Integrating ecological models to secure biodiversity across flammable continents

I’ve just moved to Spain to start an exciting new research project with the Forest Sciences Centre of Catalonia and the Centre for Ecological Research and Forestry Applications, Catalonia. Here’s a bit about my veski Fellowship via an interview I did with ARC CEED.

CEED Research Fellow Luke Kelly was recently awarded one of five Victorian Postdoctoral Research Fellowships that will see him travel to Spain to study the threat of fires to biodiversity at the Forest Sciences Centre of Catalonia.

The Fellowship is part of Victoria’s most prestigious science and innovation awards. Awarded by veski on behalf of the Victorian government, the Fellowship gives Luke the opportunity to spend two years as a guest researcher in Spain, followed by a third year at the University of Melbourne.

Luke has worked with CEED (through the University of Melbourne) as a research fellow for four years and credits the knowledge gained on the project to securing the grant.

“I was thrilled to be offered the Fellowship. It’s a fantastic career opportunity and I certainly owe some of the credit to the ARC CEED project,” he said.

Luke’s PhD research tested the hypothesis that ‘pyrodiversity promotes biodiversity’.

“Working on the ARC CEED project provided me with an excellent opportunity to build on this work and to tackle new ideas and approaches to conservation management.”

“I get to do fun things like building species distribution models in forest ecosystems, modelling biodiversity in Melanesia, surveying mammals in arid landscapes, and working with talented scientists from Melbourne and around the world.”

Fires are now one of the biggest threats to biodiversity in Victoria. One of the greatest challenges of land management in Victoria is managing fire to reduce the risk to human life and property, yet maintain our globally significant biodiversity.

“One reason this challenge is complex is because we make fire management decisions with imperfect information such as how plants and animals respond to fire and the probability of future events such as bushfires and droughts. There is also uncertainty about the effectiveness and cost of fire management options.”

Luke said that being awarded the fellowship means he can further develop his skill set, research knowledge and international networks to better contribute to global conservation challenges.

“It’s also a great adventure for me and my family. My partner Clare and I have a 16-month year old daughter and we are really looking forward to getting involved in the local community in Solsona and learning the local languages.”

solsona landscape

Solsona, Lleida, Spain. Home of the Forest Sciences Centre of Catalonia and some stunning landscapes.

So why Spain?

The Forest Sciences Centre of Cataloniain Spain is an ideal location for the collaboration. It includes world leaders, such as Dr Lluis Brotons, in modelling biodiversity responses to global change. They also offer access to cutting-edge fire and climate modelling tools, and provide access to their extensive European networks.

“Spain is also ideal because its Mediterranean climate, vegetation, and fire regimes are similar to parts of Victoria. We face very similar threats. But there are some important differences – and these will help to make the approaches we develop more globally transferable.”

Luke hopes his research will allow him to champion Australian fire science internationally.

“I’ll use this fellowship to develop a framework for predicting the impact of future fire regimes on biodiversity, and for designing and evaluating alternative fire management strategies,” he said.

“I hope to bring back new techniques and tools that will benefit Victorian communities and make economic savings, and help to secure the future of biodiversity across the flammable landscapes of Victoria.”

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Optimal Fire Histories for Biodiversity Conservaiton

A summary of my new paper in Conservation Biology:

Fire is used as a management tool for biodiversity conservation worldwide. A common objective is to avoid population extinctions due to inappropriate fire regimes. However, in many ecosystems, it is unclear what mix of fire histories will achieve this goal. We determined the optimal fire history of a given area for biological conservation with a method that links tools from 3 fields of research: species distribution modeling, composite indices of biodiversity, and decision science. We based our case study on extensive field surveys of birds, reptiles, and mammals in fire-prone semi-arid Australia. First, we developed statistical models of species’ responses to fire history. Second, we determined the optimal allocation of successional states in a given area, based on the geometric mean of species relative abundance. Finally, we showed how conservation targets based on this index can be incorporated into a decision-making framework for fire management. Pyrodiversity per se did not necessarily promote vertebrate biodiversity. Maximizing pyrodiversity by having an even allocation of successional states did not maximize the geometric mean abundance of bird species. Older vegetation was disproportionately important for the conservation of birds, reptiles, and small mammals. Because our method defines fire management objectives based on the habitat requirements of multiple species in the community, it could be used widely to maximize biodiversity in fire-prone ecosystems.

land fire

Planned burning in semi-arid Australia. Photo: Peter Teasdale (Parks Victoria).

