentration（Nmass, Narea） and leaf dry matter content（LDMC） for 110 plant species in Xinjiang Junggar Basin, NW China.Plant family, plant functional group and climatic factors（plant water availability：α;mean temperature of the warmest month：MTWA） were used as the dependent variables to explain the species-level variation in LDMC, LMA, Nmass, and Narea.The plot-level leaf trait values were related to α and MTWA via stepwise regression.Our results indicated that：（1） the species-level leaf trait variations are to large extent determined by plant family, while the influence of functional group and climatic factor tends to be the second;（2） At the plot-level, LMA increases as the climate becomes drier, while Nmass is positively related to the simultaneous optimization of α and MTWA, i.e., Nmass tends to be higher in warm-wet habitats than in cold-dry one.LDMC and Nmass are less relevant to the climatic gradient.Plants in the study area have demonstrated an overall adaptation to the extremely dry climate.However, due to the differences in phylogenic background, different species may take different strategies in the face of the same climatic gradient.It is therefore important to examine the relative importance of plant phylogenic background and the environments on plant trait variation, which may matter for our prediction of plant response to the environmental changes in arid area.