PS 83-224
Plant-derived smoke influences germination of native and invasive plants in the Northern Great Plains
Plant-derived smoke has stimulated seed germination in many fire-prone ecosystems, but forecasting influences of different types of smoke and which species are responsive remains challenging. The historic fire return interval in the Northern Great Plains (NGP) is thought to be 5-10 years; leading to a reasonable postulation that some of the native plants in the NGP may also respond positively to smoke. A positive relationship between native plant germination and smoke may have practical application in increasing success of native species restoration.
We evaluated effects of two types of smoke (mixed grass-derived and wood-derived) on germination of 10 native and invasive plant species from the Northern Great Plains. Species included invasive grasses (Bromus inermis and Poa pratensis), native grasses (Andropogon gerardii, Bouteloua curtipendula, Elymus canadensis, and Pascopyrum smithii), and native forbs (Dalea candida, Echinacea angustifolia, Geum triflorum, and Penstemon grandiflorus). Using a bee-keepers smoker, we applied dense smoke to the seeds for 1 hour. The seeds were then transferred to germination paper in 9 mm petri dishes and kept moist. Seeds were exposed to an alternating 12 hour light (10C temperature)/dark (21C) cycle. Seeds were monitored daily and were removed from the dishes after germination was observed.
Results/Conclusions
No significant difference was found across all species overall between wood-derived and grass-derived smoke but both smoke treatments were significantly different than the unsmoked control (F= 4.491,205 p=0.035).
Invasive grasses did not respond to smoke treatments. Invasive grass B. inermis achieved 100% germination within 5 days regardless of smoke treatment. Invasive grass P. pratensis did not begin germination until day 7 and was not affected by smoke treatment.
Generally, forbs were more responsive than grasses. Interestingly, native forb G. triflorum (common name= prairie smoke) incurred decreased cumulative germination in the smoke treatments compared to the control. Conversely, E. angustifolia had higher cumulative germination when treated with smoke.
Native grasses also had species-specific responses to smoke treatments. A. gerardii and P. smithii did not respond to smoke. However, B. curtipendula and E. canadensis both had higher cumulative germination when treated with smoke.
Results suggest that type of smoke had little influence, and that response to smoke was independent of plant growth form, as responses were species-specific among both forb and grass species.