Treesearch

This study examined the effects of two types of parent material, sandstone and limestone, on the response of vegetation growth after the 1990 Dude Fire in central Arizona. The operating hypothesis of the study was that, given the right conditions, severe wildfire can trigger vegetation type conversion. Overall, three patterns emerged: (1) oak density increased by 413% from unburned sites to burned sites, with the highest densities occurring on sandstone soils; (2) weeping lovegrass (Eragrostis curvula Nees), a very aggressive non-native grass species seeded after the fire, now makes up 81%...

In the quest to develop renewable energy sources, woody and agricultural crops are being viewed as an important source of low environmental impact feedstocks for electrical generation and biofuels production (Hall and Scrase 1998, Eriksson et al. 2002, Somerville et al. 2010, Berndes and Smith 2013). In countries like the USA, the bioenergy feedstock potential is dominated by agriculture (73%) (Perlack et al. 2005). In others like Finland the largest potential comes from forest resources. Forest bioenergy operational activities encompass activities of a continuing and cyclical nature such...

The on-going public debate on sustainability of bioenergy began in 2007 and 2008 after a couple of papers were published questioning the reported N2O emissions caused by cultivation of agricultural crops (Crutzen et al., 2007) and the carbon neutrality of biomass use (Searchinger et al., 2008) due to direct and indirect land use change as well as change of carbon stocks. Since these initial papers, many others have been published mainly questioning the positive climate impact of bioenergy. The impact of these papers changed the attitude towards use of bioenergy in the public and political...

Pile burning is a common means of disposing the woody residues of logging and for post-harvest site preparation operations, in spite of the practice’s potential negative effects. To examine the long-term implications of this practice we established a 50-year sequence of pile burns within recovering clear cuts in lodgepole pine forests. We compared tree, shrub and herbaceous plant abundance and documented indicators of soil degradation in openings where logging residue was piled and burned as part of post-harvest site preparation and the adjacent forests regenerating after clear cutting. We...

The potential hazard and geomorphic significance of shallow landslides depend on their location and size. Commonly applied one-dimensional stability models do not include lateral resistances and cannot predict landslide size. Multi-dimensional models must be applied to specific geometries, which are not known a priori, and testing all possible geometries is computationally prohibitive. We present an efficient deterministic search algorithm based on spectral graph theory and couple it with a multidimensional stability model to predict discrete landslides in applications at scales broader...

Extensive outbreaks of mountain pine beetle (MPB), spruce beetle (SB), and other insects are altering forest stand structure throughout western North America, and thereby contributing to the heterogeneity of fuel distribution. In forested watersheds, conifer-dominated riparian forests frequently occur as narrow linear features in the landscape mosaic and contribute to the spatial complexity of forest stands and fuel complexes. These streamside forests are valued for providing aquatic and terrestrial habitat, serving as sources of instream and floodplain large wood, and maintenance of...

Instream wood is recognized as an integral component of stream morphology in forested areas. However, few studies have evaluated the legacy effects of historic wood removal activities and associated impacts on channel morphology, contemporary wood loading, and recruitment. This study investigates the role of historic tie-driving, a widespread channel disturbance legacy, in shaping present-day stream channel conditions in southern Wyoming.Geomorphic and riparian surveys were used to assess the extent of disturbance and degree of recovery within three sets of paired tie-driven and non-driven...

Climate change threatens native plant populations and plant communities globally. It is critical that land managers have a clear understanding of climate change impacts on plant species and populations so that restoration efforts can be adjusted accordingly. This paper reviews the develop.ment and use of seed transfer guidelines for restoration in the face of global climate change, with an emphasis on the role of common garden studies in predicting climate change impacts. A method is presented for using genecological common garden data to assess population vulnerability to changing...

Flow diversions are widespread and numerous throughout the semi-arid mountains of the western United States. Diversions vary greatly in their structure and ability to divert water, but can alter the magnitude and duration of base and peak flows, depending upon their size and management. Channel geometry and riparian plant communities have adapted to unique hydrologic and geomorphic conditions existing in the areas subject to fluvial processes. We use geomorphic and vegetation data from low-gradient (¡Ü3%) streams in the Rocky Mountains of north-central Colorado to assess potential effects...

The distribution and future fate of ectothermic organisms in a warming world will be dictated by thermalscapes across landscapes. That is particularly true for stream fishes and cold-water species like trout, salmon, and char that are already constrained to high elevations and latitudes. The extreme climates in those environments also preclude invasions by most non-native species, so identifying especially cold habitats capable of absorbing future climate change while still supporting native populations would highlight important refugia. By coupling crowd-sourced biological datasets with...