Sutton T.,PO Box 942 |
Brewer P.,Cornell University
GeoInformatica | Year: 2011
Species' potential distribution modelling is the process of building a representation of the fundamental ecological requirements for a species and extrapolating these requirements into a geographical region. The importance of being able to predict the distribution of species is currently highlighted by issues like global climate change, public health problems caused by disease vectors, anthropogenic impacts that can lead to massive species extinction, among other challenges. There are several computational approaches that can be used to generate potential distribution models, each achieving optimal results under different conditions. However, the existing software packages available for this purpose typically implement a single algorithm, and each software package presents a new learning curve to the user. Whenever new software is developed for species' potential distribution modelling, significant duplication of effort results because many feature requirements are shared between the different packages. Additionally, data preparation and comparison between algorithms becomes difficult when using separate software applications, since each application has different data input and output capabilities. This paper describes a generic approach for building a single computing framework capable of handling different data formats and multiple algorithms that can be used in potential distribution modelling. The ideas described in this paper have been implemented in a free and open source software package called openModeller. The main concepts of species' potential distribution modelling are also explained and an example use case illustrates potential distribution maps generated by the framework. © 2009 Springer Science+Business Media, LLC.
Radford I.J.,Po Box 942
Austral Ecology | Year: 2012
Understanding mechanisms underlying fire regime effects on savanna fauna is difficult because of a wide range of possible trophic interactions and feedbacks. Yet, understanding mechanisms underlying fauna dynamics is crucial for conservation management of threatened species. Small savanna mammals in northern Australia are currently undergoing widespread declines and regional extinctions partly attributable to fire regimes. This study investigates mammal trophic and ecosystem responses to fire in order to identify possible mechanisms underlying these declines. Mammal trophic responses to fire were investigated by surveying mammal abundance, mammal diet, vegetation structure and non-mammal fauna dynamics in savannas six times at eight sites over a period of 3years. Known site-specific fire history was used to test for trophic responses to post-fire interval and fire frequency. Mammal and non-mammal fauna showed only minor responses of post-fire interval and no effect of fire frequency. Lack of fauna responses differed from large post-fire vegetation responses. Dietary analysis showed that two mammal species, Dasyurus hallucatus and Isoodon auratus, increased their intake of large prey groups in recently burnt, compared to longer unburnt vegetation. This suggests a fire-related change in trophic interactions among predators and their prey, after removal of ground-layer vegetation. No evidence was found for other changes in food resource uptake by mammals after fire. These data provide support for a fire-related top-down ecosystem response among savanna mammals, rather than a bottom-up resource limitation response. Future studies need to investigate fire responses among other predators, including introduced cats and dingoes, to determine their roles in fire-related mammal declines in savannas of northern Australia. © 2012 The Author. Austral Ecology © 2012 Ecological Society of Australia.
Radford I.J.,Po Box 942 |
Austral Ecology | Year: 2012
This paper documents the effects of fire on grass-layer invertebrates in tropical savannas of the Kimberley region of north-western Australia, in the context of resource availability for consumers. Inappropriate fire regimes have been identified as a factor threatening a number of vertebrate groups, including small mammals, across northern Australia, and a possible mechanism might be through the effects of individual fires or fire regimes on food availability. We test for a fire effect on grass-layer invertebrate resources, which may affect insectivorous savanna vertebrates. Wet season sweep-net invertebrate samples were taken in two tropical savanna habitats, with contrasting laterite and sandstone substrates, in 2008, 2009 and 2010. Sites were stratified by post-fire interval to analyse invertebrate successional change after fire. In addition, experimental burns were implemented in 2010 to investigate immediate post-fire invertebrate responses. Total invertebrate numbers declined by 80-90% immediately (1week) following fire, reflecting the loss of grass-layer habitat. Of the commonly sampled invertebrate groups, Araneae, Coleoptera, Hempitera, Lepidoptera, Formicidae and Diptera were all reduced in numbers immediately post-fire, whereas Orthoptera showed no immediate post-fire decline. Invertebrate numbers were rapidly restored to pre-fire levels by the first wet season after fire, and no detectible change was observed in numbers or composition from 1 to 3-4years post-fire (the longest post-fire interval available). This suggests that the effects of individual fires on grass-layer invertebrates are very short-lived. Such short-lived post-fire responses among grass-layer invertebrates, plus evidence that most ground-layer invertebrate groups are fire-resilient, suggest that food resource limitation is not a tenable explanation for fire-related declines among insectivorous savanna vertebrates. However, wet season burning could result in significant invertebrate resource depletion in highly flammable habitats (Triodia and Sorghum spp. savannas) during important vertebrate breeding/recruitment periods, if burning is extensive and if grass-layer invertebrates do not recover within a few weeks of fire. © 2012 Ecological Society of Australia.
Andersen A.N.,CSIRO |
Bocciarelli D.,Agro ParisTech |
Fairman R.,PO Box 942 |
Radford I.J.,PO Box 942
Journal of Insect Conservation | Year: 2014
The remote and sparsely populated Kimberley region is a major centre of endemism in the Australian monsoonal tropics that is threatened by uncontrolled fire following the disruption of Aboriginal burning practices. A recent study of the ant fauna of the Mitchell Falls area of the northern Kimberley revealed that 44 % of the species are known only from the Kimberley region. The fauna appeared to be highly resilient in relation to fire. Levels of endemism in the Mitchell Falls region are likely to be particularly high because it occurs in a high rainfall zone (>1,200 mm per year) that is isolated from similar zones elsewhere in northern Australia. In contrast, the lower rainfall eastern and southern Kimberley form part of continuous climatic bands that extend right across northern Australia, and so species from these areas might be expected to be more widely distributed. Here we describe the ant fauna of Mirima National Park in the eastern Kimberley, in the context of a broader biogeographic analysis of the Kimberley ant fauna and an understanding of its response to wildfire. We specifically test two hypotheses: first, that the ant species of Mirima tend to be more widely distributed across northern Australia than those of Mitchell Falls; and, second, that Mirima ant communities are highly resilient in relation to fire, as revealed by a weak relationship with time-since-fire. Analysis of distributional ranges revealed that 24 % of Mirima ant species are known only from the Kimberley, which, as hypothesized, is substantially lower than at Mitchell Falls (44 %). Also as we hypothesized, the Mirima ant fauna shows little relationship with time since fire, with no systematic variation in ant species richness between sites with 1-4 years since fire, and no relationship between time since fire and site similarity based on overall ant species composition. Although our study indicates that levels of endemism in the ant fauna of the eastern Kimberley are lower than those in the northern Kimberley, they are still extremely high. It seems that at least a quarter of all Kimberley ant species are endemic to the region. This confirms the Kimberley as a highly significant region for ant biodiversity. We have also shown that the regional ant fauna is highly resilient in relation to the key threatening process in the region. © 2014 Her Majesty the Queen in Right of Australia.