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1 <br />1 <br /> 4.3 Vegetation Sampling Analysis and Discussion: 1986, 1988, and 1993 Studies <br /> <br /> 4.3.1 Cover <br />' <br /> Figure 30 provides a comparative illustration of vegetation cover trends over the ten <br />yeaz life of the Test Plots and Reference Area. Several trends in vegetative cover aze <br /> appazent from the data. The general trend of increasing vegetative cover with <br /> increasing soil depth remained consistent over the ten years of Test Plot existence. In <br />' the Test Plot 1 48" treatment a decrease in cover from the 24" treatment was noted in <br /> 1986 and 1988, while cover in the 48" treatment was equivalent to that of the 24" plot <br />' in 1993. This uniform trend suggests that the 48" treatment depth provides no <br /> advantage in revegetation success in terms of total vegetative cover, and may in fact <br /> yield lower cover. In all treatments in Test Plot 2 during all study yeazs, cover <br />' increased with increasing soil depth. Total vegetation cover in Test Plot 2 was also <br /> higher overall than cover in the treatments of Test Plot 1. Test Plot 3 treatments were <br /> more variable in mean total cover spread than either Test Plots 1 or 2, but showed <br />' higher average cover (mean cover of all treatments within Test Plots by study year). <br /> Test Plot 3 treatments again illustrated the general trend of higher vegetation cover with <br /> increasing soil depth. In most treatments, in corresponding study years, total <br />vegetation cover was greater than in the Reference Area. <br /> <br /> 4.3.2 Herbaceous Production <br /> Herbaceous production over the life of the Test Plots did not show as many distinct <br />' trends as did vegetation cover (Figure 31). Total herbaceous production showed the <br /> generaltrend of increased herbaceous production with increasing soil depth. The <br /> notable exception to this trend is again illustrated by the Test Plot 1 48" treatment <br />' which had lower herbaceous production than the 24" Test Plot 1 treatment in two of the <br /> three study years (1986, 1993). Variability in study year growing season weather often <br /> confounds results regazding absolute values of vegetation parameters, however it is <br />' apparent from the three years data that 1993 growing conditions were conducive to <br /> greater herbaceous production as evidenced by the greater values for herbaceous <br /> production across all treatments and the Reference Area. Herbaceous production in all <br />' treatments exceeded Reference Area herbaceous production in 1986 and 1988. Data <br /> from this year indicates that only the deeper soil treatments were equivalent to or <br />' exceeded the Reference Area value and/or the herbaceous production success standard. <br />Whether this indicates a longer term trend or is a result of this productive growing <br /> season cannot be speculated on without further corroborating information. <br /> <br />67 <br />