Our research focuses on the population dynamics of plants and how they are influenced by impacts of natural disturbances and global environmental change. We are particularly interested in the interactive effects of fire, grazing and drought in grasslands and woodlands in southern Australia, and how climate change, fragmentation and shrub encroachment affect ecosystems.

Monday 23 December 2013

Are alpine ecosystems being transformed by climate change and fire?

I'll let you be the judge!

Below is a series of paired photos that I'm using to look for obvious changes in the 'woodiness' of alpine ecosystems in the Victorian Alps over the last few decades that might help us understand how alpine vegetation is responding to global change drivers such as climate change and fire.

Theory predicts that with climate warming - and there has already been a 0.8 deg C increase in Australian mountains over the last century - that alpine treelines should migrate upslope to higher elevations, while grassy communities might become shrubbier. Where low temperatures might have limited woody growth in the past, warming eases or relaxes those environmental filters.

First, I searched the Trove website to find historical photos that show mountain landscapes - this is the archive of the National Library of Australia. Mountains are good places to look for vegetation change over time using old photos because it is often easy to relocate the approximate location where the original photo was taken. You can match up ridgelines, rock outcrops, mountain summits etc and get a pretty good approximation of the original location. This is important if you want to re-photograph that same view from which to then make comparisons over time.

While it sounds easy, many of the original shots are too grainy to use, or there is a horse / cow / cattleman obscuring the really important bit of the landscape you want to see. Eventually, however, I found about 40 photos across eight mountain regions that looked promising for comparative purposes. I went up to the mountains last summer and tried my hardest to line up the old shot so I could take something as close as possible to the original. Surprisingly it is really difficult to get the exact same shot, although I think I succeeded some of the time!

While the interpretations are qualitative rather than quantitative at this stage, it is clear that there has been very little obvious change in the woody component of the landscape over a 60-100 year period. This was somewhat surprising given the substantial regional warming that has occurred over the last few decades. There have also been several fires in the alps over the last 80 years and these are generally expected to favour shrub establishment and hence, an increase in heathy vegetation in grasslands. My overriding impression is that treelines have not moved much. Total tree cover is higher in some photos, but this is mainly due to resprouting after fire rather new plants 'infilling' the landscape. Shrub cover is higher in some places but not others. Hence, structural transformation is not apparent.

I hope you enjoy these comparisons. If you think you have photos that might be useful to examine structural changes in alpine areas of Australia, I'd be really keen to hear from you (J.Morgan@latrobe.edu.au). Even better, how about you go up and take a shot of the same view and let me know whether you think the alpine is transforming!

Mt Hotham, looking towards Mt Loch (1929 and 2012).
Note substantial growth of trees in most recent photo (after 2003 fires).
These trees can be seen in the original photo - reshooting after
the 1926 fires.


Looking west towards The Bluff (in 1953 and 2012) from
Mt Eadley Stoney. Snow Gums appear more common now.
Low heathland still dominates much of the area. 


On the ridgeline towards Mt Loch (from Mt Hotham): 1946 and 2012
Note: trees seem more prominent in both the foreground and mid-ground where
grassy patches were previously more prominent


Mt Feathertop 1913 and 2013. Note very little difference in
position of upper treeline

Monday 16 December 2013

Ngadju kala: fire management in woodlands


A new fire management report, lead by CSIRO scientist Dr Suzanne Prober, challenges common beliefs about Aboriginal burning practices in Australia.

Contrary to the common assumption that Aboriginal burning was widespread and frequent (e.g. Bill Gammage's book The Biggest Estate on Earth - see this YouTube video of Bill's view of the role of aboriginal burning), the report shows that the Ngadju community from south-western Australia were highly selective in where they burnt their country. Ngadju country covers a significant part of the region known as the Great Western Woodlands in south-western Australia. This region is nationally and internationally significant for its large, relatively intact expanses of eucalypt woodlands, shrublands, salt lake systems and mallee. When I was there a few years ago, I was blown away by the shear scale of the woodlands, and the beauty of the landscape. It's well-worth putting it on your itinerary when you're in Western Australia.

Ngadju used fire as a cultural tool for looking after rockholes and grassy areas, for protecting important cultural sites and special plants such as water trees, for access and hunting, and for encouraging grasses. The old growth woodlands were rarely burnt deliberately. Large-scale burning was not a common practice.

Some of the report’s key findings include:
  • The extensive old growth woodlands were rarely burnt deliberately, because they take hundreds of years to recover.
  • The extensive sandplain shrublands were only occasionally burnt with planned fire. Mostly they burnt naturally by wildfires that were allowed to take their course.
  • Rather, Ngadju used fire as a cultural tool for keeping the country clear around rockholes, for encouraging grasses in open grasslands and mallee, and to smoke out animals when hunting. These fires were often small, around 1 ha.
  • They also used fire to protect important cultural sites and special plants such as water trees; and to maintain access along walking tracks and in coastal shrublands.
  • Other activities such as firewood collecting around the edges of woodlands and rockholes, and sweeping and scraping up litter around individual trees, were undertaken to help control wildfire.
  • Ultimately these activities would have led to a fine-scale fire mosaic over the top of the natural vegetation mosaic.
The report, written to document Ngadju knowledge about fire in Ngadju country, can be
downloaded at http://www.csiro.au/Outcomes/Environment/Biodiversity/Ngadju-kala.  As a land management tool, fire obviously has a more select role in Ngadju country than in other regions of Australia such as the tropical savannah and spinifex country where large parts of the landscape are frequently burnt. It highlights the importance of interpreting anecdotal historical information about fire and landscape structure (e.g. settler's diaries, paintings, etc) through the lens of local (rather than regional) scale ecological processes.
 

Thursday 12 December 2013

Geographic distribution ecology

The Austral Grass Tree - what happens to it with climate
change won't be just about climate space. Grasstrees
tend to be found on impoverished soils, so
predicting response is not just about projecting
future suitability of the climate.
(Photo: Michele Kohout)
I've just come back from the annual meeting of the Ecological Society of Australia (held jointly with the New Zealand Ecological Society this year). I saw lots of talks with climate change as their key focus. Many of the talks were excellent, and included projecting/forecasting future species distributions using modelling approaches (SDMs). However, I also saw a glaring absence of field experiments in the general area of 'climate change biology'. I want to raise this apparent research gap here (and perhaps start a discussion amongst the scientific community about how (or if) we can change this).