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The rediscovery of an “extinct” small mammal

In 1856 the Blandowski Expedition set out to document the natural history of the Murray Mallee region. The expedition collected over 30 species of native mammals and provided a remarkable record of Australia’s historical fauna.

Sadly, one-third of the mammals recorded in this area are regionally extinct. This is due to several factors: land clearing, grazing by introduced stock and rabbits, predation by cats and foxes, and inappropriate fire regimes.

A notable find by the Blandowski Expedition was a small rodent with rufous-brown hair. Naturalist Gerard Krefft wrote that the species was “found in large numbers” in the “Murray and Darling scrub”. Until recently the Desert Mouse had not been seen in the Murray Mallee for 150 years.

Tarawi Nature Reserve is located in the northern Murray Mallee. In early 2012, Ray Dayman from the National Parks and Wildlife Service was continuing his long-term surveys of small mammals in the reserve. In one of the pitfall-traps was a rodent with a prominent orange eye-ring. Another individual was captured in a follow-up survey (pictured here).

After 150 years the Desert Mouse was back.

The Desert Mouse. Indigenous Australian’s of the Murray Mallee knew it as “Pethack” or “Ramm Ramm”. Troughton described it as Pseudomys desertor in 1932. I prefer Ramm Ramm. Photo: Ray Dayman

But why now?

In 2011 Tarawi Nature Reserve received its highest rainfall on record. The reserve is located in semi-arid Australia and the vegetation is dominated by mallee eucalypts and spinifex. In these dry landscapes, high rainfall often results in pulses of primary productivity. This means more food for rodents such as shoots, seeds and invertebrates.

Many arid-zone rodents have life histories geared to take advantage of these good times: they can produce multiple litters per year, they have a short gestation period, and they can reach maturity relatively quickly.

The Desert Mouse is no exception. In areas where it’s more common, such as in central Australia,  good rains have been followed by a 24-fold increase in capture rates of the species.

Two other rodents occur at Tarawi Nature Reserve: the endangered Bolam’s Mouse and the introduced House Mouse. In 2011, I captured record numbers of both species within the reserve.

Annual rainfall at Tarawi Nature Reserve (1967-2011). Lines are the median, the 90th percentile, and the 10th percentile. The record rainfall of 2011 is circled.

So, the rediscovery of the Desert Mouse is probably linked to rainfall-driven changes in population numbers. This is consistent with recent population booms of rodents across much of the arid-zone.

But there are a few things we don’t know. The nearest known population of the Desert Mouse is in Sturt National Park, over 400 km away. Are there closer populations? Has the Desert Mouse been present in the Murray Mallee region this whole time? What refuges have helped to maintain or reconnect populations? What role has the management of introduced predators, herbivores and fire regimes played?

It’ll be fun finding out.

What we do know is that long-term surveys – such as those completed by Ray Dayman and NPWS – provide valuable insights into the determinants of animal distribution and abundance.


Bennett, A.F., Lumsden, L.F, & Menkhorst, P (2006) Mammals of the Mallee Region, Victoria : past, present and future. Proceedings of the Royal Society of Victoria, 118, 259-280.

Krefft, G (1866) On the vertebrated animals of the lower Murray and Darling, their habits, economy, and geographic distribution. Transactions of the Philosophical Society of New South Wales, 1, 1-38.

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Test your model: making the most of historical data

We build models for a few reasons. Sometimes we want to understand ecological patterns and processes. Other times we want to make predictions about what will happen at different times and in different places. Both explanatory and predictive models are integral to conservation science, but the latter probably receives less attention in the ecological literature.

One way to test the predictive ability of models is to use cross-validation. That is, partitioning the data into subsets (folds), building a model using one subset (training data), and testing the data on another subset (validation data). Another option is to test models using independent data collected at different times and locations. This is arguably a stronger test of model performance.

