2002-07-08_GENERAL DOCUMENTS - M2002004 (4)

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1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 COLORADO SCHOOL OF MINES RESEARCH INSTITUTE 7 Seeds were planted using a hand seed drill calibrated to deliver the equiva- lent of 323 live seeds per m (30 live seeds per ft Research in Montana found that excessively high seeding rates do not improve plant establishment and may be detrimental to reclamation objectives (DePuit and Coenenberg, 1979; Holechek, et al., 1981). Seeding depth was 2 cm for all species. Rows were oriented south to north and parallel to the gradient in soil depth. Immediately following seed- ing, jute netting was applied to each plot. This material was used as a mulch because of ease of application to a small area and because it provided a uniform cover for the plots. The buffer area surrounding the plots was also seeded and fertilized as described above. In most cases crested wheatgrass was seeded in this area at the same row spacing as within the plot. PLOT MAINTENANCE During mid - spring, plots supporting excessive weed growth were sprayed with 2,4 -D ester at an application rate of 1 kg per ha. Small rodents were controlled using traps, poison, and wire mesh fencing. However, such control efforts were not particularly successful and rodent damage was noted at some plots. For the ;Big Horn, Noonan, and one of the Big Sky plots, initial seeding did not produce the desired grass density, and reseeding was necessary. Reseeding was conducted in the fall of 1977 and followed the procedures listed above, with exception of fertilization. Where necessary, water diversion structures were maintained to preclude surface water entry. In two of the plots, settling in excess of 5 cm was noted for small areas where soil depth was approximately 150 -cm. These areas were filled during the fall with soil acquired from adjacent areas. DATA ACQUISITION Production Perennial grass production (or yield) was harvested during August of 1978 through 1981 in 0.91 -m wide strips perpendicular to the gradient in soil depth. Plots were not harvested until each plot had completed its second growing season. At the time of harvest, the plants were mature and seed heads were filled. In some areas, seed dispersal was underway when the plants were harvested. Stubble height was either 10 or 20 cm, depending on the species and its production. Clipping at these heights removed from 50% to 70% of the aboveground biomass, thus simulating a moderate level of grazing according to Ganskopp and Bedell (1981). Stubble height was kept as high as possible in an effort to trap snow and increase the available moisture during the following growing sea- son; Young, Evans, and Elkert (1969) successfully used grass stubble as a snow trap. In 1978 and 1979, grasses were harvested by species in 0.91 -m strips oriented perpendicular to the soil gradient. Grasses were weighed to the nearest 0.1 kg immediately after clipping to obtain a wet weight measurement for each strip. In 1980 and 1981, the grasses were harvested by individual rows within a given strip for each species. These samples were immediately weighed to the nearest 0.1 g to obtain wet weight production for each row in each strip. Samples of each species were collected from randomly chosen strips and rows and placed in a sealed container. In the laboratory, these samples were oven