The effect of soil inoculants on seed germination of native and invasive species

Successful re-introduction of native species through ecological restoration requires understanding the complex process of seed germination. Soil microbes play an important role in promoting native establishment, and are often added to restoration sites during seed sowing. We tested the role of soil and lab-grown bacterial inoculants on germination timing and percent germination for nineteen species of plants commonly found in coastal California. Each species exhibited a different response to inoculant treatments, but overall time-to-germination was longer and percent germination was lower with soil inoculant compared to control or other treatments. The invasive species in our study had the highest percent germination of all species and germinated faster than all native shrubs. Germination timing was negatively correlated with percent germination and with seed weight. Our results suggest that lab grown inoculant and chemical treatment are effective at increasing germination in some native species, while soil inoculant is not. Given differences in germination timing between native and invasive species, restoration practitioners could consider using herbicide to treat areas seeded with native shrubs immediately following germination of invasive species without harming most natives, although germination timing and herbicides need further study in relation to microbial effects on seed germination.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author