Sustained restoration of Phragmites-infested wetlands: A vegetation alternative to cyclic spray and burn.

摘要

A major issue in coastal restoration in the United States is combating the invasion of wetlands by Phragmites australis. Currently, the common way to control Phragmites is to cyclically spray the plants with an herbicide and then burn the dead canes. A vegetation alternative for Phragmites control relies on the development of varieties of desired species that can block the invasion of Phragmites and subsequently planting the varieties at the key points where Phragmites might establish and further spread. Such a variety, with potential blocking characteristics (for example, dense shoot/root systems and thick upright shading canopies), can be selected from tissue culture regenerated plants of the desired species by screening somaclonal variants that are produced during the tissue culture process.; Plants were regenerated from tissue culture in six desired species: Spartina patens, Spartina alternifora, Scirpus robustus, Juncus gerardi, Juncus roemerianus, and Baccharis halimifolia. Selected regenerants of some of these species were planted in a field plot that simulated a marsh. Phenotypic variation among regenerants was found in S. patens and J. gerardi, indicating the occurrence of somaclonal variation. Some regenerants of these two species showed potential Phragmites blocking characteristics. By using the random amplified polymorphic DNA (RAPD) technique, genomic variation in S. patens regenerants was detected. Several desired species were also planted in a Phragmites infested natural marsh to test the blocking strategy. Most plants of B. halimifolia, I. frutescens, J. roemerianus, and S. patens , either wild type or tissue culture regenerants, planted as a multi-layered wall of plants, demonstrated effectiveness in controlling Phragmites by blocking its spread.; The availability of the tissue culture regenerated plants of the desired species makes it possible to select lines or varieties that have desirable characteristics for wetland creation and restorations projects, such as blocking the invasion of Phragmites. Also important, tissue culture and plant regeneration is an efficient way of producing large numbers of plants required for wetland creation and restoration. In addition, tissue culture regenerated plants may contain greater genetic diversity than vegetatively propagated plants and therefore have greater adaptability, enabling the plants to thrive in the non-pristine created or restored wetland environment.