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<br />002726 <br /> <br />Opportunities for Ecological Improvement Along the Lower Colorado River <br />Mark Briggs and Steve Cornelius <br />7/24/97 <br /> <br />Even though wire baskets were used, rabbits and deer still managed to damage <br />significant numbers of planted vegetation. After the third growing season, honey <br />mesquites not significantly damaged by rabbits were roughly three meters (10 feet) tall. <br />By 1988, some honey mesquites were larger than the planted cottonwoods. Most <br />screwbean mesquites also grew well and were about 1.5 meters tall after two years of <br />growth. Palo verde growth rates were generally slower than that of mesquite. <br />Quailbush grew rapidly and by the third growing season, some were over one meter <br />tall and producing seed. However, rabbit damage to the lower branches outside of the <br />protective baskets was common. Wolfberry (Lydum spp.) appeared to be stressed <br />during the early portion of the first growing season but seemed to grow better during <br />the fall months. In heavy textured saline soils, Lydum torreyi appeared to be more <br />vigorous than Lydum andersonii (Pinkney 1992). <br />Lessons Learned: Planting riparian trees adjacent to areas where they may receive <br />supplemental water (however artificially) can be the difference between success and <br />failure. Using plants that are adapted to the site's current ecological condition (rather <br />than basing plant material "selection solely on what was on site prior to disturbance) can <br />greatly improve revegetation effectiveness. Results also underscore the need for <br />further research describing the salt and water tolerances of non-agricultural plant <br />species. <br /> <br />Site #9 <br />Fortuna Fish Pond <br />Location and Size: This 3.2-hectare (eight-acre) revegetation site surrounds the Fortuna <br />Fish Pond, is located about 10 miles east of Yuma, Arizona at the confluence of the Gila <br />River and Fortuna Wash. <br />Objective: To mitigation for impacts from the construction of the Yuma desalinization <br />plant <br />Completion Date: Spring of 1985 <br />Pre-Project Site Conditions: Saltcedar (Tamarix chinensis), arrowweed (Pluchea sericea), <br />and creosote bush (Larrea tridentata) were the dominant woody species found on the site <br />prior to project initiation. Soil survey indicated generally sandy soils with a 15 cm <br />thick clay layer found approximately 1.2 meters beneath the soil surface on the western <br />portion of the site. Depth to saturated soils was estimated to be less than three meters <br />(10 feet). However, soil moisture readings indicated that there was a significant <br />difference in water availability above and below the clay layer (25 percent and 3 <br />percent, respectively) (Pinkney 1992). <br />Project Strategy: Approximately 300 cottonwood, willow, and mesquite seedlings <br />(grown in one-gallon containers) were planted in pre-augered holes around the <br />periphery of Fortuna Pond during the spring of 1985. In November 1986, <br />approximately 100 cottonwood and willow cuttings and poles were also planted. The <br />cuttings were planted in saturated soils around the edge of the pond; no holes were <br />augered for the cuttings. The poles were 2.5 to three meters long and were planted in 5 <br />em-diameter holes augered to about one meter deep. Most of the plants were protected <br />initially with 3-foot tall chicken wire baskets. In 1986, 4-foot tall, welded wire baskets <br /> <br />Page 14 <br />