Field transplant experiments are the most important missing information for understanding species movements under climate change. There is lots of modelling suggesting species ranges will shift, i.e.  observed climate envelopes (realized niches in environmental space) are being projected into the future on a large scale using SDMs but the problem is, we don't know what stops species from establishing populations beyond their range boundaries, i.e.  is climate the direct or indirect driver of species distributions?  I'd argue that field transplant experiments across geographical range boundaries are urgent to test this basic question. They are the reality-test for what sets range boundaries, and especially for when it is climate directly versus when it is a competitive milieu mediated by climate.

Why didn't I see much on this?

Well, such field experiments are difficult and time-consuming. It is crucial that such experiments involve transplanting species beyond the range, with and without amelioration of suspected limiting factors, both physical and biotic. Hence, they can get pretty complicated and pretty quickly! 

But such field experiments are also the essential reality test in relation to SDMs. The general point here is that we need to know not how plants grow where they do occur (this is ecophysiology), nor how much two species compete with each other where both occur (this is experimental community ecology) but rather, what happens when species move into new areas where they experience new species compliments, soils and pathogens (this is geographical distribution ecology).

Unfortunately, the experiments conducted in the 1970s-90s were the era of field experiments on competition and predation, with the overwhelming majority directed at measuring intensity of interactions within a geographical range, with very few at determining why range boundaries are where they are. Hence, we've lost a couple of decades already in trying to understand this crucial question.

I suspect that if we rely on chance decisions by individual research groups to undertake geographical distribution experiments, it's likely that several more decades will pass before a useful number will accumulate to inform the general question: what sets range boundaries? We really need to arrive at a situation within a decade or two where we have a moderately well-founded overview so we can far better understand the response of biota to massive shifts in climate.  Suppose optimistically that, say, 30 experiments a decade could be achieved worldwide. Can the research community collaborate to target them in such a way as to obtain generalization across species and boundary-types as efficiently as possible?

One way might be to assemble a global network with standardised protocols - much like has been done in the Nutrient Network (which tests top-down versus bottom-up controls on diversity in herbaceous ecosystems) or the International Tundra Experiment  (which tests the effect of warming on tundra and alpine vegetation). Both networks have simple protocols and clear questions and they encourage collaborative research across a large range of field sites. Hence, the power of the experiments lies in their spatial distribution with uniform methods.

I think this approach is one that could work to test range boundaries (once it is clear what sort of factors would need to be manipulated), and am in the process of writing a review paper on this idea with (hopefully) a rallying call for such experiments. Stay tuned....

Sunday 1 December 2013

Since when do elephants have trunks? Why climate science communication is failing us?

I had a really frustrating 'discussion' about the general topic of climate change today with a farmer from western Victoria. He was a great old bloke who has been on the land all his life. We got to talking about climate change and what evidence he saw for it. The fact that he can now grow wheat in an area once thought much too wet to do so made me think he'd recognise that things were changing. Surely there would be some reasonable explanation for this!!

Long droughts are pushing trees to the limit all over the world. Climate change
will affect rainfall patterns and intensify drought impacts in many areas.
(Photo: http://uanews.org/story/droughts-are-pushing-trees-limit)


Instead,  the general arguments for the changes he could acknowledge went along the lines of "climates have always changed, it's impossible for humans to influence complex systems like climate, scientists aren't even sure what is going on, why should we pay to reduce emissions because we (Australians) are a tiny contributor to global pollution, emission trading schemes will threaten jobs and wreck the economy, greens have an agenda that threatens the man on the land" etc, etc, etc.

His response is not unique. Far from it.

For me, it was frustrating because much of the discussion clearly related to belief systems. Sure, climate science is complex and not one that most people have a very good grasp on, but nor are other fields such as astrophysics, electrical engineering, dendrochronology, all topics the average Joe Blow doesn't necessarily have strong opinions on. Yet, in the case of climate change mitigation and adaptation, we've allowed non-informed/misinformed discussion to persist all the way from our political leaders through to the general public. This seems to be a failure of the science to adequately communicate why, how and where climate change is occurring. Regardless of what you believe, policy discussion and action should be based on evidence rather than self-interest, and it is then the job to tell people why you're acting the way you are.

I don't want to knock science communication per se. Indeed, in Australia, we are lucky enough to have the Climate Council, a superb means of disseminating scientific information about climate uncertainty, climate variability and climate extremes. However, I think there is a much greater problem and, after thinking about it for a while, I think it boils down to our general philosophy about learning and knowledge and its general role in society.



The Climate Council - a great source of independent
information about climate change in Australia.
see www.climatecouncil.org.au

Science communication is not just about communication of data and facts, although this certainly is immeasurably important. I think we should also view science communication as the task of teaching people enough scientific method and understanding to investigate and see the answer for themselves, and to understand the role of debate in that process. This clearly isn't happening very well in Australia.

Currently, much of the 'debate' I see is about the degree of persuasion that can be generated (by politicians, interest groups, etc) as opposed to informing a better scientific understanding of the problem and hence, the potential solutions. Hence, a genuine scientific understanding by the public, as well as informed decision-making by our politicians, almost appears an impossible dream at this stage.

What is currently missing in climate change discussions, like the one I had with the farmer, is anything on the specifics of the climate debate. This is probably the greatest failing of science communication but hints at a greater malaise about the role of science in society and how evidence-based decision making should be central to the debate. For instance, I use the following checklists in discussions with students and others when discussing climate change to see just what sort of understanding they have about the actual issue:

  • Can people say what the debate is about, what the competing claims are, and what evidence they depend upon?

  • What arguments do people come up with to support or criticise their positions?

  • Can people outline the extent and limits of our knowledge, and comment in an informed way on what reasonably accessible further evidence could resolve some of those uncertainties?

By and large, the answers to the above are skeletal, non-existent, or just plain wrong. How could we have let this happen in a well-educated, secular society? I'm not sure, but in a culture where sport rules and the latest gossip can be newsworthy, clearly we have a problem of engagement with intelligence and ideas.

One thing puzzles me the most.

It seems odd to be discussing and debating climate change without ever discussing any of its contents. Sure, the information is complex, there is lots of it, and there is uncertainty (in model predictions, species-specific responses, temporal and spatial variation). But, an analogy might be drawn from another field of science - biology.

To me, the current public discourse about climate is like discussing the biology of elephants and never mentioning that they have a long trunk. Until this is recognised, I'm not sure we are going to make much progress on dealing with Australia's understanding of, and response to, climate change, at least in the short-term. And this is a pity.

Understanding how the climate is changing (including the consequences of this for weather extremes and hence, human health and wellbeing) should be one of the most important discussions to be had in every household across the country! And science (and scientists more generally) needs our society's support and encouragement (not contempt) so that it can meaningfully contribute to figuring out the best way forward.

