At the Appleton-Whittell Research Ranch, an ungrazed grassland preserve in southeastern Arizona, soil seed banks were sampled in June, August, and October 2002 and June 2003. Wildfire had previously burned 90% of the research ranch in May 2002. Seed density and species richness in burned native grassland (2 plots) were compared to those in burned exotic grassland (2 plots). Averaged over 4 sample dates, seed densities were as follows: burned native grassland, 591 ± 243.1 seeds ⋅ m–2 and 784 ± 334.9 seeds ⋅ m–2; burned exotic grassland, 501 ± 198.9 seeds ⋅ m–2 and 196 ± 123.8 seeds ⋅ m–2. Species richness in the seed bank, also averaged over 4 sample dates, was as follows: burned native grassland, 16.3 ± 1.7 species ⋅ m–2 and 19.5 ± [...]
