PARENT SESSION
Poster Session #20: Arid Lands Restoration.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Does topsoil removal, storage and replacement decrease abundance of viable seed?

Scoles, Sara^*,1, DeFalco, Lesley¹, Newton, Alice², ¹ US Geological Survey - Western Ecological Research Center, Las Vegas, Nevada² National Park Service, Lake Mead National Recreation Area, Boulder City, Nevada

ABSTRACT- Topsoil reclamation facilitates the re-establishment of native vegetation following surface disturbance by preserving and eventually replacing the indigenous seed bank. The process of topsoil removal, storage and replacement has had varying success in re-establishing vegetation at Lake Mead National Recreation Area (National Park Service) but to date these observations have not been quantified. We measured the change in the abundance of viable seed for a project that redirected a major roadway within the park. Soil was collected to a depth of 15 cm (6 inches), stored for two months, and redistributed upon completion of the new roadway. Soil temperature and moisture within the topsoil pile (20, 50 and 70 cm) were also measured and related to seed bank dynamics. The greatest loss of seed (>50% of total) occurred during the process of soil collection (p<0.05). Losses of viable seed also occurred during the two month storage of topsoil and following soil replacement, however these losses were negligible (each <5% of total loss, p>0.05). We relate these results to the short-term revegetation success of sites that have been reclaimed between 1 and 9 years within the park. The reduction in the abundance of viable seed during topsoil reclamation was primarily due to the dilution of seeds when soil fractions were mixed during collection and not due to mechanical injury to seed or to topsoil pile conditions.

KEY WORDS: restoration, topsoil reclamation, seed bank dynamics