Burning Modifies Composition of Emergent Seedlings in Fescue Prairie

Fire plays a crucial role in mediating species composition in Fescue Prairie. However, previous studies focused on responses of plant community to burning without disentangling the effects of burning on seedling emergence in Fescue Prairie. In this study, seedlings emerging in the field and from soil seed banks incubated in a greenhouse were examined after burning in the spring of 2012 and 2013 near Saskatoon, Canada. Soil seed bank samples were taken from the top 5 cm of the soil profile, separated into litter, 0- to 1-cm soil, and 1- to 5-cm soil layers. In the 2-yr field study, 11 plant families with 1 graminoid and 22 nongraminoids were identified among emerged seedlings. Burning significantly increased the number of 3 native and 1 non-native seedlings emerging, as well as total seedlings emerging from the field in both years (P < 0.05). Species richness and diversity of seedlings emerging from the field were increased by burning. Species composition of emerged seedlings from the field was significantly altered by burning in 2012 (P = 0.03) and 2013 (P < 0.01). In the 2-yr soil seed bank study, 19 plant families with 10 graminoids and 56 nongraminoids emerged. Burning had more prominent effects on seedling density of native species and forbs, rather than non-native species and graminoids. Species composition was altered by burning in all studied soil layers (P < 0.05). Fire appears to stimulate recruitment of some species, especially early seral species, contributing to potential changes in species composition of the Fescue Prairie.