Spending on postfire emergency watershed rehabilitation has increased during the past decade. A west-wide evaluation of USDA Forest Service burned area emergency rehabilitation (BAER) treatment effectiveness was undertaken as a joint project by USDA Forest Service Research and National Forest System staffs. This evaluation covers 470 fires and 321 BAER projects, from 1973 through 1998 in USDA Forest Service Regions 1 through 6. A literature review, interviews with key Regional and Forest BAER specialists, analysis of burned area reports, and review of Forest and District monitoring reports were used in the evaluation. The study found that spending on rehabilitation has increased to over $48 million during the past decade because the perceived threat of debris flows and floods has increased where fires are closer to the wildland-urban interface. Existing literature on treatment effectiveness is limited, thus making treatment comparisons difficult. The amount of protection provided by any treatment is small. Of the available treatments, contour-felled logs show promise as an effective hillslope treatment because they provide some immediate watershed protection, especially during the first postfire year. Seeding has a low probability of reducing the first season erosion because most of the benefits of the seeded grass occurs after the initial damaging runoff events. To reduce road failures, treatments such as properly spaced rolling dips, water bars, and culvert reliefs can move water past the road prism. Channel treatments such as straw bale check dams should be used sparingly because onsite erosion control is more effective than offsite sediment storage in channels in reducing sedimentation from burned watersheds. From this review, we recommend increased treatment effectiveness monitoring at the hillslope and sub-catchment scale, streamlined postfire data collection needs, increased training on evaluation postfire watershed conditions, and development of an easily accessible knowledge base of BAER techniques.Keywords: burn severity, erosion control, BAER, burned area emergency rehabilitation, mitigation, seeding, monitoring. Abstract ___________________________________________The use of trade or firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.Acknowledgments _____________

Large, high-severity wildfires remove vegetation cover and expose mineral soil, ofen causing erosion and runoff during postfire rain events to increase dramatically. Land-management agencies in the United States are required to assess site conditions after wildfire and, where necessary, implement emergency watershed rehabilitation measures to help stabilize soil; control movement of water, sediment, and debris; prevent permanent impairment of ecosystem structure and function; and mitigate significant threats to human health, safety, life, property, or downstream values. One of the most common postfire treatments is broadcast seeding of grasses, usually from aircraft. Non-native annual or perennial grasses typically are used to provide quick, temporary ground cover to hold soil in place until native plants are reestablished. Critics argue that seeded grasses compete with native vegetation and do not effectively reduce erosion. Few data exist on the effectiveness of erosion control; less than half of the studies I reviewed showed reduced sediment movement with seeding. In all vegetation types, successful growth of seeded grasses-enough to affect erosion-appears to displace native or naturalized species, including shrub and tree seedlings. Due to the competitiveness of seeded grasses, they are used to attempt suppression of noxious weeds in some postfire seeding operations. In burned sagebrush range, postfire seeding is frequently used to replace non-native cheatgrass ( Bromus tectorum) with native or introduced bunchgrasses, with at least short-term success. In recent years, native species and sterile cereal grains have increasingly been used for seeding. Use of aerially applied straw mulch has increased as well, with the risk of weed introduction from contaminated bales. More research on the effectiveness and ecosystem impacts of these alternatives is needed.Siembra Post-incendio para Control de Erosión: Efectividad e Impactos sobre Comunidades de Plantas Nativas Resumen: Los incendios grandes, de alta severidad, remueven la vegetación y exponen el suelo mineral, con lo que la erosión y el escurrimiento incrementan dramáticamente durante eventos de lluvia post-incendio. Las agencias de gestión de tierras en los Estados Unidos deben evaluar las condiciones del sitio después del incendio y, donde sea necesario, implementar medidas de emergencia para la rehabilitación de cuencas de agua para ayudar a estabilizar el suelo; el control del movimiento de agua, sedimentos y detritos; la prevención de la degradación permanente de la estructura y función del ecosistema y la mitigación de amenazas significativas a la salud, seguridad, vida y propiedades humanas y a valores río abajo. Uno de los tratamientos post-incendio más comunes es la siembra de pastos, usualmente desde aviones. Típicamente se utilizan pastos anuales o perennes no nativos para proporcionar cobertura rápida, temporal para mantener al suelo en su lugar hasta que se puedan reestablecer plantas nativas. Los críticos argumentan que los pastos sembrados compit...

