Germination patterns of the scrublands in response to smoke: The role of functional groups and the effect of smoke treatment method

Smoke is thought to be one of the most important fire cues stimulating seed germination of species from both fire-prone and fire-free ecosystems. The impact of smoke on seed germination at the community level of certain habitats in Western Asia has not been investigated yet. We aimed to analyze the effects of different smoke treatments on soil seed germination of different plant functional groups in a scrubland habitat. A soil seed bank was used to count seedling emergence following aerosol smoke (15 min or 30 min exposure) or smoke-water (1:1000 and 1:500, v/v) treatment. Smoke-induced germination was then separated into five functional groups (i.e. annual grasses, perennial grasses, annual herbs, perennial herbs, and legumes). The results showed that seeds of annuals were stimulated with smoke. In contrast, germination of perennial grasses was reduced by the smoke treatments, whereas perennial forbs and legumes showed no particular response to the smoke treatments. The longer exposure time to the aerosol smoke (30 min) and the higher concentration of smoke-water (1:500, v/v) were not at detrimental levels and resulted in maximum germination among the functional groups, other than perennial grasses. Our results indicate that smoke-stimulated germination of annuals plays an important role in species establishment after fire in the scrublands of Western Asia. Smoke treatments impacted differently on the different functional groups, and it is useful to determine the smoke response-classifications of these species to understand the effects of fires on the plant communities.