Environment: Seed Mix

Areial reseeding loading plane with seeds.The long-term goal of reclamation at the Usibelli Coal Mine is to establish self-sustaining plant cover on the mined site that helps restore ecosystem function and maintain long-term water quality. This involves backfilling and regrading the mined sites to appropriate topography, then seeding herbaceous species and transplanting woody seedlings to control surface erosion in the short term. This initiates the establishment of long-term plant cover that will change naturally, much like on floodplains and deglaciated areas.

Grass seeding is critical to stabilize the surface for plants to take hold and add significant organic material to the soils. The seed mix is a combination of cultivars of commercially available native and introduced species selected for their suitability to the environment shortly after regrading. The introduced species usually grow more quickly than native species, thus providing protective cover more quickly. Grasses are used, even though they are not common in the surrounding vegetation, because their fibrous root network helps minimize surface erosion. However, as the soils develop and shade is provided by grasses and woody plants, the plant community changes into one dominated by local plant species, especially the woody plants that dominate the surrounding vegetation. The original grasses provide initial cover, temporary litter cover and organic matter; help catch seeds dispersed by plants in native vegetation; and eventually disappear from the site.

Aerial reseeding plane.In addition to the grass seedings, UCM reclamation crews plant thousands of woody seedlings on the sites each year. These plus the grasses provide the first stages of succession. Seeds from surrounding vegetation are transported by wind and animals, and those plants start colonizing the reclaimed areas. Over approximately 5 to 8 years, the original seeded grasses die back, the litter decomposes, and the colonizing species may dominate the site by year 10. The seedings and transplants help the native vegetation become established by stabilizing the site, providing wind protection, and adding organics to the soil.

Aerial reseeding plane spreading seed mix in flight.