Wednesday 20 November 2013

What constitutes a 'substantial' contribution to ecological science?

Good dress sense only gets
 you so far in science!
I've been musing about how one decides whether they've made  a contribution to ecological science. This thought process arose because I was asked the other day, for an educational video being developed for high school students: "what is your most important contribution to plant ecology?" Wow! Condense 20 years of work down to one key finding or breakthrough. No pressure!

I'm not bold enough to nominate what that contribution might be (others can do that), although I do suspect that rather than one key contribution, my work probably needs to be seen as a series of inter-related studies that have enhanced ecological understanding of herbaceous ecosystems at a range of spatial and temporal scales. I've been interested in population processes, competitive interactions, species coexistence concepts, outcomes of disturbance regimes such as fire and, more recently, controls on species distributions and how plant traits help us both understand and predict vegetation responses. But how does this contribute to ecological science.

There are many ways one could assess this.

Are my scientific papers being read and cited. The short answer is "yes". This is good for ones ego. But it also says the work you do - be that the hypotheses you're testing, the experiments you're conducting, or the conclusions you are drawing - are legitimate in the eyes of your peers. This is a pretty crucial starting point for making a contribution to the discipline.

Am I getting asked to collaborate with others. Thankfully, "yes". Some of the most interesting work that I've contributed to recently has been as part of Working Groups that come together to develop new ideas on a current topic, or to analyse big datasets in meta-analyses such as the one I was recently involved in with Margie Mayfield (UQ) and others. I'm also a network contributor to projects such as the global NutNet project. This, I'm really pleased to say, has been a real eye opener about collaboration and excellent science. I think we will leave some really important legacies from such work.

Is my work (which is primarily of an applied nature, but based on sound ecological theory) being adopted by managers. The short answer is "yes". Recently it has been very satisfying to find that grassland managers around Melbourne have been trying to implement many of the recommendations my research has made over the years. This includes implementing fire regimes to advantage preservation of grassland vigour and diversity, a challenging task in urban environments.

But I think the real acid test of how your work is perceived really plays out in a wider forum. Much of my work probably hasn't had such an impact at this level (although I've got time to remedy this). But real, long-lasting contributions play out when you speak to the core of the discipline. This is hard (impossible) for most of us, but that should not stop us from thinking about making these types of contributions. 

The debates that have persisted over 20-30 years now about how plant communities are structured in calcareous pasture (Phil Grime's study system in England) versus the Minnesota sand plain (where Dave Tilman has worked most of his life) have had a profound impact on me as a plant ecologist. And probably shaped the type of ecology I do. No. They have shaped my ecology. Why? Because at their heart, both ecologists (with very different views of the world) have made me think. How do these divergent ideas apply to grasslands in Australia? Do I understand their core concepts? Why do I find such work fascinating? How is this relevant to management? How do I make managers / Post-Grads/ under-grads appreciate such theory?

In many respects, these ecologists from half way around the world epitomize what it means to have a career that matters ‐ both have forced others to have an opinion about their work, to take a side, to test claims with their own experiments and decide for themselves whether the world is structured according to resource ratios and local niches (Tilman) or CSR theory and infrequent disturbance (Grime).

The lesson to young ecologists is both inspiring and clear: at the end of the day, have you stuck your neck out enough? Both careers have involved a series of (sometimes heated) debates. At their core,  however, both ecologists - whose work is steeped in theory - have made important observations about, and given importance guidance to,  the field of environmental sustainability. Indeed, as others better versed in such matters have stated, "Dave Tilman has brought what were once academic disagreements into the forefront of the modern environmental movement. I can think of no higher achievement for an ecologist in our era."


Monday 18 November 2013

Kangaroo Grass; Rooigrass; Red Grass

Kangaroo Grass, Wonangatta Valley, Victoria


One of my favourite plants of grasslands in southern Australia is the dominant grass Themeda triandra. So much of grassland ecology revolves around the species: competition, gaps, nutrient cycling, fire, litter, habitat. And I'm intrigued by its capacity to be so adaptable. In Victoria alone you can find it growing in dune swales at Wilsons Promontory, in subalpine plains near Mt Hotham at about 1350 m and in vegetation verging on mallee at 400 mm near Quambatook.

Two new reviews on Themeda triandra have been published in the last year and I thought I'd bring them to your attention. They focus primarily on distribution, cytology, germination biology, forage quality, fire response and ecosystem processes. I've include the Abstracts below in case you want to chase them up.

Some things you may not know about Themeda triandra:
  • The species is found in all states of Australia, South Africa, Indonesia, New Guinea, Japan, India, Saudi Arabia, southern Turkey and Mongolia! It's also become naturalised in New Zealand.
  • In Australia, there are two main genetic races - the diploids that occur south and east of the Great Divide (i.e. coastal populations), and tetraploids that occur in drier, inland areas.
  • The species probably evolved in tropical Asia and migrated down the east coast of Australia (although there is a crazy hypothesis that suggests that Themeda colonised Australia via the importation of camels from Asia and Africa in the 19th century!!)
  • there have been no crossing trials between South African and Australian populations to see if they can breed.
  • it is an important forage species in Africa for impala, antelope, wildebeest, zebra and buffalo.
  • Themeda can decline in the absence of disturbance because tillers are shade-intolerant, and flowering culms are rarely produced on plants that are moribund.
  • up to 94% of seed falls within 50 cm of maternal plants.
  • Almost without exception, sheep have been shown to negatively impact Themeda.

Dell'Acqua et al. (2012) A tropical grass resource for pasture improvement and landscape management: Themeda triandra Forssk. Grass and Forage Science 68, 205-215.

Themeda triandra Forssk. is one of the most widespread grasses in the dry to mesic prairie ecosystems of Africa, Asia and Australia. It is of particular interest due to its high value as a forage species for wildlife and livestock, and its potential use in landscaping practices. In this review we have collated information from the many studies that have been devoted to this species since the 1960s to provide information about the species’ distribution, taxonomy, morphology, ploidy and reproduction, and to describe its vegetation and germination and their relationship with the most important ecological aspects of its preferred habitats. Agronomic aspects are considered in detail, with particular focus on the role of T. triandra as a forage species and the relative importance of grazing, fire and rainfall regimes for its management. We also explore how this species can help with the rehabilitation of degraded areas, soil and water conservation, countering exotic species invasion and landscaping in general. We conclude with a brief discussion of the as yet unresolved taxonomic relationship between the African species T. triandra and the Australian species Themeda australis.


