HYDRO20750 - Laserfiche WebLink

Home Browse Search

number of reports focused on salvage logging "best management practicea° evaluationbut also mentioned BAER treatments. Reports dated from 1962 through 1998. Grass seeding (aerial or ground) was usually per- ceived as "effective° if: (1) it produced at least 30 percent cover by the end of the first growing season; (2) seeded species comprised a significant amount of the total plant cover at the end of the first growing season; or (3) less sediment movement was measured compared to an unneeded plot or watershed. Statisti- calaignificanceofobaerveddifferencesbetweenseeded and unneeded sites was seldom tested. In the first year after fire, seeding was considered generally effective in 9 of 16 quantitative monitoring reports (56 percent). Second year effectiveness was similar (10 of 16 reports or 62.5 percent). One 1978 rehabilitation review from Region 3 collected data from 12 fires, ranging from 1 to 12 years after treatment. They found that seeding was generally successful (produced cover) onforeated sites but not on chaparral sites (Taylor and others 1979). The amount of cover produced by seeded greases during the first and second years after fire varied widely (tables 14 and 15). Many of the monitoring reports contained data on annual ryegrass and cereal grains (rye, barley or oats), the species most in use in recent years. More information was available from California (Region b) than any other area, most of it from chaparral sites. Annualryegrasa andcereal grains produced considerable cover in some cases. In others, they did not appreciably increase plant cover or reduce erosion, especially the first year after fire. In the nonquantitative reports, needing was judged to be "effective" or successful the first year after fire in 22 of 28 cases (79 percent), generally based on the presence or absence of grass, evidence of tilling, or amount of cover compared to unneeded areas. Second- year results were similar, with 11 of 14 caaea (79 percent) considered successful. In some caaea seeding was considered "effective" in producing cover but prob- ably not necessary, as natural vegetation regrowth was abundant ae well (Bitterroot National Forest 1997). In others it was given a mixed rating because the seeded species persisted for many years or ap- peared to crowd out native vegetation (Isle 1988, Loftinandothera 1998). Sometimesaeedingwasjudged effective in one part of a project but not another {Herman 1971, Liewer 1990, Ruby 1995, Story and Kracht 1989). Loftin and others (1998; Region 3) suggested that protection from grazing could be the single moat effective method for enhancing cover pro- duction by both seeded grasses and recovering native vegetation. Contour-felled loge were judged to be effective in all 5 documentsinwhichaome kindofdatawerereported. Accumulation ofaediment uphill ofthe barriers (Green 1990), lack of tilling in the treated area, or reduction in sediment collected downhill compared to an un- treatedplot were considered "effective" outcomes. For example, DeGraff (1982) measured "sediment trap efficiency" (STE) at 0.7 on elopes of less than 35 percent on the Sierra National Forest, meaning that 70 percent of the length of a log, on average, had accumulated sediment. Logs on steeper elopes exhib- ited anaverage STE of 0.57. Griffith (1989a) observed 1.5 t ac 1(3.4 Mg ha 1) of sediment behind a silt fence below a watershed treated with contour-felled loge, compared to 10.7 t act (24.2 Mg ha 1) from an un- treated waterahed,duringthe first postfireyear onthe Stanislaus National Forest. Both watersheds were salvage-logged the following year, and sediment out- put increased to 10 t ac 1(23 Mg ha 1) on the treated and over 34 t ac 1(77 Mg ha 1) on the untreated wa- tershed. Several reports frem the first few years after the Foothills Fire (Boise National Foreet) stated that no significant amounts of sediment were produced from any of several experimental watersheds treated with contour-felled loge, whether or not they were salvage-logged (e.g., Maloney and Thornton 1995). The reports noted that the area experienced no major thunderstorms until late summer 2 years alter the fire. In nonquantitative reporta,contour-felled loge were considered effective in 11 of 13 caaea (86 percent) in which they were actually tested by storms. Several reports pointed out that contour-felled logs are de- signed to reduce water flow energy and promote infil- tration, not trap sediment, but they showed some benefit as direct sediment traps and also enhanced establishment of seeded gr&saes. Different terminol- ogy was sometimes used by different Regions in the reports. The term "contour-felled log' was synony- mous with "log erosion barrier" in moat areas, but in Region 3contour-felling referred only to felling of material, not anchoring and sealing it. There the terms "log erosion barrier" or "log terracette° were used for anchored loge. The nonanchored loge wars not considered a successful treatment. Mulch was evaluated in two quantitative monitor- ingreportsand foundtobevery effective. For exam~le, Faust (1998) collected only 0.8 t ac 1(1.8 Mg ha ) of sediment below a slope mulched and seeded with oats, compared to 5.8 t ac 1 (12.9 Mg hat) below a elope seeded with oats alone. Kidd and Rittenhouse (1997) rated mechanically dug contour trenches as the "best" treatment in trap- ping sediment after the Eighth Street Fire, Boise National Foreet, Idaho. However they rated hand-dug contour trenches as the "worst" treatment due to poor construction (shallow depth) and layout (off contour). These trenches often contributed to tilling. Mechani- cally constructed contour trenches worked better 32 USDA Forest Service Gen. Tech. Rep. RMRS-GTRE3. 2000