Habitat Development Field Investigations Miller Sands Marsh and Upland Habitat Development Site Columbia River, Oregon. Appendix E. Postpropagation Assessment of Botanical and Soil Resources on Dredged Material.

摘要

This report describes the study area, methods, and resutls of habitat development experiments conducted at Miller Sands, a dredged material disposal site near the mouth of the Columbia River. The study consisted of investigations and experimental plantings on the older upland portion of the island and on the more recently constructed spit and marsh area. Soil analyses showed relatively uniform soil conditions with sand texture on both experimental sites. However, at the low elevation on the spit, silt and clay contents were higher than elsewhere. The soil was also very low in organic matter and nitrogen but had relatively high base status and pH, with the upland being about pH 6 and the marsh soils about pH 7. The phosphorus level was also relatively high, being above soil phosphorus levels found in adjacent natural soils. Although marsh soils were somewhat less oxidized at lower elevations, the soil was relatively well aerated and contained no sulfides or nitrides. There was some nitrate present on the upland, but prior to fertilization nitrate levels were very low in the marsh. Good plant growth was obtained with most species planted on the upland considering the late date of establishment in the fall of 1976. Hairy vetch showed particularly good early growth, but many plants died before maturity due to spring black stem disease. Fertilization was necessary for the establishment of most species even though competition from invading grasses greatly increased with application of fertilizer. Barley, red clover, white clover, and bentgrass produced flowers after the first year of growth, but seed production was poor.