1992-06-05_GENERAL DOCUMENTS - C1981017 (2)

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emvtronmema!scientists and engineers contributing 21.5 percent and 20.2 percent of the total vegetation cover overall. (Table 5 gives a listing of common and scientific plant names.) Sheep fescue, tufted hairgrass, timothy and blue aster are also abundant. Table 3 shows vegetation production data. These data are summarized in Table 4. Average production over a I plots is 12.6 g 0.25m-2(oven-dry). The highest producing species is cicer milkvetc at 3.3 g 0.25m-2 (oven-dry), averaged over all plots. Orchardgrass and sheep fescue contribute 2.6 g 0.25m-2 (oven-dry) and 1.7 g 0.25m-2 (oven-dry) total productio ,respectively, averaged over all plots. It was noted that the plot area at Mine#4 had ben grazed. Utilization was estimated to be about 10 percent. No shrubs were encountered in either transect or quadrat sampling. Other Observations The most limiting factor in successfully revegetating these sites is the steep slopes. Surface instability due to sloughing and creeping can diminish plant survival. This effect was noted in 1987 and is still apparent at all three plot locations. It is not known to what extent this may also be due to ineffective seed coverage on the lower parts of plots when the plots were seeded. In addition,the plots at Mine#1 have been severely affected by gully erosion: The figures below provide a graphic comparison of total vegetation cover measured in the third and fifth years of this study. Total vegetation cover has declined since 1987 and species composition has shifted. Orchardgrass has held its position as one of the dominant species, although in 1989 it is less consistently present at all locations. Cicer milkvetch has increased ir total cover, but it is significantly present only at Mine #5 where it appears robust aid vigorous. Bromar brome and timothy have declined in total cover. For 1989, sheep fescue and hard fescue were treated as a single species, and together these show a 4,light increase over 1987. Total forb cover exclusive of cicer milkvetch has declined. Over a period as short as two years, these trends may not be particularly meaningful, ar►d caution must be exercised in drawing conclusions from these data. IMS understands these plots will continue to be monitored IMS would recommend the collection of a few soil san6ples from each location when the plots are next monitored. Soil samples should be analyzed for basic soil fertility properties; these analyses can be performed economically by the Soils Testing Laboratory at Colorado State University in Ft. Collins: , 4