How does socio-economic and demographic dissimilarity determine physical and virtual segregation?

It is established that socio-economic and demographic dissimilarities between populations are determinants of spatial segregation. However, the understanding of how such dissimilarities translate into actual segregation is limited. We propose a novel network-analysis approach to comprehensively study the determinants of communicative and mobility-related spatial segregation, using geo-tagged Twitter data. We constructed weighted spatial networks representing tie strength between geographical areas, then modeled tie formation as a function of socio-economic and demographic dissimilarity between areas. Physical and virtual tie formation were affected by income, age, and race differences, although these effects were smaller by an order of magnitude than the geographical distance effect. Tie formation was more frequent when destination area had higher median income and lower median age. We hypothesize that physical tie formation is more costly than a virtual one resulting in stronger segregation in the physical world. Economic and cultural motives may result in stronger segregation of relatively rich and young populations from their surroundings. Our methodology can help identify types of states that lead to spatial segregation and thus guide planning decisions for reducing its adverse effects

A sensitive soil biological indicator to changes in land-use in regions with Mediterranean climate

The demand for reliable indicators to quantify soil health has increased recently. We propose and test the use of soil microbial functional diversity as an indicator of multifunctional performance in agriculturally important areas. Agricultural fields in the Mediterranean and semiarid regions of Israel were selected as test sites and measured in Spring and Autumn seasons. Measurements included microbial parameters, basic soil abiotic properties and biological responses to agricultural management relative to measures of a natural ecosystem. Using a canonical correlation analysis we found that soil moisture was the most important basic soil property with different responses in Spring and Autumn. In Spring, it had a strongly negative relation with microbial biomass (MB), community level physiological profiling (CLPP) and the Shannon-Weaver index H', while in Autumn it had a strong relation with CLPP. We further show a significant interaction between CLPP and climate for land-use type "orchards". CLPP measured in the autumn season was thus identified as a useful and rapid biological soil health indicator, recommended for application in semiarid and Mediterranean agricultural regions. Apart from obtaining a better understanding of CLPP as the soil indicator, the study concludes that CLPP is well suited to differentiate between soils in different climates, seasons and land use types. The study shows a promising direction for further research on characterizing soil health under a larger variety of conditions.</p

Geoinformatics and water-erosion processes

Geomorphologists have commonly published conclusions about soil erosion and water movement based on experimental data obtained at the catchment scale. The underlying assumptions were that there exists little spatial variation in conditions at the hillslope scale (the fundamental unit) and that the catchments are representative of other catchments in the same region. These assumptions are unlikely to be tenable in practice. Indeed, we suggest that there is substantial spatial variation in geomorphological properties even at small distances when observed at fine spatial resolution and that modern geoinformatics approaches can be used to quantify and characterize this variation. This introduction reviews the ten papers that comprise this Special Issue on Studying Water-Erosion Processes with Geoinformatics, drawn from across the geomorphological sciences. The water erosion processes studied in these papers include sediment transport, fluvial processes, slope denudation, landsliding, bank erosion and bank line migration. The findings suggest that innovative measurement and modeling approaches such as GPS measurements, geostatistics, image processing techniques, and physically-based models deliver new data with which to study water erosion processes. These findings involve domains that are associated with fundamental aspects of geomorphology. Hence, there are strong grounds for claiming that geoinformatics can contribute to greater understanding of water erosion processes through characterization of space–time dynamics. We suggest that geomorphologists need to use more geoinformatics to collect more data relating to the outcomes of water erosion processes, to seek out and apply innovative processing methods and, finally, model the data to provide greater understanding of processes and to forecast and explore future scenarios

Web-based and traditional public participation in comprehensive planning : a comparative study

The present paper examines whether the potential advantages of the expanding practice of web-based public participation only complement the benefits of the traditional techniques, or are empowering enough to replace them. The question is examined in a real-world case of neighbourhood revitalization, in which both techniques were practiced simultaneously. Comparisons are made at four major planning junctions, in order to study the contributions of each technique to the qualities of involvement, trust, and empowerment. The results show that web-based participants not only differ from the participants of traditional practices, but they also differ from each other on the basis of their type of web participation. The results indicate that web-based participation is an effective and affective complementary means of public participation, but it cannot replace the traditional unmediated techniques

Web-based and traditional public participation in comprehensive planning: a comparative study

The present paper examines whether the potential advantages of the expanding practice of web-based public participation only complement the benefits of the traditional techniques, or whether they are empowering enough to replace them. The question is examined in a real-world case of neighborhood revitalization, in which both techniques were practiced simultaneously. Comparisons are made at four major planning junctions, in order to study the contributions of each technique to the qualities of involvement, trust, and empowerment. The results show that web-based participants not only differ from the participation of traditional practices, but they also differ from each other on the basis of their type of web participation. The results indicate that web-based participation is an effective complementary means of public participation, but it cannot replace the traditional unmediated techniques.

Ecological sustainability in rangelands: the contribution of remote sensing

Rangelands in temperate areas provide food to herds of domesticated animals and, therefore, provide the infrastructure for two major industries: (a) the meat industry that feeds large populations around the globe; and (b) the wool industry that uses fibre from sheep. In the semiarid zone, rangelands have a socio-economic role as they support the economy and culture of pastoral societies. However, despite their importance, rangelands are under constant threat due to encroachment by humans and invasion by noxious plants, due to degradation and erosion processes and due to drought effects. Remote sensing can be used to identify and monitor the threats to ecological processes in rangelands and, thus, to their ecological sustainability. This article provides a review of the scientific literature on the remote sensing of rangelands and discusses recent developments with respect to mapping thematic classes of vegetation and vegetative cover, mapping biophysical properties such as primary production, and monitoring land-use changes, including those driven by anthropogenically enhanced processes such as soil erosion. In the light of the reviewed studies, we expect that future research on monitoring rangeland sustainability with remote sensing will focus on hyperspectral measurements of the spectra of rangeland plant species, on lidar measurements of canopy height, and on synthetic aperture radar for biomass assessment. In the long-term, more predictive (or at least heuristic) modelling of degradation scenarios due to erosion, invasion of noxious species, and land-use transformations can be anticipated

Correction: Secondary dispersal driven by overland flow in drylands: Review and mechanistic model development.

After publication of this work [1], we noted that we inadvertently misspelled the name of author Dr. Ana Trakhtenbrot. Here, the author list is updated to reflect the correct spelling of Dr. Trakhtenbrot's name

Correction: Secondary dispersal driven by overland flow in drylands: Review and mechanistic model development

After publication of this work [1], we noted that we inadvertently misspelled the name of author Dr. Ana Trakhtenbrot. Here, the author list is updated to reflect the correct spelling of Dr. Trakhtenbrot's name