Fundamental drivers of plant spectral diversity

植物光谱多样性--植物物种的叶子如何与太阳辐射有差异地相互作用--是生物多样性的一个非常有希望但在很大程度上仍不为人所知的方面。植物光谱多样性之所以引起人们的高度关注，是因为它可以被直接遥感，也因为它是植物系统发育和功能多样性的强大整合因子。因此，一个名为“光谱组学”的新领域正在彻底改变我们获取大区域高分辨率生物多样性数据的方式。然而，我们仍然对叶片光谱跨物种和环境变化的基本驱动因素知之甚少。我的研究计划的总体目标是确定植物物种、群落内部和之间以及土壤肥力梯度之间叶片光谱差异的根本驱动因素。拟议的研究计划建立在我之前的Discovery Grant沿着自然土壤肥力梯度进行的基于特征的植物生态学的基础上，并开发了关于光谱多样性及其与系统发育和功能多样性的联系的令人兴奋的新研究方向。中心假设是，叶片光谱变化主要由系统发育决定，其次由环境决定。这项研究计划围绕三个短期目标进行组织。在第一个目标中，我将确定不同物种之间叶片光谱变化的基本轴。在这里，我将测试光谱变化沿着三个主要轴组织的假设，表达：(1)叶片经济光谱，(2)化学和结构防御之间的权衡，以及(3)叶片水力光谱。为此，我将利用我们在澳大利亚的土壤时间序列网络，对分布在广泛土壤和气候梯度上的大量树冠植物物种的光谱和特征进行大规模的实地调查。我的第二个目标是量化植物物种中光谱可塑性的程度。具体地说，我将测试这一假设，即具有更广泛土壤生态位的物种显示出更高的光谱可塑性。为此，我将使用长期土壤时间序列的田间观察和跨越大土壤肥力梯度的常见园艺实验相结合，以提供迄今为止最全面和最严格的叶片光谱可塑性量化。最后，我的第三个目标是确定跨越肥力梯度的社区内部和社区之间叶片光谱多样性的驱动因素。特别是，我将测试这一假设，即土壤肥力梯度上的光谱多样性在群落水平上的变化表明植物分类和功能多样性的变化。这项研究将沿着澳大利亚的朱利安湾土壤年代序列进行，这是迄今所描述的最强的自然土壤肥力梯度之一。通过揭开植物物种和环境中叶片光谱变化的根本驱动因素，我的研究将为未来由光谱组学提供信息的全球生物多样性观测站铺平道路。

Plant spectral diversity -how leaves of plant species differentially interact with solar radiation- is a highly promising but still largely unknown facet of biodiversity. Plant spectral diversity is of high interest because it can be directly remotely sensed, and because it is a powerful integrator of plant phylogenetic and functional diversity. As a result, a new field called "spectranomics" is revolutionizing how we acquire high-resolution biodiversity data over large regions. However, we still know little about the basic drivers of leaf spectral variation across species and environments. The overall objective of my research program is to determine the fundamental drivers of leaf spectral variation within and among plant species, communities, and across soil fertility gradients. The proposed research program builds from my previous Discovery Grant in trait-based plant ecology along natural soil fertility gradients, and develops exciting new research directions about spectral diversity and its linkages with phylogenetic and functional diversity. The central hypothesis is that leaf spectral variation is primarily determined by phylogeny, and secondarily by the environment. The research program is organised around three shorter-term objectives. In the first objective, I will identify fundamental axes of leaf spectral variation among species. Here, I will test the hypothesis that spectral variation is organised along three major axes expressing: (1) the leaf economics spectrum, (2) a trade-off between chemical and structural defences, and (3) a leaf hydraulics spectrum. To do so, I will conduct a large-scale field survey of spectra and traits for a large number of canopy plant species spread across broad edaphic and climatic gradients, using our network of soil chronosequences in Australia. My second objective is to quantify the degree of spectral plasticity within plant species. Specifically, I will test the hypothesis that species with broader edaphic niches show higher spectral plasticity. To do so, I will use a combination of field observations along long-term soil chronosequences and common garden experiments spanning large soil fertility gradients to provide the most comprehensive and rigorous quantification of leaf spectral plasticity to date. Finally, my third objective is to determine the drivers of leaf spectral diversity within and among communities across fertility gradients. In particular, I will test the hypothesis that community-level shifts in spectral diversity across soil fertility gradients express changes in plant taxonomic and functional diversity. This research will be conducted along the Jurien Bay soil chronosequence in Australia, which is one of the strongest natural soil fertility gradients ever described. By unravelling the fundamental drivers of leaf spectral variation across plant species and environments, my research will pave the way for a future global biodiversity observatory informed by spectranomics.