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Drought is understood as both a lack of water (i.e., a deficit as compared to some requirement) and an anomaly in the condition of one or more components of the hydrological cycle. Most drought indices, however, only consider the anomaly aspect, i.e., how unusual the condition is. In this paper, we present two drought hazard indices that reflect both the deficit and anomaly aspects. The soil moisture deficit anomaly index, SMDAI, is based on the drought severity index, DSI, but is computed in a more straightforward way that does not require the definition of a mapping function. We propose a new indicator of drought hazard for water supply from rivers, the streamflow deficit anomaly index, QDAI, which takes into account the surface water demand of humans and freshwater biota. Both indices are computed and analyzed at the global scale, with a spatial resolution of roughly 50 km, for the period 1981-2010, using monthly time series of variables computed by the global water resources and the model WaterGAP2.2d. We found that the SMDAI and QDAI values are broadly similar to values of purely anomaly-based indices. However, the deficit anomaly indices provide more differentiated, spatial and temporal patterns that help to distinguish the degree of the actual drought hazard to vegetation health or the water supply. QDAI can be made relevant for stakeholders with different perceptions about the importance of ecosystem protection, by adapting the approach for computing the amount of water that is required to remain in the river for the well being of the river ecosystem. Both deficit anomaly indices are well suited for inclusion in local or global drought risk studies.
Case numbers of endemic Ca-deficiency rickets (CDR) have been reported to be alarmingly rising among children of subsistence farms in developing countries within the last 30 years. Fluoride toxicities in the environment are known to not be related to the disease. To investigate if, instead, CDR is caused by a nutrient deficiency in the environment, subsistence farms in an endemic CDR area near Kaduna, northern Nigeria, were investigated for bedrock, slope forms, soil types, and soil characteristics. The natural environment was investigated according to the World Reference Base, soil texture was analysed by pipette and sieving, and plant-available macronutrients were determined using barium-chloride or Ca-acetate-lactate extraction. The analyses showed that granite and slope deposits were the dominant parent materials. The typical slope forms and soil types were Lixisols and Acrisols on pediments, Fluvisols in river valleys, and Plinthosols and Acrisols on plains. Compared with West African background values, all of the soils had normal soil textures but were low in macronutrients. Comparisons to critical limits, however, showed that only the P concentrations were critically low, which are typical for savanna soils. A link between nutrient deficiency in soils and CDR in the Kaduna area was therefore considered unlikely.
Aim: Recent studies in southern Africa identified past biome stability as an important predictor of biodiversity. We aimed to assess the extent to which past biome stability predicts present global biodiversity patterns, and the extent to which projected climatic changes may lead to eventual biome changes in areas with constant past biome.
Location: Global.
Taxon: Spermatophyta; terrestrial vertebrates.
Methods: Biome constancy was assessed and mapped using results from 89 dynamic global vegetation model simulations, driven by outputs of palaeoclimate experiments spanning the past 140 ka. We tested the hypothesis that terrestrial vertebrate diversity is predicted by biome constancy. We also simulated potential future vegetation, and hence potential future biome patterns, and quantified and mapped the extent of projected eventual future biome change in areas of past constant biome.
Results: Approximately 11% of global ice-free land had a constant biome since 140 ka. Apart from areas of constant Desert, many areas with constant biome support high species diversity. All terrestrial vertebrate groups show a strong positive relationship between biome constancy and vertebrate diversity in areas of greater diversity, but no relationship in less diverse areas. Climatic change projected by 2100 commits 46%–66% of global ice-free land, and 34%–52% of areas of past constant biome (excluding areas of constant Desert) to eventual biome change.
Main conclusions: Past biome stability strongly predicts vertebrate diversity in areas of higher diversity. Future climatic changes will lead to biome changes in many areas of past constant biome, with profound implications for biodiversity conservation. Some projected biome changes will result in substantial reductions in biospheric carbon sequestration and other ecosystem services.
