Studies of Plant Establishment Limitations in Wetlands of the Willamette Valley, Oregon.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
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The Willamette Valley was historically dominated by three types of wetlands wet prairies, shrubscrub, and forested. As a consequence of drainage for agriculture and urban development, most of these diverse wetlands have been lost. Restoration of native wetlands is limited by a lack of knowledge about native plant species growth and establishment requirements. This report presents results from four investigations of establishing wetland vegetation native to the Willamette Valley. In the first study, Pest Plant and Seed Bank Reduction Chapter 2, three site preparation techniques were applied to a disturbed wet prairie that contained exotic species. The objectives of the study were to determine a whether the treatments reduced pest plant abundances for more than 1 year, b if treatments also reduced native plant species, and c whether treatment effects were consistent among years. Tilling with fall owing and solarization heating under plastic were generally found to be more effective than burning at reducing existing plants. Native plants were affected by all treatments. Although each treatment was effective at reducing at least one exotic plant species, none of the treatments were generally effective at controlling pest plants. This may have been due to cool, dry weather conditions during the treatments that were not conducive to seed germination. The authors conclude that site treatments should be applied for more than 1 year, and native plant materials should be planted as soon as possible to outcompete the recovering exotic species.
- Agronomy, Horticulture and Aquiculture