Obvious effects of drought in Australian alpine vegetation

When thinking about climate change impacts in alpine ecosystems, rising temperatures are thought to be one of the most important threats to their long-term persistence, particularly in places like Australia where there is very little elevation above treeline. It is generally accepted, and has even been demonstrated, that alpine species will need to migrate upslope to persist with climate warming. This hints that temperature is the most important determinant of alpine species distribution.

The Australian Alps - vulnerable to climate change because there is very
little capacity for upslope migration

But climate change is also likely to affect the frequency, intensity and amount of rainfall that occurs. And in Australian mountains that experience summer drought, the impacts of increasing drought severity and frequency are likely to also be very important to the persistence of alpine plants.

To illustrate this, I have shot a 11 min video about the drought impacts I observed recently in some Australian mountains. Interestingly, Mt Feathertop (which I point out in the video) was burning in a bushfire only 10 days after I shot this footage, hinting that drought also interacts strongly with fire in Australian mountains.


You can find my video on You Tube at
http://www.youtube.com/watch?v=ryn987ICBHs&feature=youtu.be

I focus on why I think drought is important in the Australian alps:

• because our mountains are covered in soil, vegetation grows across the entire mountain and therefore, is subject to water stress on shallow soils when there are dry spells
• how aspect affects moisture stress (remember, in the southern hemisphere, northerly aspects are the hot, dry slopes)
• show examples of some species showing signs of drought stress (note the effects on the dominant grass Poa hothamensis)
• think about the traits that may pre-dispose species to drought stress, and;
• conclude with the assertion that drought likely will be an important determinant of vegetation distribution in the coming century in mountains. This will likely be exaccerbated by rising temperatures.

Hope you enjoy my foray into 'film' making.
JOHN

Further reading on drought impacts in Australian alpine vegetation:

• Griffin & Hoffmann (2012) Mortality of Australian alpine grasses (Poa spp.) after drought: species differences and ecological paterns. Journal of Plant Ecology 5: 121-133.   
• Morgan (2004) Drought-related dieback in four subalpine shrub species, Bogong High Plains, Victoria. Cunninghamia 8: 326-330.