2012-06-20_PERMIT FILE - C2010089 (61)

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TABLE 6.- SPECIES DIVERSITY BY YEAR AND SOIL HORIZON A/B AB YEAR A 1978 1.0325* 1.0728 0.9418 1.0272 1981 0.7995 ac** 1985 0.4489 a 0.3557 c 7 a 0.5149 a 0.3875 a *Duncan's evaluation not conducted on 1978 data. * *Means within a row followed by the same letter are not significantly different at the 0.05 level. Species richness in 1978 tended to be higher on plots having B horizon soil (Table 7). 1981, the highest number of species was associated with the treatments containing some or a A horizon soil. In 1985, of species per sampling transect was associated with the A/B horizon plots, but the means were not significantly different. TABLE 7. SPECIES RICHNESS BY YEAR AND SOIL HORIZON A B A/B AB YEAR 16.0* 19.0 19.0 18.0 1988 19.9 ** 9.9 a 1981 9.9 a 8.5 a 9.7 a 1985 6.2 a 7.0 a 7.2 a 6.2 a *Duncan's evaluation not conducted onm1978tdata. * *Means within row followed by not significantly different at the 0.05 level. Topsoil Depth Study Density and Stand Ratings Grass seedling density counts in 1977 on the topsoil depth study ranged from 21.41 to 31.00 plants/m4. The differences among the means were reported to be nonsignificant. Stand ratings in 1978 ranged from 1.19 to 3.39. The differences among these means were reported to e 20 b croepth significant tre tent was associated el soci atedwith the highest stand rating of 3.39. Cover Total plant cover in 1979 was found to be greatest on the 30 cm topsoil depth, but the differences among means were not significant (Table 8). In 1981, total plant cover values tended to increase with increasing soil depth, but no advantage in topsoil depth beyond the 20 cm could be documented. Maximum cover in bu85all rtreatment the were statistically equal. TABLE 8.-- PERCENT TOTAL PLANT COVER BY YEAR AND SOIL THICKNESS YEAR 0 CM 10 CM 20 CM 30 CM 46 CM 1979 1981 1985 *Means within a row followed by the same letter are not significantly different at the 0.05 level. Total plant cover appeared to be partially correlated with soil thickness. The calculated coefficient of correlation for total plant cover and soil thickness for the three monitoring periods yielded values of r = 0.55, (P< 0.34) r = 0.99, (P< 0.001), and r = 0.42, (P< 0.48), respectively. These values are presented to demonstrate over time, there is no consi nt correlation between topsoil thickness' An total p'Tant cover. Individual species cover values indicate certain species responded to depth of respread topsoil. Alfalfa cover in 1979 was significotter higher at the 30 cm tepth (Table 9). species showed responses to soil depth in 1979. In 1981, significant responses in growth for orchardgrass, smooth brome and meadow brome by soil depth were observed. Maximum cover of orchardgrass was observed at the 30 cm depth while cover of smooth brome and meadow brome showed a progressive increase in cover as the depth of respread topsoil increased. By 198 only alfalfa and smooth brome showed a statistically significant response to topsoil depth. Both species showed trends of increasing cover with increasing soil thickness. Alfalfa cover increased from 0 cm to the 30 cm thickness then declined. Smooth brome showed a progressive increase in cover with each thickness of respread topsoil. K=3 -6 36.0 a* 34.5 a 38.5 a 57.0 a 42.0 a 64.8 a' 68.0 a 21 ° _r 79.9 ac 86.1 87.0 a 9 89.7 a 92.8 a Production Biomass production in 1979 was found to increase linearly with increasing topsoil depth (Table 10). The coefficient of correlation for the two variables was r = 0.97 (P< 0.007). In 1981 and 1983, biomass production followed a similar pattern with coefficient of correlation values of r = 0.96 (P< 0.01), r = 0.94 (P< 0.017), respectively. In 1985, no differences among means could be documented, and the maximum biomass production had shifted from the 46 cm topsoil depth to the 20 cm depth. The coefficient of correlation value between total biomass and soil thickness was r = 0.44 (P< 0.46).