Background: Environmental noise is ubiquitous in population growth processes, with a well acknowledged potential to affect populations regardless of their sizes. It therefore deserves consideration in population dynamics modelling. The usual approach to incorporating noise into population dynamical models is to make some model parameter(s) (typically the growth rate, the carrying capacity, or both) stochastic and responsive to environment fluctuations. It is however still unclear whether including noise in one or/and another parameter makes a difference to the model performance. Here we investigated this issue with a focus on model fit and predictive accuracy. To do this, we developed three population dynamical models of the Ricker type with the noise included in the growth rate (Model 1), in the carrying capacity (Model 2), and in both (Model 3). We generated several population time series under each model, and used a Bayesian approach to fit the three models to the simulated data. We then compared the model performances in fitting to the data and in forecasting future observations. Results: When the mean intrinsic growth rate, r, in the data was low, the three models had roughly comparable performances, irrespective of the true model and the level of noise. As r increased, Models 1 performed best on data generated from it, and Model 3 tended to perform best on data generated from either Models 2 or Model 3. Model 2 was uniformly outcompeted by the other two models, regardless of the true model and the level of noise. The correlation between the deviance information criterion (DIC) and the mean square error (MSE) used respectively as measure of fit and predictive accuracy was broadly positive. Conclusion: Our results suggested that the way environmental noise is incorporated into a population dynamical model may profoundly affect its performance. Overall, we found that including noise in one or/and another parameter does not matter as long as the mean intrinsic growth rate, r, is low. As r increased, however, the three models performed differently. Models 1 and 3 broadly outperformed Model 2, the first having the advantage of being simple and more computationally tractable. A comforting result emerging from our analysis is the broad positive correlation between MSEs and DICs, suggesting that the latter may also be informative about the predictive performance of a model.
Worldwide, academics and practitioners are developing ‘planning-oriented’ approaches to reduce the negative impacts of car traffic for more sustainable urban and transport development. One such example is the design of car-reduced neighborhoods, although these are controversial issues in the hegemonic ‘system’ of automobility. Despite the reduction of emissions and frequent recognition as ‘best practice examples’, ‘planning-critical’ research questions the underlying objectives and narratives of such sustainable developments. Our study contributes to this research perspective by improving the understanding of narratives that emerge along with car-reduced housing developments. For this purpose, we analyze two car-reduced neighborhoods in the City of Darmstadt (Germany) by conducting interviews with different actors involved in the planning and implementation processes. Our investigation reveals that the development of car-reduced neighborhoods (i) is consciously embedded in the context of sustainability, (ii) is characterized by power relations, (iii) follows normative indicators, and (iv) does not always correspond to lived realities. Altogether, the traced narratives of car-reduced neighborhoods are embedded in the overarching debate on sustainability, while at the same time revealing the dependence of society on the automobile. Thus, the hegemonic ‘system’ of automobility—although it is beginning to crack—continues to exist.
No more technology? A TPACK-survey for pre-service teachers with social media in the digital world
(2023)
In the digital age, social media are integrated into everyday life. To include corresponding topics of the digital world in the classroom, future teachers require specific knowledge and abilities. The extent to which these prerequisites are connected to technology, however, needs to be reevaluated in light of social media's ubiquitous nature. Through adopting the TPACK model for an exemplary topic of the digital world, constructions of space in Geography education, a self-evaluation survey instrument for pre-service teachers is compiled and validated (n = 364); social media are conceptualized as an aspect of technological knowledge. Confirmatory factor analysis confirms that the TPACK model is appropriate for the data, as fit-indices show favorable results. A transformative view of the model is supported. Correlations among all constructs exist, endorsing previous studies’ findings on the difficulties in distinguishing the TPACK knowledge constructs. Technological knowledge, noticeably, displays comparatively low correlations with the other knowledge constructs. This result is contrary to previous studies on TPACK and social media, as well as the relation of TPACK to technological knowledge. Albeit these results are not generalizable for all digital world content in pre-service teacher education, this study, by way of example, contributes to a debate on the conceptualization of technological knowledge when introducing phenomena of the digital world that are related to social media through the TPACK model. Additionally, this study advances research in the area of embedding pre-service teacher education with social media in domain-specific pedagogies.
