Getting to the roots of trait-based plant ecology

生态学的两个最大挑战是预测(i)生物多样性将如何对环境变化作出反应，以及反过来（ii）生物多样性的变化将如何改变生态系统的功能。关注有机体功能特征的方法——决定个体在特定环境中的表现的形态或生理特征——为解决这两个挑战提供了一条有希望的途径。然而，最近植物功能生态学的研究几乎完全集中在一组易于测量的叶片性状上。相比之下，直接影响土壤资源获取的生态相关特征受到的关注要少得多，尽管土壤资源可得性是全球植被组成和陆地生产力的关键驱动因素。此外，人类活动正以前所未有的速度改变养分循环，对生物多样性和生态系统功能产生重大影响。特别是，化石燃料燃烧产生的氮(N)在大气中的沉积正在滋养全世界的生态系统。这从根本上改变了生态系统中的营养平衡，并可能导致植物生长从氮限制向磷(P)限制转变。利用两种不同的“自然实验”，在这些实验中，一系列生态系统显示出从氮到磷限制的明显转变，我将探索植物物种之间叶和根性状之间的关系，以预测植物群落组成和多样性。我还将确定在N或P限制下植物性状如何驱动根和叶凋落物分解。这很重要，因为分解控制着养分循环和碳(C)储存。我的研究将有助于我们更好地预测养分污染后植物生物多样性变化的功能后果。

Two of the biggest challenges in ecology are to predict (i) how biodiversity will respond to environmental changes, and, in turn, (ii) how changing biodiversity will alter the functioning of ecosystems. Approaches that focus on functional traits of organisms – morphological or physiological characters that determine individual performance in a given environment – offer a promising way to tackle these two challenges. However, recent research in plant functional ecology has focused almost exclusively on a set of easily-measured leaf traits. In contrast, ecologically relevant traits that directly influence soil resource acquisition have received much less attention, despite the fact that soil resource availability is a key driver of vegetation composition and terrestrial productivity worldwide. Moreover, human activities are altering nutrient cycles at unprecedented rates, with major consequences for biodiversity and ecosystem functioning. In particular, atmospheric deposition of nitrogen (N) from fossil fuel combustion is fertilising ecosystems worldwide. This fundamentally alters nutrient balance in ecosystems and can lead to shifts from N to phosphorus (P) limitation of plant growth. Using two different ‘natural experiments’ where series of ecosystems show clear shifts from N to P limitation, I will explore the relationships between leaf and root traits among plant species in order to predict plant community composition and diversity. I will also determine how plant traits drive root and leaf litter decomposition under N or P limitation. This is important because decomposition controls nutrient cycling and carbon (C) storage. My research will help us to better forecast the functional consequences of changing plant biodiversity following nutrient pollution.