1,721,012 research outputs found
The admixture of Quercus sp. in Pinus sylvestris stands influences wood anatomical trait responses to climatic variability and drought events
Full text linkIntroduction: Forests are threatened by increasingly severe and more frequent drought events worldwide. Mono-specific forests, developed as a consequence of widespread management practices established early last century, seem particularly susceptible to global warming and drought compared with mixed-species forests. Although, in several contexts, mixed-species forests display higher species diversity, higher productivity, and higher resilience, previous studies highlighted contrasting findings, with not only many positive but also neutral or negative effects on tree performance that could be related to tree species diversity. Processes underlying this relationship need to be investigated. Wood anatomical traits are informative proxies of tree functioning, and they can potentially provide novel long-term insights in this regard. However, wood anatomical traits are critically understudied in such a context. Here, we assess the role of tree admixture on Pinus sylvestris L. xylem traits such as mean hydraulic diameter, cell wall thickness, and anatomical wood density, and we test the variability of these traits in response to climatic parameters such as temperature, precipitation, and drought event frequency and intensity.Methods: Three monocultural plots of P. sylvestris and three mixed-stand plots of P. sylvestris and Quercus sp. were identified in Poland and Spain, representing Continental and Mediterranean climate types, respectively. In each plot, we analyzed xylem traits from three P. sylvestris trees, for a total of nine trees in monocultures and nine in mixed stands per study location.Results: The results highlighted that anatomical wood density was one of the most sensitive traits to detect tree responses to climatic conditions and drought under different climate and forest types. Inter-specific facilitation mechanisms were detected in the admixture between P. sylvestris and Quercus sp., especially during the early growing season and during stressful events such as spring droughts, although they had negligible effects in the late growing season.Discussion: Our findings suggest that the admixture between P. sylvestris and Quercus sp. increases the resilience of P. sylvestris to extreme droughts. In a global warming scenario, this admixture could represent a useful adaptive management option
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
Impact of Climate Trends and Drought Events on the Growth of Oaks (Quercus robur L. and Quercus petraea (Matt.) Liebl.) within and beyond Their Natural Range
Full text linkDue to predicted climate change, it is important to know to what extent trees and forests
will be impacted by chronic and episodic drought stress. As oaks play an important role in European
forestry, this study focuses on the growth response of sessile oak (Quercus petraea (Matt.) Liebl.) and
pedunculate oak (Quercus robur (L.)) under contrasting climatic conditions. Analyses cover both site
conditions of their natural occurrence (Southern Germany and Northeast Italy) and site conditions
beyond their natural range (South Africa). The sites beyond their natural range represent possible
future climate conditions. Tree-ring series from three different sites were compared and analysed
using dendrochronological methods. The long-term growth development of oak trees appears to be
similar across the sites, yet the growth level over time is higher in the drier and warmer climate than
in the temperate zone. When compared with previous growth periods, growth models reveal that oak
trees grew more than expected during the last decades. A recent setback in growth can be observed,
although growth is still higher than the model predicts. By focusing on the short-term reactions of the
trees, distinct drought events and periods were discovered. In each climatic region, similar growth
reactions developed after drought periods. A decline in growth rate occurred in the second or third
year after the drought event. Oaks in South Africa are currently exposed to a warmer climate with
more frequent drought events. This climatic condition is a future prediction also for Europe. In view
of this climate change, we discuss the consequences of the long- and short- term growth behaviour of
oaks grown in the climate of South Africa for a tree species selection that naturally occurs in Europe
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
Structural and functional analysis of trees in integrated land use systems
No full textThe following manuscripts constitute this dissertation:1. Bohn Reckziegel R, Larysch E, Sheppard JP, Kahle H-P, Morhart C. Modelling andComparing Shading Effects of 3D Tree Structures with Virtual Leaves. RemoteSensing. 2021; 13(3):532. https://doi.org/10.3390/rs130305322. Bohn Reckziegel R, Sheppard JP, Kahle H-P, Larysch E, Spiecker H, Seifert T,Morhart C. Virtual pruning of 3D trees as a tool for managing shading effects inagroforestry systems. Agroforestry Systems. 2022; 96(1), 89-104.https://doi.org/10.1007/s10457-021-00697-53. Bohn Reckziegel R, Mbongo W, Kunneke A, Morhart C, Sheppard JP, Chirwa P, duToit B, Kahle H-P. Exploring the Branch Wood Supply Potential of an AgroforestrySystem with Strategically Designed Harvesting Interventions Based on TerrestrialLiDAR Data. Forests. 2022; 13(5):650. https://doi.org/10.3390/f1305065
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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