Ecological Rants

I just discovered Charley Krebs Blog page called "Ecological Rants". It's worth a look.

Krebs is an excellent ecologist who has written one of the best textbooks on ecology (Ecology: The Experimental Analysis of Distribution and Abundance) and, because of his age, has been around long-enough to have seen the field both stagnate, get bogged down and ultimately, make some massive gains about the understanding of the natural world. I've always thought his insights were interesting, even if I don't always agree with him.

There's excellent 'rants' about:
- answering unanswerable questions
- when academics should retire
- conservative politics and science
- biodiversity research
- science and money
- what bureaucrats need to do to let scientists get on with their job

I really like Charley's approach (elder statesman type of thing) and it's great to see (once again) how Blogs can get scientists to reach out to other scientists (and the public) beyond their academic publications.

Shrubs in woodlands - directional or cyclic?

One of the things that ecologists have noticed in (some) grassy woodlands in southern Australia over the last two decades is that woody cover has been on the rise. This can take the form of increases in shrubs (such as Leptospermum spp., Acacia spp.), or dense regeneration of trees.

My own work (and that of my students and other scientists) show this increase might be due to changes in management (such as the removal of stock grazing from long-grazed forests upon reservation for nature conservation), altered fire regimes (usually a decline or exclusion of fire), overgrazing by native and exotic herbivores (that reduce competition from the ground-layer vegetation, as well as encouraging unpalatable species at the expense of palatable ones), and potentially even changes in atmospheric CO2 levels that favour woody plants over grasses.

Increases in woody plants have been recorded at several locations in southern Australia. This increase has generally been thought to be a uni-directional change that requires management intervention to alter this trajectory. So, at Wilsons Promontory National Park for instance, dense thickets of native Tea Tree that have established in swale grasslands and woodlands over the last 40 years are now being actively managed by carefully timed fire to open up the closed shrublands to benefit biodiversity and amenity.

Parks Victoria staff undertaking a burn to manage Coast Tea Tree (Leptospermum laevigatum) at Wilson's Promontory NP
(Photo: Greg McCarthy)

Just the other day, however, I saw evidence that woody plant encroachment isn't always uni-directional.

Herb-rich woodlands at Langi Ghiran
in mid-winter, before flowering.

At Langi Ghiran, there are fabulous herb-rich woodlands. Spring is a sight to behold - indeed, some of the highest species richness levels in Australia have been recorded there. Shrubs appear to be localised and generally sparse.

Hedge Wattle (Acacia paradoxa), a shrub native to the system, began spreading about a decade ago at this site and forming thickets. I'm not sure why it did this - was it climatically stimulated, was there a change in grazing pressure form native herbivores, was this a response to rising CO2?

It established prolifically in the inter-tree gaps, which are common in this woodland (and support much of the plant diversity), and establishes in the absence of fire. It also seems pretty unpalatable to the resident kangaroos and wallabies. I began to think that the end game here would be dense stands of wattle, a decline in diversity, and a landscape transformed visually.

However, when I last visited, the scene had changed a little bit.

Hedge Wattle - the dead looking stuff in the centre of the image - at
Langi Ghiran, 22nd June 2014.

Across 10's of hectares, Hedge Wattle had died, or was senescing. I'm pretty sure this was not because of old age - most shrubs are (and this is just a guess) less than 15 yrs old. We know from work by my Honours student Julia Franco that Hedge Wattles can live for five decades.

Where plants were not quite dead, the phyllodes were brown and desiccated and clearly the individuals looked like they were on the way out.

I first noticed this browning off in summer after a hot and dry spell. Now, in mid-winter, there seems no signs of recovery. This hints (to me) that drought has probably played a key role in the population dynamics of Hedge Wattle at this site. It hints that the population might be cyclical - assuming that the rise and fall of Hedge Wattle has occurred before, but just gone un-noticed.

If this is the case, it suggests a few important lessons:
- long-term observations can help decipher directional versus cyclical patterns in nature.
- if drought is at play here, was this drought 'extreme' and hence, might we expect its frequency (and potential effects) to increase over time?
- drought plays a key role in the dynamics of many woody plant populations but its effects are sometimes under-appreciated.