Snyman et al. (2013) Themeda triandra: a keystone grass species. African Journal of Range and Forage Science 1-27.

Themeda triandra is a perennial tussock grass endemic to Africa, Australia and Asia. Within these regions it is found across a broad range of climates, geological substrates and ecosystems. Because it is widespread across these areas it has great economic and ecological value, as it is a relatively palatable species across most of its range. It is of critical importance in supporting local populations of both native and introduced herbivores, and is thus central to wildlife and livestock production, and consequently rural livelihoods. It is an important climax or subclimax species that is well adapted to fire, a common element in many areas where it is found. Inappropriate grazing management, however, can result in a decline of Themeda, as it is not well adapted to an uninterrupted, selective grazing regime. A decline in abundance of Themeda in a grassland is usually coupled to a decline in grazing value, species richness, cover and ecosystem function. In spite of its significant ecological and economic importance, there has been no attempt to review and synthesise the considerable body of research undertaken on this grass. Our aim is to summarise and synthesis work previously undertaken and identify areas where further research is required.


 

 

Friday 8 November 2013

Signs of Life: Part 2

The seeds I found hidden away
after 25 years of storage.
A few months ago, I posted a Blog on Signs of Life. This was about some seed I'd discovered, hidden away in a cold room, that had been stored at about 2 degree Celsius in the dark. Seeds that were in sealed containers that dated back to the mid-1980s.

And these weren't just any seeds. These were seeds of native grassland plants that we know have now been lost from some of the sites where they had been collected from. A good example was some glass jars that had somewhere between 5000 and 10000 seeds of the Button Wrinklewort from a population on a railway line near Melbourne (called 'Manor'). We know that this population has now disappeared despite the fact that the population numbered more than 300 plants just two decades ago. There were other rare plants such as the Large-fruited Groundsel (Senecio macrocarpus) and orchids such as the White Diuris (Diuris fragrantissima) that have been lost from the wild populations from where they were collected.

So this was rather exciting. Here were seeds of populations of plants now extinct at those locations and hence, potentially an opportunity to restore those plants (and maintain the genetic diversity as well).

Of course, we don't know much about seed longevity, so I was unsure whether these seeds had remained viable.

So we took the seeds, and my trusty research assistant Karina Salmon and I tried to germinate them under controlled conditions in the growth cabinet. We placed them on wetted filter paper in petri dishes, at 20 degrees Celsius, a condition known to germinate many of these species without any pre-treatment. There were lots of species, and lots of populations. We focused on all the non-orchid populations. After a month, we scored the seeds for germination. Previous work of mine says that many grassland species should have germinated by then.

Unfortunately, almost all of the species and all of the populations failed to germinate.

Of the 21 species we sowed (encompassing over 35 populations), only three species germinated (see the list below for those species that did germinate, and those that did not). Of those that didn't germinate, a squeeze test at the end of the experiment confirmed there was no live embryo.

Frankly, this was a huge disappointment.

An example of a grassland "tuber bank" - this is the
enormous root storage structure of Featherheads
(Ptilotus macrocephaalus)
 
All the daisies did not germinate, and these made up the majority of the collection. This was perhaps not surprising. In the grassland flora near Melbourne, much of the annual regeneration comes from a 'bud and tuber' bank, not a soil seed bank. Ecological work by Ian Lunt (who did some neat seed burial experiments), Andrew Scott and others tells us that many seeds are short-lived in the soil - this is termed a "transient soil seed bank".

Under storage conditions, we might expect persistence to be longer. There are no soil organisms devouring seeds, seeds are not germinating, nor is rotting an issue.  But inherent survival clearly did not extend to two and a half decades of storage.

So where does this leave us?

To me, it suggests a few things. If you are going to collect seed from wild populations, you should use it! Storing it in a paper bag in the back of a cupboard, to be forgotten about, is wasteful. You may as well be collecting the seed and putting it in the bin. This type of data tells us  that many seeds are not viable for the long-term under the conditions many of us would store such seeds. Hence, we lose the opportunity to maintain genetic diversity from small, compromised populations. Projects such as the Millenium Seedbank have much more advanced seed storage techniques that may keep seeds alive for decades - and will be crucial for protecting many threatened species - but most of us work at very local scales and on short-time frames with far less sophisticated storage facilities.

This study provides us with a bit of a reality check. Averting extinction is not just about saving seeds in seed banks. It's also about saving the plants in the wild. My discovery of seeds in jars, while the source populations went extinct, highlights just this point. No matter how well meaning seed collection and storage is, if there is never any intention of using that seed and returning plants to the wild, we are (perhaps) exacerbating small population decline. Populations size is one of the best ways to estimate extinction risk - so any intervention (such as seed collection) that affects long-term population size, must have a sound rationale for its practice.

Below is a list of species that did  and did not germinate in our study. Remember, most seed here was collected between 1984 and 1987. It remains unclear just how long seed of herbaceous grassland species can be stored, but my guess would be that its is years rather than decades.

Species that did germinate after >25 years storage: Ptilotus spathulatus; Glycine tabicina; Rytidosperma laevis

Species that did not germinate after >25 yrs storage: Arthropodium strictum, Caesia calliantha, Chrysocephalum apiculatum, Chrysocephalum semipapposum, Cynoglossum suaveolons, Elymus scaber, Lepidium aschesonii, Lepidium hyssopifolium, Leucochrysum albicans var. tricolor, Microseris lanceoloata, Minuria leptophylla, Plantago gaudichaudii, Podolepis jaceoides, Rutidosis leptorrhychoides, Senecio macrocarpus, Senecio quadridentatus, Velleia paradoxa, Vittadinia cuneata
 

Thursday 19 September 2013

Restoring ecosystem stability

There are many aims of ecological restoration. Some might include: to enhance native diversity. To stop soil erosion. To connect fragmented ecosystems. To recover disturbances caused by D9 bulldozers.


In bushfires, firebreaks often get bulldozed along tracks. These areas need to be restored afterwards. Here, in the mountains of Victoria, restoration usually is about getting high vegetation cover back (as soon as possible) to reduce soil loss.
(Photo: Sera Cutler, somewhere near Mt Hotham, 2003)


Given these aims, it is often fairly clear what needs to be reported upon to determine the success of restoration. So, for the above examples, you'd probably want to report on the following:
- changes in native species richness or native:exotic species richness ratio
- reduce bare ground (%)
- movements of habitat specialists between patches via corridors
- increased native species cover and low exotic species cover.

