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Title: W-519 Sagebrush Mitigation Project FY-2004 Final Review and Status

Technical Report ·
DOI:https://doi.org/10.2172/15020758· OSTI ID:15020758

This report summarizes activities conducted as mitigation for loss of sagebrush-steppe habitats due to Project W-519, the construction of the infrastructure for the Tank Waste Remediation System Vitrification Plant. The focus of this report is to provide a review and final status of mitigation actions performed through FY2004. Data collected since FY1999 have been included where appropriate. The Mitigation Action Plan (MAP) for Project W-519 prescribed three general actions to be performed as mitigation for the disturbance of approximately 40 ha (100 acres) of mature sagebrush-steppe habitat. These actions included: (1) transplanting approximately 130,000 sagebrush seedlings on the Fitzner-Eberhardt Arid Lands Ecology Reserve (ALE); (2) rectification of the new transmission line corridor via seeding with native grasses and sagebrush; and (3) research on native plant species with a goal of increasing species diversity in future mitigation or restoration actions. Nearly 130,000 Wyoming big sagebrush seedlings where planted on ALE during FY2000 and FY2001. About 39,000 of those seedlings were burned during the 24-Command Fire of June 2000. The surviving and subsequent replanting has resulted in about 91,000 seedlings that were planted across four general areas on ALE. A 50% survival rate at any monitoring period was defined as the performance standard in the MAP for this project. Data collected in 2004 indicate that of the over 5000 monitored plants, 51.1% are still alive, and of those the majority are thriving and blooming. These results support the potential for natural recruitment and the ultimate goal of wildlife habitat replacement. Thus, the basic performance standard for sagebrush survival within the habitat compensation planting has been met. Monitoring activities conducted in 2004 indicate considerable variation in seedling survival depending on the type of plant material, site conditions, and to a lesser extent, treatments performed at the time of planting. The principle findings include: (1) a clear indication that in most settings, bare-root seedling survival is considerably higher than tubling survival; (2) we can expect low plant survival at sites with a high cover of large native bunchgrasses--especially bluebunch wheatgrass; (3) mycorrhizal root treatments appeared to increase growth and survival at the Coppice Dune and 98-Burn Undisturbed sites, but appeared to have little effect at the 98-Burn Disturbed, 111-Road Sitanion, or Cold Creek sites; (4) use of a hydrogel dip at planting increases survival of bare-root plants compared to dipping roots in plain water; (5) reducing leaf area via clipping after planting did not increase survival of bare-root plants; (6) seedlings planted on a south-aspect hillside at the Lower Cold Creek planting area had higher survival than seedlings planted on the hilltop or northern-aspects although these survival rates were lower than the survival rate down on the flats at this same location. Rectification of the transmission line corridor occurred in early March 2001, with the broadcast seeding of Sandberg's bluegrass and sagebrush. Success criteria for this site-of-disturbance rectification required a grass establishment after four years with greater than 25% total canopy cover with 60% of the plant cover from planted species (DOE 1998). This planting met the total canopy criterion but failed the criterion of 60% relative coverage of planted species. Although the performance standard was not met, the planting is not necessarily a failure; the communities on the tower pads appear to be developing toward the desired end state. We feel that there are no reasonable mitigative actions that can be taken at this time that would significantly alter or speed up the plant community development on these sites. In fact, most options, such as overseeding, may cause damage to the currently establishing communities on those sites.

Research Organization:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC05-76RL01830
OSTI ID:
15020758
Report Number(s):
PNNL-14901; 830403000; TRN: US0504696
Country of Publication:
United States
Language:
English