habitat

The Joys of Watching Grass Grow

Not long ago, I wrote about how the structural complexity of tall mountain ash forests allows a diverse array of animals to co-occur at the same place. Grasslands, with the dominant plants rarely standing more than a metre tall, offer little in the way of opportunities for animal communities to assort themselves vertically. But just as they say you shouldn’t judge a book by its cover, so too should you never judge a landscape by its vegetation cover. I was recently able to fully appreciate this while doing fieldwork in the Western Grassland Reserves right on the fringe of Melbourne’s western suburbs.

Structural diversity also plays a role in shaping grassland biodiversity; the process occurs at a smaller scale, though. For instance, small depressions have higher water availability and rushes, such as gold rush (Juncus flavidus), grow best in these locations. Similarly, breaks in the grass cover that result in patches of bare ground are where the small rosette form of spur velleia (Velleia paradoxa) is most likely to be found. Just like giants of the forest that emerge above the canopy of a mountain ash forest, so too does artichoke thistle (Cynara cardunculus) tower above the surrounding grasses and herbs. In the same way that small differences in habitat influence the plants that occur at a site, animals respond to variation in vegetation structure. Nestled tightly amongst dense grass tussocks, millipedes can be found; this may be due to the microclimate created as the many tightly clustered grass stems trap a pocket of moist air. Sitting atop the taller artichoke thistles, Eurasian skylarks (Alauda arvensis) or Horsfield’s bush larks (Mirafra javanica) may often be sighted singing their rich and melodious songs. These species are also dependent on the dense cover provided by thick grass because it is amid these grasses that they most often situate their nests.

Normal 
 0 
 
 
 
 
 false 
 false 
 false 
 
 EN-GB 
 X-NONE 
 X-NONE 
 
  
  
  
  
  
  
  
  
  
 
 
  
  
  
  
  
  
  
  
  
  
  
  
    
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
  Introduced artichoke thistles tower above the surrounding grasses and herbs, but offer great perches for Eurasian skylarks and Horsfield’s bush larks to sing from.  Image: Rowan Mott

Introduced artichoke thistles tower above the surrounding grasses and herbs, but offer great perches for Eurasian skylarks and Horsfield’s bush larks to sing from. Image: Rowan Mott

As you can see from the species I’ve mentioned, there is more than just grass in a grassland. So why then, if many different plant species are able to grow in a grassland, do trees not occur there and turn the grassland into a woodland or forest? Grassland biomes predominantly occur where there is low to moderate rainfall; any less and the landscape becomes desert, any more and forests or woodlands predominate. Disturbance is also a key factor. Grassland plants are able to reach reproductive maturity rapidly after disturbances such as fire and grazing. Therefore, in environments that would otherwise be amenable to the growth of woody vegetation, repeated disturbances at frequent intervals favour the presence of grasslands.

Succession post-disturbance can be key to determining what grassland plants are present at a site. In the immediate aftermath of a grass fire, light is able to reach the ground layer. This prompts many sun-loving species to germinate and, for a short period of time, flourish. As time passes, other plants re-colonise the landscape and compete for light and nutrients. This process may see some species disappear from a landscape until the next fire passes through. Re-colonisation may rely on seed stored in the soil seedbank, or plants may have seeds with a high dispersal capacity and recolonise via seed arriving from other locations. Many grassland plant species have underground stems and structures that are protected from the passage of fire by the soil. These enable them to re-grow quickly in the post-fire landscape. The successional changes following fire also influence animal assemblages. Once plant species have recovered, ground-dwelling stubble quail (Coturnix pectoralis) may re-appear at a site. However, if the grass cover becomes too thick with the passing of time, they too may disappear in search of more favourable habitat elsewhere.

Normal 
 0 
 
 
 
 
 false 
 false 
 false 
 
 EN-GB 
 X-NONE 
 X-NONE 
 
  
  
  
  
  
  
  
  
  
 
 
  
  
  
  
  
  
  
  
  
  
  
  
    
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
   
 
 /* Style Definitions */
 table.MsoNormalTable
	{mso-style-name:"Table Normal";
	mso-tstyle-rowband-size:0;
	mso-tstyle-colband-size:0;
	mso-style-noshow:yes;
	mso-style-priority:99;
	mso-style-parent:"";
	mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
	mso-para-margin-top:0cm;
	mso-para-margin-right:0cm;
	mso-para-margin-bottom:8.0pt;
	mso-para-margin-left:0cm;
	line-height:107%;
	mso-pagination:widow-orphan;
	font-size:11.0pt;
	font-family:"Calibri",sans-serif;
	mso-ascii-font-family:Calibri;
	mso-ascii-theme-font:minor-latin;
	mso-hansi-font-family:Calibri;
	mso-hansi-theme-font:minor-latin;
	mso-ansi-language:EN-GB;
	mso-fareast-language:EN-US;}
 
