Dissecting Solidago canadensis-soil feedback in its real invasion

Abstract

The importance of plant-soil feedback (PSF) has long been recognized, but the current knowledge on PSF patterns and the related mechanisms mainly stems from laboratory experiments. We aimed at addressing PSF effects on community performance and their determinants using an invasive forb Solidago canadensis. To do so, we surveyed 81 pairs of invaded versus uninvaded plots, collected soil samples from these pairwise plots, and performed an experiment with microcosm plant communities. The magnitudes of conditioning soil abiotic properties and soil biotic properties by S. canadensis were similar, but the direction was opposite; altered abiotic and biotic properties influenced the production of subsequent S. canadensis communities and its abundance similarly. These processes shaped neutral S. canadensis-soil feedback effects at the community level. Additionally, the relative dominance of S. canadensis increased with its ability of competitive suppression in the absence and presence of S. canadensis-soil feedbacks, and S. canadensis-induced decreases in native plant species did not alter soil properties directly. These findings provide a basis for understanding PSF effects and the related mechanisms in the field conditions and also highlight the importance of considering PSFs holistically.

Keywords: abiotic effect; biotic effects; community structure and function; competitive tolerance and suppression; invader–soil feedback; structural equation modeling.

Figure 1

An image of a plant community invaded by Solidago canadensis heavily in southern China. Photograph credit: L.J. Dong

Figure 2

Total biomass of microcosm Solidago communities (also termed as mixtures: plant communities consisting of Solidago and three Chinese natives) (a) and relative abundance of Solidago in mixtures (b) grown in uninvaded and invaded soils. Data are means ± 1 SE (n = 81). Abiotic effect, biotic effect, and total effect in two soils indicate how Solidago‐induced changes in soil abiotic properties, soil biotic properties, and soil abiotic and biotic properties influence the Solidago community production and the relative abundance of Solidago in mixtures. See Section 2 for more details on determining abiotic effect, biotic effect, and total effect

Figure 3

Competitive tolerance ability of Solidago to native plants in mixtures (i.e., plant communities consisting of Solidago and three Chinese natives) (a) and competitive suppression ability of Solidago against native plants in mixtures (b) grown in uninvaded and invaded soils. Data are means ± 1 SE (n = 81). Abiotic effect, biotic effect, and total effect in two soils indicate how Solidago‐induced changes in soil abiotic properties, soil biotic properties, and soil abiotic and biotic properties influence the competitive tolerance and suppression ability of Solidago in mixtures. See Section 2 for details on determining abiotic effect, biotic effect, and total effect

Figure 4

Path models examining how Solidago invasion alters soil abiotic properties and soil biotic properties through direct and indirect pathways and how these changes in soil abiotic and biotic properties in turn influence the production of subsequent Solidago communities (i.e., mixtures: plant communities consisting of Solidago and three Chinese natives) and the relative abundance of Solidago in mixtures. Solid and dashed arrows indicate significant and no significant relationships between latent variables at the level P = .1, respectively. Red and black arrows indicate negative and positive relationships between latent variables. Numbers associated with pathways between variables represent standardized path coefficients