What else might be going on?? It's probably important to survey Hedge Wattle at Langi Ghiran to see if mortality is linked to particular aspects, slopes or soil types. Perhaps it is exacerbated in close proximity to century old trees. Might smaller plants be more susceptible than older ones (because they have less extensive root systems)? What about density? Are dense populations more or less susceptible to desiccation as individuals compete strongly for water?

Whatever the cause, this site illustrates that woody plant encroachment doesn't always end in permanent site occupation. Trying to figure out where it does would improve our understanding of both the process, and the management response.

Building community-based monitoring

Latrobe students quantifying the effects of fire
in the Little Desert NP.
(Photo: John Morgan)

I teach undergrad Botany and Ecology at La Trobe University. My university has a really good reputation for training field-based biologists, and many of our graduates are now making great contributions to conservation through their work in ecological consultancies, local government, government research organisations, NGOs, environmental education and parks management. Many of the undergrads I teach, particularly the mature-aged students, have a real passion for the natural world and really know that they want to make a difference.

As part of my outreach activities, I also engage with local community groups - such as Friends Groups (like my local group called Holly Hill Revegetation Group), local plant groups (e.g. Australian Plant Society), Landcare Groups and naturalist societies. This is also really rewarding - here's a bunch of (mostly) amateur enthusiasts wanting to making their local environment better, and protect what little bits we have left by taking an active interest in their management. Unlike the university students I teach, many of these people don't know much about biology and ecological principles. I see my role here as one of educating to ensure better outcomes.

Engaging with the "community" is a crucial way to get them interested in natural systems and harness their desire to do positive things. We've done this well on many fronts. One thing that is really taking off amongst these community groups is the field of citizen science monitoring. Here, local people are keeping tabs of environmental change in their local area, often doing excellent work that universities and governments are unable to do. WaterWatch is a good example of a programme that relies on volunteers to assess water quality in local catchments.

This is a great way to engage with people. But is it useful as a scientific activity to improve management by changing land management practices, i.e. learning by doing and then adapting management? I don't want to get into semantics about the quality of data that is collected, or the motivations of people who collect data. I'm more interested in thinking about "what is useful monitoring" and how to we maximise the benefits we get from such monitoring.

I've been musing about this a little because I'm often asked to help design monitoring for community groups, knowing full well that such monitoring, to be useful, needs to be simple, long-term and consistent. Here's a couple of suggestions that might help us think about what useful monitoring might be.

1) Identify the 'problem' first! The best monitoring has a clear question(s) / objective in mind from the outset that really determines what the monitoring should be and how it should be undertaken. Importantly, the information gained from the monitoring should help establish better practices in the future rather than just documenting change.

Planting Buloke trees into ex-pasture
(Photo: John Morgan)

Here's a simple example. Your local Landcare Group is revegetating some upper slopes box ironbark woodlands and will plant tubestock to establish trees. Your main concern is the need for weed control in the initial establishment phase because you've observed that establishment success seems patchy in previous years. Hence, it would seem logical to (a) plant some trees into intact understorey and (b) plant some trees where you've sprayed the understorey out. You count the number of individuals in each area then return yearly to recount the trees to assess survival. A more nuanced monitoring would record tree height to see if plants are also growing faster where there are no competitors in the initial phases. This might seem an obvious "experiment" but it is worth monitoring because the outcomes would really help us better use our resources - should we spray weeds out  or if we don't need to spray, can we plant more trees. This monitoring might highlight where the real problem lies too. Trees might do really poorly in both areas because of herbivores, or low soil moisture per se, hence allowing us to design better plantings in future. While this monitoring may not be that "exciting" to do, it is very useful.

2) Keep it simple! When thinking about monitoring, the best information tends to be that which addresses Primary Questions. I tend to think of ecological questions as exiting in a hierarchy that span from Primary, Secondary and Tertiary level questions. Here's an example, about mistletoes.

