Department of Forestry, Michigan State University, 126 Natural Resources Bldg., East Lansing, MI 48824, USA.
Tree Physiol. 2013 Mar;33(3):297-310. doi: 10.1093/treephys/tps134. Epub 2013 Jan 30.
Interspecific relationships among species mean leaf traits, performance and species resource/climate distributions help provide the foundation for a predictive, functionally based plant ecology. Intraspecific responses of leaf traits and performance to resource gradients and how these vary among species may be equally important but have received less attention. Here, we examine relationships between proxies of soil resource availability, leaf traits and growth (height at 25 years, SI25) for winter deciduous Larix decidua Mill. and evergreen Pinus resinosa Ait. trees distributed over soil resource gradients in the Great Lakes region of North America. We predicted that (i) leaf trait responses to soil resources within species will be similar to reported distributions of mean leaf traits over soil resource gradients among species; (ii) soil resource-related variation in leaf traits can help explain SI25; and (iii) SI25 will be greater for Larix than Pinus at higher soil resources and greater for Pinus than Larix at lower soil resources and this pattern will be associated with species differences in leaf trait responses to soil resources. Among the measured leaf traits (live N, Mg, Ca, K, P, and Mn, litter N, N resorption, carbon isotope discrimination, specific leaf area, lifespan), soil resources only impacted live and litter N for both species and K for Pinus. In turn, only the leaf traits responsive to soil resources affected SI25 in the expected manner. Larix had greater SI25 than Pinus across soil resource gradients and both species had similar growth and leaf trait sensitivities to resources. In summary: (i) several leaf traits reported to be associated with performance and edaphic distributions across species were, within species, unresponsive to nitrogen and water availability and unrelated to growth; (ii) leaf N showed high plasticity to soil resources and this plasticity was functionally relevant to growth over its entire range of response; (iii) large species-level differences in leaf traits between Larix and Pinus did not translate into different leaf trait and growth responses to soil resources.
种间关系意味着叶片特征、表现和物种资源/气候分布有助于为预测性、基于功能的植物生态学提供基础。种内叶片特征和表现对资源梯度的反应以及这些反应在物种间的差异可能同样重要，但受到的关注较少。在这里，我们研究了北美五大湖地区土壤资源梯度上分布的落叶松和常绿松的土壤资源可用性、叶片特征和生长（25 年时的高度，SI25）的代表之间的关系。我们预测：(i) 种内叶片特征对土壤资源的响应将类似于种间土壤资源梯度上平均叶片特征的报告分布；(ii) 叶片特征与土壤资源相关的变异可以帮助解释 SI25；(iii) 在较高的土壤资源中，Larix 的 SI25 将大于 Pinus，在较低的土壤资源中，Pinus 的 SI25 将大于 Larix，这种模式将与物种对土壤资源的叶片特征响应差异相关。在所测量的叶片特征（活体 N、Mg、Ca、K、P 和 Mn、凋落物 N、N 再吸收、碳同位素分馏、比叶面积、寿命）中，土壤资源仅影响两种物种的活体和凋落物 N 和 Pinus 的 K。反过来，只有对土壤资源有反应的叶片特征以预期的方式影响 SI25。Larix 的 SI25 大于 Pinus，跨越土壤资源梯度，两种物种的生长和叶片特征对资源的敏感性相似。总之：(i) 几种与种间表现和土壤分布有关的叶片特征在种内对氮和水分供应没有反应，与生长无关；(ii) 叶片 N 对土壤资源表现出高度的可塑性，这种可塑性在其整个反应范围内对生长具有功能相关性；(iii) Larix 和 Pinus 之间的叶片特征在物种水平上存在很大差异，但并没有转化为对土壤资源的不同叶片特征和生长反应。
