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Using Functional Traits to Improve Estimates of Height–Diameter Allometry in a Temperate Mixed Forest
No full textAccurate estimates of tree height (H) are critical for forest productivity and carbon stock assessments. Based on an extensive dataset, we developed a set of generalized mixed-effects height–DBH (H–D) models in a typical natural mixed forest in Northeastern China, adding species functional traits to the H–D base model. Functional traits encompass diverse leaf economic spectrum features as well as maximum tree height and wood density, which characterize the ability of a plant to acquire resources and resist external disturbances. Beyond this, we defined expanded variables at different levels and combined them to form a new model, which provided satisfactory estimates. The results show that functional traits can significantly affect the H–D ratio and improve estimations of allometric relationships. Generalized mixed-effects models with multilevel combinations of expanded variables could improve the prediction accuracy of tree height. There was an 82.42% improvement in the accuracy of carbon stock estimates for the studied zone using our model predictions. This study introduces commonly used functional traits into the H–D model, providing an important reference for forest growth and harvest models
Estimating height-diameter relations for structure groups in the natural forests of Northeastern China
No full textLinking drought characteristics and community functional traits to explain multidimensional forest stability
No full textSummary The increasing frequency and intensity of drought events in temperate regions threaten forest ecosystem stability. However, the multidimensional stability, including resistance, recovery, and temporal invariability, and its ecological drivers, remain poorly understood. In this study, we integrate trait‐based approaches with biomass dynamics reconstructed using tree rings from temperate forests in northeastern China to explore how functional composition and diversity influence multidimensional stability across varying drought regimes. Using 234 drought events, we quantified four dimensions of stability: resistance (capacity to withstand drought), recovery (ability to regain productivity after drought), resilience (return to pre‐drought levels), and temporal invariability (long‐term stability in productivity). We found significant linear and nonlinear relationships among stability dimensions, demonstrating their interdependencies. Communities dominated by conservative strategies, characterized by higher wood density, exhibited greater resistance and temporal invariability. By contrast, communities dominated by acquisitive strategies, characterized by larger specific leaf area, showed rapid recovery, though the benefits of these strategies decreased with increasing drought intensity. Functional diversity improved resistance during prolonged droughts but hindered recovery, highlighting context‐dependent trait effects. This study emphasizes the importance of establishing a comprehensive stability framework that integrates drought characteristics and community traits to predict forest responses to climate extremes.National Key Research and Development Program of China https://doi.org/10.13039/50110001216
Linking individual- and species-level leaf traits with ontogenetic size to explain tree performance within competitive and environmental contexts
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
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Age and moisture affect the relationship between competition and tree growth
Get PDFThe frequent and intensifying droughts caused by climate warming are leading to widespread declines in tree growth and increased mortality, posing a significant threat to the health and vitality of forest ecosystems. While competition among trees is recognized as a critical factor influencing their growth, the precise mechanism underlying its impact remains unclear. Here, we investigate the role of crown size in the process of competition affecting tree growth across varying gradients of age and moisture conditions. Our analysis is based on comprehensive data collected from natural forests of Xing'an larch (Larix gmelinii) located in the northeastern region of China. We observed that competition indirectly impacts tree growth by diminishing crown size, and this influence is modulated by both tree age and environmental moisture conditions. Specifically, mature trees are better able to withstand competition pressure than young trees. The stimulatory effect of crown size on tree growth enhances in young tress, but diminishes in mature trees. Additionally, the negative impact of competition on tree crown size is more pronounced in high moisture regions, and larches experiencing crown reduction under intense competition exhibit a heightened sensitivity to water availability. Our findings provide robust evidence that competition indirectly influences tree growth by modifying their phenotypic traits. Notably, the crown, serving as a crucial organ for nutrient acquisition in trees, was a mediating factor between competition and growth. This result holds significant implications for the sustainable management of forest ecosystems in the face of a warming climate in the future
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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