Mistletoes are really important in woodland and forest ecosystems in Australia because they are food and habitat for a whole heap of birds and animals, and have important roles to play in nutrient turnover. Hence, if I was an restoration practitioner who had been planting trees in agricultural landscapes for connectivity, habitat enhancement, etc, I'd be keen to ask the following (hierarchical) questions:

Dropping Mistletoe
(Photo: http://davesgarden.com/guides/pf/showimage/189316/)

Primary: Are mistletoes naturally colonising revegetation plantings?
Secondary: Does distance to nearest patch of remnant vegetation affect whether mistletoes are colonising reveg plantings?
Tertiary: Are mistletoes more numerous on some reveg tree species than others?

Hopefully you can see here that the Primary Question, about whether mistletoes are colonising plantings, is probably the most important question to ask first. It is probably also a pretty simple question to answer with monitoring: go out to XX planting sites and search for mistletoe colonisation on trees. Record which plantings have them. The information derived from this exercise informs us about their capability to recolonise reveg plantings, and from this we can start to understand the Secondary and Tertiary Questions. However, there is no need to ask the latter questions if the answer to the Primary Question is "No". You can see from this example, the monitoring could be very simple - there is not need to complicate things initially. Resurveying plantings 3-5 yrs later would then tell us about whether the situation is stable or changing.

3) Archive data somewhere!  Citizen science is a great concept, but for it to be useful, the data that is collected needs to be stored somewhere that is accessible into the future. Importantly, the data needs to be used periodically to inform understanding and leverage decision making processes.  Most ecologists who study long-term dynamics do so knowing that dynamics will span decades. In Australia, there are ecological experiments that have now been going for many years (in some cases 50-100), but they are only valuable because the data is archived and can be accessed for future comparison. Indeed, the new Terrestrial Ecological Research Network (TERN), a federal government initiative, is almost entirely about databasing old and new data. This will be a great resource for scientists over the coming century if it can be maintained. A similar approach is needed for citizen science.

This might span a range of scales. If your local bush group is into collecting information about birds and plants, perhaps by annual surveys, then this data is most useful if archived in national databases where such records already occur. The Atlas of Living Australia (ALA) is a superb repository for such data - species location records are a powerful way of observing changes over time. Because these databases are free to access, they really are an excellent place to put your data (which you can then always access) and they allow others to profit from your hard work. Imagine 25 years of bird count data, collected from across Melbourne, being in the ALA and accessible for all. It would give a great overview of the status of native birds in a rapidly growing city. Indeed, such databases are already contributing to this understanding. WaterWatch is an excellent example of collecting data and archiving it as an online resource - it's worth checking out.

Of course, there are much smaller scale ways of archiving data. In local Friends Groups, perhaps the group nominates a 'data manager' and their role is to report annually on what data was entered into their local database. If this was minuted each year, it would be pretty easy to know what was being monitored and where that data resided. I often think it would be great if I could access dates of burning of native grasslands where local groups have now been monitoring them for years. Sadly, such data is not being kept.

This returns me to my original thoughts - be clear about what it is you are monitoring, and why? If it is just to engage with local communities, let's not call it monitoring. Let's call it scientific outreach where we teach people how to monitor. But if we are to monitor, let's do it well and have a clear reason for doing it. And let's use the information being collected to make better environmental decisions.

Fire in native grasslands: getting to grips with some key unknowns (part 2)

In Part 1, I introduced the notion that we don't have a good idea of historical (post-European settlement) fire regimes in native grasslands (let alone pre-European), but by using the Minutes of rural fire brigades, it is clear that some of the best examples of grasslands in western Victoria have been burnt near annually for 70 years. This won't apply everywhere, but it tells a story of fire in the landscape that has previously gone un-noticed in some ways.

In this Blog, I return to one of the big unknowns about fire in grasslands. Despite it's importance, there is almost no data on fire behaviour in temperate grasslands.

Fire behaviour describes the fire event: the fire intensity, the thoroughness, the extent, the duration of heating. While there has been much research examining the effects of historic fire regimes (1 versus 3 versus 5 year burning frequencies), managers have almost no information about how individual fires vary and what the implication of these differences in fire events might mean for mortality processes and rates of regrowth.