In order to encourage a shift from the car to the more sustainable transport mode of cycling, cycle streets have been implemented in cities all over the world in the last few years. In these shared streets, the entire carriageway is designated for cyclists, while motorized traffic is subordinated. However, evidence on the impact of cycle street interventions related to travel behavior change has been limited until now. Therefore, the objective of this study was to evaluate whether cycle streets are an effective measure to facilitate bicycle use and discourage car use, thus contributing to the aim of promoting sustainable travel. For this purpose, we conducted a written household survey in the German city of Offenbach am Main involving participants affected by a cycle street intervention (n = 701). Based on two stage models of self-regulated behavioral change (SSBC), we identified the participants’ level of willingness to use a bicycle frequently and to reduce car use. By means of bivariate and multivariate statistical methods, we analyzed the influence of awareness, use, and perceptions of the cycle street on the willingness to change behavior towards more sustainable travel. The results show that the intervention has a positive impact on frequent bicycle use, while we observed only a limited effect on car use reduction. Traffic conflicts and car speeding within the cycle street adversely affect the acceptance of the intervention. The study’s findings provide new insights into the actual effects of a cycle street and its potential to encourage sustainable travel behavior.
Highlights
• Explanation of mobility design and its practical, aesthetic and emblematic effects on travel behaviour.
• Review of recent studies on mobility design elements and the promotion of non-motorised travel.
• Discussion of research gaps and methodological challenges of data collection and comparability.
Abstract
To promote non-motorised travel, many travel behaviour studies acknowledge the importance of the built environment to modal choice, for example with its density or mix of uses. From a mobility design theory perspective, however, objects and environments affect human perceptions, assessments and behaviour in at least three different ways: by their practical, aesthetic and emblematic functions. This review of existing evidence will argue that travel behaviour research has so far mainly focused on the practical function of the built environment. For that purpose, we systematically identified 56 relevant studies on the impacts of the built environment on non-motorised travel behaviour in the Web of Science database. The focus of research on the practical design function primary involves land use distribution, street network connectivity and the presence of walking and cycling facilities. Only a small number of papers address the aesthetic and emblematic functions. These show that the perceived attractiveness of an environment and evoked feelings of traffic safety increase the likelihood of walking and cycling. However, from a mobility design perspective, the results of the review indicate a gap regarding comprehensive research on the effects of the aesthetic and emblematic functions of the built environment. Further research involving these functions might contribute to a better understanding of how to promote non-motorised travel more effectively. Moreover, limitations related to survey techniques, regional distribution and the comparability of results were identified.
Highlights
- Cost-free ticket increases public transport use even when the share was high beforehand
- Free tickets are more effective than just a price reduction (zero-price effect)
- Low income, female and older employees benefit the most
- Not only travel behaviour but also attitudes change
- Cost-free public transport is one component in a set of travel demand management tools
Abstract
To increase its attractiveness for employees, to save costs regarding parking supply and to foster modal shift away from the car, employers can offer sharply cost-reduced public transport tickets. In the state of Hesse/Germany, public authorities have gone one step further by introducing a cost-free public transport ticket for all state employees. We argue that the step from sharply cost-reduced to cost-free is more than just a monetary difference. The aim of this study is to assess whether the ticket is actually affecting employees and what changed their travel behaviour. Therefore, we have analysed a two-wave survey conducted at Goethe University in Frankfurt: one from before and one from after the introduction of the new ticket. The results show a substantial increase in the use of public transport (pt) for commuting and other trip purposes. Car use and availability, however, did not decrease. In particular, those who had no cost-reduced jobticket beforehand switched to public transport after the introduction. Furthermore, we identified increasing public transport use for low-income employees (inclusion hypothesis) and several indicators pointing towards a more multimodal behaviour (multimodal hypothesis).
We performed an intercomparison of river discharge regulated by dams under four meteorological forcings among five global hydrological models for a historical period by simulation. This is the first global multimodel intercomparison study on dam-regulated river flow. Although the simulations were conducted globally, the Missouri–Mississippi and Green–Colorado Rivers were chosen as case-study sites in this study. The hydrological models incorporate generic schemes of dam operation, not specific to a certain dam. We examined river discharge on a longitudinal section of river channels to investigate the effects of dams on simulated discharge, especially at the seasonal time scale. We found that the magnitude of dam regulation differed considerably among the hydrological models. The difference was attributable not only to dam operation schemes but also to the magnitude of simulated river discharge flowing into dams. That is, although a similar algorithm of dam operation schemes was incorporated in different hydrological models, the magnitude of dam regulation substantially differed among the models. Intermodel discrepancies tended to decrease toward the lower reaches of these river basins, which means model dependence is less significant toward lower reaches. These case-study results imply that, intermodel comparisons of river discharge should be made at different locations along the river's course to critically examine the performance of hydrological models because the performance can vary with the locations.