Moyano Jaime, Rodriguez-Cabal Mariano A, Nuñez Martin A
Grupo de Ecología de Invasiones, INIBIOMA, CONICET, Universidad Nacional del Comahue, Quintral 1250, San Carlos de Bariloche, CP 8400, Argentina.
Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont, 05405, USA.
Ecology. 2021 May;102(5):e03330. doi: 10.1002/ecy.3330. Epub 2021 Apr 13.
The ideal-weed hypothesis predicts that invasive plants should be less dependent on mutualisms. However, evidence in favor of or against this hypothesis comes mainly from observational studies. Here, we experimentally tested this hypothesis using a two-factor greenhouse experiment, comparing the seedling growth response of different Pinus species (varying in invasiveness) to ectomycorrhizal fungal inoculation. Most species showed no response until they were 6 mo old, at which point inoculation increased growth between 10 and 260% among the different species. This growth response was higher for species with lower seed mass, higher dispersal ability, higher Z score (a proxy for invasiveness) and higher number of naturalized regions, all of which correspond to higher invasiveness. Our results show that timing is a crucial factor when comparing mycorrhizal dependency of different species. Dependence on mutualistic microorganisms could be part of a strategy in which invasive species produce smaller seeds, in greater number, which can disperse further, but where seedlings are more reliant on mycorrhizas to improve access to water, nutrients, and protection from pathogens. Our results suggest that reliance on mutualisms may enhance, rather than limit, nonnative species in their ability to spread, establish, and colonize.
理想杂草假说预测，入侵植物应该较少依赖共生关系。然而，支持或反对这一假说的证据主要来自观察性研究。在此，我们通过一项双因素温室实验对这一假说进行了实验验证，比较了不同松树物种（入侵性各异）的幼苗生长对外生菌根真菌接种的反应。大多数物种在6个月大之前没有表现出反应，此时接种使不同物种的生长增加了10%至260%。种子质量较低、扩散能力较高、Z值较高（入侵性的一个指标）以及归化地区数量较多的物种，这种生长反应更高，所有这些都与更高的入侵性相对应。我们的结果表明，在比较不同物种的菌根依赖性时，时间是一个关键因素。对共生微生物的依赖可能是一种策略的一部分，在这种策略中，入侵物种产生数量更多、体积更小的种子，这些种子可以传播得更远，但幼苗更依赖菌根来改善对水、养分的获取以及抵御病原体。我们的结果表明，对共生关系的依赖可能会增强而非限制外来物种的传播、定殖和殖民能力。
