Soil fertility impact on plant photosynthetic strategies: from global scale to Maple-dominated forests to Sugar Maple individuals

了解土壤肥力如何促进陆地生态系统的生产力是目前的热门话题。生态系统生产力取决于组成生态系统的功能策略以及它们在群落中的组合。在重要的策略中，植物交替利用水（H2O）或氮（N）资源以实现给定叶片光合速率的能力对预测生态系统生产力具有重要的理论影响。然而，在沿着空间梯度上，为植物提供大部分水氮资源的土壤光合功能策略却被忽视了。此外，在何种程度上采用最佳光合作用战略（最大限度地增加碳在叶尺度）濒危物种在社区规模的优势地位，是必不可少的，但几乎没有探索，以连接功能战略与生态系统生产力。 我最近的研究表明，土壤pH值是更经典的土壤肥力变量的决定因素，以了解全球模式的叶片营养和H2O利用。然而，这些空间模式的机制知之甚少。 在这个提议中，我计划确定土壤肥力如何通过其pH值调节枫树为主的森林之间和内部的光合作用策略的分布。该生态系统对北美东部具有很强的生态、文化和经济重要性，但由于以前的酸性大气沉积而濒临灭绝。 首先，我们将定义的机制，土壤pH值的影响，物种采用捕获，运输，使用N和H2O资源和最大限度地增加碳的功能特性的最佳组合。其次，我们将确定这种最佳的性状组合如何定义一个社区吸引点，物种将收敛，以占主导地位。然后，我们将确定土壤pH值如何定义围绕这个吸引点的功能策略的方差。 土壤pH值受气候的影响很大，重要的是要在空间上分离其研究。我们将在三个互补的尺度上开展工作：（i）在全球范围内使用全球性状数据集;（ii）在给定的气候和植被范围内，通过由底层地质引起的自然土壤pH梯度;（iii）在单个树木水平上，通过对历史酸化土壤进行长期石灰处理。 将功能与群落生态学相结合，我们将阐明土壤肥力在预测群落间最佳功能策略、群落内功能策略的分布以及最终生态系统生产力方面的作用。该计划的核心是，六名高素质的人员将学习专业研究技术，并使用多学科方法来利用知识获取。

Understanding how soil fertility promotes the productivity of terrestrial ecosystems is currently under hot debate. Ecosystem productivity depends on the functional strategies that compose the ecosystem as well as their assembly within the community. Among important strategies, the ability of plants to alternatively use water (H2O) or nitrogen (N) resources for achieving a given leaf photosynthetic rate, has important theoretical impact to predict ecosystem productivity. However, photosynthetic functional strategies have been overlooked along spatial gradient of soils, which deliver most of the H2O and N resources to plants. In addition, the extent to which the adoption of an optimal photosynthetic strategy (maximizing carbon gain at the leaf scale) endangered confers dominance to species at the community scale, is essential but virtually unexplored in order to link functional strategies with ecosystem productivity. My recent research has demonstrated that soil pH is determinant over more classical soil fertility variables to understand the global patterns in leaf nutrition and H2O utilization. However, the mechanisms underlying these spatial patterns are poorly understood. In this proposal, I plan to determine how soil fertility, through its pH values, modulates the distribution of photosynthetic strategies between and within Maple-dominated forests. This ecosystem is of strong ecological, cultural and economic importance to Eastern North America but is endangered due to previous acidic atmospheric depositions. First we will define the mechanisms by which soil pH influences the optimal combination of functional traits that species adopt to capture, transport, use N and H2O resources and maximize carbon gain. Second we will determine how this optimal trait combination defines a community attractive point toward which species would converge in order to dominate. Then we will determine how soil pH defines the variance of functional strategies around this attractive point. Soil pH is strongly influenced by climate and it is important to spatially decouple its study. We will work at three complementary scales: (i) at the global scale using a global trait dataset; (ii) within a given climatic and vegetation envelope through a natural soil pH gradient caused by the underlying geology; (iii) at the individual tree level through a long-term liming treatment on a historically acidified soil. Coupling functional with community ecology, we will shed light on the role of soil fertility on the prediction of the optimal functional strategy between communities, the distribution of functional strategies within community and ultimately the ecosystem productivity. Central to this program, six highly qualified personnel will learn specialized research technologies, as well as using a multidisciplinary approach in order to leverage knowledge acquisition.