Invasion of Solidago gigantea in contrasting experimental plant communities: effects on soil microbes, nutrients and plant–soil feedbacks

Abstract

Summary1. Plant-soil feedbacks can influence the success of non-native plant invasions. We investigated if these feedbacks and the underlying invasion effects on soil microbes and nutrients depend on the species composition of the invaded vegetation, and whether these effects are related to differences in the invasibility of native plant communities. 2. We carried out a mesocosm experiment simulating the invasion of Solidago gigantea into three wetland plant communities (Molinion, Magnocaricion and Filipendulion), each composed of five plant species but differing in productivity. To study plant-soil feedbacks, we used different soil inoculum types from invaded and non-invaded field sites of the corresponding communities and a reference site. Invasion success was assessed by measuring the biomass of S. gigantea after three growing seasons and by analysing soil properties several times during the experiment. 3. Invasion success varied significantly among communities and soil inoculum types. Solidago gigantea produced more biomass in the Molinion than in the two more productive communities. In all three communities, it exhibited a negative feedback upon itself, producing 31-46% less biomass when the substrate was inoculated with soil from a stand invaded with S. gigantea. 4. The presence of S. gigantea did not influence total biomass in any community nor N and P availability in soil. However, it led to a decrease in soil bacterial and an increase in soil fungal biomasses. These changes were similar in the three communities and unrelated to the biomass of S. gigantea biomass in the invaded communities. 5. Synthesis. The experimental comparison between effects of an invasive plant species on soil properties in different native communities showed similar effects despite pronounced differences in the ability of the invasive species to grow in the different communities. In this system, plant-soil interactions may thus affect invasion, but not explain differences in the invasibility of different communities. The invasive species increased soil fungal biomass, particularly in its own soil, compared to native species and experienced a negative feedback, suggesting that the course of its invasion might be affected by species-specific soil pathogens.

Species-specific effects of plant invasions on activity, biomass, and composition of soil microbial communities

“…Both plant species increased mycorrhizal frequency but decreased species richness of AMF (Zubek et al unpublished). Our results agree with those of Scharfy et al (2009Scharfy et al ( , 2010 and Quist et al (2014) who found that S. gigantea invasion had no influence or decreased soil respiration, bacterial biomass, or phosphomonoesterase activity but increased fungal biomass and/or fungal:bacterial ratio. S. gigantea litter may support fungal rather than bacterial growth as it has lower tissue concentrations of most nutrients and higher C:N ratio than adjacent native vegetation Thorn and Lynch 2007;Dassonville et al 2008).…”

“…However, such differences in tissue nutrient concentrations were not found by other authors (Stefanowicz et al unpublished). High fungal biomass detected in this study may suggest that S. gigantea stimulates fungal pathogens in its introduced range (Scharfy et al 2010), as shown previously for other invasive species (Nijjer et al 2007;Mangla et al 2008). For example, Mangla et al (2008) found that Chromolaena odorata, a destructive tropical invasive weed, accumulated high concentrations of the generalist soil-borne fungi, Fusarium semitectum, thereby creating a negative feedback to native plant species.…”

“…These modifications may lead to changes in soil nutrient pools and element cycling, engendering positive feedback that potentially stabilizes current or accelerates further invasion, and prevent re-establishment of native species (Ehrenfeld 2003;Niu et al 2007;Liao et al 2008;Pii et al 2015). The greater the invader-induced changes in soil, the greater the feedback that may be expected (Scharfy et al 2010).…”

“…These species are considered transformers (Tokarska-Guzik et al 2010), i.e., invasive species that Bchange the character, condition, form, or nature of ecosystems over a substantial area^ (Pyšek et al 2004); therefore, their effects on soil microbial processes and thus soil functioning (Nannipieri et al 2003) require detailed investigations. Previous research has been often conducted using either one or a small number of study sites, a single invasive species/ genus, and/or measuring few microbial properties, making generalizations on the impact of the invasion on soil functioning problematic Herr et al 2007;Scharfy et al 2009Scharfy et al , 2010Aguilera et al 2010;Dassonville et al 2011;Tharayil et al 2013;Mincheva et al 2014). To the best of our knowledge, data on the influence of R. laciniata invasion on soil microbial properties are lacking.…”

Differential influence of four invasive plant species on soil physicochemical properties in a pot experiment

“…To date, only few experimental studies have tested the impact of I. glandulifera, R. japonica, R. laciniata, or S. gigantea on soil (Scharfy et al 2010(Scharfy et al , 2011Bardon et al 2014Bardon et al , 2016. Scharfy et al (2010) performed a mesocosm experiment simulating the invasion of a single species-S. gigantea into three wetland plant communities and found no invasion effect on N and P availability in soil.…”