Treesearch

Soil surface conditions can have profound effects on plant seedling emergence and subsequent seedling survival. To test the hypothesis that different soil-surface treatments with logging residue affect range grass seedling emergence and survival, 6 alternative forest-residual treatments were established in the summer of 1998 following thinning of mature trees from approximately 500 to 133 trees [times] ha21. The treatments included 1) whole logging debris, hand-piled; 2) whole logging-debris piles that were burned; 3) whole logging-debris piles that were chipped; 4) whole logging-debris...

There are varying definitions of old-growth forests because of differences in environment and differing fire influence across the Intermountain West. Two general types of forests reflect the role of fire: 1) forests shaped by natural changes in structure and species makeup-plant succession-that are driven by competitive differences among species and individual trees and by small-scale disturbances, and 2) forests where plant succession processes are disrupted by major biological disturbances (fire, insects, wind, or drought) extending across larger areas. Some case examples of old-growth...

Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) is a nonindigenous perennial grass that was introduced to North America to improve the condition of degraded rangelands. It has proven to be a successful revegetation species due to its superior ease of establishment, strong competitive ability, and ability to tolerate grazing. However, crested wheatgrass is criticized for its ability to form monotypic stands that result in low plant diversity. The main objective of this study was to determine the effect of crested wheatgrass control methods on native plant establishment using a...

Classic ecological concepts and forestry language regarding old growth are not well suited to frequent-fire landscapes. In frequent-fire, old-growth landscapes, there is a symbiotic relationship between the trees, the understory graminoids, and fire that results in a healthy ecosystem. Patches of old growth interspersed with younger growth and open, grassy areas provide a wide variety of habitats for animals, and have a higher level of biodiversity. Fire suppression is detrimental to these forests, and eventually destroys all old growth. The reintroduction of fire into degraded frequent-fir...

Native forb seed is needed to restore rangelands of the Intermountain West. Commercial seed production is necessary to provide the quantity of seed needed for restoration efforts. A major limitation to economically viable commercial production of native forb seed is stable and consistent seed productivity over years. Variations in spring rainfall and soil moisture result in highly unpredictable water stress at seed set and development. Excessive water stress during seed set and development is known to compromise yield and quality of other seed crops. Native forbs are not competitive with...

Vegetation response and burn severity were examined following eight large wildfires that burned in 2003 and 2004: two wildfires in California chaparral, two each in dry and moist mixed-conifer forests in Montana, and two in boreal forests in interior Alaska. Our research objectives were: 1) to characterize one year post-fire vegetation recovery relative to initial fire effects on the soil surface that could potentially serve as indicators of vegetation response (and thus, ultimately longerterm post-fire ecosystem recovery), and 2) to use a remotely-sensed indicator of burn severity to...

Wildfire effects include loss of vegetative cover and changes to soil properties that may lead to secondary effects of increased runoff, erosion, flooding, sedimentation, and vulnerability to invasive weeds. These secondary effects may threaten human life and safety, cultural and ecological resources, land use, and existing infrastructure. Current Burned Area Emergency Response (BAER) assessment procedures require identification and valuation of values-at-risk (VAR) from the potential secondary effects of wildfires. However, guidelines to estimate the monetary value of these resources are...

Compared to bioclimatic variables, remote sensing predictors are rarely used for predictive species modelling. When used, the predictors represent typically habitat classifications or filters rather than gradual spectral, surface or biophysical properties. Consequently, the full potential of remotely sensed predictors for modelling the spatial distribution of species remains unexplored. Here we analysed the partial contributions of remotely sensed and climatic predictor sets to explain and predict the distribution of 19 tree species in Utah. We also tested how these partial contributions...

Astragalus filipes Torr. Ex A. Gray (basalt milkvetch) is a leguminous plant species that has a wide distribution in western North America. A series of greenhouse and field experiments were conducted to identify rhizobial strains and populations (accessions) of basalt milkvetch that have potential for use in revegetation and restoration programs in the western U.S.A. In the first greenhouse experiment, six rhizobial strains were evaluated with several basalt mikvetch accessions for their N-fixation characteristics. Rhizobial treatments and basalt milkvetch accessions exhibited no significan...

My objective was to determine if polymorphic information from the 18S-5.8S-26S nuclear ribosomal DNA internal transcribed spacer regions and the trnK-psbA, trnK-rps16 chloroplast DNA spacer regions is sufficient 1) to identify a plant specimen to the species level, and 2) to establish the phylogenetic relationship between species. The first study examined the relationship of various North American as well as European and Asian species of perennial, Leymus wildrye grasses (Poaceae). Three North American Leymus taxa, including L. flavescens, L. innovatus, and L. mollis, displayed unique...