Degraded Great Basin sagebrush communities are at risk of conversion to cheatgrass-dominated systems. Restoration of these communities is often attempted without understanding the existing soil seed pool or the potential impacts of restoration treatments on the seed pool. Within the framework of a regional scale restoration project (SageSTEP), seed pools in control and prescribed burn plots at one restoration site were quantified and compared to aboveground vegetation before and after burning in order to answer the following questions:
1) What is the relationship between the seed pool and the aboveground vegetation?
2) Does prescribed burning affect the seed pool and the relationship between the seed pool and aboveground vegetation?
The study site was near the Onaqui Mountains in Tooele County, Utah, USA. Pre-treatment seed pool and vegetation data were collected in summer 2006. Post-treatment seed pool samples were collected immediately following fire (fall 2006), and post-treatment vegetation was surveyed summer 2007. Sørensen’s similarity index was calculated to compare at the level of presence/absence the seed pool to the aboveground vegetation and the seed pool before and after prescribed burning.

Results/Conclusions

Aboveground vegetation and seed pool compositions were moderately similar prior to burning in both control and burn plots (Sørensen’s similarity coefficients; 0.483 and 0.538, respectively), although fewer species were present in the seed pool in both plots and before and after burn. Burning did not strongly affect the relationship between the seed pool and the aboveground vegetation (Sørensen’s similarity coefficients; 0.500 and 0.500, respectively) or the seed pool composition at the level of species present (Sørensen’s similarity coefficients, before and after; control: 0.545, burn: 0.696).
Because many species in the aboveground vegetation were also in the seed pool, and prescribed burning did not strongly affect species presence in the seed pool, the seed pool may contribute to recovery of a similar community post-fire. However, preliminary results suggest shifts in relative abundances of species in the seed pool following fire which could greatly affect overall composition even if similar species are present. These apparent shifts in relative abundance presently are being further investigated with ordination methods.