Treesearch

In this short piece we address the question of how aquatic ecosystems and species can change in response to disturbances, such as those related to the influence of wildfire on stream ecosystems. Our focal species is rainbow trout (Oncorhynchus mykiss) in the Boise River, Idaho. Rainbow trout in this system have persisted in the face of widespread and often severe wildfires occurring since the 1990s (Rieman and others 1997; Burton 2005; Dunham and others 2007).

The occurrence of wildfires within municipal watersheds can result in significant impacts to water quality and ultimately human health and safety. In this paper, we illustrate the application of geospatial analysis and burn probability modeling to assess the exposure of municipal watersheds to wildfire. Our assessment of wildfire exposure consists of two primary components: (1) wildfire hazard, which we characterize with burn probability, fireline intensity, and a composite index, and (2) geospatial intersection of watershed polygons with spatially resolved wildfire hazard metrics. This...

Wildfire management within the United States continues to increase in complexity, as the converging drivers of (1) increased development into fire-prone areas, (2) accumulated fuels from historic management practices, and (3) climate change potentially magnify threats to social and ecological values (Bruins et al., 2010; Gude et al., 2008; Littell et al., 2009). The need for wildfire risk assessment tools continues to grow, as land management agencies attempt to map wildfire risk and develop strategies for mitigation. Developing and employing wildfire risk assessment models can aid...

Mountain pine beetle outbreaks have caused an unprecedented amount of tree mortality in northern Colorado and southern Wyoming forests over the past decade. The extensive overstory mortality and associated salvage logging activities may threaten the sustained delivery of clean water from beetle-affected forests. In this study, we evaluate nutrient retention by riparian buffers consisting of beetle-killed trees and examine nutrient responses to harvesting of hillslope and riparian forests dominated by lodgepole pine. Here, we compare nutrient leaching and soil nutrient pools between...

Headwaters are known to be important in the global carbon cycle, yet few studies have investigated carbon (C) pools along stream-riparian corridors. To better understand the spatial distribution of C storage in headwater fluvial networks, we estimated above- and below-ground C pools in 100-m-long reaches in six different valley types in Rocky Mountain National Park, Colorado. Valley types were distinguished based on downstream gradient and valley-bottom width relative to active channel width (valley geometry) and the presence of biotic drivers, such as beaver dams and channelspanning...

We examine the tradeoffs between utilizing multiple ecosystem services in an economic model of the Lower Mississippi-Atchafalaya River Basin. We show how economic development in the basin degraded the ecosystem, but diversified the economy. A degraded ecosystem and more employment opportunities elsewhere reduced the region's reliance on agriculture and other resource-related industries such as fishing. We compare the size of actual economic damages from reduced water quality associated with agricultural runoff in the upper basin with those that would have occurred without economicecosystem...

The importance of movement corridors for maintaining connectivity within metapopulations of wild animals is a cornerstone of conservation. One common approach for determining corridor locations is least-cost corridor (LCC) modeling, which uses algorithms within a geographic information system to search for routes with the lowest cumulative resistance between target locations on a landscape. However, the presentation of multiple LCCs that connect multiple locations generally assumes all corridors contribute equally to connectivity, regardless of the likelihood that animals will use them....

Nursery response of evergreen trees to fall fertilization has been studied widely, but little attention has been given to deciduous trees. Bareroot Olga Bay larch (Larix olgensis Henry) seedlings were fertilized in the nursery with urea at four rates (0, 30, 60, 90 kg N ha-1), with half of each rate applied on two dates (September 16 and October 1, 2009). The seedlings were excavated for evaluation on October 15. In the unfertilized (control) treatment, root and shoot dry mass increased by 100% and 57% respectively, while N concentration in the roots and shoots increased by 43% and 40%...

Fusarium root disease can be a serious problem in forest and conservation nurseries in the western United States. Fusarium inoculum is commonly found in most container and bareroot nurseries on healthy and diseased seedlings, in nursery soils, and on conifer seeds. Fusarium spp. within the F. oxysporum species complex have been recognized as pathogens for more than a century, but attempts to distinguish virulence by correlating morphological characteristics with results of pathogenicity tests were unsuccessful. Recent molecular characterization and pathogenicity tests, however, revealed...

In this chapter, we focus on the vulnerability of U.S. freshwater supplies considering all lands, not just forest and rangelands. We do not assess the condition of those lands or report on how much of our water supply originates on lands of different land covers or ownerships, because earlier Resources Planning Act (RPA) Assessment work addressed these topics. Regarding the source of water supply, we found that forests are the source of more than one-half of the U.S. water supply and of fully two-thirds of the water supply in the West and the South, and that national forests and grasslands...