 Invertebrate herbivores, such as this anthelid caterpillar, are likely to be major consumers of plant biomass in Victoria’s grasslands.  Image: Rowan Mott

Invertebrate herbivores, such as this anthelid caterpillar, are likely to be major consumers of plant biomass in Victoria’s grasslands. Image: Rowan Mott

Normal 
 0 
 
 
 
 
 false 
 false 
 false 
 
 EN-GB 
 X-NONE 
 X-NONE 
 
  
  
  
  
  
  
  
  
  
 
 
  
  
  
  
  
  
  
  
  
  
  
  
  Victoria’s Volcanic Plains support important grassland habitats. Remnants of their volcanic past can also be seen in the geology if you can get out there.  Image: Rowan Mott

Victoria’s Volcanic Plains support important grassland habitats. Remnants of their volcanic past can also be seen in the geology if you can get out there. Image: Rowan Mott

Whilst fire is a major method by which biomass is removed from grasslands in our state, it is not the only process by which this occurs. Across the Indian Ocean in Africa, large herbivores such as zebras, wildebeest, and many species of antelope extensively graze the grasslands. In Australia, grassland herbivores are typically smaller. Of course there are eastern grey kangaroos and the introduced European rabbit, but the biomass of invertebrates is much greater than these groups. Across Australia’s Top End, the mounds of grass-eating termites interrupt the horizon; closer to Melbourne, orthopterans (grasshoppers, locusts, and crickets) as well as the larvae of many lepidopterans (butterflies and moths) are major consumers of above-ground plant material. The effects of invertebrate-grazing in Victoria’s grasslands remains little studied. However, although they are only small, individuals from these groups can occur in high abundance and the cumulative effect of their feeding is likely to exceed that of grazing vertebrates (except of course where native grasslands are subject to grazing by sheep and cattle!).

Normal 
 0 
 
 
 
 
 false 
 false 
 false 
 
 EN-GB 
 X-NONE 
 X-NONE 
 
  
  
  
  
  
  
  
  
  
 
 
  
  
  
  
  
  
  
  
  
  
  
  
    
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
   
 
 /* Style Definitions */
 table.MsoNormalTable
	{mso-style-name:"Table Normal";
	mso-tstyle-rowband-size:0;
	mso-tstyle-colband-size:0;
	mso-style-noshow:yes;
	mso-style-priority:99;
	mso-style-parent:"";
	mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
	mso-para-margin-top:0cm;
	mso-para-margin-right:0cm;
	mso-para-margin-bottom:8.0pt;
	mso-para-margin-left:0cm;
	line-height:107%;
	mso-pagination:widow-orphan;
	font-size:11.0pt;
	font-family:"Calibri",sans-serif;
	mso-ascii-font-family:Calibri;
	mso-ascii-theme-font:minor-latin;
	mso-hansi-font-family:Calibri;
	mso-hansi-theme-font:minor-latin;
	mso-ansi-language:EN-GB;
	mso-fareast-language:EN-US;}
 
 Stubble quail have Goldilocks habitat requirements: grass not too sparse, not too thick. They will leave a site if the habitat isn’t just right.  Image: Rowan Mott

Stubble quail have Goldilocks habitat requirements: grass not too sparse, not too thick. They will leave a site if the habitat isn’t just right. Image: Rowan Mott

We Melburnians are lucky. Our metropolitan area is fringed to the west by the Victorian Volcanic Plains. The importance of the grasslands that occur on these fertile plains cannot be understated. They are one of the most heavily impacted ecosystems in our state and suffer at the hands of urban expansion, weed invasion, loss of characteristic fire regimes, and past land use. Many of the best examples occur on roadside and railway reserves because these have escaped intensive agricultural use, and may have received regular burning. These grasslands support a wealth of biodiversity including the Critically Endangered golden sun moth (Synemon plana) and spiny rice-flower (Pimelea spinescens subsp. spinescens). At a cursory glance, the flat landscape and uniform grass cover may seem uninspiring. Yet, if you are intrepid enough to take a closer look, you will see that they are every bit as deserving of your attention as the tall mountain ash forests to our east that gain so many visitors.


Rowan Mott

Rowan is a PhD student studying seabird ecology. When he's not thinking about the ocean, he likes to think about woodland birds. 

You can find him on Twitter at @roamingmoth


Banner image courtesy of Rowan Mott.

Evolving in a Changing World

Climate change is causing temperatures to rise, but what does this actually mean for the various species and populations of the world? Organisms have always had to respond to naturally occurring climate change. However, anthropogenic greenhouse emissions are prompting changes in environmental factors - not just temperature, but also factors such as rainfall and ocean acidity  - at a rate and scale of change far above what would have occurred naturally. Consequently, there is a considerable amount of concern regarding whether natural populations can respond fast enough to ‘keep up’ with this increased rate of change.

