Thouvenot Lise, Ferlian Olga, Beugnon Rémy, Künne Tom, Lochner Alfred, Thakur Madhav P, Türke Manfred, Eisenhauer Nico
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
Institute of Biology, Leipzig University, Leipzig, Germany.
Front Plant Sci. 2021 Mar 16;12:627573. doi: 10.3389/fpls.2021.627573. eCollection 2021.
As ecosystem engineers, invasive earthworms are one of the main drivers of plant community changes in North American forests previously devoid of earthworms. One explanation for these community changes is the effects of earthworms on the reproduction, recruitment, and development of plant species. However, few studies have investigated functional trait responses of native plants to earthworm invasion to explain the mechanisms underlying community changes. In a mesocosm (Ecotron) experiment, we set up a plant community composed of two herb and two grass species commonly found in northern North American forests under two earthworm treatments (presence vs. absence). We measured earthworm effects on above- and belowground plant biomass and functional traits after 3 months of experiment. Our results showed that earthworm presence did not significantly affect plant community biomass and cover. Furthermore, only four out of the fifteen above- and belowground traits measured were affected by earthworm presence. While some traits, such as the production of ramets, the carbon and nitrogen content of leaves, responded similarly between and within functional groups in the presence or absence of earthworms, we observed opposite responses for other traits, such as height, specific leaf area, and root length within some functional groups in the presence of earthworms. Plant trait responses were thus species-specific, although the two grass species showed a more pronounced response to earthworm presence with changes in their leaf traits than herb species. Overall, earthworms affected some functional traits related to resource uptake abilities of plants and thus could change plant competition outcomes over time, which could be an explanation of plant community changes observed in invaded ecosystems.
作为生态系统工程师，入侵蚯蚓是北美以前没有蚯蚓的森林中植物群落变化的主要驱动因素之一。对这些群落变化的一种解释是蚯蚓对植物物种繁殖、补充和发育的影响。然而，很少有研究调查本土植物对蚯蚓入侵的功能性状反应，以解释群落变化背后的机制。在一个中型生态系统（生态otron）实验中，我们在两种蚯蚓处理（存在与不存在）下，建立了一个由北美北部森林中常见的两种草本植物和两种禾本科植物组成的植物群落。在实验进行3个月后，我们测量了蚯蚓对地上和地下植物生物量以及功能性状的影响。我们的结果表明，蚯蚓的存在并没有显著影响植物群落的生物量和覆盖度。此外，在测量的15个地上和地下性状中，只有4个受到蚯蚓存在的影响。虽然一些性状，如分株的产生、叶片的碳和氮含量，在有或没有蚯蚓的情况下，功能组之间和组内的反应相似，但我们观察到其他性状有相反的反应，如在有蚯蚓的情况下，一些功能组内的高度、比叶面积和根长。因此，植物性状反应是物种特异性的，尽管两种禾本科植物对蚯蚓存在的反应比草本植物更明显，其叶片性状发生了变化。总体而言蚯蚓影响了一些与植物资源吸收能力相关的功能性状，因此随着时间的推移可能会改变植物竞争结果，这可能是入侵生态系统中观察到的植物群落变化的一个解释。
