_GENERAL DOCUMENTS - C1981017 (227)

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STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1313 Sherman St., Room 215 Denver,Colorado 80203 DIVISION o F Phone:(303)866-3567 M I N E RA L S FAX:(303)832-8106 DATE: August 21,2000 GEOLOGY RECLAMATION MINING-SAFETY TO: Steve Renner ;r kill, Bill Owens FROM: Dan Mathews Governor Greg E Walcher RE: Coal Basin Noxious Weed Sampling Executive Director Michael B.Long Division Director Enclosed are vegetation data summaries from the noxious weed"reference"areas at Coal Basin,sampled this year on June 27 and 28. A brief history of the weed control efforts and associated monitoring conducted over the last few years is provided here,for the record. The reference areas were established,and initially sampled in 1998,with second year sampling conducted in 1999. The reference areas are located within larger noxious weed infestations in the Sutey Refuse Pile vicinity and along the reclaimed belt line corridor between the former rock tunnel and coal stockpile areas. They were established in order to monitor the effectiveness of control efforts initiated in 1998 following the initial sampling. The infestations were sprayed with Tordon(picloram)at 2 quarts per acre following sampling in 1998 and 1999. This year,you broadcast seeded the Sutey Pile Reference Area 2 and adjacent areas of the Sutey Pile,and these areas were intensively grazed with goats in early July,while the remaining monitored areas were sprayed with Tordon as previously. Your observations regarding the goat grazing operation are worth noting,specifically that while the goats consumed virtually all leafy vegetation growth,they tended to avoid the flowering stalks of the plumeless thistle(a primary target). The herder chopped off these stalks with a machete. You have indicated that a Fall 2000 Tordon application is tentatively planned for all areas where significant concentrations of noxious species remain. 2000 sampling was conducted as in previous years by crews from the OSM Denver Office(Becci Siegle, Barbara Bowerman,and Roger Baker)and DMG(Sandy Brown,Jim Burnell and me). Reference area locations,dimensions,and sampling methodologies are as described in my memo of July 23, 1998. Unless otherwise noted, sampling methods were identical to those employed in 1998. The reference area corners are marked with wood stakes,which I still intend to replace with steel posts,for reasons cited last year. Reference sites should be sampled again next year,with an evaluation to be made following the sampling regarding the need for continued treatment and monitoring. Reference Area No. 1 (flat area adjacent to Sutey Refuse Pile) Total vegetation cover was somewhat higher than 1999,similar to 1998 cover level. The area had been grazed by cattle prior to sampling in 1999,but this was not the case in 1998 or 2000. Relative cover of grasses has increased from 12.9%in 1998 to 61.7%in 2000,with a corresponding decline in relative cover of non-noxious forts,from 70.8%in 1998 to 20.7%in 2000. Noxious species absolute cover did not vary significantly among sample years,however both total noxious density and thistle density were significantly lower in 2000 than in previous sample years. Based on comparison of sample means,thistle density declined approximately 73%from 1998 to 2000. Density is the more precise tool for assessing treatment effect,as cover levels vary more from year to year due to proportion of seedlings vs. mature plants,and climatic conditions,potentially masking treatment effects. Due apparently to the unusually warm and dry spring,plant growth stage appeared to be a couple weeks ahead of the last couple years.