Fire behaviour in grasslands will be a function of fuel amount, fuel type, fuel moisture  and conditions on the day
of burning. How grasslands are burnt (i.e. lighting patterns)  also has a profound affect on fire behaviour. Here, in a grassland near Dunkeld, we can see a patchy fire. But why?
(photo: John Morgan) 

To address this information gap, my Honours student Karina Salmon and I have been quantifying Fire Intensity and Residence Time for a number of grassland fires this summer. These two measures tell us something about (a) amount of energy released by a fire (I = fuel load * rate of fire spread * constant) and (b) duration of heating (above 200 deg C). Clearly, Intensity will vary with fuel and fire weather conditions on the day; faster moving fires are generally more intense. Fast moving fires probably also have lower residence times at a point, although this is not well-established in the literature for mesic grasslands.

Below is a link to a video that shows how grassland managers burn grasslands (in this case, a local Council near Sunbury). I want you to observe a couple of things here: rate of spread and flame height. While watching this, observe the lighting patterns and weather conditions. This has a tremendous effect on the way the grassland burns.

A couple of questions to ask yourself: Is this an "intense" fire? What is the ecological impact of this fire?

Let's answer the first question. Is this an intense fire?

How long is a piece of string?? Fire intensity is a relative measure in many respects. Forest fires can exceed 100,000 kW/m in intensity and hence, no grassland fire will ever be this intense as the fuel loads do not accumulate to the same degree. Hence, it is better to ask: is this an intense fire relative to other fires you get in grassy ecosystems. Even then, that answer is not straightforward. In tropical savannah, fire intensities up to 18,000 kW/m have been recorded, but fuel loads can be enormous - annual grasses take advantage of the wet season and put on several metres of growth each year. So we need to narrow this question even further. Is this an intense fire in the native grasslands in southern Australia?

We characterised this fire at about 500 kW/m, which isn't very high.

This is a one of the 'middle of the road' fire intensities that have been recorded in native grasslands. But it clearly 'looks' like a decent burn that you may have initially thought was 'high intensity'. It goes to show that just observing fires isn't very informative. All fires are hot, to some extent, so value judgements like 'low' intensity, or 'cool' burn aren't very helpful.

Of great interest to me is another (almost completely ignored) aspect of fire behaviour: Residence Time.

This fire had a temperature above 200 deg C for an average of 29 seconds (at the point of recording by a Type-K thermocouple). This heating, from a relatively low intensity fire, is what plants and animals actually have to put up with. Burning for half a minute is the real challenge here when thinking about probability of survival. Interestingly, at very low Fire Intensity, we found that Residence Time can be quite long, more than a minute in some cases. When fires are slow moving (as low fire intensity fires usually are), heating above 200 deg C is prolonged - the flames are not moving away from a point quickly. Hence, an (unintended) outcome of 'low fire intensity fires', by slow back burning of the grassland is that they heat for longer durations than higher intensity fires, and they burn very thoroughly. Almost no fuel goes unburnt in some cases.

Hence, it is clear we still have much to learn about ignition patterns, fire intensity and residence time, and how these interact to affect plant and animal population dynamics. I'm keen to explore these ideas next summer, so if you're planning on burning a grassland, I'd be keen to set up some dataloggers and quantify what's actually going on.

Fire in native grasslands: getting to grips with some key unknowns (part 1)

We've now had 35+ years of grassland research in the temperate regions of south-east Australia. Native grasslands, in many respects, are now amongst the best studied systems in Australia.

