2017-02-28_REPORT - C1981028 (30)

Home Browse Search

Keenesburg Mine 2016 Vegetation Monitoring Report Figure 6: Cheatgrass Relative Cover 2012 — 2016 70 E 50 0 40 P 30 20 10 0 O O O O H O O O O O O O O O O O N N N N D N N N D N N N N N N N N E Area 23 Area 25 Area 29 Area 30 Area 31 7.1.1 Vegetation Cover Trends over Time Vegetation data have been collected in Reclamation Area 29 since 2006 and in Reclamation Area 30 since 2009. These data sets were each started in the third growing season after seeding. They allow for some evaluation of trends over time. In 2006, Reclamation Area 29 was co -dominated by warm season perennial grasses and annual introduced forbs each comprising close to 30% of the relative cover (Table 17, Figure 7). Cool season perennial grasses, annual native forbs, and cheatgrass comprised relatively equal portions of the remaining cover. The seed mixture used in 2003 was 84% warm season grasses and 16% cool season grasses, thus this composition is not unexpected for a recently reclaimed site in this location. Spring 2007 precipitation was almost double the average likely resulting in a flush of annual species germination. However, from 2006 to 2011, the cover of warm season perennial grasses increased along with total cover, and the relative cover of annual species decreased as would be expected in a newly reclaimed area. Warm season grass species thrive when monsoonal precipitation coincides with warm temperatures in the mid to late summer months as is common in Colorado. In 2012, the herbicide treatment appeared to reduce annual species and the drought likely impacted the cool season grasses more than the warm season grasses. While we do not have data for 2013, the prolonged drought likely continued to take its toll on both the warm and cool season grasses; however, warm season species tend to be more drought tolerant and likely fared Habitat Management, Inc. 25 October 2016