Photosynthetic characteristics of three species of Sphagnum common in the foothills of the Brooks Range on the North Slope of Alaska were investigated. Generally, light-saturated rates of net photosynthesis decreased in the order S. squarrosum, S. angustifolium, and S. warnstorfii when plants were grown under common growth chamber conditions. For field-grown S. angustifolium, average light compensation point at 10°C was 37 μmol ms photosynthetic photon flux density (PPFD), and light saturation occurred between 250 and 500 μmol m s. At 20°C, compensation point increased to 127 μmol ms and the PPFD required for light saturation increased to approximately 500 μmol ms, while maximum rates of CO uptake increased only slightly. Light response curves of chamber-grown plants exhibited substantially lower compensation points and higher light-saturated rates of CO assimilation than field-grown material, due perhaps to a higher percentage of green, photosynthetically competent tissue. All three species exhibited broad responses to temperature, with optima near 20°C, and maintained at least 75% of maximum assimilation between approx. 13° and 30°C. Rates at 5°C were approx. 50% of maximum. Studies of the microclimate of Sphagnum at the field research site suggest that CO uptake should occur at near light-saturated rates during the day in open tussock tundra but that PPFD may often be limiting under Salix and Betula canopies in a water track drainage. Simulations using a simple model provided a seasonal estimate of 0.78 g dry weight (DW) of S. angustifolium produced from each initial g of photosynthetic tissue under willow canopies, assuming no water limitations. Although the simulation model suggests that production would be 66% higher in open tussock tundra, S. angustifolium is rarely found in this potentially more stressful habitat. To explain the relative abundance of Sphagnum in shaded water track areas as compared to open tussock tundra, we postulate that the vascular plant canopies provide protection from adverse effects of high temperatures, excess irradiance and reduced water availability. Under conditions of normal water availability, removal of the vascular plant cover did not affect the tissue water content of S. squarrosum, but resulted in a strong decrease in photosynthetic capacity, accompanied by chlorophyll bleaching. These results suggest that photoinhibition may limit production under certain conditions.

Between 1998 and 2002, six sites were established immediately after large wildfires in the western United States to determine the effectiveness of contour-felled log erosion barriers in mitigating post-wildfire runoff and erosion. In each pair of matched, burned, and small watersheds (1–13 ha), one was treated with contour-felled log erosion barriers and one was left untreated as a control. For 4 to 6 post-fire years, runoff and sediment yields were measured and correlated with rain properties. High-intensity rainfall produced most of the measured runoff and sediment yields except in the southern California site, where long-duration rain events produced most of the runoff and erosion. For small rain events (less than the 2-year return period for the 10-min duration), the runoff, peak flows, and sediment yields were lower in the treated watersheds than in the control watersheds, but there was no treatment effect for rain events with larger return periods. Improper installation and degradation over time reduced the effectiveness of contour-felled log erosion barriers. Rainfall characteristics and installation procedures should be carefully considered before choosing contour-felled log erosion barriers for post-fire hillslope stabilisation.

In the southern Sierra Nevada, California, relatively thin soils overlie granitic bedrock that is weathered to depths of several metres. The weathered granitic bedrock is porous and has a plant-available water capacity of 0.124 m3·m–3, compared with 0.196 m3·m–3 for the overlying soil. Roots confined within bedrock joint fractures access this rock-held water, especially during late summer when overlying soils are dry. We sought to determine seasonal soil and bedrock water changes in a Jeffrey pine (Pinus jeffreyi Grev & Balf.) plantation and to examine concurrent effects on the water relations of Jeffrey pine and greenleaf manzanita (Arctostaphylos patula Greene). In 1996, plant-available water in the 75 cm thick soil was depleted by late June, with soil water potential (ψsoil) <–2.2 MPa, but below 75 cm, bedrock water potential (ψbedrock) was still > –2.2 MPa. Thus, the bedrock, not the soil, supplied water to plants for the remainder of the dry season. Higher values of, and smaller fluctuations in, seasonal predawn pressure potential (ψpredawn) for Jeffrey pine indicated that it is deeply rooted, whereas active roots of greenleaf manzanita were interpreted to be mostly within the upper 100 cm. The extra rooting volume supplied by weathered bedrock is especially important to pine relative to manzanita.