An empirical evaluation of three elevation change symbolization methods along routes in bicycle maps

ABSTRACT

Elevation change is critical for choosing a route when bicycling. We detail an empirical study in which we comparatively evaluated three linear symbolization types (color hue, color-coded arrows, and elevation profiles) to depict elevation change in bicycle maps for two common bicycle route planning tasks: relative height detection and slope identification. Participants performed most accurately with the color-coded arrows for relative height detection tasks, whereas symbolization did not significantly influence map-use performance for slope identification. Participants preferred the elevation profile, in spite of their lowest performance with this method overall. Our rare empirical findings offer much needed new insights into the function and appropriateness of common elevation symbolization methods, specifically to identify elevation change in bicycle route planning tasks in urban areas where map display real estate is already very limited.     

Thinning effects on walnut stem and crown diameter growth and fruiting in the walnut-fruit forests of Kyrgyzstan

The walnut-fruit forests (Juglans regia L.) in southern Kyrgyzstan are considered to be biodiversity hotspots and of considerable economic and ecological importance to local populations. The fruiting ability and stability of these forests are, however, decreasing because of infrequent silvicultural interventions and non-existent natural regeneration. Continuous inventories and walnut harvest measurements were carried out on 18 trial and control plots over the course of 13 year. Results showed that i) thinning had a positive influence on diameter at breast height (dbh) increase, ii) dbh growth and crown area increases are strongly and positively correlated, iii) large crowns enhanced the production of fruits, and iv) temperature conditions had a major influence on the production of fruits. The above-mentioned points are particularly relevant for young plantations but are also valid for relatively old plantations (> 50 years). We conclude that regular thinning substantially improves diameter growth, fruit production and ability of trees to withstand wind and snow damage in both young stands and in older walnut-fruit forests.     

Capturing the multifaceted phenomena of socioeconomic vulnerability

Vulnerability and disaster risk assessment has been evaluated from different perspectives with focus on global or national scale. There is a lack of methodologies on city scale, which are able to capture inner-city disparities with regard to socioeconomic aspects. Therefore, the main objective was to develop a transparent and comprehensive indicator-based approach which is flexible in terms of data availability and is not tied to a specific case study side. This research proposes two flexible methodological approaches on how to perform socioeconomic vulnerability assessment. Susceptibility, Coping and Adaptation are the main elements of a modular hierarchical structure to capture the societal sphere of vulnerability. The first method is completely based on official census data at block scale. The second method is an expansion and includes data derived from a field survey to add components of risk perception. The proposed methodologies were developed and applied in the city of Genoa (Italy). The results are displayed spatially explicit on maps. Furthermore statistical analysis, to reveal the driving forces which influence vulnerability, was performed. The census-based approach revealed that vulnerability is forced along the river by the inherent susceptibility, as well as the lack of adaptation. The two approaches can be used effectively in gaining different insights. The flexibility of the framework proved to be suitable to the objective of the research. However, the values computed in this research do not claim completeness, and the aim was to provide useful information for stakeholders in decision making process to reduce vulnerability and risk.     

Spatio-temporal variability in debris-flow activity: a tree-ring study at Geisstriftbach (Swiss Alps) extending back to AD 1736

Past debris-flow activity on the forested cone of the Geisstriftbach torrent (St. Niklaus, Valais, Swiss Alps) was assessed from growth disturbances in old conifer trees, providing a much improved record of past events. The study of 633 tree-ring sequences sampled from 252 European larch (Larix decidua Mill.), Norway spruce (Picea abies (L.) Karst.) and Silver birch (Betula pendula Roth.) trees allowed reconstruction of 53 debris-flow events since AD 1736. The spatial analysis of trees affected during particular events on the geomorphic map allowed for a spatial representation of individual events and a reconstruction of four flow patterns. Based on our results and Siegfried maps, we believe that before the formation of a dogleg near the cone apex in the late 1890s, debris flows preferentially used the channels located in the west-southwestern part of the Geisstriftbach cone. This study contributes to our understanding of debris-flow processes on cones and provides an example of how dendrogeomorphic techniques may help in the reconstruction and understanding of debris flows in Alpine areas.