J Plant Ecol ›› 2020, Vol. 13 ›› Issue (6): 667-675.DOI: 10.1093/jpe/rtaa052

• Research Articles •     Next Articles

Contrasting responses of native and alien plant species to soil properties shed new light on the invasion of dune systems

Stefano Vitti1,2, *, Elisa Pellegrini2,3, Valentino Casolo2, Giacomo Trotta2 and Francesco Boscutti2   

  1. 1 Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy, 2 Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, via delle Scienze 91, Udine 33100, Italy, 3 Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 København Ø, Denmark

    *Corresponding author. E-mail: stefano.vitti@phd.units.it
  • Received:2020-02-24 Revised:2020-07-03 Accepted:2020-08-03 Online:2020-08-11 Published:2020-12-01

Abstract:

Aims

Among terrestrial ecosystems, coastal sandy dunes are particularly prone to alien plant invasion. Many studies related the invasion of dune habitats to anthropic causes, but less is known about the role of soil properties and plant traits in plant invasion. In this study, we tested the relationships between soil features and alien plant invasion in dune systems, focusing on the interplay between soil nutrients, soil salinity and plant functional traits.

Methods

Study sites were sandy barrier islands of the Marano and Grado lagoon (northern Adriatic Sea). One hundred plots (4 m × 4 m) were selected within 10 areas according to the main habitats occurring along the ecological gradient of dune system (foredune, backdune and saltmarsh). In each plot, we recorded all plant species occurrence and abundance and we collected a soil core. For each soil sample, soil texture, conductivity (as proxy of soil salinity), organic carbon and nitrogen content were analyzed and related to the species number and cover of native and alien plants. Variation of main reproductive and vegetative functional traits among habitats was also analyzed for both alien and native species.

Important Findings

Soil properties were strongly related to overall plant diversity, by differently affecting alien and native species pools. In backdune, the most invaded habitat, a high soil conductivity limited the number of alien species, whereas the content of soil organic carbon increased along with alien plant abundance, suggesting also the occurrence of potential feedback processes between plant invasion and soil. We found a significant convergence between native and alien plant functional trait spectra only in backdune habitat, where environmental conditions ameliorate and plant competition increases. Our findings suggest that in harsh conditions only native specialized plants can thrive while at intermediate conditions, soil properties gradient acts in synergy with plant traits to curb/facilitate alien plant richness.

Key words: invasive alien species, functional traits, soil nutrients, plant communities, dune system

摘要:

在陆地生态系统中,沿海沙丘特别容易受到外来植物的入侵。许多研究将沙丘生境的入侵归因于人为因素,但对土壤性质和植物性状在植物 入侵中的作用却知之甚少。本研究考察了沙丘系统土壤特征与外来植物入侵的关系,重点研究了土壤养分、土壤盐分和植物功能特征之间的相互作 用。研究地点是马拉诺和格拉多泻湖(北亚得里亚海)的沙质堰洲岛。根据沙丘系统生态梯度上的主要生境(前沙丘、后沙丘和盐沼),在10 个区域内选择100个地块(4 m × 4 m)。在每个地块中记录所有植物物种的发生和丰度,并收集一个土壤核。对每个土壤样品进行土壤质地、电导率(代表土壤盐 分)、有机碳和氮含量分析,并与本地和外来植物的种类数和覆盖度相关联。分析外来和本地物种主要的生殖功能和营养功能性状在生境中的变化。研究结果表明,土壤性质对外来物种库和本地物种库的影响不同,与植物整体多样性密切相关。在后沙丘(最易入侵)的生境中,高的土壤导电性限制了外来物种的数量,但土壤有机碳含量随着外来植物丰度的增加而增加,这也表明植物入侵与土壤之间存在潜在的反馈过程。只有在后沙丘生境中,随着环境条件的改善和植物竞争的加剧,本地植物和外来植物的功能性状谱有显著的趋同。本研究结果表明,在恶劣条件下,只有本地特有植物才能茁壮成长,而在中等条件下,土壤特性梯度与植物特性协同作用,抑制/促进外来植物丰富度。

关键词: 外来入侵物种, 功能特性, 土壤养分, 植物群落, 沙丘系统