Short = 1/2 life 4 months; moderate = 1/2 life 5-8 months; long = 1/2 life 8-12 months. ae = acid equivalent; ai = active ingredient. Season of application may vary depending upon local conditions. 1/ LD 50 = a standard measure of toxicity; the lethal dosage rate of a substance that will kill 50 percent of a group of experimental organisms. Table 3-6 Results of Herbicide Monitoring in South Umpqua and Rogue Rivers Station No. 14312260 South Umpqua River near Roseburg, Oregon 1/ The source (USGS) reported these values in micro grams per liter (ug/L) rather than parts per billion (ppb). The two values are essentially the same at these small concentrations. 2/ None signifies specifically looked for but not detected. Source: Computer printout from the U.S. Geological Survey "WATSTORE" system for western Oregon. Sediment yield from disturbed lands would lands would increase 15,650 tons under the proposed action. While impacts to overall water quality would not be significant, localized areas could be significantly affected. Should these areas feed recreational water bodies, impacts to water quality for recreation may occur (Section 3.7.1). Harvesting by both clearcutting and shelterwood methods, and slash burning nutrient enrichment (nitrogen and other nutrients) of streams. Impacts would be localized immediately downstream of activities and may result in algal blooms or changes in the aquatic habitat. Use of herbicides and fertilizers in the JKS YUS would not significantly impact water quality. A summary of the effects of the proposed action on water quality of the JKS YUS is found in Table 3-7. This is a summary only, and does not replace the information contained in the text. The removal of trees creates openings in the forest canopy, which allows more light to penetrate to lower forest strata. Timber harvesting initiates secondary plant succession similar to that caused by natural disturbances. Different cutting practices open the forest canopy to different degrees, thereby influencing the plant composition and duration of the plant communities differently. Clearcutting Clearcutting completely removes the forest canopy, thereby allowing the establishment of a well developed grass/forb stage. Approximately 4,000 acres (400 acres per year) would be clearcut in the JKSYUS under the proposed action. Shelterwood Cutting Two-stage shelterwood cutting, by virtue of lessened canopy removal, does not allow as much grass/forb development and produces an initial community more similar to a transitional grass/forb-shrub/seedling community. Approximately 27,200 acres of commercial forest in the JKS YUS would be converted to this transitional stage. Single Tree Selection As the name implies, the single tree selection harvest system involves the removal of individual, mature trees scattered throughout the stand. In heavily stocked forests, openings created by the removal of single trees NOTE: slight decrease no change 22,335 lb propor- increase 15,650 tons from disturbed propor- increase FEFE over 5 as for years total nitrogen lands over 5 years as for nitrogen Some slight hazard of water contamination by herbicide drift or residue would exist This table is for summary and comparison only; it is not intended to replace derivative narrative. |