scholarly journals Biogeographic, climatic and spatial drivers differentially affect α -, β - and γ -diversities on oceanic archipelagos

2014 ◽  
Vol 281 (1784) ◽  
pp. 20133246 ◽  
Author(s):  
Juliano Sarmento Cabral ◽  
Patrick Weigelt ◽  
W. Daniel Kissling ◽  
Holger Kreft
Keyword(s):  
Vascular Plants ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Spatial Arrangement ◽  
Relative Importance ◽  
Methodological Framework ◽  
Spatial Factors ◽  
Units Of Analysis ◽  
Precipitation Seasonality ◽  
Oceanic Archipelagos

Island biogeographic studies traditionally treat single islands as units of analysis. This ignores the fact that most islands are spatially nested within archipelagos. Here, we took a fundamentally different approach and focused on entire archipelagos using species richness of vascular plants on 23 archipelagos worldwide and their 174 constituent islands. We assessed differential effects of biogeographic factors (area, isolation, age, elevation), current and past climate (temperature, precipitation, seasonality, climate change velocity) and intra-archipelagic spatial structure (archipelago area, number of islands, area range, connectivity, environmental volume, inter-island distance) on plant diversity. Species diversity of each archipelago ( γ ) was additively partitioned into α , β , nestedness and replacement β -components to investigate the relative importance of environmental and spatial drivers. Multiple regressions revealed strong effects of biogeography and climate on α and γ , whereas spatial factors, particularly number of islands, inter-island distance and area range, were key to explain β . Structural equation models additionally suggested that γ is predominantly determined by indirect abiotic effects via its components, particularly β . This highlights that β and the spatial arrangement of islands are essential to understand insular ecology and evolution. Our methodological framework can be applied more widely to other taxa and archipelago-like systems, allowing new insights into biodiversity origin and maintenance.

scholarly journals Stand Structure and Abiotic Factors Modulate Karst Forest Biomass in Southwest China

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 443 ◽  
Author(s):  
Lu Liu ◽  
Fuping Zeng ◽  
Tongqing Song ◽  
Kelin Wang ◽  
Hu Du
Keyword(s):  
Carbon Storage ◽  
Structural Equation ◽  
Southwest China ◽  
Structural Equation Models ◽  
Abiotic Factors ◽  
Forest Biomass ◽  
Tree Density ◽  
Forest Carbon ◽  
Driving Factors ◽  
Spatial Factors

Understanding the driving factors of forest biomass are critical for further understanding the forest carbon cycle and carbon storage management in karst forests. This study aimed to investigate the distribution of forest aboveground biomass (AGB) and the effects of stand structural and abiotic factors on AGB in karst forests in Southwest China. We established a 25 ha plot and sampled all trees (≥1 cm diameter) in a subtropical mixed evergreen–deciduous broadleaf forest. We mapped the forest biomass distribution and applied a variation of partitioning analysis to examine the topographic, stand structural, and spatial factors. Furthermore, we used structural equation models (SEM) to test how these variables directly and/or indirectly affect AGB. The average AGB of the 25 ha plot was 73.92 Mg/ha, but that varied from 3.22 to 198.11 Mg/ha in the 20 m × 20 m quadrats. Topographic, stand structural, and spatial factors together explained 67.7% of the variation in AGB distribution. The structural variables (including tree density and the diameter at breast height (DBH) diversity) and topographic factors (including elevation, VDCN (vertical distance to channel network), convexity, and slope) were the most crucial driving factors of AGB in the karst forests. Structural equation models indicated that elevation, tree density, and DBH diversity directly affected AGB, and elevation also indirectly affected AGB through tree density and DBH diversity. Meanwhile, AGB was indirectly influenced by VDCN, convexity, and slope. The evaluation of stand structural and abiotic drivers of AGB provides better insights into the mechanisms that play a role in carbon storage in karst forests, which may assist in improving forest carbon management.

scholarly journals Antecedents of entrepreneurial and intrapreneurial intentions: evidence from Brazil

2018 ◽  
Vol 17 (3) ◽  
pp. 913-926 ◽  
Author(s):  
Danilo Magno Marchiori ◽  
Maria José Aguilar Madeira ◽  
Anabela do Rosario Leitão Dinis
Keyword(s):  
Higher Education ◽  
Data Analysis ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Business Administration ◽  
Entrepreneurial Intentions ◽  
Relative Importance ◽  
Significant Relationships ◽  
Property Income ◽  
Career Options

