REP31696 - Laserfiche WebLink

Home Browse Search

• Perennial grasses not only dominated total herbaceous production for all reclaimed areas in 1997, they were very consistent, with a ranging from 89.4 to 92.0 percent of the total herbaceous production. Perennial grass production from the Osgood Sand Reference Area was also the dominant component, totaling 85.2 percent of the total production. Interestingly, the forb component contribution to herbaceous production rose significantly from 1995 to 1997 in both the 1985 and 1986 Reclamation Areas despite the 50.8 percent January-July precipitation decrease from 1995 to 1997. In the 1985 Reclamation Area herbaceous production of fortis rose from 6.81 percent of the total herbaceous production in 1995 (Savage and Savage, 1995) to 7.97 percent of the total herbaceous production in 1997. Within the 1986 Reclamation Area forb production rose from 4.48 to 10.62 percent between 1995 and 1997. During the same years in the Osgood Sand Reference Area, forb herbaceous production decreased from 40.78 percent to 12.68 percent. A decrease also occurred in the 1987 Reclamation Area, from 19.14 percent (1995) to 8.96 percent (1997). Notably, the magnitude of forb production decrease between 1995 and 1997 in the 1987 Reclamation Area was not as great (53.2%) as that in the Osgood Sand Reference Area (68.9%). Based on the results of the 1997 sampling, the 1985, 1986, and 1987 Reclamation Areas would meet the final revegetation success criterion for total herbaceous production. The 1986 and 1987 Reclamation Areas have mean total herbaceous production values greater than the Osgood Sand Reference Area, and the 1985 Reclamation Area is not significantly less than 90 percent of the mean value of the • Osgood Sand Reference Area with 90 percent statistical confidence. SPECIES COD~IPOSII'ION The Colorado Division of Minerals and Geology considers species composition of the revegetated and reclaimed areas to be an indicator of successful vegetation establishment. A standazd has been set by CDMG for the evaluation of species composition at the Keenesburg Mine. To be judged successful, a[ 6na1 bond release, this standard requires that, "the species composition on the reclaimed azea is such that there are at least seven perennial species of which four are warm season grasses and one is a forb. No one component of the above species should comprise greater than 40% relative importance nor less than 3% relative importance. Relative importance will be measured by calculating relative cover of the revegetation species. Vegetation species which may be used in the calculation of species composition may be any plant species not defined as a noxious or prohibited plant species, and may be native or introduced." Species presence and representation on the reclaimed areas was less than encountered in 1996. As noted elsewhere, this observation is likely related to the 1997 precipitation regime. The Osgood Sand Reference Area contained one more species in 1997 than in 1996. A comparison of the 1995 species composition data with the revegetation • success standard reveals that all of the reclaimed areas sampled in 1997 would meet the final bond release species composition success standazd. -15-