As an ecologist, I'm interested in longer-term outcomes of restoration. I'm really curious to know whether initial recovery predicts longer-term recovery. And, importantly, having restored vegetation, how 'stable' is this vegetation in the decades after it was first introduced.

I think one of the under-reported outcomes of restoration is stability. We know that ecosystems fluctuate from year to year in response to climate and biotic factors - hence, the term "non-equilibrium dynamics" is often applied when considering vegetation dynamics. Yet, as a restoration practitioner, I'm pretty sure that you'd hope your restoration outcomes, while fluctuating across the years, was introducing a vegetation that was rather resilient to big changes. Big change might normally be considered negative change. For example, change could involve (a) invasion by exotic species overwhelming the re-introduced natives or, (b) recruitment failure leading to restoration collapse once the lifespan of the plants has been reached.

Tilman's experimental plots in Minnesota
test ideas about the role of species diversity
on ecosystem function.
Theory suggests that introducing more native species gives the system greater stability. Dave Tilman's experimental grassland plots in Minnesota are often cited as the best example of this - severe drought had less impacts on rich assemblages compared to species-poor plots. Diverse plots also had effects on invasion by exotics (rich plots resisted invasion) and nutrient capture/drawdown (rich plots use more resources, reducing leakage of resources).

However, in the native grasslands that I work in, very few species contribute most of the biomass and occupy most of the basal area, i.e. the dominant tussock grasses. So, is stability driven by many species, or few abundant ones?

This is not something we have much data on in Australia, so I'm not going to be able to answer that question very well at this stage. But, we can use one of the longest running grassland restoration projects in Australia to get insight into the capacity of restored grasslands to persist over two decades and to resist invasion by exotic species.

In the mid 1980s, a group of ambitious (and enthusiastic) volunteers from the Friends of the Organ Pipes National Park teamed up with a state government scientist to re-introduce native grassland plants to an area that had been transformed to exotic species by agriculture.  This was a mighty task, for in those days there was little seed available of the now threatened grassland species, there was little known about the autecology and cultivation of the native species, nor had anyone tried to reintroduce them back into the 'wild' to create the 'wild'!

I dug up some photos from about 1985/86 when I first got interested in native grasslands. Keith McDougall, a fabulous grassland ecologist, took me on as a Student Research Cadet for 6 months, and I helped harvest seed of native grasses, sow the seed in experimental plots testing different establishment treatments,  and then monitored the resulting seedlings and recovery. I've been doing it ever since!

You can see in this photo the plots we initially created.
The experimental plots at Organ Pipes National Park, around 1985. Each 10 x 10m plot is examining
how Kangaroo Grass establishment is effected by treatments such as burning.
About 2-2.5 ha was sown in this way over a 5 year period.
(Photo: Keith McDougall)
Here you can see Kangaroo Grass thatch being spread onto plots that have been unburnt & burnt.
(Photo: Keith McDougall)


Each treatment plot was about 10 x 10 m. The aim here was to create the matrix first - the native tussock grasses - so as to build the grassland structure before introducing diversity later. Exotic species were variously removed by fire, herbicides and their interaction, but only for the initial establishment phase of the grassland. In this ecosystem restoration model, we explicitly assumed that native diversity would increase with time as we first occupied the site with native grasses, then added inter-tussock native species later.

I decided to go back to Organ Pipes recently. I was curious whether the grasses that we had sown (almost exclusively Kangaroo Grass) had (a) persisted after 25 years, (b) had resisted invasion by exotic species. While the plot markers are gone, it is very obvious where we sowed native grasses because the plot outlines are almost still visible. Inside the plots was Kangaroo Grass - at high density, with tussocks of varying sizes hinting at self-replacement,, and seemingly acting as the mono-dominant species we see in nature. And, surprisingly, there were very few exotic grasses present. These were restricted to areas outside our sowings where native grasses had no yet colonised.

Restored native grasses creating a matrix for future re-introduction of native species.
Note the tall exotic grass Avena fatua in the general vicinity of our initial walkways.
Organ Pipes National Park
(Photo: John Morgan)
Kangaroo Grasses dominate in areas first sown in 1985.
Organ Pipes National Park
(Photo: John Morgan)

So, from a field of exotic annual grasses (comprising Avena spp, Bromus spp. and Vulpia spp.) a native-dominated grassland has arisen. This hints at a great (perhaps increasing) stability of the native grassland - one that maintains itself yet buffers against invasion. While native species diversity remains low (reintroducing herbs to the matrix has proven a challenge), one could argue that an unstable annual exotic system has been replaced by a more stable native system. And, importantly, the native system still provides an opportunity to return the ever-diminishing native grassland plants to a secure habitat.

I hope you've found this insight inspiring. And maybe it makes us think about restoration in a slightly different way. We need to create systems for the long-term, ones that can buffer environmental change, and ones that provide us with opportunities to continue to enhance their biological value over the decades.

Tuesday 13 August 2013

Botanical literacy amongst Under-Grads

Do you know what these plants are?

 
 
 
 
 

I'd be happy if you knew the Genus or Common Name. If you could get the whole botanical name, I'd suggest you knew your plants.

The reason I ask is because I think many undergraduates that I see in biological science courses don't seem to be very botanically literate. This is an observation rather than a judgement. I have no idea whether this has always been the case, but it seems that more and more students I encounter really have very little understanding of the plant world around them.

Why might this be?

Perhaps plants are harder to 'sell' as organisms, despite their importance for habitat, plant-animal interactions, ecosystem processes, and beauty. Perhaps our urbanizing society explores natural places less, and has less space around homes to 'experiment' with gardens.

To test the idea that under-grads are not particularly botanically literate, I showed a group of students 10 images of plants I'd expect they would know if they had been paying attention to the world around them in Australia. Most of the plants I showed them were common or showy things that you can't help but notice - the sort of magpies, silver gulls, blue wrens of the bird world. Indeed, I'm sure if you showed them these birds, many students would probably be able to identify these species, which kind of would highlight even further that plants are invisible to many people. I showed them all the plants above, as well things like kangaroo paws, pink heath (the state floral emblem) and banksia.

Somewhat surprisingly, they did OK (well, some did - no-one got 10/10). Here's the data - I've plotted the number of specimens correctly identified on the x-axis, and the number of students in each group on the y-axis.



As you can see, 40/79 students got less than 50% of the plant names right. The species that were most recognisable were (sadly) white clover (a weed of natural systems but an important agricultural pasture plant), kangaroo paws (maybe because they are common in nurseries and spectacular to boot), and Golden Wattle (the floral emblem of Australia). Much to my horror, the beaut red-flowering gum above was recognised as a gum tree by less than 50% of students!!!!