Abstract: The general objective of the present study is to identify the antecedents of the entrepreneurial and intrapreneurial intentions of 266 potential entrepreneurs, represented by students of the degree courses in Business Administration and Accounting Sciences in brazilians higher education institutions. For this purpose, as specific objectives we sought to identify whether entrepreneurial and intrapreneurial behavior are seen as different career options by students, as well as understanding the degree of relative importance for students of the attributes of property, income expectation, extra work tolerance, desire for autonomy and risk of income variation. For the data analysis, we specified structural equation models, with a confirmatory factorial analysis, as well as using the conjoint analysis approach of the attributes selected for the study. The results indicate that the constructive entrepreneurial intentions and intrapreneurial intentions are perceived as different career options by the students. The results also indicate that the most valued attribute by the respondents to define professional choice is income expectation and the least valued is the tolerance to the accomplishment of additional effort. Finally, the results point out that the income expectation variable is antecedent of the entrepreneurial intentions, and no other significant relationships were detected.Keywords: Entrepreneurial intentions. Intrapreneurial intentions. Intrapreneurship. Structural equation models. Conjoint analysis.Antecedentes das intenções empreendedoras e intraempreendedoras: evidências do BrasilResumo: O objetivo geral com o presente estudo foi identificar os antecedentes das intenções empreendedoras e intraempreendedoras de 266 potenciais empreendedores, representados por estudantes dos cursos superiores de administração e ciências contábeis de instituições de ensino superior brasileiras. Para tanto, como objetivos específicos, buscou-se identificar se o comportamento empreendedor e o intraempreendedor são vistos como diferentes opções de carreira por estudantes, bem como compreender o grau de importância relativa para os estudantes dos atributos propriedade, expectativa de renda, tolerância ao trabalho extra, desejo de autonomia e risco de variação de renda. Para a análise dos dados foram especificados modelos de equações estruturais, com a realização de análise fatorial confirmatória, bem como utilizada a técnica da análise conjunta dos atributos selecionados para o estudo. Os resultados indicam que os construtos intenções empreendedoras e intenções intraempreendedoras são percebidos como diferentes opções de carreira pelos estudantes. Os resultados indicam, ainda, que o atributo mais valorizado pelos respondentes para a definição da escolha profissional foi a expectativa de renda, e o menos valorizado foi a tolerância à realização de esforço adicional. Por fim, os resultados apontaram que a variável expectativa de renda também é antecedente das intenções empreendedoras, não tendo sido detectadas outras relações significativas. Palavras-chave: Intenções empreendedoras. Intenções intraempreendedoras. Intraempreendedorismo. Modelos de equações estruturais. Análise conjunta.

Relative importance of climate, vegetation, and spatial factors in the community and functional composition of wood-inhabiting fungi in discontinuously distributed subalpine spruce forests

2021 ◽  
pp. 1-10
Author(s):  
Yu Fukasawa ◽  
Kimiyo Matsukura ◽  
Yoko Ando ◽  
Satoshi N. Suzuki ◽  
Kunihiro Okano ◽  
...  
Keyword(s):  
Brown Rot ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Functional Composition ◽  
Relative Importance ◽  
Picea Jezoensis ◽  
Spatial Factors ◽  
Brown Rot Fungi ◽  
Precipitation Seasonality ◽  
Study Sites

Wood-inhabiting fungi are critically important for the decomposition of coarse woody debris (CWD). To evaluate the relative importance of climate, vegetation, and spatial factors in the functional composition of fungal communities that inhabit CWD in discontinuously distributed subalpine Hondo spruce (Picea jezoensis (Sieb. & Zucc.) Carr. var. hondoensis (Mayr) Rehder) forests, a metabarcoding analysis was conducted on spruce deadwood samples obtained from six subalpine forests in central Japan using a high-throughput DNA sequencing technique. We detected 454 fungal operational taxonomic units (OTUs) from 67 spruce CWDs and determined that spatial factors explained a larger fraction of community variation than environmental (climate and vegetation) factors at all six study sites. However, environmental factors explained a larger fraction than spatial factors if we excluded data from one site that is geographically distant from other study sites. The OTU number and the occurrence of brown-rot fungi were positively associated with mean annual temperature and negatively associated with mean annual precipitation. Similarly, the principal component of forest vegetation significantly affected the OTU number and occurrence of brown-rot fungi. Precipitation seasonality was positively associated with the OTU number of undefined saprotrophs. These results suggest that fungal OTUs belonging to different functional groups respond differently to environmental variables.

Measuring the Big Five in Self-Report and Other Ratings

2000 ◽  
Vol 16 (1) ◽  
pp. 31-43 ◽  
Author(s):  
Claudio Barbaranelli ◽  
Gian Vittorio Caprara
Keyword(s):  
Big Five ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Error Variance ◽  
The Self ◽  
Self Report ◽  
Sources Of Information ◽  
Third Person ◽  
Fit Indexes ◽  
Response Modes

Summary: The aim of the study is to assess the construct validity of two different measures of the Big Five, matching two “response modes” (phrase-questionnaire and list of adjectives) and two sources of information or raters (self-report and other ratings). Two-hundred subjects, equally divided in males and females, were administered the self-report versions of the Big Five Questionnaire (BFQ) and the Big Five Observer (BFO), a list of bipolar pairs of adjectives ( Caprara, Barbaranelli, & Borgogni, 1993 , 1994 ). Every subject was rated by six acquaintances, then aggregated by means of the same instruments used for the self-report, but worded in a third-person format. The multitrait-multimethod matrix derived from these measures was then analyzed via Structural Equation Models according to the criteria proposed by Widaman (1985) , Marsh (1989) , and Bagozzi (1994) . In particular, four different models were compared. While the global fit indexes of the models were only moderate, convergent and discriminant validities were clearly supported, and method and error variance were moderate or low.

