The distribution and abundance of bull trout (Salvelinus confluentus) spawning were affected by geomorphology and hyporheic groundwater - stream water exchange across multiple spatial scales in streams of the Swan River basin, northwestern Montana. Among spawning tributary streams, the abundance of bull trout redds increased with increased area of alluvial valley segments that were longitudinally confined by geomorphic knickpoints. Among all valley segment types, bull trout redds were primarily found in these bounded alluvial valley segments, which possessed complex patterns of hyporheic exchange and extensive upwelling zones. Bull trout used stream reaches for spawning that were strongly influenced by upwelling. However, within these selected reaches, bull trout redds were primarily located in transitional bedforms that possessed strong localized downwelling and high intragravel flow rates. The changing relationship of spawning habitat selection, in which bull trout selected upwelling zones at one spatial scale and downwelling zones at another spatial scale, emphasizes the importance of considering multiple spatial scales within a hierarchical geomorphic context when considering the ecology of this species or plans for bull trout conservation and restoration.

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/ Habitats or environmental factors that convey spatial and temporal resistance and/or resilience to biotic communities that have been impacted by biophysical disturbances may be called refugia. Most refugia in rivers are characterized by extensive coupling of the main channel with adjacent streamside forests, floodplain features, and groundwater. These habitats operate at different spatial scales, from localized particles, to channel units such as pools and riffles, to reaches and longer sections, and at the basin LeveL. A spatial hierarchy of different physical components of a drainage network is proposed to provide a context for different refugia. Examples of refugia operating at different spatial scales, such as pools, large woody debris, floodplains, below dams, and catchment basins are discussed. We hope that the geomorphic context proposed for examining refugia habitats will assist in the conservation of pristine areas and attributes of river systems and also allow a better understanding of rehabilitation needs in rivers that have been extensiveLy altered.

Floodplains are among the world's most threatened ecosystems due to the pervasiveness of dams, levee systems, and other modifications to rivers. Few unaltered floodplains remain where we may examine their dynamics over decadal time scales. Our study provides a detailed examination of landscape change over a 60-year period (1945-2004) on the Nyack floodplain of the Middle Fork of the Flathead River, a free-flowing, gravel-bed river in northwest Montana, USA. We used historical aerial photographs and airborne and satellite imagery to delineate habitats (i.e., mature forest, regenerative forest, water, cobble) within the floodplain. We related changes in the distribution and size of these habitats to hydrologic disturbance and regional climate. Results show a relationship between changes in floodplain habitats and annual flood magnitude, as well as between hydrology and the cooling and warming phases of the Pacific Decadal Oscillation (PDO). Large magnitude floods and greater frequency of moderate floods were associated with the cooling phases of the PDO, resulting in a floodplain environment dominated by extensive restructuring and regeneration of floodplain habitats. Conversely, warming phases of the PDO corresponded with decreases in magnitude, duration, and frequency of critical flows, creating a floodplain environment dominated by late successional vegetation and low levels of physical restructuring. Over the 60-year time series, habitat change was widespread throughout the floodplain, though the relative abundances of the habitats did not change greatly. We conclude that the long- and short-term interactions of climate, floods, and plant succession produce a shifting habitat mosaic that is a fundamental attribute of natural floodplain ecosystems.

Forest ecosystems in the western United States evolved over many millennia in response to disturbances such as wildfires. Land use and management practices have altered these ecosystems, however, including fire regimes in some areas. Forest ecosystems are especially vulnerable to postfire management practices because such practices may influence forest dynamics and aquatic systems for decades to centuries. Thus, there is an increasing need to evaluate the effect of postfire treatments from the perspective of ecosystem recovery. We examined, via the published literature and our collective experience, the ecological effects of some common postfire treatments. Based on this examination, promising postfire restoration measures include retention of large trees, rehabilitation of firelines and roads, and, in some cases, planting of native species. The following practices are generally inconsistent with efforts to restore ecosystem functions after fire: seeding exotic species, livestock grazing, placement of physical structures in and near stream channels, ground-based postfire logging, removal of large trees, and road construction. Practices that adversely affect soil integrity, persistence or recovery of native species, riparian functions, or water quality generally impede ecological recovery after fire. Although research provides a basis for evaluating the efficacy of postfire treatments, there is a continuing need to increase our understanding of the effects of such treatments within the context of societal and ecological goals for forested public lands of the western United States.Gestión Post-Incendio en Terrenos Boscosos Públicos en el Oeste de E. U. A. Resumen: Los ecosistemas boscosos en el oeste de Estados Unidas evolucionaron a lo largo de muchos mile-nios en respuesta a perturbaciones tales como incendios naturales. Sin embargo, las prácticas de uso y gestión del suelo han alterado estos ecosistemas, incluyendo los regímenes de fuego en algunasáreas. Los ecosistemas boscosos son especialmente vulnerables a las prácticas de gestión post-incendio porque tales prácticas pueden influir en la dinámica del bosque y en los sistemas acuáticos de décadas hasta siglos. Por tanto, hay una mayor necesidad de evaluar el efecto de tratamientos post-incendio desde la perspectiva de la recuperación † † †email robert.beschta@oregonstate.edu ‡ ‡ ‡Current address: 958Postfire Management of Public Forests Beschta et al.del ecosistema. Examinamos, vía la literatura publicada y nuestra experiencia colectiva, los efectos ecológicos de algunos tratamientos post-incendio comunes. Con base en esa examinación, las medidas de restauración post-incendio prometedoras incluyen la retención deárboles grandes, la rehabilitación de guardarrayas y caminos y, en algunos casos, la siembra de especies nativas. Las siguientes generalmente son inconsistentes con los esfuerzos para restaurar funciones del ecosistema después del incendio: siembra de especies exóticas, pastoreo, colocación de estructuras físicas en y cerca del canal de arroyos, tala ...

