Invasive earthworm effects on plant functional traits and diversity

非土著物种对自然群落的入侵是对当地生物多样性的威胁，目前被列为最重要的全球规模环境问题之一。当入侵物种引入与本地群落不同的新特征时，它们可以从根本上改变本地生态系统。在地下入侵者中，入侵蚯蚓正受到越来越多的关注，因为它们在陆地生态系统中扮演着生态工程师的角色，而且它们在功能上与世界各地的本土土壤动物不同。外来蚯蚓的入侵往往会导致地上和地下多样性的非随机变化，这表明蚯蚓入侵可能会改变性状介导的机制对生态系统功能的影响。本项目旨在以北美北部无蚯蚓地区为模式系统，阐明外来蚯蚓入侵如何影响种内植物功能性状变异和植物群落组成。为了对蚯蚓入侵改变植物群落组成的机制提出一个全面的框架，我们将评估具有活跃蚯蚓入侵前沿的不同森林中的植物功能特征以及植物群落的分类和功能组成。我们还将通过实验室实验来解开这些修饰的潜在机制。对已发表的关于入侵蚯蚓对植物群落的影响的文献的荟萃分析将补充经验性的工作。因此，这项拟议的工作通过使用野外观察、实验室实验和荟萃分析的新颖综合组合，整合了不同的生态尺度(从植物物种特定的生理和形态特征到种群到植物群落)。首先，一项全面的实地研究将探索入侵的蚯蚓群落对落叶林入侵和非入侵地区(WP1)已实现的植物特性的植物群落功能多样性的影响。其次，实验室研究将使我们能够区分不同生态类群的蚯蚓对植物群落组成的影响，并通过研究它们对植物-植物和植物-食草动物相互作用(WP2)的影响来解开潜在的机制。第三，荟萃分析将整合现有文献和WP1和WP2的信息，以调查蚯蚓作为环境过滤器的作用，根据观察到的植物群落组成的变化来选择特定的植物特征(WP3)。这一荟萃分析将比较不同生态类群和(入侵)蚯蚓群落对植物特性、植物群落多样性和植物群落组成/同质化的影响。基于功能特征的方法将使我们能够开发出植物对外来蚯蚓的反应的一般概念框架。

Invasions of natural communities by nonindigenous species are a threat to native biodiversity and are currently rated as one of the most important global-scale environmental problems. Invasive species can radically transform native ecosystems when they introduce novel traits that are dissimilar from those of the native community. Among belowground invaders, invasive earthworms are receiving increasing attention because of their role as ecosystem engineers in terrestrial ecosystems and their functional dissimilarity to the native soil fauna at various locations around the world. The invasion of exotic earthworms often causes non-random changes in diversity above- and belowground, suggesting that earthworm invasion may alter how trait-mediated mechanisms impact ecosystem functioning.This project aims to elucidate how invasive exotic earthworms affect intraspecific plant functional trait variation and plant community composition using earthworm-free regions of northern North America as a model system. In order to derive a comprehensive framework regarding the mechanisms by which earthworm invasions could modify plant community composition, we will assess the plant functional traits and the taxonomic and functional composition of plant communities in different forests with active earthworm invasion fronts. We will also disentangle the underlying mechanisms to these modifications with laboratory experiments. Empirical work will be complemented by a meta-analysis of published literature on invasive earthworm effects on plant communities. Thus, the proposed work integrates different ecological scales (plant species-specific physiological and morphological traits to populations to plant communities) by using a novel, synthetic combination of field observations, laboratory experiments, and meta-analyses. First, a comprehensive field study will explore the effects of invasive earthworm communities on the functional diversity of plant communities based on realized plant traits in invaded and non-invaded areas of deciduous forests (WP1). Second, a laboratory study will allow us to differentiate the effects of different ecological groups of earthworms on plant community composition, and to disentangle the underlying mechanisms via the study of their effects on plant-plant and plant-herbivore interactions (WP2). Third, a meta-analysis will integrate the information from existing literature and WPs 1 and 2 to investigate the role of earthworms as environmental filters selecting for specific plant traits based on observed changes in plant community composition (WP3). This meta-analysis will compare the effects of different ecological groups and communities of (invasive) earthworms on plant traits, plant community diversity, and plant community composition/homogenization. The functional trait-based approach will allow us to develop a general conceptual framework of plant responses to exotic earthworms.