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drilling the seed rather than the straw mulch. 1978 observations indi- <br />Gated that most of the stzaw blew off the plots early is the 1978 <br />growing season. <br />2. Relative effects of slope angle and mulch treatment on plant <br />growth on aarth and south aspects {Table 3.4-6). <br />As previously discussed, second year density showed a strong re- <br />sponse to aspect. In this analysis, all south aspect treatment means <br />are not significantly different from each other, but all are signifi- <br />cantly lower than north aspect treatments means. Within each mulch <br />treatment (control, excelsior), there are no significant density dif- <br />ferences between different slopes on the same aspect. Density on excel- <br />sior is significantly higher than density on the control on the two <br />north-facing slopes. <br />Cover data show a similar response to aspect. Cover values oa all <br />south aspect treatments are not significantly different from each other <br />but all are significantly lower than nay north aspect treatment. Within <br />each mulch treatment (control, excelsior), control cover oa the 2:1 <br />north slope is signifieaatlg lower than the 4:1 north slope; the excel- <br />sior treatment cover is non-significant between different slopes on the <br />' north aspect. Cover for excelsior-treated plots is higher than foz the <br />control on the 2:1 north slope, but cover differences are non- <br />significant on the 4:1 north slope. <br />Production data follow a pattezn very similar to that described for <br />density and cover. Productivity values on all south aspects were not <br />significantly different from each other, and all were sigaificaatly <br />lower Lhaa on north aspect treatments. The 2:1 north control is <br />sigaificaatly lower than the 4:1 north control, but the two excelsior <br />treatments on different slopes oa the north aspect are non-significant. <br />Production was sigaificaatly higher on excelsior-treated plots than on <br />the control oa both slopes on the north aspect. <br />Jn summary, this analysis shows a strong differential response by <br />test species to aspect. All south-facing treatment means were signifi- <br />cantly lower than north-facing treatment means, regardless of slope and <br />mulch treatment. Significantly higher levels of cover and production <br />were recorded for 4:1 over 2:2 slopes, and excelsior treatments <br />~~ generallq showed significantly higher cover, density, and production <br />34 <br />