Restoration in the Colorado Desert: Management Notes
Prepared for the California Department of Transportation District 11, 2829 Juan Street,San Diego, CA 92186 as part of the Desert Plant Project July 1993
Matthew W. Fidelibus and David A. Bainbridge
Outplanting seedlings is an important element of many restoration projects. Although the dominant trees and shrubs of California's deserts are relatively easy to grow in a nursery, container grown seedlings are traditionally bulky, heavy, and awkward to ship, making outplanting expensive (Bainbridge an Virginia, 1990). The economics and handling costs without significantly reducing survival.
Plants to be jellyrolled are removed from cells, and the roots or entire plants are wrapped up in a roll of moistened Kimtex™ fabric. Ten to fifteen plants are included in a roll. Jellyrolling has been widely used in forestry for nearly a century (Laird, 1992). Most foresters believe that jellyrolling reduces the moisture stress of seedlings (which are otherwise shipped bare root in insulated bags) during outplanting, resulting in better establishment (Lopushinsky, 1986). Jellyrolling has been used recently in Colorado desert revegetation projects in an attempt to reduce the cost of shipping and handling planting stock (rather than to increase survival).
Jellyrolling greatly reduces the weight, bulk, labor, andcosts associated with transportation and handling. While a rackof 98 sand filled super cells (10 inch plastic cells) weighsalmost 50 pounds, an ice chest holding 1000 jellyrolled plantsand ice may weigh only 30 pounds, a significant decrease inweight and volume per plant.
Jellyrolling also increases planting speed and efficiency. Workers are usually fatigued and less efficient in the hot and dry conditions of desert planting sites making it important to minimize field labor. Jellyrolled seedlings require less handling in the field, thus, fewer workers working less hours are needed for planting. Preliminary field studies suggest that planting desert shrub seedling from jellyrolls is 1.5-2 times faster than planting from supercells.
Removing plants from their containers is on of the most time consuming processes of any outplanting technique. Jellyrolling is advantageous in that the seedlings are removed at the nursery where the job can be completed more quickly and efficiently. Jellyrolling requires some extra labor at the greenhouse, but workers can work comfortably and efficiently at a bench top in the nursery setting. The seedlings can be removed inside or in the evening when plant photosynthesis has stopped, and the cool, moist environment is also less damaging for seedlings. The extra labor at the greenhouse is compensated for by labor saving experienced in the field. Some nurseries in the Northwest now offer jellyrolling as a service at the nursery prior to shipping seedling, further reducing costs. The U.S.D.A. Forest Service Medford nursery in Oregon has a jellyrolling machine that can roll more than 7,000 seedlings per hour (Valenzuela, 1992). A commercial operation can jellyroll plants for about 1¢ per seedling (Lopushinsky, 1986).
To be suitable for arid land revegetation projects, jelly rolling must provide protection form root desiccation and damage. Deans et al. (1990) found that root growth of Sitka spruce bare root seedlings was reduced 59% by desiccation, 85% by rough handling, and 98% by a combination of the two. Similar reduction of root growth will result in complete failure of a desert outplanting operation where rapid root growth is the key to plant establishment.
To survive outplanting stress, seedling must: 1) recover from injuries and stresses resulting from shipping and handling; 2) grow new roots to avoid moisture stress; 3) continue maintenance and growth respiration; and 4) adapt to a more hostile environment (Rietveld, 1989). Preliminary outplanting survival data for jellyrolled seedlings compares favorable to containerized plants. The effects of jellyrolling on desert plants were evaluated in and experiment monitoring differences in plant water potential (as a measure of desiccation) between jellyrolled, containerized, and bare rooted Ambrosia dumosa (bur sage) seedlings over 24 hours (typical shipping duration and conditions). Plantings of jellyrolled desert shrubs have also been evaluated. In a large study, Ambrosia dumosa and Hymenoclea salsola (cheese bush were compared to seedlings planted from plant bands to evaluate field success.
A greenhouse experiment to determine the effect of jellyrolling on plant water potential was performed using Ambrosia dumosa seedlings. A rack of seedlings (98) in supercells was divided into five groups: 1)Jellyrolled, 2)left in super cells, 3) chilled and jellyrolled, 4)left in chilled supercells, and 5) a bare root control. To simulate typical shipping conditions, the plants were kept in a room without photosynthetically active ratiation for the duration of the experiment (chilled treatments were stored in coolers with ice). The water potentials of several plants in each group were periodically measured (after 2,4,6 and 24 hours) using a pressure bomb ( Waring and Clearym, 1967).
In 1992, Larrea tridentata (creosote bush) were jellyrolled at San Diego State University before shipping to a revegetation site in Anza-Borrego Desert State Park. Survival was compared with survival of Larrea shipped in containers. After 45 days, there were no statistically significant differences in survival between jellyrolled and containerized plants.
After pilot studies in the Colorado desert indicated little difference in plant establishment success between shrubs planted form jellyrolls or containers, a larger study was initiated at Red Rock Canyon State Park. Hymenoclea salsola and Ambrosia dumosa seedlings shipped form the L.A. Moran Restoration Center in Davis, CA, in jellyrolls and six inch plant band containers were outplanted on April 8,1993. The health and survival of the plants will be followed for two years after outplanting. Several jellyrolled Larrea tridentata, Ambrosia dumosa and Cleome isomeris (bladder pod) seedlings were not planted due to time constraints; these plants were brought to San Diego State University, stored in a refrigerator, and replanted in containers after being jellyrolled for more than one week. (Figure 5).
Results and Discussion
Ambrosia dumosa seedling became more hydrated than containerized plants during the first six hours of storage (figure 1). Apparently, the moist jellyroll fabric provided more water to the plant roots than growth medium suggesting that desiccation is not a problem with jellyrolled A. dumosa seedlings for short shipping or storing durations (under six hours). After twenty four hours there was no significant difference in moisture stress between jellyrolled or containerized plants (figure 2). If moisture stress at planting is a major factor in determining outplanting success (as Reitveld suggests 1990), this data indicated that planting jellyrolled A. dumosa seedlings may result in better outplanting success than planting from containers.
The survival data figures 3 and 4, is based on monitoring through May 24, 1993. Neither A. dumosa nor H. salsola experienced statistically significant differences in survival after 46 days. New data collected on July 7, 1993 further supports the hypotheses that jellyrolled desert plants do not suffer higher mortality than plants shipped in planting containers.
Revegetation sites can be far from where the plants are raised, requiring shipping durations of hours to days. It is recommended that plants be jellyrolled just prior to shipping so that plants spend a minimum of time in this condition. However, some species have tolerated jelly for more than a week (figure 5). The species being shipped and the time plants will spend in jellyrolls are factors that need to be considered.
Jellyrolling greatly reduce shipping weight and bulk and makes field planting faster and easier. These labor and equipment savings can significantly reduce the cost of revegetation, reclamation, and restoration projects. Although jellyrolling has been used for nearly a century in forestry, its potential for other planting projects has not been widely studied. Species specific reactions necessitate some experimentation to insure that jellyrolling is a suitable alternative to container shipping. The roots of many desert shrubs are fragile and easily desiccated, but jellyrolling does not seem to significantly impair outplanting success for most species tested, The results of these desert studies suggest that jellyrolling could be used in many other ecosystems where desiccation is less severe and root damage less critical.
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