Plant diversity and ecosystem services in wetlands

越来越多的证据表明，生物多样性的丧失导致群落获取资源、产生生物量、循环养分或抵抗入侵的效率降低。多样性与生态系统功能和服务之间的这种关系可能因土壤肥力而异。例如，多样性效应可能在营养有限的环境中更为重要，如天然草原，那里对资源的竞争是对称的。相比之下，天然湿地是地球上最具生产力的生态系统之一，部分原因是它们从排水的分水岭中吸收沉积物和营养物质。然而，生态学文献很少报道在湿地进行的多样性实验的经验证据。因此，在这个高产的生态系统中，人们对“多样性-生态系统功能”的关系知之甚少。我的研究项目主要集中在生物多样性驱动生态过程和支持湿地生态系统功能和服务的机制。对于目前的提案，我和我的学生将1)评估物种丰富度和功能多样性对湿地生物抵抗外来植物入侵的影响，2)测试湿地的生态服务是否由于互补效应而随着植物多样性的增加而增加，以水净化为衡量标准。为了实现第一个目标，我们将在法国生物研究所（Institut de recherche en biologie vsamg<e:2> research site）进行群落恢复介域实验。我们将通过使用不同丰富度和功能多样性的种子混合物来操纵初始物种组成。在接下来的三年里，我们将调查群落重组和入侵植物物种的建立情况。这将使我们能够确定物种和功能群身份的贡献，物种和功能群相互作用和非生物条件，以及这些因素如何相互作用以确定生物抗性。第二个目标，我们将评估植物多样性和组成对不同数量浮游植物的湿地生态系统中养分同化和矿化的影响。我们还将比较不同植物丰富度和功能多样性的湿地土壤的生态过程测量，包括实验中生态系统和魁北克南部的大型湿地。由于去除污染物的过程不同，我们的湿地实验将为检验生物多样性生态系统的多功能性假设提供理想的环境，即植物多样性如何同时影响几种生态功能。我们的研究结果不仅使我们能够从根本上了解植物相互作用和多样性如何影响湿地生态系统过程，而且还将对植被管理、湿地恢复和用于废水处理的人工湿地的设计产生影响。

Plant diversity and ecosystem services in wetlands There is accumulating evidence that the loss of biodiversity results in a reduction of the efficiency with which communities capture resources, produce biomass, recycle nutrients or resist invasion. This relationship between diversity and ecosystem functions and services may vary depending on soil fertility. For example, diversity effects may be more important in nutrient limited environments, such as natural grasslands, where the competition for resources is symmetric. In contrast, natural wetlands are among the most productive ecosystems on earth in part because they receive sediments and nutrients from the drained watershed. Yet, the ecological literature reports little empirical evidence from diversity experiments conducted in wetlands. As a result, little is known about the "diversity - ecosystem functions" relationship in this highly productive ecosystem. My research program focuses on the mechanisms by which biodiversity drives ecological processes and supports ecosystem functions and services in wetlands. For the current proposal, my students and I will 1) evaluate the effect of species richness and functional diversity on biotic resistance to invasion by exotic plant species in wetlands and 2) test whether ecological services in wetlands, as measured by water purification, increase with plant diversity due to complementarity effects. For the first objective, we will conduct a community restoration mesocosm experiment at the Institut de recherche en biologie végétale research site. We will manipulate initial species composition by applying seed mixtures of varying richness and functional diversity. We will then survey community reassembly and invasive plant species establishment over three years. This will allow us to establish the contribution of species and functional group identity, species and functional group interactions and abiotic conditions, and how these factors interact to determine biotic resistance. For the second objective, we will evaluate the effect of plant diversity and composition on nutrient assimilation and mineralization in wetland mesocosms with varying numbers of floating plant species. We will also compare measures of ecological processes in wetland soils with varying plant richness and functional diversity, both in experimental mesocosms and in a large wetland in southern Quebec. Because the processes for removing pollutants differ, our wetland experiments will offer an ideal situation for testing hypotheses on the multifunctionality of biodiversified ecosystems, i.e. how plant diversity may simultaneously affect several ecological functions. The results of our research program will not only allow us to understand, at the fundamental level, how plant interactions and diversity influence wetland ecosystem processes, but will also have implications for vegetation management, wetland restoration and design of constructed wetlands used for wastewater treatment.