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• Sampling Year(cont'd) Stems /acre <br />1991 228 <br />1992 157 <br />1993 253 <br />1994 234 <br />1995 364 <br />1996 209 <br />1997 184.1 <br />Although these data were collected from different areas during these years, and the numbers <br />are thus not strictly comparable, the trend of decreasing, or at least not increasing, shrub <br />density through 1992 is probably real and may be related to competition from the heavy <br />herbaceous growth that comprises the high herbaceous production discussed above. It may <br />also be related to effects of the on-going drought from the period of 1988 through 1990. It <br />would appear from climatic data (Figures 7 through 10), that, although the drought moderated <br />in 1990, the period of 1991 to early 1992 did not show a great increase in terms of total <br />• moisture. Since shrubs suffer in competition with herbaceous plants, it is reasonable to believe <br />that the resurgence in herbaceous cover in 1991 may have had a negative effect on the density <br />of shrubs. This may have also been the case in 1996 and 1997 after the very abundant growth <br />of herbaceous species during the period of 1995 through 1997. <br />Climate data confirm that late 1992 through the first half of 1993 was a period of relatively <br />abundant moisture for the first time since 1987 (see climate data in ESCO 1994a). It would <br />appear that an increase in shrub density occurred between 1992 and 1993. This level has <br />experienced a slow decline since then, although the 1995 values were higher because in that <br />year, the 1978 reclamation area was included and it is distinctly higher in shrub density than <br />typical reclamation areas. The 1996 value of 209 stems per acre is probably the result of a <br />further decline in overall density that was exaggerated compared to 1995 because that year <br />included sampling of an area with unusually high values. <br />In the Wadge Pasture, shrub densities in 1988 through 1997 were 320, 476, 408, 288, 344, <br />356, 295, 223, 251, and 210 stems per acre, respectively. The apparent substantial increase in <br />• density in 1989 was partially lost by 1990, and, by 1991, a substantial decrease was <br />encountered, yet in 1992 an increase was measured. In 1991, seedlings were encountered in <br />18 <br />