Plant interactions and ecosystem function in wetlands

在过去的二十年里，有越来越多的证据表明，生物多样性的丧失导致群落捕获资源、生产生物量和回收养分的效率降低，但目前尚不清楚这种总体模式是否适用于高生产力、营养丰富的湿地。湿地维管植物之间的竞争可能很激烈，往往导致一个或几个(有时是外来的)物种在当地占据优势。我的研究计划侧重于高产植物物种之间的竞争相互作用，以及入侵物种造成的多样性丧失对生态系统功能和服务的影响。在目前的提案中，我和我的学生将测试1)湿地的生态服务(以净水衡量)是否因互补效应而随着植物多样性的增加而增加，以及2)湿地中竞争性克隆物种的扩张是否减少了与生态服务相关的生态功能和属性。对于第一个目标，我们将评估植物多样性和组成对养分同化、矿化和微生物活性的影响，使用不同植物种类和几种不同营养条件下的处理湿地中隔。对于第二个目标，我们将监测魁北克南部一大片湿地地区密集的、接近单一物种的克隆物种林内外的生态属性和空间动态。为了补充实地调查，我们将使用一个原始的中观实验来测量植物相互作用对生态属性的影响，该实验旨在复制具有克隆生长的湿地植物物种之间的竞争。我们的研究结果不仅将使我们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，而且将对植被管理、湿地恢复和用于污水处理的人工湿地具有指导意义。

Over the last two decades, there has been accumulating evidence that loss of biodiversity results in a reduction of the efficiency with which communities capture resources, produce biomass and recycle nutrients, but it remains unclear whether this overall pattern applies to highly productive, nutrient-rich wetlands. Competition among vascular plants can be intense in wetlands, often resulting in the local dominance of one or a few (sometimes exotic) species. My research program focuses on competitive interactions between highly productive plant species and the impact of loss of diversity caused by invasive species on ecosystem functions and services. For the current proposal, my students and I will test whether 1) ecological services in wetlands, as measured by water purification, increase with plant diversity due to complementarity effects and whether 2) expansion of competitive clonal species in wetlands reduces ecological functions and attributes associated with ecological services. For the first objective, we will evaluate the effect of plant diversity and composition on nutrient assimilation, mineralization and microbial activity using treatment wetland mesocosms with varying numbers of plant species and under several different nutritional conditions. For the second objective, we will monitor ecological attributes and spatial dynamics within and outside dense, nearly monospecific stands of clonal species in a large wetland area of southern Quebec. To complement the field survey, we will measure the effect of plant interaction on ecological attributes using an original mesocosm experiment designed to reproduce competition between wetland plant species with clonal growth. Results of our study 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 constructed wetlands used for wastewater treatment.