Tidal Freshwater Marsh Establishment on Dredge Spoils in the Columbia River Estuary1
- Michael E. McVay,
- Paul E. Heilman,
- David M. Greer,
- Stanton E. Brauen and
- Aaron S. Baker2
A study of marsh establishment through seeding and transplanting of tufted ha|rgrass [Deschampsia cespitosa (L.) Beauv.] and slough sedge (Carex obnupta Bailey) on sandy dredge material in an intertidal location in the Columbia River Estuary is reported. The experiment included treatments with single and split applications of a mixed N, P, and K fertilizer. Survival and growth of plants and N, P, and K concentrations in plant tissues are presented.
Survival and biomass production differed significantly with respect to elevation with few plants of either species surviving after the first winter below 0.7 m above Mean Lower Low Water (MLLW). The best growth of tufted hairgrass transplants was in upper elevations (Average about 1.9 m above MLLW), but satisfactory stands were obtained down to about 0.9 m above MLLW. The best growth of slough sedge was at middle elevations (about 1.1 m above MLLW) with satisfactory growth down to about 0.8 m above MLLW. Direct seeding was not a satisfactory means for establishing these species, although natural seeding of tufted hairgrass began to occur in the second year of the plantings in areas protected and stabilized by the transplants.
Fertilizer significantly increased growth of tufted hairgrass during both growing seasons, particularly at the upper tier. With slough sedge, except for a slight increase in the number of culms, fertilizer had no significant effect on growth in either year.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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