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Title: LONG-TERM PLANT COMMUNITY RESPONSES TO TOPSOIL REPLACEMENT DEPTH ON RECLAIMED MINED LAND

Author
item BOWEN, C - UNIVERSITY OF WYOMING
item OLSON, R - UNIVERSITY OF WYOMING
item Schuman, Gerald
item INGRAM, L - UNIVERSITY OF WYOMING

Submitted to: American Society for Surface Mining & Reclamation Annual Meeting Proceeding
Publication Type: Proceedings
Publication Acceptance Date: 5/24/2002
Publication Date: 6/9/2002
Citation: Bowen, C.K., Olson, R.A., Schuman, G.E., Ingram, L.J. 2002. Long-term plant community responses to topsoil replacement depth on reclaimed mined land. pp. 130-140. In: Proceedings of the 19th Annual Meeting of the American Society of Mining and Reclamation, June 9-13, 2002, Lexington, KY.

Interpretive Summary: Topsoil replacement on mined lands enhances plant community development. Scientists have postulated for several years that replacing topsoil at various depths on regraded mine spoils may further enhance the development of the desired plant communities and landscapes more closely resembling that of undisturbed lands. Since plant succession and community development requires considerable time, we were fortunate to be able to assess the effects of variable topsoil replacement 24 years after initiation (1977) of a research study. We found that the shallower topsoil depths 0 and 200 mm had the greatest species richness and diversity while canopy cover and aboveground biomass was greatest at the 400 and 600 mm topsoil replacement depths. Increased biomass at the greater topsoil replacement depth on mined lands could increase landscape and community diversity and create a more natural looking ecosystem. However, the reduced cover on the shallower topsoil depths may not be adequate to protect the soil from erosion; therefore, we would need to be very careful in our landscape design to ensure limited opportunity for potential erosion.

Technical Abstract: The use of topsoil on reclaimed mine lands may enhance plant community development and influence reclamation success. This study assessed the long-term (after 24 years) effects of different topsoil replacement depths (0,200, 400, and 600 mm) on plant community cover, production, and diversity at a research site established in 1977 in south-central Wyoming. Plant species richness (number of species), canopy cover, aboveground biomass, and diversity were evaluated at the four topsoil depths in 2001. Plants were clipped, by species, to obtain mean biomass and to calculate importance values. Shannon-Wiener diversity indices were calculated for each topsoil depth. Species richness was highest (7.5) at the zero topsoil depth and lowest (5.6) at the 600 mm topsoil depth. Total canopy cover was greatest (average 26.7%) at 400 and 600 mm of topsoil and least (21.5%) at the zero topsoil depth. Seeded species canopy cover and seeded species biomass were also greatest at the 400 mm topsoil depth. Total biomass was similar for the 400 (734 kg/ha) and 600 mm (727 kg/ha) topsoil depths and lower but similar at the 200 mm depth (506 kg/ha) and 0 mm depth (513 kg/ha). Plant species richness and diversity index were highest at 0 mm (7.5 and 2.36, respectively) and lowest at 600 mm (5.6 and 1.87, respectively) of topsoil. Number of species and diversity decreased as topsoil depth increased. Increased plant biomass at the 400 and 600 mm depths indicate that variable replacement depths of topsoil can enhance reclamation success through greater species diversity and by creating a greater mosiac of vegetation. However, the reduced cover observed at these shallower topsoil depths may not be adequate to protect the soil from erosion.