Abstract. Floristic data from paired roadside‐paddock analyses from grassland in central Queensland, Australia, were ordinated. The mean direction of the vectors between these pairs was almost perfectly aligned with the indirect gradient represented by the first axis of Non‐metric Multi‐dimensional Scaling. It confirms anecdotal evidence of a trend from infrequently grazed roadsides to constantly grazed paddocks. The increasing abundance of annual herbs and grasses along this putative gradient is consistent with documented trends from elsewhere in the world. The response patterns of individual species along the disturbance gradient is consistent with ecological theory predicting unimodal peaks in abundance along physical environmental gradients. The ancestral perennial dominants of the grasslands, Dichanthium sericeum and D. queenslandicum, exhibited a declining response to grazing disturbance. Even the generally unpalatable perennial grass Aristida leptopoda declined considerably in the upper segments of the grazing disturbance gradient. A suite of herbaceous trailing legumes had peaks in their abundance near the middle of the grazing disturbance gradient, trends that can be readily explained by the combination of their palatability and intolerance to competition from tall perennial grasses. Several species including the noxious exotic herb Parthenium hysterophorus showed increasing abundance along the grazing disturbance gradient. The methodology may have application as a rapid method of assessing disturbance impacts elsewhere, and is most suited where a management differential between paired plots can be reliably generalized and where the physical environment is relatively monotonous.

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To understand biotic responses to an Antarctic cooling trend, we analyzed diatom samples from glacial meltwater streams in the McMurdo Dry Valleys, the largest ice‐free area in Antarctica. Diatoms are abundant in these streams, and 24 of 40 species have only been found in the Antarctic. The percentage of these Antarctic diatom species increased with decreasing annual stream flow and increasing harshness of the stream habitat. The species diversity of assemblages reached a maximum when the Antarctic species accounted for 40–60% of relative diatom abundance. Decreased solar radiation and air‐temperatures reduce annual stream flow, raising the dominance of these Antarctic species to levels above 60%. Thus, cooling favors the Antarctic species, and lowers diatom species diversity in this region.

ABSTRACT:The relationship between the seasonality of ischaemic heart disease (IHD) mortality and temperature is explored for the purpose of evaluating the climate-based predictability of the magnitude and timing of the annual IHD mortality peak for 5 English counties. Seasonality is described by the amplitude (magnitude) and phase (timing) of the first harmonic of the annual cycle of IHD mortality and mean and minimum temperature. Study results reveal a positive association between the amplitude of the annual IHD mortality cycle and temperature seasonality such that years with an exaggerated mortality peak are associated with years characterised by strong temperature seasonality. Overall, the timing of the annual mortality peak is positively associated with the timing of the lowest temperatures. Such findings provide some optimism for exploring the development of experimental climate-based health-forecasting models. This is because the simple climate-seasonality diagnostics presented here provide a fundamental source of predictability of the magnitude and timing of the annual IHD mortality peak.KEY WORDS: Climate and mortality seasonality · Climate-based health forecasting · Seasonal prediction · Ischaemic heart disease mortality Resale or republication not permitted without written consent of the publisher