The results are perhaps not surprising and help argue for the need to teach undergrads about the biodiversity that resides in their local environment. It's why I teach into a  second year undergraduate course that focuses on the basics of taxonomy, plant identification and plant ecology. These are fundamental skills to be acquired by botanists, and biologists more generally. We think this is crucial - botanical literacy is low it appears, yet many of the applied conservation jobs in Australia rely on good botanical skills. I hear over and over that our grads are valued because they can identify a plant (often the job interview includes a plant ID test), they can sample vegetation (in a quantitative sense), and they can analyse floristic data (using complex multivariate methods).

But, Botany Departments are in 'decline'. In July 2013, the last botany undergraduate in the United Kingdom completed their degree at the University of Bristol (British Ecological Society Bulletin 44, June 2013). Botany has now disappeared from the curricula of British Universities. It's been made extinct! Is this moving with the times, or an admission that plants are just not fascinating enough for students?

We are lucky to have two dedicated Botany Departments in my home state of Victoria - at the University of Melbourne and La Trobe University. Fortuitously, they do very different types of 'botany' - at UoM, there is a strong emphasis on modelling, while at LTU we focus on developing field-based skills, taught in dedicated botany classes with plant systematics and taxonomy an important underpinning philosophy, as is plant identification more generally. We think there is a place for students to have to learn about plant families and their spotting characteristics, to learn botanical terminology and nomenclature, and to collect herbarium specimens for lodging as voucher specimens in university and state herbaria. Others might disagree, but given the low botanical literacy levels amongst under-grads, there is a clear need for such teaching.

I plan to survey the students again at the end of the semester, after a strong prac component that introduces them to taxonomic keys, spotting characters and field sampling (species-area curves, quadrats, cover abundance estimates). The aim (hope) is that they'll improve their scores (making us feel relieved that we've taught them something!), but I'm just as interested in developing their appreciation of plants, and hope that some of them join us again in third year to continue their botanical quest.

[and, in case you're wondering, the plants above are: Themeda triandra, Eucalyptus macrocarpa, Acacia pycnantha, Trifolium repens, Xanthorroea australis]

Monday 29 July 2013

Advertising research: invasions in alpine ecosystems


Ox-eye Daisy - I think this will
be one of the big threats to
alpine systems in the coming decades.
Photo: John Morgan, Dinner Pain, Jan 2013
Here's a little bit of an advertisement about my research on invasions in the Australian alps. My university is big on doing these little staff profiles (your research in 3 Dot Points!), so I thought I'd share with you.

Go to:
https://www.youtube.com/watch?feature=player_embedded&v=HNWfcrBOUJk

Interestingly, many of my colleagues groan when asked to do this sort of thing, but I see it as very much part of my 'job'. Communicating to land managers, policy makers, peers and the public should be fundamental to the discipline. After all, much of what we do is contest ideas about how nature works, how it can be predicted, and what sort of environmental future we want to encourage. These ideas are often new, challenge accepted paradigms and, importantly, can lead to improved land management. It's unlikely they'll just magically be adopted.

So why are (some) research academics so poor at communicating ideas to those outside academia?

There are some excellent exceptions to this of course! If you follow an ecologist on Twitter, a Blog, or excellent sources such as The Conversation, then you've already come across those scientists willing to engage beyond their own field of peers. But what about how this is perceived?

Personally, I think there is a view that 'advertising' your research can be seen as (a) needy and (b) self-congratulatory. "The work should speak for itself!" Perhaps! But, and as the tenor of discussion at meetings I attend with managers would attest, perhaps this view is (c) selfish and (d) arrogant. Particularly in the current era where scientific publication rates and volumes are sky-rocketing. I have enough trouble keeping up to date with new and exciting research.  To assume that those that use science (i.e. students, managers, governments) need to seek it out themselves would seem to immensely under-value our work. Why would they seek it out........unless they knew it existed in the first place.

This is not a call for ecologists to get on the media bandwagon, nor do stunts to get noticed. Far from it. Rather, I think what I'm really suggesting is that ecologists need to know that the 'users' of their work are really hungry for information. Ecological literacy in the field of conservation and land management is rising and, because there are lots of vehicles to engage with these users, ecologists should be open to engaging in these non-traditional ways.

There is a danger that end-users of information will rely heavily on those ecologists that are accessible to them. Such a narrowing of world views is probably not desirable. But what is really undesirable for ecologists is to ignore the possibility that their research might just have even greater impact if they engage (or is that 'advertise') through new mediums.

Monday 22 July 2013

What do you wish you'd learnt at University??

Grass-trees in the Warby Range
I've been chatting to former students of late, trying to find out what we could have done at University to better prepare them for life in the workforce/academia. I'm in the enviable position where many of my students have gone on to work in the botanical field and many have gone on to make great contributions - as environmental officers, as university researchers, as advocates for conservation of biodiversity, as government policy makers. Hence, we must be doing something right. Finding out how they could have got more out of their education has been really eye-opening (and perhaps not surprising).

It's clear that former students of mine have two very clear regrets, representing two very different skill sets.

1) Far and away the biggest 'regret' expressed by former students is that they wished they'd tried to learn the major plant families (better than they did!) and, in particular, the spotting characteristics that help you to quickly narrow down your options. Frequently I hear them state that plant identification is a critical skill in their current jobs, but one of the skills not well learnt at uni. Hence, they have struggled with this important aspect of their work. This might be because it is not well taught in undergrad courses or, more likely, as an undergrad it is not immediately clear that such skills are pivotal and hence worth learning well. Teaching the basics is an investment in future ecologists, but one that those future ecologists must be willing to learn, no matter how hard or boring it might seem at the time.


2) A close second relates to statistics. This one is not surprising to me - most undergrads really shy away from mathematics and data analysis more generally. I suspect that a lot of this has to do with the fact that biology students don't immediately see the relevance of statistics. Many just want to get on with improving conservation outcomes, but experimental design, evidence-based management and data interpretation are central to many ecological disciplines and can't be avoided. I always challenge my students to understand their stats, and to be proficient in writing code to generate graphs and simple models. Ultimately, they never complain! Well, that's what I tell myself!

Of the other 'regrets' expressed by my ex-students, the dotpoints below consistently get raised. The idea of highlighting them here is to encourage current undergrads to think outside the box, to engage with concepts perhaps not central to their current thinking about ecology, and to ensure that they are aware of the types of skills necessary in the workforce that (perhaps) only seem like annoying things needed to pass a final exam.

