Bernard Aston

Inventories of species recently extinct or threatened with extinction may be found in global databases. However, despite the large number of published fossil based-studies, specific databases on the vulnerability of species in the past are not available. We compiled a worldwide database of published…

The New Zealand flora has a high proportion of endemic species but has been invaded by almost the same number of non-native plant species. To support management of invasive plant species, we provide an updated inventory of New Zealand’s naturalised flora and compare it with the native flora to ident…

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Aim: Geographic distributions of mushroom species remain poorly understood despite their importance for advancing our understanding of the habitat requirements, species interactions and ecosystem functions of this key group of organisms. Here, we estimate geographic range extents (maximum within‐spe…

The Cape Floristic Region (CFR) is one of the world's major biodiversity hotspots, and much work has gone into identifying the drivers of this diversity. Considered regionally in the context of Quaternary climate change, climate stability is generally accepted as being one of the major factors promo…

Plant species with divaricate forms are particularly common in New Zealand, where approximately 10% of all endemic woody species can be categorised as divaricate. A number of potential selective pressures have been proposed in order to explain this unusual feature of New Zealand flora. It has been s…

Plant species with divaricate forms are particularly common in New Zealand, where approximately 10% of all endemic woody species can be categorised as divaricate. A number of potential selective pressures have been proposed in order to explain this unusual feature of New Zealand flora. It has been suggested that divaricate architecture is a defensive adaptation that limits damage caused by either moa browsing or by climatic stresses. Climate-based hypotheses have proposed that the growth form confers a selective advantage in variable environments that are windy, droughty or frost-prone. One specific mechanism proposed for a climatic explanation is that the divaricate form might shield inner foliage from photoinhibition on cold sites with high winter solar irradiance. By determining which climatic factors are most associated with the occurrence of divaricate plants, we aim to evaluate these hypothesised climate relationships. This study uses organism occurrence records and logistic regression to compare the climate relationships of 12 divaricate species with those of larger-leaved congeners. Of the seven climatic variables that were considered, July minimum temperature was the variable that most consistently differentiated between divaricate species and their broad-leaved congeners, the former growing on sites that were significantly colder on average during this month. In general, divaricate plants were associated with lower winter light intensity than their broad-leaved congeners; although moderation analysis showed that this relationship was reversed on the coldest sites, the small size of this effect gives little support to the hypothesis that the divaricate form is especially advantageous in environments conducive to photoinhibition. However, the strong association with cold winters adds to a body of evidence that the divaricate form is favoured in frosty environments.

The uptake and deposition of silicon (Si) as silica phytoliths is common among land plants and is associated with a variety of functions. Among these, herbivore defense has received significant attention, particularly with regards to grasses and grasslands. Grasses are well known for their high sili…

Across the glacial-interglacial cycles of the late Pleistocene (~700 k.y.), temperature variability at low latitudes is often considered to have been negligible compared to changes in precipitation. However, a paucity of quantified temperature records makes this difficult to reliably assess. In this…

Concern about the course of the current environmental problems has raised interest in investigating the different scenarios that have taken place in our planet throughout time. To that end, different methodologies have been employed in order to determine the different variables that compose the envi…