Department of Biological Sciences, Kent State University, Kent, OH, 44242, USA.
Oecologia. 2013 Dec;173(4):1295-307. doi: 10.1007/s00442-013-2710-z. Epub 2013 Jul 10.
Plant-soil interactions directly affect plant success in terms of establishment, survival, growth and reproduction. Negative plant-soil feedback on such traits may therefore reduce the density and abundance of plants of a given species at a given site. Furthermore, if conspecific feedback varies among population sites, it could help explain geographic variation in plant population size. We tested for among-site variation in conspecific plant-soil feedback in a greenhouse experiment using seeds and soils from 8 natural populations of Lobelia siphilitica hosting 30-330 plants. The first cohort of seeds was grown on soil collected from each native site, while the second cohort was grown on the soil conditioned by the first. Our goal was to distinguish site-specific effects mediated by biotic and/or abiotic soil properties from those inherent in seed sources. Cohort 1 plants grown from seeds produced in small populations performed better in terms of germination, growth, and survival compared to plants produced in large populations. Plant performance decreased substantially between cohorts, indicating strong negative feedback. Most importantly, the strength of negative feedback scaled linearly (i.e., was less negative) with increasing size of the native plant population, particularly for germination and survival, and was better explained by soil- rather than seed-source effects. Even with a small number of sites, our results suggest that the potential for negative plant-soil feedback varies among populations of L. siphilitica, and that small populations were more susceptible to negative feedback. Conspecific plant-soil feedback may contribute to plant population size variation within a species' native range.
植物与土壤的相互作用直接影响植物在建立、生存、生长和繁殖方面的成功。因此，对这些特征的负向植物-土壤反馈可能会降低特定物种在特定地点的密度和丰度。此外，如果同一种群的反馈在种群地点之间存在差异，它可以帮助解释植物种群大小的地理变异。我们使用来自 8 个自然种群的种子和土壤，在温室实验中测试了同一种群植物-土壤反馈的地点间变异，这些种群中含有 30-330 株半边莲。第一批种子在每个原生地采集的土壤中生长，而第二批种子则在第一批种子调节的土壤中生长。我们的目标是区分由生物和/或非生物土壤特性介导的特定地点效应与种子来源固有的效应。与来自大种群的种子相比，从小种群中产生的种子所培育的第一批次植物在发芽、生长和生存方面表现更好。两批植物之间的表现差异很大，表明存在强烈的负反馈。最重要的是，负反馈的强度与原生植物种群的大小呈线性关系（即，负反馈程度较低），特别是在发芽和生存方面，土壤效应比种子源效应更好地解释了这一点。即使只有少数几个地点，我们的结果表明，半边莲种群之间存在负向植物-土壤反馈的潜力，而且小种群更容易受到负向反馈的影响。同一种群的植物-土壤反馈可能有助于物种原生范围内植物种群大小的变异。
