1,720,952 research outputs found
The effects of post-fire logging on microclimate and surface fuels
Full text link2021 Spring.Includes bibliographical references.Wildfire is increasing in size and severity in forests of the western US, driven by climate change and land management practices during the 20th century. Altered fire regimes have resulted in a greater need for knowledge on best practices for managing burned landscapes, especially in instances where a return to a previous forested ecosystem is desired. Our study location was the Spring Creek Fire in the Rockies of Colorado, where we examined soil moisture, soil temperature, and soil disturbance as well as surface fuel loading and understory vegetation recovery in areas that burned at low and high severity, a subset of which received post-fire logging treatments. Two years post-fire, we found no difference in understory vegetation response; however, logged sites demonstrated lower daily average and minimum soil moisture and higher fuel loading across most fuel size classes, and were more likely to show evidence of compaction, erosion, and rutting. This suggests that post-fire logging may create unfavorable conditions for tree regeneration while increase short term site susceptibility to reburns. Careful consideration should be taken when conducting post-fire logging to prevent detrimental ecological effects
Post-fire vegetation and bird habitat use in piñon-juniper woodlands
Full text link2022 Spring.Includes bibliographical references.Global climate change has caused fire activity and behavior to shift from historical norms due to hotter and drier conditions. Although the ecological effects of changing fire regimes have been explored in many systems, the resilience of some forest types, such as piñon-juniper, are often overlooked. Piñon-juniper is a dominant forest type in the western US and provides breeding habitat for many obligate or semi-obligate bird species. Similarly, this system is supported by a critical mutualism, where the regeneration and infilling of these trees is reliant on several bird species that disperse piñon pine and juniper seeds. This study aimed to assess woodland resilience by evaluating post-fire forest structure and the associated avian communities one-year and 20+ years post-fire. More specifically, seedling regeneration and the habitat use of piñon-juniper obligate bird species, semi-obligates, piñon seed dispersers, and juniper seed dispersers were compared across burned, refugia, and unburned patches. Replicate patches of each habitat type were selected within three fire locations, and 3-4 bird point count stations and 1 forest inventory plot were established in each patch. No tree regeneration was observed 1-year post-fire, and after 25 years, there were few juniper seedlings and no piñon seedlings observed in burned plots. Seedling regeneration and forest structure in refugia and unburned plots were not different, regardless of fire age. Results from occupancy models indicated that Woodhouse's Scrub-jay, a piñon seed disperser, used all habitats equally. American Robin had the highest habitat use in the recent burned patches. Obligate and semi-obligate bird species had differing responses to habitat types, with the habitat use of Ash-throated Flycatcher and Spotted Towhee not differing across habitat types, Virginia's Warbler having the highest habitat use in old burn and refugia patches, the Gray Vireo, Black-throated Gray Warbler, and Gray Flycatcher having highest habitat use in unburned, refugia, and recent burn patches, and the Blue-grey Gnatcatcher having the highest habitat use in the old burn. While there is a need for longer term studies, our work highlights that even 25 years post-fire, little tree recovery is observed and the associated bird species continue to differ, emphasizing the potential transition or long recovery time in these sensitive areas
The ecological effects of multiple disturbances on subalpine forest structure and recovery in a changing climate
Full text link2020 Fall.Includes bibliographical references.Due to the shifting global climate, the severity, size, and frequency of climate-driven disturbances are increasing, inevitably causing disturbances to interact in time and space. Bark beetle epidemics and wildfires have historically shaped the disturbance regimes of western North American forests. Their interactive effects on stand dynamics and recovery are inadequately studied in Engelmann spruce (Picea engelmannii)- subalpine fir (Abies lasiocarpa) dominant forests; understanding these interactions is imperative to the management and health of forested ecosystems. Tree seedling densities and species composition, surface fuel loading, and stand structure characteristics were compared across 80 sites that experienced either high tree mortality from epidemic spruce beetle outbreaks (>50% affected basal area), high-severity wildfire (>90% tree mortality), post-outbreak high-severity wildfire (1-3 years post-outbreak), or no disturbance (control) in northern Colorado and southern Wyoming. The beetle-affected sites span multiple years post-outbreak from 1996-2017, ultimately comprising a chronosequence of beetle-affected stands. Structural changes in subalpine stands following spruce beetle outbreaks include species compositional shifts in overstory trees, and significant increases in fuel loading over time-since-outbreak. Tree seedling densities among outbreak and control sites differ significantly from burned areas, indicating that wildfires override the effects of repeated disturbances on regeneration. While a cursory assessment of post-outbreak regeneration based on height resulted in the appearance of consistent and stable forest recovery, subsequent aging techniques shed additional light on the drivers of subalpine tree establishment. Subalpine tree regeneration may remain suppressed in the understory for over a century; post-outbreak recovery dynamics cannot be fully understood through the use of height as a proxy for seedling age. Given the strong correlation between Engelmann spruce and subalpine fir establishment with cool and moist growing conditions, there remains significant uncertainty about post-disturbance recovery and the persistence of spruce-fir forests in a warming and drying world. It is critical to understand post-disturbance fuel dynamics and stand recovery to identify hazards for subsequent fire suppression, implement treatments to enhance forest resilience, and to understand the potential consequences of climate-induced shifts in disturbance regimes on forest health
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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