I reckon four key insights have been revealed by this work, with each insight critically interacting with the others to inform our understanding of vegetation dynamics:
1) land use history affects vegetation composition and species diversity. Importantly, by quantifying vegetation structure and composition using land use comparisons (i.e. grazed grasslands versus burned but ungrazed grasslands), it is apparent that native species richness and functional trait diversity is highest when disturbed by fire rather than by other agents such as slashing or stock grazing, and that frequent fire maintains higher alpha diversity than infrequent fire.
2) when frequent burning of grasslands is relaxed, species can go locally extinct. This has been well documented in recent times by Nick Williams & others as socio-economic drivers of burning change.
3) many intertussock species are poor competitors for light and space (and these species can be predicted by their traits). Just as there is a war going on in woodlands between trees and grasses, the war extends to grasslands where grasses often outcompete forbs because they are taller, accumulate more biomass (and hence, sequester more of the light and nutrient resources) and they grow faster.
4) many grassland forbs have transient soil seed banks (i.e. seed does not accumulate in large numbers in the soil). This has important consequences for regeneration. Once grassland plants are lost from grasslands (because of grazing or lack of fire), they are unlikely to re-populate from dormant seed stored in the soil.

The core findings all lead back to the key role that fire plays in the dynamics of the system.

This has long been recognised. But curiously, despite the importance of fire in the function of grasslands, we still know relatively little about (a) fire history (particularly as it relates to the high quality grasslands that sustain much of the species diversity of this ecosystem), nor (b) how fire behaviour varies in grasslands.

Recent research is shedding new light on both these questions. In this Blog, I'll tackle the first question - if frequently burned temperate grasslands are the "gold standard" for grasslands, just when did this regime start?

Sarah Dickson-Hoyle (University of Melbourne) recently completed a Master of Forest Ecosystem Science thesis with the core question being: when did Country Fire Authority (CFA) burning by rural brigades in western Victoria start, and why? She focused her attention on the 3-chain wide roads around Dunkeld-Cavendish where there has been settlement since the mid-1800s. Until now, I'm not aware of when this burning started nor why it started in the first place.

Sarah interviewed current CFA brigade captains in the area about why they burn, how often they burn, and whether they knew about the grasslands and their ecological values. She also examined brigade Minutes to try and pinpoint when this burning began.

In this district, she found that burning for fire protection began in the period 1941 to 1947. This is before much of the land was re-settled by soldiers returning from the Second World War. Burning was implemented on 2- and 3-chain wide roadsides as frequently as possible to maintain low fuel levels.

Interestingly, according to the Minutes of CFAs, burning began largely because of the introduction of exotic pasture grasses such as Phalaris (as superphosphate use increased) and the perception that they created an elevated fire risk due to their high fuel loads and early curing. Burning of roadsides started because local communities wanted risk reduction strategies implemented. It was thought that 1-2 year intervals between fires would provide the greatest protection to the community, with little regard for the ecological effects of such regimes.

I think the dating of the start of frequent fires in these systems in the 1940s is at least 10-20 years earlier than most grassland botanists had estimated.


The original survey of the Karabeal Plains from 1865 showing 2 and 3 chain wide roadsides that later became
 strategic fire breaks and, fortuitously, some of the best temperate grassland remnants in Australia.

It is likely that burning of native grasslands by Europeans probably started in earnest at this time not just around Dunkeld, but across the plains in many areas, just as the landscape was transforming due to sowing of improved pastures. It's hard to know what was happening before then of course. Perhaps travelling stock periodically reduced biomass. It is clear that the subsequent 70 yrs of very frequent burning in this district  has given us species-rich native grasslands with minimal invasion by exotics. Such practices have also shaped our ecological thinking about vegetation dynamics in productive grasslands. Without such burning, I suspect our understanding of the potential role of fire on diversity, productivity, recruitment and species-interactions would be very different. Paradoxically, an ageing rural population and increasing paperwork mean that frequent burning by the CFA is now in decline in some districts, and being replaced by slashing or inaction.  This change in regime will undoubtedly shape the future native grasslands as much as any impact of climate change.

In Part 2 on fire, I'll return to the question: what do we know about fire behaviour in grasslands? We've been quantifying fire this summer, and getting some surprising results.

Dickson-Hoyle, S. (2013) Risk, remnants and roadsides: understanding fire and conservation management along a rural road, western Victoria. Master of Forest Ecosystem Science thesis, University of Melbourne.