Encouragingly, we’re seeing some species respond to climate change through migration. Natural populations, including species of insects, birds, mammals, plants, fish and marine invertebrates, have shifted their range poleward towards cooler areas of higher latitude.  

Australian species of sea urchins are among those shifting their distribution poleward in recent years. Photo: Peter Southwood (Wiki Commons)

Australian species of sea urchins are among those shifting their distribution poleward in recent years. Photo: Peter Southwood (Wiki Commons)

Unfortunately, migration is more challenging for some species than others. Many have poor dispersal abilities and others lack any suitable alternative habitat to disperse to. The latter is especially an issue for those that are specialised to small or sporadically distributed habitats, such as high altitude alpine areas. The ability of natural populations to migrate has also been severely hampered by habitat fragmentation and the construction of human-made structures, including cities and roads, which may act as barriers to migration. 

Natural populations in which migration is not a sufficient solution to adapting to the effects of climate change must either adapt or face extinction. While factors such as temperature are expected to shift beyond what many natural populations can currently tolerate, groups of animals may have the capacity to respond to these changes by undergoing adaptive evolution.

Evolution involves changes in a population’s genetic make-up from one generation to the next. In the case of adaptive evolution to climate change, these genetic changes over multiple generations may facilitate changes in traits, such as thermo-tolerance, that can allow populations to mitigate the effects of climate change. 

Although evolution is frequently perceived as a laboriously slow process, this is often not the case. Evolution can be rapid, especially for species with short lifetimes. For instance, an ecologically important species of phytoplankton was shown in an experimental study to significantly improve its performance under increased levels of ocean acidity in less than a year of adaptive evolution. We are also seeing evidence of populations being able to adaptively evolve to the effects of climate change through studies on natural populations. One example of this is the Canadian Red Squirrel, that has adapted to seasonal changes in food availability by giving birth to offspring earlier in Spring when more food is available.

Some species, such as the Canadian red squirrel, have shown an evolutionary response to the effects of climate change. Photo: Gilles Gonthier (Wiki Commons)

Some species, such as the Canadian red squirrel, have shown an evolutionary response to the effects of climate change. Photo: Gilles Gonthier (Wiki Commons)

However, it is far from all good news. Some populations have been found to possess worryingly limited potential to adapt to climate change. In tropical Queensland, populations of fruit flies have very little ability to improve their resistance to lower levels of environmental humidity, which are predicted to occur with future climate change. While I can certainly see how the possible extinction of a fly species might sound like fantastic news to some, such results in any natural population are troubling. Furthermore, even if a population has the capacity to adapt to current rates of climate change, this does not guarantee that they will be able to continue to evolve fast enough to keep up with changes in the future. 

Continued research is crucially important. Photo: Evatt Chirgwin

Continued research is crucially important. Photo: Evatt Chirgwin

Evolution is likely to have an enormous role in determining which species and populations can adapt to long-term climate change, and as such needs to be considered by natural resource managers. Through incorporating evolutionary processes into their management strategies to counter climate change, these managers can create more efficient methods of protecting biodiversity. For instance, identifying species of low evolutionary potential can assist them in identifying which species are of high vulnerability to extinction from climate change. 

Importantly, natural resource managers need to employ strategies to safeguard against loosing the existing evolutionary capacity held by natural populations. Though this is often easier said than done, the best way to protect a population’s ability to adapt is by maintaining a large population size. The larger a population, the more likely it is to to maintain high levels of genetic diversity, and the less likely it is to loose beneficial genes that could confer a greater ability for adaptation to climate change.

Additionally, management can protect the evolutionary capacity of species by sustaining connectivity between populations through habitat preservation or establishment of artificial wildlife corridors. Connectivity can allow genes that are beneficial for adaption to spread more easily through multiple populations. Alternately, if natural links are not possible, it may be appropriate in some circumstances for individuals to be artificially moved between populations of the same species to aid the spread of beneficial genetic information.

Increasing population connectivity can aid the movement of beneficial genes between populations. Photo: Krd (Wiki Commons)

Increasing population connectivity can aid the movement of beneficial genes between populations. Photo: Krd (Wiki Commons)

Despite the potential of these and several other possible strategies to reduce the effects of climate change on biodiversity, most simply treat the symptoms of the problem and not the problem itself. The most effective strategy in protecting biodiversity is to reduce anthropogenic greenhouse emissions as greatly and as quickly as possible, so that our planet’s range of amazingly diverse species have a better chance to survive.

Cover photo taken by Allison Chirgwin.