But independent data is hard to get. Right? Well, not always. There’s already a large amount of wildlife, spatial and historical data available to ecologists. Perhaps there’s more scope to test our models then is currently recognized. Here’s an example.

During my PhD I modelled the responses of several small mammal species to fire history. One species, the Mallee Ningaui, was strongly associated with fire history and I wanted to assess how well the model performed when tested on independent data. I put together a novel test dataset in three steps.

1. Wildlife data. I searched for small mammal surveys that had been undertaken in the study region, and obtained data from government agencies, conservation groups and other scientists. Two datasets used the same trapping methods as I had: including wildlife surveys completed in 1985-1987 (25 sites) and 2005-2008 (9 sites). 2. Spatial data. The fire history of these sites was unknown. So, I exported data into ArcMap and determined the post-fire age of each site using mapping my colleagues and I had recently completed. 3. Historical data. Some of these survey sites had not burnt within the time frame of available satellite imagery (1972-2007) and this meant that an alternative approach was required. So, I used historical maps of fires that occurred from the 1930s to 1972 to determine the post-fire age of the remaining sites. I then went into the field with my colleagues and ground-truthed the historical maps.

The Mallee Ningaui is associated with mature vegetation characterised by its cover of hummock-grass

In summary, the test dataset was compiled relatively quickly using a combination of available wildlife data, spatial data and historical data. And it turned out our model performed quite well. The occurrence of the Mallee Ningaui could accurately be predicted using fire history and vegetation data, across a large geographical area. With the increasing amount of data available to scientists I think this is something we should do more of, particularly if we want our work to influence environmental decisions.

For more details check out this paper.

Kelly, L.T., Nimmo, D.G., Spence-Bailey, L.M., Haslem, A., Watson, S.J. Clarke, M.F.&  Bennett, A.F. (2011) The influence of fire history on small mammal distributions: insights from a 100-year post-fire chronosequence. Diversity and Distributions, 17, 462-473. Abstract

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Managing fire mosaics for mammal conservation

Fire management increasingly is focused on maintaining ‘fire mosaics’ comprising heterogeneous patches of differing fire history. However, almost any fire regime will create a ‘mosaic’. What’s lacking is empirical data that distinguishes the characteristics of mosaics that will enhance the conservation of biodiversity. So, how does the composition of fire histories in the landscape influence species distributions? What other ecological processes are important? And what mosaic characteristics are desirable for biodiversity conservation? In a new study, published in Journal of Applied Ecology, my colleagues and I set out to get some answers.

We conducted a broad-scale natural experiment in semi-arid Australia. Our focus was on a small mammal assemblage including dasyurids, burramyids and murids. We surveyed mammals in landscapes selected to represent a range of fire histories, and therefore different fire mosaic properties. Specifically, we examined the influence of five landscape properties on the distribution of small mammals: the extent of fire age-classes, the diversity of fire age-classes, the composition of vegetation types, rainfall history and biogeographic context.

     Wildfire in semi-arid mallee vegetation (photo by Lauren Brown)

What did we find? We identified the total extent of habitat, particularly that of a suitable seral stage, as a key spatial property of fire mosaics. Areas of older post-fire vegetation provided particularly important habitat for native small mammals. Recent rainfall and biogeographic context were also strong influences on capture rates of small mammals. Interestingly, there was little evidence that the diversity of fire age-classes influenced either individual species or species richness.

What does this mean for ecological management? Sufficient habitat at a suitable seral stage within the landscape is a key requirement for species conservation. In mallee ecosystems, the retention of older vegetation is recommended to create more desirable fire mosaics for native small mammals. In addition to such spatial properties of mosaics that are amenable to manipulation, an understanding of how other ecological processes affect the biota (such as rainfall) is also essential for informed conservation management.

Want to find out more? Email me for a copy of the paper:

Kelly, L.T., Nimmo, D.G., Spence-Bailey, L.M., Taylor, R.S, Watson, S.J. Clarke, M.F.& Bennett, A.F. (2012) Managing fire mosaics for small mammal conservation: a landscape perspective. Journal of Applied Ecology 49, 412-421. Abstract

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