Inoculation with native grassland soils improves native plant species germination in highly disturbed soil

Background

Grasslands are globally imperiled, facing continued threats from anthropogenic disturbances. Seeding remains a common grassland restoration method, and yet, is typically met with limited success, partially because soils of degraded systems inhibit the germination of native species.

Methods

We assessed the germination success of 16 native grassland species sown in soils collected from a degraded grassland converted into a nonnative warm-season perennial grass, Bothriochloa ischaemum, and areas previously subjected to the eradication of this nonnative species. Our objectives were as follows: (1) determine native seed germination in soils collected from B. ischaemum or eradication control sites, compared to germination in native grassland soil, and (2) assess if native soil inoculation improves germination, compared to germination in degraded soils without inoculation.

Results

Germination of native species was exceedingly low when seeded into soil dominated by B. ischaemum, or in soil previously treated with combinations of herbicide and prescribed fire, relative to native grassland control. However, amendments with native grassland soil resulted in germination equivalent to native grasslands, alleviating the negative influences of degraded soils.

Conclusions

Our results highlight the role of native soil in improving the germination of desirable plant species following intensive management and soil degradation. Our research may improve restoration outcomes for managers focused on the conservation and restoration of grasslands.