Land managers frequently thin small-diameter trees and apply prescribed fire to reduce fuel loads and restore ecosystem structure, function, and process in forested areas. There is increasing concern ...that disturbances associated with these management practices can facilitate non-native plant invasions. Cheatgrass ( Bromus tectorum ), an annual grass from the Mediterranean, has invaded large areas of the interior West and has become the dominant species in many of these areas. In 2003, a ponderosa pine ( Pinus ponderosa ) ecological restoration site on Mount Trumbull in the Uinkaret Mountains of northern Arizona experienced a large increase in cheatgrass. Thinning and burning projects had been conducted on this site since 1996. Cheatgrass cover increased 90-fold on the thinned and burned plots between 1996 and 2003. While cheatgrass also increased on thinned plots that were not burned and the untreated control plots, the cover of cheatgrass remained low. There were two additional factors that may have influenced the cheatgrass invasion. In 2002, the region experienced the most extreme drought recorded in the past 100 years. Substantial rainfall returned to the area in September 2002, coincident with the timing of cheatgrass germination. Additionally, cattle were reintroduced to the study area in August 2002 after a four-year hiatus in grazing. We present data suggesting that the interaction of prescribed fire and small-diameter tree thinning, potentially exacerbated by cattle grazing and drought, was the primary cause of the spread of cheatgrass. Furthermore, we offer management recommendations for reducing the risk of non-native plant invasion on ecological restoration projects.
Keywords: cheatgrass ( Bromus tectorum ), ecological restoration, drought disturbance, prescribed fire, southwestern pine forests
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Objective To determine the inter-rater reliability of the Institute for Healthcare Improvement's Global Trigger Tool (GTT) in a practice setting, and explore the value of individual triggers. Design ...Prospective assessment of application of the GTT to monthly random samples of hospitalized patients at four hospitals across three regions in the USA. Setting Mayo Clinic campuses are in Minnesota, Arizona and Florida. Participants A total of 1138 non-pediatric inpatients from all units across the hospital. Intervention GTT was applied to randomly selected medical records with independent assessments of two registered nurses with a physician review for confirmation. Main Outcome Measure The Cohen Kappa coefficient was used as a measure of inter-rater agreement. The positive predictive value was assessed for individual triggers. Results Good levels of reliability were obtained between independent nurse reviewers at the case-level for both the occurrence of any trigger and the identification of an adverse event. Nurse reviewer agreement for individual triggers was much more varied. Higher agreement appears to occur among triggers that are objective and consistently recorded in selected portions of the medical record. Individual triggers also varied on their yield to detect adverse events. Cases with adverse events had significantly more triggers identified (mean 4.7) than cases with no adverse events (mean 1.8). Conclusions The trigger methodology appears to be a promising approach to the measurement of patient safety. However, automated processes could make the process more efficient in identifying adverse events and has a greater potential of improving care delivery and patient ‘outcomes’.
Prescribed burning has been suggested as a method to prevent shrub encroachment on desert grasslands. A concern for range managers is the prevalence of introduced African lovegrasses (
Eragrostis ...spp.). These exotic grasses may compromise the effectiveness of fire as a range management tool in these areas due to their fire tolerance. In this study we examined the response of an established patch of Lehmann lovegrass to a prescribed burn. While Lehmann lovegrass was not adversely affected by the prescribed burn, all of the native grasses were compromised to some degree.
An important goal of forest restoration is to increase native plant diversity and abundance. Thinning and burning treatments are a common method of reducing fire risk while simultaneously promoting ...understory production in ponderosa pine (
Pinus ponderosa) forests. In this study we examine the magnitude and direction of understory plant community recovery after thinning and burning restoration treatments in a ponderosa pine forest. Our objective was to determine if the post-treatment community was a diverse, abundant, and persistent assemblage of native species or if ecological restoration treatments resulted in nonnative species invasion. This project was initiated at the Grand Canyon-Parashant National Monument, Arizona, USA in 1997. We established four replicated blocks that spanned a gradient of soil types. Each block contained a control and a treated unit. Treated units were thinned to emulate pre-1870 forest stand conditions and prescribed-burned to reintroduce fire to a system that has not burned since ∼1870. We measured plant cover using the point-line intercept method and recorded species richness and composition on 0.05
ha belt transects. We examined the magnitude of treatment responses using Cohen's
d effect size analysis. Changes in community composition were analyzed using nonmetric multidimensional scaling (NMS). Native plant species cover and richness increased in the thinned and burned areas compared to the controls. By the last year of the study, annual species comprised nearly 60% of the understory cover in the treatment units. Cheatgrass (
Bromus tectorum), a nonnative annual grass, spread into large areas of the treated units and became the dominant understory species on the study site. The ecological restoration treatments did promote a more diverse and abundant understory community in ponderosa pine forests. The disturbances generated by such treatments also promoted an invasion by an undesirable nonnative species. Our results demonstrate the need to minimize disturbances generated by restoration treatments and argue for the need to proactively facilitate the recovery of native species after treatment.
Seeding native plants is an increasingly common management technique for promoting plant diversity and stabilizing soil on restoration and post-fire rehabilitation projects. The effectiveness of the ...technique is uncertain, however, especially in semiarid southwestern forests, as very few studies have been conducted to monitor the results. Land managers in the Mount Trumbull area of the Grand Canyon-Parashant National Monument (GCPNM) in northwestern Arizona have been seeding with natives since 1996 as part of ponderosa pine (Pinus ponderosa) forest ecological restoration treatments. Early research on the effects of seeding treatments there (Springer et al. 2001, Springer and Laughlin 2004) showed an increase in overall species richness when seeding with a diverse mix of native grasses, forbs, and shrubs, but did not conclusively detect an increase in cover of the seeded species. Subse-quendy, managers with the Bureau of Land Management (BLM, which co-administers the GCPNM along with the National Park Service) have trimmed their seed mix to a smaller assortment of grasses and forbs, and we have refined our monitoring methods to better detect changes in species cover at multiple scales.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Research at the Digital Mapping Laboratory has focused on the automated analysis of aerial imagery for cartographic feature extraction. However, it has long been the authors' belief that optimal ...performance in cartographic feature extraction can be obtained only by the combination, or fusion, of feature extraction systems which use differing information sources and processing methods. This paper describes experiments on the pairwise fusion of cartographic feature extraction systems; surface material maps obtained from the classification of hyper-spectral imagery, digital elevation models derived from stereo panchromatic imagery, and three-dimensional (3D) building hypotheses generated from single panchromatic images. Fusion experiments were performed on three test areas and detailed evaluations conducted. The results showed that using surface material or stereo information to focus processing of the building extraction system led to significantly better overall performance and runtimes. Utilizing building hypotheses to refine material classification showed mixed results, due partially to residual registration errors.
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