3) Some students really wish they had mastered computer programmes that are now pretty much 'tools of trade' for ecologists - ArcGIS, Access Databases and R get mentioned a lot. I tend to agree. Computers are part of the arsenal of all ecologists, as is modelling and data storage, so it's important to challenge yourself to learn these programmes. Rarely will they be taught in general undergrad courses to levels that approximate 'expert proficiency'. Instead, you often have to master them yourself (with the help of willing allies like Post-Grads and Post-Docs).

4) Contributing to discussion groups. Science is a contest of ideas. But many undergrads avoid serious discussion of concepts, theory and data. I'm not sure why this is (although the obvious reason probably goes something along the lines of "I don't want to look stupid or say something seen as dumb"). This outlook needs to change. Coherently arguing a position, based on well-researched information, is central to decision-making, so any opportunity to practice these skills at uni should be grasped with both hands. One of the things you'll also have to learn, however, is to take criticism constructively.  This ensures rigorous debate, and sound ideas rise to the surface. What might seem like short-term pain will ultimately have a long-term gain to your ability to contribute to the discipline.

5) Time management. We all know the story of the undergrad that leaves their assignment to the last minute or the Post-Grad student that takes two, three, four or more years longer than anticipated to finalise their research thesis. But as your career progresses, you find you have less and less time to do all the tasks that you've been handed. Several students have told me that they wish I'd been harder on them when they failed to deliver what was promised - that if they failed to meet a deadline, there should have been a consequence beyond a stern (but often sympathetic) look. I'm working on this!!! But getting into the habit at uni of meeting deadlines, and developing a system that works for you, can only help you later in the workforce. And being a reliable, efficient team member should not be under-estimated.

6) Ecophysiology. Surprisingly, several students wished they'd taken more classes in this topic. The role of ecology is to understand the abundance and distribution of organisms and, for field biologists, knowing how to measure this is crucial. But what underpins much of this (aside from dispersal processes) is how plants respond to stresses such as water-limitation, frost and extreme heat. These outcomes are often observable as effects on cell or organ function, and it's only after university that some students begin to realise the importance of this.

7) When many students enter university, they do so because they have an interest in a particular species (such as a koala), or a group of organisms (e.g. big cats, whales, orchids). But it soon becomes pretty obvious that it is near impossible to study all species in great depth to understand them, yet the pressures to 'manage' them is high. Many students tell me that they enjoy learning about plants from a functional trait viewpoint, largely because the concept allows conceptualization of responses of whole communities to things such as disturbance, climate change and urbanization. Perhaps we need to teach this concept more rigorously from 1st year level biology, and emphasize to students that the best understanding of annual plants or C4 grasses can be gained by viewing those plants by their traits. Such thinking will need students to move beyond the specific natural history that drew them to biology, and look for broader patterns in nature.

Tuesday 16 July 2013

Why grasslands need 'champions'

Because native grasslands exist as small, isolated fragments in an agricultural landscape across most of south-east Australia, they present challenges to management on lots of levels. Indeed, their small size is one of the biggest challenges, mostly because of the perception that small remnants are hard to conserve.


A native grassland on a three-chain wide roadside in western Victoria. A 'chain' is about 22m long, and was used by early surveyors to measure distances for road reserve allocations, blocks, town commons, etc. Ptilotus macrocephalus is the flowering plant you see in the foreground, surrounded by tussocks of the C4 grass Themeda triandra.
(Photo: Fiona Sutton)
Edge effects, weed invasions, small populations, isolation and inbreeding are all very real problems faced by remnant grasslands. But I've found one of the biggest challenges we face to conserve biodiversity in grasslands is to get management implemented. Consistently. This is not meant to attack the people who manage grasslands but, rather, highlight that we need to be aware that despite lots of excellent ecological research that informs management, and the fact that there are many enthusiastic, dedicated professionals and volunteers in this field, grasslands need intensive and on-going inputs to maintain their values. And the difficulty of doing this should not be under-estimated when thinking about management over multi-decadal scales.

I've just achieved one small gain for grassland conservation. In this Blog post, I want to tell you about the journey I had to take because I think there is a salient lesson to be learnt.

Truganina Cemetery is one of the jewels in the crown for grassland conservation in the Melbourne area. It might only be approx. 1.5 ha in size, but it contains large populations of at least two nationally endangered plant species (Button Wrinklewort, Spiny Rice-flower), is species-rich, and hardly has any weed invasion. The earliest gravestones date to the 1860s, and we know there are unmarked graves of early European settlers that date from even earlier times as they made their way to the goldfields of Ballarat. Because it was set aside from grazing at least 160 yrs ago, it retains a complement of native species that are missing from the surrounding grazed, species-poor grasslands. Indeed, many of the native species can only be found in places like Truganina.

Truganina Cemetery in late autumn, 2013. The centre of the cemetery is a superb example of a little grazed native grassland.
(Photo: John Morgan)


Such sites are crucial for conserving local genes of once-widespread species. And they are the place where we might collect seed to develop seed orchards, and produce plants to introduce into conservation reserves when restoration is attempted. We can't under-estimate their role: if we want to save the ecosystem, we have to save all the pieces!

To maintain the plant diversity of native grasslands, the impact of the dominant tussock grasses on smaller, less competitive inter-tussock species need to be moderated. This has been done by burning in many areas, although it is feasible that slashing (and removal of the cut material) could achieve the same aims (as might stock grazing in areas where grazing has been part of the recent history of  the grassland). I've written about this in previous posts, and it's been a central idea in the ecological literature since John Stuwe & Bob Parson's seminal paper on grassland floristics and management effects (see Australian Journal of Ecology 2, 467-476).

At Truganina, the last management burn was approx. 10 yrs ago (in 2002, although the record keeping is hazy on this). Since that time, there has been a long and protracted drought, and this seems to have slowed down the rate of biomass accumulation, such that the necessity to burn has been quite low. It's been interesting to see how grassland productivity at Truganina is tied to annual rainfall (as it is in prairies). In drought years, I'd suggest there has been a decline in grass biomass as litter decay exceeds litter build-up via new tiller growth. But, with the breaking of the drought in 2010-11, productivity increased dramatically. By 2012, it was clear that the grassland needed disturbance (to the vegetation) to open up inter-tussock spaces and if this did not occur, it was probable (i.e. highly likely) that the biodiversity values would be compromised.

No-one disagreed with this assessment. But to get Truganina burnt, our preferred option, took a little longer than might have been hoped and hints that to achieve management outcomes (sometimes) requires persistence and dogged determination.

