Soil modification by invasive plants: effects on native and invasive species of mixed-grass prairies

Abstract

Invasive plants are capable of modifying attributes of soil to facilitate further invasion by conspecifics and other invasive species. We assessed this capability in three important plant invaders of grasslands in the Great Plains region of North America: leafy spurge (Euphorbia esula), smooth brome (Bromus inermis) and crested wheatgrass (Agropyron cristatum). In a glasshouse, these three invasives or a group of native species were grown separately through three cycles of growth and soil conditioning in both steam-pasteurized and non-pasteurized soils, after which we assessed seedling growth in these soils. Two of the three invasive species, Bromus and Agropyron, exhibited significant self-facilitation via soil modification. Bromus and Agropyron also had significant facilitative effects on other invasives via soil modification, while Euphorbia had significant antagonistic effects on the other invasives. Both Agropyron and Euphorbia consistently suppressed growth of two of three native forbs, while three native grasses were generally less affected. Almost all intra-and interspecific effects of invasive soil conditioning were dependent upon presence of soil biota from field sites where these species were successful invaders. Overall, these results suggest that that invasive modification of soil microbiota can facilitate plant invasion directly or via 'cross-facilitation' of other invasive species, and moreover has potential to impede restoration of native communities after removal of an invasive species. However, certain native species that are relatively insensitive to altered soil biota (as we observed in the case of the forb Linum lewisii and the native grasses), may be valuable as 'nurse'species in restoration efforts.

Early Spring Flora of the Sub-Pannonic Steppic Grassland (NATURA 2000 Site) in Bilje, Northeast Croatia

“…Generally, trees and shrubs encroach on the sites and develop layers of high cover leading to a rapid decrease in species richness (Dú-bravková and Hajnalová 2012). Invasive species, due to the biological characteristics (Lonsdale 1999), may outcompete native species for resources (Brewer and Cralle 2003), suppress their growth (Jordan et al 2008), and have a negative infl uence on species diversity (Dogra et al 2010).…”

Assessment of Soil Biological Activity in Northern Aspen Parkland Native and Seeded Pasture Using Bait Lamina

“…Jordan et al (2008) suggested that smooth brome may be dependent on soil biota to aid in self-facilitation, and that smooth brome may condition the soil by creating a hostile environment for native plant species.…”

Earthworm, microbial biomass, and leaf litter decay responses after invasive honeysuckle shrub removal from urban woodlands.

“…First, invasive plants species can alter the abiotic and biotic properties of soils in ways that benefit themselves (Klironomos 2002;Callaway et al 2004;Levine et al 2006;Bever et al 2010) while also harming native species (Reinhart et al 2003;Reinhart and Callaway 2006;Stinson et al 2006;Jordan et al 2008;Rodríguez-Echeverría et al 2013). These changes may persist for years after invasive species removal, creating soil legacies that may inhibit native species re-establishment and alter nutrient cycling via changes in the microbial communities (Levine et al 2006;Reinhart and Calloway 2006).…”