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Ants (Hymenoptera: Formicidae) are known to be a thermophilic group with fewer species at higher latitudes. They are ubiquitous in the sub-boreal forests of west-central British Columbia (Canada) in the early seral ages of forest succession, nesting almost exclusively in woody debris. Individual species begin to disappear with advancing seral ages as the canopy closes, suggesting the hypothesis that heat gain from insolation is critical to many species. We experimentally manipulated shading of two wood-nesting ant species - Leptothorax muscorum (Nylander) and Formica aserva Forel - to emulate advancing seral age, in an environment documented to support their normal habitation. Shaded down woody debris (DWD) was found to be ca. 2 °C cooler than unshaded DWD, whereas stumps were ca. 1.5 °C cooler when shaded than when unshaded. We found significantly fewer colonies of both L. muscorum and F. aserva in shaded wood, as compared to unshaded, in a pattern consistent with how each species has been observed to respond to advancing seral age. Temperature monitoring during the experiment indicated that soil was cooler than either stumps or DWD, possibly explaining the absence of soil-nesting ant species in these forests. The species-specific differences in ant colony abundance in response to small temperature differences, found in this study, support other research on the significance of temperature in structuring ant assemblages. [ABSTRACT FROM AUTHOR]

The aim of the present study was to compare the accuracy and reproducibility of six statistical models for the calculation of olive ( Olea europeae L.) heat requirements to trigger the onset of flowering in three Portuguese regions: Reguengos de Monsaraz, Valença do Douro, and Braga. Other aims were to ascertain the date on which the heat-accumulation period started and the threshold temperatures above which the development of reproductive structures starts in olives. The starting and peak dates for the regional O. europeae flowering season were estimated by monitoring airborne pollen from 1998 to 2004 using “Cour” type samplers. The threshold temperature values calculated for the three regions were very similar (9.0 °C for Valença do Douro, 9.2 °C for Reguengos de Monsaraz, and 9.7 °C for Braga). The accumulated daily mean temperature model had less interannual and inter-regional variation, showing best predictive results for 2004, with absolute differences between the observed and predicted dates of 4 d in Reguengos de Monsaraz and 2 d in Valença do Douro and Braga for the onset of flowering date and of 2 d in Reguengos de Monsaraz, 7 d in Valença do Douro, and 4 d in Braga for peak flowering dates. This model was the most accurate, reproducible, and operational to calculate heat requirements for olives to flower, with an average mean temperature accumulation of 1 446 °C in Reguengos, 1 642 °C in Valença do Douro, and 1 703 °C in Braga to reach the onset of flowering. The best initial date for this accumulation was 1 January. (Managing editor: Wei Wang) [ABSTRACT FROM AUTHOR]