Bob Parsons and I (and others) wrote to the secretary for the  Minister for Environment in the state of Victoria in December 2012, talking about the need to burn important grassland sites around Melbourne (not Truganina specifically) in autumn 2013 because of the dramatic build-up of grass biomass. We got a letter back from the Regional Director (11th January 2013), thanking us for raising the issue, and that they'd look into this.

On the 29th January 2013, we raised the need for burning at Truganina.

What proceeded to occur was that we had a further 23 emails/phone calls/interactions with the people needed to undertake the burn. These interactions highlighted the need to (a) follow-up on requests, (b) find out the status of proposed actions and (c) nag when things weren't moving in a manner we thought satisfactory.

I want to stress that I'm not having a go at the wonderful individuals that have helped us along the way. Rather, it highlights that managing grasslands in an urban context is difficult! Government agencies, OH&S requirements, contractor availability, the weather and public liability all came into the equation at some stage.

On the 5th June 2013, Truganina was burnt. As the photos show, the fire was low intensity and patchy. Crucially, it occurred before re-sprouting and seedling emergence had occurred, and I'm hoping we will see a flush of growth, flowering and regeneration in the coming year. This is an excellent outcome for this tiny remnant and ensures that the values we cherish so much are likely to hold on for another decade or so.
Truganina grassland - burning for the first time in a decade or so.


Truganina grassland, a few days after burning in June 2013
(Photo: John Morgan)


This experience has taught me a lesson: the value of championing a site. If you have a local grassland that you want preserved and managed well, then agitate for it to happen. I'm pretty sure that with local inputs into local remnants, better outcomes will ultimately be achieved for the protection of those remnants. By championing small sites, we ensure that they don't fall through the management cracks.

Thursday 27 June 2013

Management burns and refuges for animals

Chris Helzer has an excellent Blog called The Prairie Ecologist. Check it out if you're interested in land management and nature conservation in grasslands. Chris has a fabulous writing style (and beautiful photos) and makes prairie conservation sound super-exciting.

A couple of weeks ago, something he wrote really caught my attention:

In the aftermath of any prescribed fire, there are winners and losers.  Fire rapidly and dramatically alters habitat and growing conditions in ways that favor some plant and animal species and put others at a disadvantage.  Fires also kill some insects and other animals outright.  For example, dormant season (late fall through early spring) fires burn up a lot of invertebrates that overwinter in prairie thatch.  Growing season fires, of course, can kill numerous small animals – especially slow-moving non-flying ones.  We usually don’t see the evidence of those impacts, but when we do, it’s no fun.  Over the years, I’ve seen way too many fried snakes and scorched nests, in addition to animals who suffered injuries from our fires.  It can be tough to deal with the knowledge that I made the decision to light the fires that killed or maimed those animals.

 
I was interested in this insight because I'm sure it's also very relevant to the fires we light for management purposes, particularly in native grasslands and grassy woodlands in southern Australia. Some of you may grapple with exactly the same issues.
 
Burnt grassland near Horsham
May 2013
Fires in temperate, productive grasslands are necessary to allow native plant species to coexist at high density, and have a role in maintaining animal habitat via manipulation of sward structure. This is pretty well-known and has been the basis for developing management burn plans in grasslands for many years now.
 
I've always accepted that some animals will die in fires, unpalatable as this may be, and that for the long-term function of the system, such losses are both inevitable and acceptable. After-all, we know that fires kill plants and their propagules, but this event also creates the necessary conditions for seedling regeneration and species turnover. Indeed, I know this better than most. My PhD was looking at exactly the issue of recruitment by native forbs in grasslands under different fire regimes.
 
If timed correctly, fire need not cause excessive animal mortality, knowing full well that no mortality is highly unlikely. There is very little data, however, that I know of that quantifies when the 'best' time to burn is to reduce animal deaths.
 
Intuitively, it is likely that summer burns will have the least effect on animals because they occur when there are cracks in the soil where reptiles, frogs and ground dwelling invertebrates can escape, and bird and invertebrate breeding is largely over. Summer burns, however, are very difficult (if not impossible) to implement so an alternative time to burn needs to be found.
 
Spring burning, I suspect, likely impacts on breeding in many species as it coincides with the most productive phase of temperate grasslands. Very late autumn burning (even stretching into winter) often occur after cracks have disappeared as soils re-wet with the autumn rains; it's also a time of emergence of many invertebrates after the summer drought and hence, likely to be sub-optimal if the aim was to reduce animal mortality.
 
Early dry season burning in Darwin. Note low flame height.
There is one place I had never though of as a refuge from fire that I recently observed while burning savannah in the Top End. Last week, as part of the CSIRO Burning for Biodiversity project that I help out on (with Dick Williams and friends), we observed something very curious. Something I'd never considered before, but that might be very relevant to fires in grassy woodlands in southern Australia.
 
After fire ignition, but well before the fire front approached, frogs, geckoes, lizards and invertebrates started moving up tree stems into the canopy. I presume that many of these were in the grassy sward initially. Jumping up the trunk must be hard work for frogs, in particular, (and dangerous, because it probably exposes them to predators), but in early season savannah fires, this is probably an excellent refuge. Flame heights are rarely more than 2-3 m at this time of year (and tree canopies are 8-12 m high, well away from the flames). Residence time of the fire at any point is mostly only 30-90 seconds as the fire passes, and smoke clears quickly once the fire front has moved on. Hence, moving up to escape fire seems to me a very logical thing to do for an animal to survive the fire event. As a refuge from fire, it shouldn't be under-estimated given the probability of canopy fire is exceedingly low.
 
Early season savanna fire in Darwin.
Flames rarely reach the lower tree canopy.
I, nor my invertebrate ecologist friend Michael Nash who observed this phenomenon with me, have little idea what the cues are for this behaviour. Apparently there is some research that says frogs respond to the sound of fire (and they make their way into the ground). I'd also think that smoke (or some chemical cue in smoke) likely triggers this response. It's like a siren has gone off, and the critters are well-drilled to respond. One thing I think we could rule out is that these critters were responding to heat generated by the fire itself. They began moving well before any fire was near, and besides, waiting for it to get hot before responding is probably a strategy fraught with too much danger to be successful in the long-term.
 
So, if you manage a system with trees and grasses in it, think about the role that individual trees might play on creating refuges for animals from the fire event itself. And document this if it does occur. There is so much still to be learnt about fire response by animals yet simple observations, like the one I have described above, could be crucial for understanding how plants and animals coexist with fire.