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We documented immediate and mid-term (5 years) impacts on streams from a large (15,500 ha) wildfire in northwestern Montana. Fire-related impacts were ecosystem-wide, extending from water chemistry to fish. During the initial firestorm, phosphorus and nitrogen levels increased 5-to 60-fold above background levels resulting from aerial deposition from smoke and ash. Nutrients returned to background concentrations within several weeks after the fire. During subsequent years, nutrient concentrations periodically increased in fire-impacted sites compared to reference sites, especially during spring run-off.Evidence of post-fire changes was also documented in the aquatic food web via stable isotope analyses. Macroinvertebrates and fish from fire-impacted sites were significantly more enriched in 15 N and depleted in 13 C than consumers from forested reference sites (P < 0:001). The post-fire isotopic shift in consumers was consistent with increased utilization of algae and/or other autochthonous food sources together with decreased reliance on terrestrial leaf litter and other allochthonous food sources. Such a post-fire shift from a detritus based on a periphyton-based food web fits predictions of the river continuum concept following canopy removal and nutrient enrichment.Following decades of active fire suppression, forest managers are now contemplating aggressive efforts to reduce the fuel build-up noted in forests throughout the western US. Such efforts could involve increased use of fire and mechanical thinning and harvest. Results from our work and others suggest that expanded fire activity could mobilize substantial quantities of highly available nutrients to lakes and streams. With significant nutrient delivery mechanisms involving water, as well as airborne transport via smoke and ash, the potential for increased nutrient loadings to surface waters could extend well beyond the catchment of any particular fire. As natural resource managers contemplate expanding the use of fire as a forest restoration tool, they face the dilemma that such efforts could run counter to a decades-long effort to reduce nutrient loadings to lakes and other surface waters threatened by eutrophication. #

The Rocky Mountains in the USA and Canada encompass the interior cordillera of western North America, from the southern Yukon to northern New Mexico. Annual weather patterns are cold in winter and mild in summer. Precipitation has high seasonal and interannual variation and may dier by an order of magnitude between geographically close locales, depending on slope, aspect and local climatic and orographic conditions. The region's hydrology is characterized by the accumulation of winter snow, spring snowmelt and autumnal base¯ows. During the 2±3-month`spring runo' period, rivers frequently discharge 470% of their annual water budget and have instantaneous discharges 10±100 times mean low¯ow.Complex weather patterns characterized by high spatial and temporal variability make predictions of future conditions tenuous. However, general patterns are identi®able; northern and western portions of the region are dominated by maritime weather patterns from the North Paci®c, central areas and eastern slopes are dominated by continental air masses and southern portions receive seasonally variable atmospheric circulation from the Paci®c and the Gulf of Mexico. Signi®cant interannual variations occur in these general patterns, possibly related to ENSO (El NinÄ o±Southern Oscillation) forcing.Changes in precipitation and temperature regimes or patterns have signi®cant potential eects on the distribution and abundance of plants and animals. For example, elevation of the timber-line is principally a function of temperature. Palaeolimnological investigations have shown signi®cant shifts in phyto-and zoo-plankton populations as alpine lakes shift between being above or below the timber-line. Likewise, streamside vegetation has a signi®cant eect on stream ecosystem structure and function. Changes in stream temperature regimes result in signi®cant changes in community composition as a consequence of bioenergetic factors. Stenothermic species could be extirpated as appropriate thermal criteria disappear. Warming temperatures may geographically isolate cole water stream ®shes in increasingly con®ned headwaters. The heat budgets of large lakes may be aected resulting in a change of state between dimictic and warm monomictic character. Uncertainties associated with prediction are increased by the planting of ®sh in historically ®shless, high mountain lakes and the introduction of non-native species of ®shes and invertebrates into often previously simple food-webs of large valley bottom lakes and streams. Many of the streams and rivers suer from the anthropogenic eects of abstraction and regulation. Likewise, many of the large lakes receive nutrient loads from a growing human population.We concluded that: (1) regional climate models are required to resolve adequately the complexities of the high gradient landscapes; (2) extensive wilderness preserves and national park lands, so prevalent in the Rocky Mountain Region, provide sensitive areas for dierentiation of anthropogenic eects from climate eects; and (3) future research should ...