Environment: Seed Mix Summary
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.
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.
Components of the Restoration seed mix:
Wainwright Slender Wheatgrass
Wainwright Germplasm slender wheatgrass was collected at Fort
Wainwright, Alaska, in 1994. Wainwright is ideal for seed mixes for reclamation. Its seedlings are vigorous. Because of its short life, Wainwright helps colonize and stabilize the area. It then disappears so other plants have a chance to become established. Its tolerance of acidity is an important characteristic for mine reclamation.
Nortran Tufted Hairgrass
‘Nortran’ is a cultivar developed by the Agricultural and Forestry Experiment Station of the University of Alaska—Fairbanks. Based on native plant collections made in Alaska and Iceland, it was released in 1986. This cultivar can tolerate acidic soils, cold and wet conditions, and low fertility locations. ‘Nortran’ has the ability to reseed itself on disturbed lands, is persistent under continual cutting or foraging, and seems resistant to many rusts and snow molds.
Arctared and Borreal Red Fescue
Arctared and Boreal Red Fescue grasses are native to Alaska. Both will grow in gravel and form an anchor mat to hold down rocks. This fescue shows dependable winter survival. It has rapid seed germination and excellent seedling vigor.
Annual ryegrass is best for erosion control on newly excavated or reclamation areas, as a winter overseeding grass of warm season turf and as a “nurse” grass in low maintenance areas while the permanent turf is establishing. Annual ryegrass will persist for 1 to 2 years. The adaptability of this cool season grass to many soils and climates coupled with fast germination and prolific growing rate make this grass an important factor in establishing lawns and pastures.
Durar Hard Fescue
Durar is medium tall, semi-erect, long-lived, densely tufted bunchgrass. It is a large form of sheep fescue. It has broader, longer, coarser, more lax leaves than sheep fescue. It is fairly drought tolerant and is a heavy root producer. This plus its abundant dense leaves and low crown make it an excellent erosion control plant.
To enhance the new grass growth, 450 pounds of 20-20-10 fertilizer is applied per acre.
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