Determinants of fire intensity in working landscapes of an African savanna

Background An often cited rule of savanna fire ecology is that early dry-season fires burn less intensely than late dry-season ones; however, few studies base their experimental design on the practices of fire managers in working landscapes. The objective of this research was to study the factors influencing fireline intensity, combustion, and patchiness for a West African savanna under common vegetation and land management practices. We conducted 97 experimental fires by selecting burn plots and seasonal timing (early, n = 33; middle, n = 44; or late, n = 20) based on local practices in a typical working landscape. We collected data for biomass consumed, grass type, scorch height, speed of fire front, visual efficiency (patchiness), fire type, and ambient air conditions. We used multiple regression analysis to determine the key factors affecting fire intensity. Results Mean intensity was lowest for the middle season fires and highest for the late season fires. Minimum fire intensity increased over the fire season except for a sharp drop mid season, while maximum intensity progressively decreased. Seasonal values were highly variable. Fire intensity was moderately positively correlated with scorch height and more modestly correlated with visual efficiency, but only marginally correlated with combustion completeness. Average combustion completeness increased weakly as the dry season progressed. Intensity of back-fires was determined primarily by seasonal timing and the associated ambient humidity and wind and, to a lesser extent, grass characteristics. Head-fire intensity was only feebly responsive to wind speed. Conclusions We found that, at the peak time of West African savanna burning, the intensity of fires decreased. Fire behaviors in working West African landscapes were more dependent on fire type and wind than seasonality. Finally, we found that fire intensity values were lower than those reported elsewhere due to the more representative conditions of the fire setting (under lower afternoon winds) and fuel loads (lower biomass on working landscapes). Future research should focus on the ecological impacts of fires set under such conditions on growth and death rates of savanna trees.

Predictor Selection Using Lasso to Examine the Association of Motor Proficiency, Postural Control, Visual Efficiency, and Behavior With the Academic Skills of Elementary School-Aged Children

The associations between motor proficiency, postural control, and visual efficiency with teacher and parent ratings of children’s behavior and academic skills were examined among a sample of elementary school-aged children (N = 50). Teacher and parent ratings of students’ academic skills were analyzed separately to examine the predictive nature of measures of motor proficiency. Spearman rank order correlations reported low to moderate relationships between motor proficiency, postural control, and children’s behavior (e.g., ADHD inattention) and academic skills. The least absolute shrinkage and selection operator (lasso) procedure is demonstrated as an approach for variable selection of measures of children’s motor proficiency, postural control, and visual efficiency to predict academic skills. For teacher and parent ratings of academic skills, ADHD symptom of inattention was the strongest model predictor, whereas directional control (postural control) was also a predictor for parent ratings. Study findings shed light on practical and methodological factors associated with motor skills in educational contexts.

Redundant color words are more efficient than shorter descriptions

It is well documented that people use color words when it is not necessary. This type of redundancy challenges influential work from cognitive science and philosophy suggesting that communication is efficient. The results of an eye-tracking study explain these seemingly contradictory findings by confirming the visual efficiency hypothesis: redundant color words can facilitate the listener’s visual search for a referent, despite making the description unnecessarily long. That is, participants were faster to find ‘the blue star’ than ‘the star’ in a display of shapes with only one star. It is proposed that a referential expression’s efficiency should be based not only on its informational value, but also on its discriminatory value, which means that redundant color words can be more efficient than shorter descriptions.

Enhancing the Effectiveness of Logic Models

One of the most widely used communication tools in evaluation is the logic model. Despite its extensive use, there has been little research into the visualization aspect of the logic model. To assess the impact that design modifications would have on its effectiveness, we applied established visualization principles to revise a program model. Participants were randomly assigned to one of the six conditions to examine the effectiveness (i.e., visual efficiency, comprised of accuracy, response time, and mental effort; credibility; aesthetics) of variations to a logic model. The results demonstrated that the revisions to the model increased accuracy, perceived message credibility, and were considered more aesthetically pleasing; furthermore, revisions decreased mental effort and reduced the amount of time taken to review the model. Together, the findings from the study support the claim that visual efficiency can be improved by modifying a logic model’s formatting and design.