Reliability of vegetation community information derived using decorana ordination and fuzzy c-means clustering

Descriptions of vegetation communities are often based on vague semantic terms describing species presence and dominance. For this reason, some researchers advocate the use of fuzzy sets in the statistical classification of plant species data into communities. In this study, spatially referenced vegetation abundance values collected from Greek phrygana were analysed by ordination (DECORANA), and classified on the resulting axes using fuzzy c-means to yield a point data-set representing local memberships in characteristic plant communities. The fuzzy clusters matched vegetation communities noted in the field, which tended to grade into one another, rather than occupying discrete patches. The fuzzy set representation of the community exploited the strengths of detrended correspondence analysis while retaining richer information than a TWINSPAN classification of the same data. Thus, in the absence of phytosociological benchmarks, meaningful and manageable habitat information could be derived from complex, multivariate species data. We also analysed the influence of the reliability of different surveyors' field observations by multiple sampling at a selected sample location. We show that the impact of surveyor error was more severe in the Boolean than the fuzzy classification. © 2007 Springer.

Energy security in the news:North/South perspectives

Analysis of newspaper reporting on the topic of energy security in eight countries – four from the global North (France, Germany, the UK, and the United States) and four from the global South (China, India, Brazil, and South Africa) – produces no support for the thesis that news is disseminated from core countries to the periphery and semi-periphery. There is an important difference between China and the other three fast-developing countries and a highly asymmetric flow of news not aligned to old core-periphery boundaries. In general, energy security is mainly covered in trade and business outlets and less in newspapers with mass circulation, indicating that the topic is still an elite concern. In some instances, attention has surged at the same time in different countries. But very few of these instances show a homogenous coverage across countries. Despite increasingly globalised media, news is created and consumed at a national level.