Mandated uniform topsoil replacement may hinder or prevent compliance with reclamation bond release standards such as canopy cover, aboveground production, shrub density, and diversity. This investigation was conducted at a coal mine in northeastern Wyoming in order to evaluate the relationship between variable topsoil replacement depths of 15, 30, and 56 cm and short-term revegetation success. Vegetation variables of total cover, total vegetation canopy cover, total number of species, and average number of species (based on cover sampling) were determined on both reclaimed and 2 native reference areas (Upland Grass and Breaks Grass) during 2000, 2001, and 2002, with aboveground production being measured in 2002. The highest total number of species encountered based on canopy cover and aboveground production sampling was in the 30-cm reclaimed treatment, many of which were desirable seeded and volunteer perennial grasses and forbs. In 2001, total vegetation cover on the 56-cm reclaimed treatment was significantly greater than on the 15-cm treatment. Comparison of the current study area to a 1991 reclaimed site indicated a consistent general pattern of species establishment. Aboveground production was also higher in the current reclaimed area than in the native reference areas, while total cover and total vegetation cover were lower. Shannon-Wiener H9 values, based on absolute total vegetation canopy cover, were greater in the 30-cm reclaimed treatment; however, a majority of diversity indices indicated that the Breaks Grass native reference area was more diverse than either Upland Grass or Reclaimed sites. From observations made at the North Antelope/Rochelle Mine, a mosaic of different topsoil depths, including the shallow 15-and 30-cm depths as well as the mandated 56-cm depth, creates the broadest range of vegetation response under a standard regime of revegetation practices. Thus, the capacity to replace different thickness of topsoil should be a reclamation practice available to mine operators. Resumen Remplazar la capa superficial del suelo a la profundidad establecida por mandato puede retardar o impedir el alcanzar los está ndares de rehabilitació n tales como: la cobertura de copa, la producció n de biomasa aérea, la densidad y diversidad de arbustos. Esta investigació n se condujo en una mina de carbon en el nordeste de Wyoming para evaluar las relació n entre el remplazo variable de la capa superficial del suelo a profundidades de 15, 30, y 56 cm y el éxito a corto plazo de la revegetació n. Durante el 2000, 2001, y 2002 se determinaron variables de vegetació n como la cobertura total, la cobertura de copa de la vegetació n total, el nú mero total de especies y el nú mero promedio de especies (basado en muestreos de cobertura), la medició n de las variables se realizó en el á rea rehabilitada así como en dos á reas nativas de referencia (Upland Grass y Breaks Grass) y en el 2002 se midió la producció n de biomasa aérea. El mayor nú mero total de especies encontrados en base los muestreos de cobertura d...

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A project was initiated in 1998 to investigate the effect of varying topsoil depths on soil parameters, plant cover, production and diversity on a coal mine in northeastern Wyoming. Soil and vegetation information was collected for three consecutive growing seasons (2000 through 2002) on reclaimed areas with three topsoil treatment depths (15, 30 and 56 cm) and from two native reference areas (Upland Grass and Breaks Grass) at the mine. For the vegetation analysis, total vegetation cover, total cover, average number of species and total number of species were the primary parameters. Vegetation production was measured in 2002 only. Analyzed soil parameters included pH, electrical conductivity and sodium adsorption ratio at 15 cm intervals throughout the treatment depth and the immediate underlying spoil material. Although three years of data has been collected for this project, the primary emphasis of this paper will be 2002. No significant differences in vegetation and soils were noted by treatment in the 2000 through 2002 data. Location effects, however, were numerous, which emphasizes the difficulty in utilizing native reference areas as standards for reclamation success on reclaimed areas. All vegetative parameters were generally higher in reference areas with the exception of production. Diversity indices on the reclaimed and reference areas were also evaluated. The Shannon-Wiener indices were significantly different by location throughout 2000 to 2002 and by treatment in 2001, i.e., the 30 cm treatment was significantly higher in diversity than the 56 cm treatment. Previous research has indicated diversity differences in topsoil depth treatment levels increase over time. For this project, differences in topsoil depth treatments will likely increase over time and/or with more typical precipitation patterns.