Collective Efficacy and Organizational Commitment in an Italian City Hall

2009 ◽  
Vol 14 (4) ◽  
pp. 363-371 ◽  
Author(s):  
Laura Borgogni ◽  
Silvia Dello Russo ◽  
Laura Petitta ◽  
Gary P. Latham
Keyword(s):  
Organizational Commitment ◽  
Collective Efficacy ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Practical Significance ◽  
City Hall ◽  
Italian City ◽  
Public Sector Managers ◽  
The Individual ◽  
Level Group

Employees (N = 170) of a City Hall in Italy were administered a questionnaire measuring collective efficacy (CE), perceptions of context (PoC), and organizational commitment (OC). Two facets of collective efficacy were identified, namely group and organizational. Structural equation models revealed that perceptions of top management display a stronger relationship with organizational collective efficacy, whereas employees’ perceptions of their colleagues and their direct superior are related to collective efficacy at the group level. Group collective efficacy had a stronger relationship with affective organizational commitment than did organizational collective efficacy. The theoretical significance of this study is in showing that CE is two-dimensional rather than unidimensional. The practical significance of this finding is that the PoC model provides a framework that public sector managers can use to increase the efficacy of the organization as a whole as well as the individual groups that compose it.

A Cautionary Note on Incremental Fit Indices Reported by LISREL

Methodology ◽  
2005 ◽  
Vol 1 (2) ◽  
pp. 81-85 ◽  
Author(s):  
Stefan C. Schmukle ◽  
Jochen Hardt
Keyword(s):  
Factor Analysis ◽  
Maximum Likelihood ◽  
Structural Equation ◽  
Structural Equation Models ◽  
Null Model ◽  
Likelihood Estimation ◽  
Parameter Estimates ◽  
Fit Indices ◽  
Cautionary Note ◽  
Confirmatory Factor

Abstract. Incremental fit indices (IFIs) are regularly used when assessing the fit of structural equation models. IFIs are based on the comparison of the fit of a target model with that of a null model. For maximum-likelihood estimation, IFIs are usually computed by using the χ2 statistics of the maximum-likelihood fitting function (ML-χ2). However, LISREL recently changed the computation of IFIs. Since version 8.52, IFIs reported by LISREL are based on the χ2 statistics of the reweighted least squares fitting function (RLS-χ2). Although both functions lead to the same maximum-likelihood parameter estimates, the two χ2 statistics reach different values. Because these differences are especially large for null models, IFIs are affected in particular. Consequently, RLS-χ2 based IFIs in combination with conventional cut-off values explored for ML-χ2 based IFIs may lead to a wrong acceptance of models. We demonstrate this point by a confirmatory factor analysis in a sample of 2449 subjects.

Forced Zero Cross-Loading Misspecifications in Measurement Component of Structural Equation Models

Methodology ◽  
2014 ◽  
Vol 10 (4) ◽  
pp. 138-152 ◽  
Author(s):  
Hsien-Yuan Hsu ◽  
Susan Troncoso Skidmore ◽  
Yan Li ◽  
Bruce Thompson
Keyword(s):  
Structural Equation ◽  
Structural Model ◽  
Structural Equation Models ◽  
Equation Model ◽  
Model Fit ◽  
Model Specification ◽  
Simulation Design ◽  
Measurement Models ◽  
Fit Statistics ◽  
Path Coefficients

The purpose of the present paper was to evaluate the effect of constraining near-zero parameter cross-loadings to zero in the measurement component of a structural equation model. A Monte Carlo 3 × 5 × 2 simulation design was conducted (i.e., sample sizes of 200, 600, and 1,000; parameter cross-loadings of 0.07, 0.10, 0.13, 0.16, and 0.19 misspecified to be zero; and parameter path coefficients in the structural model of either 0.50 or 0.70). Results indicated that factor pattern coefficients and factor covariances were overestimated in measurement models when near-zero parameter cross-loadings constrained to zero were higher than 0.13 in the population. Moreover, the path coefficients between factors were misestimated when the near-zero parameter cross-loadings constrained to zero were noteworthy. Our results add to the literature detailing the importance of testing individual model specification decisions, and not simply evaluating omnibus model fit statistics.

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