2010-03-12_REPORT - C1981019 (8)

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2.5 Planted Seed Establishment Perusal of Table 4 documents two indicator's of seeding success. The first is the overall seeding success rate or percent cover of seeded species divided by total percent plant cover. This indicator averaged 86.6% for 1999 revegetation, and 44.6% for 2002 and more recent revegetation (including revegetation from 2005 and 2007). If annual bromes or other weedy taxa were overly problematic, the seeding success (ground cover) rates would diminish with age, not increase. Therefore, it is expected that the seed success for the 2002 revegetation (minus the shrub only seed mix area) will continue to improve over time. The shrub only seed mix used on EP042 only exhibited 0.36% success. However, total plant cover on EP042 is 69.5% with 34.7% coming from perennial species, 0.25% from shrubs and, 33.5% from annual grasses. While seeding success and the resulting cover from the shrubs is quite low, it is encouraging to see how many perennial volunteers have established on the site. The second indicator of seeding success is the "relative success" by species determined for each year by dividing the percent of the seed base attributable to each species (based on number of seeds planted) into the resulting percent ground cover documented by point-intercept sampling (Table 4 and Charts 7 - 9). For example, if species Z comprised 10% of the total number of seeds planted and then exhibited 20% of the resulting ground cover, a relative success of 200% would be realized (20/10). Similarly, if species Y comprised 10% of the total number of seeds planted but only exhibited 5% of the resulting ground cover, relative success of 50% would be realized (5/10). Given this type of analysis, it has been Cedar Creek's experience that grass species exhibiting between 20% and 200% relative success are typically appropriate for the seed mix and are being planted at appropriate rates. Taxa with less than 20% relative success may need assistance through special handling (e.g., boosting the amount of seed in the mixture or adding an appropriate fertilizer or supplement), or are candidates for deletion or substitution. Taxa with more than 200% relative success should be re-evaluated for possible reduction of the amount of seed planted. Elevated success rates are often indicative of over aggressive taxa that can be detrimental to the overall community diversity. Furthermore, decisions regarding seed mix manipulations should be based on multiple years of analysis owing to climatic and other influences that occur annually. Similar "boundary" values for forbs would be 5% and 150%. Forb populations typically require far more seed to establish even minimal cover values, and most often, grass taxa are too competitive for all but the most aggressive forb species such as adapted introduced plants like alfalfa and cicer milkvetch. Finally, "boundary" values for shrubs in young reclamation would be 2% and 200% with the exception of CEDAR CREEK ASSOCIATES, Inc. Page 28 Colowyo Mine 2009 Revegetation Monitoring Report r r r