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Photo 7. Skunkbush browsed by mule deer. <br />CONCLUSIONS AND RECCOMENDATIONS <br />The cottonwood grove in the study area is the largest such stand in the vicinity. Smaller <br />stands of mixed -age cottonwoods are found immediately to the east and southeast on the <br />other side of the railroad embankment. These sites have relatively young trees and a <br />diverse mix of native shrub and herbaceous species. By contrast, the much larger <br />cottonwood gallery to the south and west contains a high proportion of older dead and <br />dying trees; the decrease in shade has resulted in an invasion of tamarisk with a <br />consequent decline in native species such as skunkbush. <br />The species diversity and corresponding crown height diversity of the younger <br />cottonwood stands provide multiple niches for wildlife, especially migratory birds and <br />raptors. Also, the relatively heavy shade under these trees limits the spread of weeds <br />such as tamarisk and cheatgrass. Due to the ecological value of healthy cottonwoods, it <br />is recommended that the stand in the study area be preserved and enhanced to the <br />maximum extent practicable consistent with Halliburton operations on the property. <br />Implementation of the 2009 weed plan, particularly with regard to tamarisk and, to a <br />lesser extent, Russian olive, should ensure continued cottonwood regeneration at the site. <br />Specifically, tamarisk removal would decrease soil salinity and allow cottonwoods, <br />willows, and other native species to colonize the wetland at the southwest end of the <br />study area through natural means; planting should not be necessary. <br />Wildlife value of this wetland/cottonwood site can be preserved by limiting human <br />intrusion during the breeding season. Vehicle traffic should be routed away from the site <br />whenever practicable, and humans on foot should not enter except for weed control and <br />WestWater Engineering Page 7 of 8 April 2010 <br />