Laserfiche WebLink
V. DISCUSSION <br />1997 PRECIPITATION REGIME <br />Precipitation from October 1996 through May 1997 yielded total precipitation in the <br />amount of 11.15 inches based on National Weather Service records from the Paonia I <br />SW station. The CDMG calculated "pre-growing season" precipitation mean for the <br />purposes of the historic record is 11.08 inches. For sampling purposes, "normal" years <br />were defined as those years with a "pre-growing season" precipitarion total (as recorded <br />by the National Weather Service or their designee) greater than 8.45 inches and less <br />than 13.71 inches. $ased on this definition, the "pre-growing season" precipitation for <br />1997 was determined to fall within the "normal" range. Vegetation parameter values <br />from the 1997 growing season should represent vegetation cover, herbaceous <br />production, and species composition from a normal precipitation year as envisioned in <br />the historic record concept for the West Elk Mine. <br />1997 VEGETATION SAMPLING <br />Vegetation sampling at the historic record study area in 1997 represented the second <br />consecutive year of data collection at the historic record vegetation community. As <br />noted, the total precipitation received prior to the 1997 growing season was 3.37 inches <br />more than in 1996. As a result of the increased precipitation, several notable <br />observations were made in 1997. <br />A 74.5 percent increase in total vegetation cover was noted in the historic record _ <br />vegetation community from 1996 to 1997. The dominant plant species remained <br />Bromus inermis followed by Poa pratensis. Bromus inermis showed a 135.1 percent <br />increase in total cover from 1996 to 1997. Poa pratensis total cover decreased from <br />1996 to 1997 by 8.49 percent. Conwlw/us arvensis revealed the largest increase in <br />total cover of all species from 1996 to 1997 with a 244.6 percent increase. A sub- <br />dominant species in 1996, Agropyron intermedium showed the largest decrease in total <br />cover from 1996 to 1997, with a 78.1 percent drop in total cover. <br />Interestingly, the dominant plant species did not show increases in relative cover <br />equivalent in value to that of the vegetation community as a whole. Bromus inermis <br />showed an increase of 28.56 percent relative cover from 1996 to 1997, while Poa <br />pratensis showed a 47.23 percent decrease in relative cover from 1996 to 1997. <br />Agropyron intermedium, asub-dominant in 1996, fell from 22.63 percent relative cover <br />in 1996 to 2.41 percent relative cover in 1997. Conw/wlus arvensis increased in <br />relative cover from 5.50 percent to 11.22 percent in one year. Nine species which <br />were not represented in cover sampling in 1996 appeared in 1997. <br />_¢ <br />