1,720,979 research outputs found
Alpine ectomycorrhizal plants as potential inoculum reservoirs for treeline conifers in southern British Columbia
No full textGlobally, many montane tree ranges are shifting elevation upward with climate change. Forest encroachment into alpine ecosystems may lead to alpine habitat loss, reduced biodiversity, and carbon cycle alterations. Alpine habitats may also become refuges for endangered subalpine tree species. Critical for successful upward tree migrations is seedling establishment. While many factors can influence this process, the presence or absence of root symbionts, which can facilitate seedling establishment, has received little attention. Many alpine plants form symbioses with ectomycorrhizal fungi (EMF) and tend to associate with a diverse array of generalist EMF. Hence, these plants may serve as sources of fungal inoculum for establishing trees. Here, I test this idea across an alpine treeline ecotone in southeastern British Columbia. I designed a study to (i) identify and quantify the EMF taxa shared between the roots of an alpine shrub, Dryas octopetala, and established seedlings of the federally-listed whitebark pine (Pinus albicaulis), and (ii) evaluate how the distribution of pine-compatible inoculum in soil relates to the proximity and cover of alpine host plants and distance from treeline. I used 3rd generation sequencing to characterize the root and soil-associated fungal communities. Results revealed high overlap between the EMF communities associated with alpine EM hosts and P. albicaulis. However, pine-compatible EMF richness in soils only varied with distance to the nearest tree and sample read depth, while neither proximity to alpine hosts, tree density, nor treeline showed any effects. EMF inoculum compatible with P. albicaulis appears to be widely available above treeline. This study provides new insights into the potential roles that alpine ectomycorrhizal plants play in facilitating climate-induced tree migrations.Science, Irving K. Barber Faculty of (Okanagan)Biology, Department of (Okanagan)Graduat
Associations between host mycorrhizal type and plant community structure within forest ecosystems
No full textMost plants form symbioses with mycorrhizal fungi, predominantly arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) fungi, which generally improve plant nutrient acquisition. Through a range of mechanisms, mycorrhizal host plants may benefit other plants that associate with the same type of fungi (“conmycorrhizal”). This may result in positive plant-soil feedbacks (PSF) and clustering among conmycorrhizal hosts. EcM fungi in particular may also protect against root pathogens, and this could help plant species overcome conspecific negative density dependence (CNDD), leading to competitive exclusion and reduced plant diversity. However, most studies of these hypotheses have focused on trees, despite most plant diversity residing in the herbaceous and shrub layers of forests. Additionally, many of these studies do not conduct appropriate null models and sensitivity analyses to test the robustness of their findings.
My goal was to examine whether patterns of whole-forest community structure are consistent with PSF and reduced CNDD in EcM hosts. Specifically, I ask whether conmycorrhizal host cover is correlated between forest layers (Chapter 2), how it compares to abiotic predictors of mycorrhizal host cover (Chapter 3), and whether plots with high EcM cover have lower evenness (Chapter 4) or richness (Chapter 5). Using 2,513 forest plots across the United States, I observed a significant positive correlation between AM host cover in the canopy and ground layer, and likewise for EcM hosts. I also found that the potential effect of mycorrhizal PSFs was often comparable in strength to that of climatic and edaphic drivers of host mycorrhizal type distributions. Lastly, I found a weak, negative effect of EcM cover on richness but not evenness.
My secondary objective was to explore how decisions made during the analysis impacted the results through sensitivity analyses, and I found that the results varied substantially in magnitude and direction. This is highly concerning as studies in this field use a variety of analytical decisions and usually do not conduct null models or sensitivity analyses, calling into question the robustness of their findings. Therefore, I argue that sensitivity analyses are vital when researchers are working with complex workflows, which are becoming increasingly common in mycorrhizal ecology.Science, Irving K. Barber Faculty of (Okanagan)Biology, Department of (Okanagan)Graduat
A two-eyed seeing approach to predicting the distribution of skʷenkʷínem (Claytonia lanceolata), a culturally significant plant
No full textColonialism and a changing climate have threatened culturally significant food plants and the well-being of those who rely on them. An example is skʷenkʷínem (western spring beauty, Claytonia lanceolata Pursh), which is significant for Secwépemc People of Skeetchestn Indian Band. Skeetchestn is located in the Deadman Valley, in the interior of what we now call British Columbia. skʷenkʷínem once comprised a large portion of Secwépemc diet, but is no longer feasible to harvest as a meaningful food source. We used a Two-Eyed Seeing approach to species distribution modelling, beginning with semi-structured interviews with three Skeetchestn community members. The interviews produced five major themes: nourishment, colonization, interconnectedness, kinship, and places, with an emphasis on the importance of the Skeetchestn community skʷenkʷínem patch. Using a set of predictors informed by the Knowledge from the interviews, and several bioclimatic variables, we used an ensemble modeling approach to predict suitable habitat for skʷenkʷínem over its known geographic extent. We predict a decrease in suitable habitat from the present to 2081-2100 across skʷenkʷínem full geographic extent and an increase within Skeetchestn Territory. These predictions use Skeetchestn’s existing Knowledge of skʷenkʷínem in our predictive models to support Skeetchestn’s goals of food sovereignty. We also discuss the existing field of species distribution modelling regarding culturally significant species, and how geographical tools can support Indigenous communities’ decision-making and sovereignty assertion. Our study is an example of reproducible species distribution modelling done in partnership with an Indigenous community, balancing the need for open science and ethical and equitable research.Science, Irving K. Barber Faculty of (Okanagan)Biology, Department of (Okanagan)Graduat
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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