BackgroundIn the summer of 2010, Europe experienced outbreaks of West Nile Fever (WNF) in humans, which was preceded by hot spells. The objective of this study was to identify potential drivers of these outbreaks, such as spring and summer temperatures, relative humidity (RH), and precipitation.MethodsPearson and lag correlations, binary and multinomial logistic regressions were used to assess the relationship between the climatic parameters and these outbreaks.ResultsFor human morbidity, significant (<0.05) positive correlations were observed between a number of WNF cases and temperature, with a geographic latitude gradient: northern (“colder”) countries displayed strong correlations with a lag of up to four weeks, in contrast to southern (“warmer”) countries, where the response was immediate. The correlations with RH were weaker, while the association with precipitation was not consistent. Horse morbidity started three weeks later than in humans where integrated surveillance was conducted, and no significant associations with temperature or RH were found for lags of 0 to 4 weeks.ConclusionsSignificant temperature deviations during summer months might be considered environmental precursors of WNF outbreaks in humans, particularly at more northern latitudes. These insights can guide vector abatement strategies by health practitioners in areas at risk for persistent transmission cycles.

In recent years the importance of facilitative interactions in ecological communities is increasingly recognized. This phenomenon has been observed repeatedly, particularly in vegetation communities, in a wide range of environmental conditions. The current hypothesis predicts that the role of facilitation becomes increasingly important in conjunction with increasing stress. Several empirical studies, however, failed to detect such patterns, particularly at the extreme ends of the stress gradients. Herein, we present a conceptual model that may resolve discrepancies between expected and observed and provides a more precise framework of the existing hypotheses. By relaxing two common assumptions commonly used by the stress‐gradient hypothesis (SGH) we are able to demonstrate that under some circumstances the importance of facilitation may be less at the extreme ends of these gradients. Namely, we first re‐emphasize the notion that physiological response is not linear with respect to environmental changes along stress gradients. Second, it is argued that the net outcome of facilitative and competitive interactions is reflected in the fitness of individuals as a product of these two processes, in contrast to the commonly applied assumption of additivity. Accordingly, a synthesis of the concepts of population biology (measures of fitness) and plant physiology (nonlinear responses) with the stress gradient hypothesis while retaining the original simplicity of the SGH model contributes to a better specification of the predictions of the stress‐gradient hypothesis and the resolution of observed contradictions.

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Due to the challenges faced by resource managers in maintaining post-fire ecosystem health, there is a need for methods to assess the ecological consequences of disturbances. This research examines an approach for assessing changes in post-fire vegetation dynamics for sites in Spain, Israel and the USA that burned in 1998, 1999 and 2002 respectively. Moderate Resolution Imaging Spectroradiometer satellite Normalized Difference Vegetation Index (NDVI) time-series data (2000–07) are used for all sites to characterise and track the seasonal and spatial changes in vegetation response. Post-fire trends and metrics for burned areas are evaluated and compared with unburned reference sites to account for the influence of local environmental conditions. Time-series data interpretation provides insights into climatic influences on the post-fire vegetation. Although only two sites show increases in post-fire vegetation, all sites show declines in heterogeneity across the site. The evaluation of land surface phenological metrics, including the start and end of the season, the base and peak NDVI, and the integrated seasonal NDVI, show promising results, indicating trends in some measures of post-fire phenology. Results indicate that this monitoring approach, based on readily available satellite-based time-series vegetation data, provides a valuable tool for assessing post-fire vegetation response.

The historic event of the Late Antique Little Ice Age (LALIA) was recently identified in dozens of natural and geological climate proxies of the northern hemisphere. Although this climatic downturn was proposed as a major cause for pandemic and extensive societal upheavals in the sixth–seventh centuries CE, archaeological evidence for the magnitude of societal response to this event is sparse. This study uses ancient trash mounds as a type of proxy for identifying societal crisis in the urban domain, and employs multidisciplinary investigations to establish the terminal date of organized trash collection and high-level municipal functioning on a city-wide scale. Survey, excavation, sediment analysis, and geographic information system assessment of mound volume were conducted on a series of mounds surrounding the Byzantine urban settlement of Elusa in the Negev Desert. These reveal the massive collection and dumping of domestic and construction waste over time on the city edges. Carbon dating of charred seeds and charcoal fragments combined with ceramic analysis establish the end date of orchestrated trash removal near the mid-sixth century, coinciding closely with the beginning of the LALIA event and outbreak of the Justinian Plague in the year 541. This evidence for societal decline during the sixth century ties with other arguments for urban dysfunction across the Byzantine Levant at this time. We demonstrate the utility of trash mounds as sensitive proxies of social response and unravel the time–space dynamics of urban collapse, suggesting diminished resilience to rapid climate change in the frontier Negev region of the empire.