Answer: I'm surprised you lost Doug Firs and Cedars to root rot - both typically thrive in wet soils! But, since you haven't been successful with them, you might consider planting cottonwood or evergreen poplar trees. Both are frequently planted when restoring wetlands. I'd stay away from bamboo; even the clumping kinds can overtake an area. Laurels are reasonably well-behaved and shouldn't pose a problem when planted in a wetland area. For additional information, you might want to contact your local Native Plant assn. (through OSU extension service in Portland).
Best wishes with your landscape!
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