Winds of Change: The impacts of climate change on Tassie's beloved Kunanyi.

Can we already see the impacts of climate change on the slopes of Kunanyi?
KTW's Danny Carney caught up with Wellington Park Management Trust's Ellen-Rose Sorensen to find out!

With the weight of the climate crisis hanging over your head, you decided ditch your theatre and creative writing studies in Queensland to dive headfirst into a Tassie science degree. Can you tell us about how you came to be studying change on Kunanyi/Mt Wellington?
When I moved to Tassie, I moved into a little house in South Hobart with most amazing view of the mountain. I think all Hobartians can relate to that feeling of connection and security that you feel gazing out your window over the mountain. I just loved it. I spent so much time up there exploring the tracks and learning about the flora of Tassie, which is so different to what I had grown up with in Queensland.

View of Kunanyi from South Hobart

Throughout the course of my undergraduate degree, I really took any opportunity I could to steer my studies towards the mountain. I developed a fascination with understanding how environments change over time - how human processes can influence and modify natural ones, and what type of landscapes result from those modifications. I was lucky enough to perfectly meld my interest in mountain flora with my interest in environmental change for my Honours research.

My project looked at the long-term impacts of fire in alpine heath on the summit of Kunanyi. Using data collected over fifty years I analysed how these ecosystems recover from fire, and whether or not that recovery had been impacted by climate change.

On the summit of Kunanyi/Mt Wellingon

What did you learn over the course of your research?
We learned that fire recovery was definitely being impacted by climate change, although not in the ways we perhaps expected. There’s some evidence to suggest that warmer temperatures are actually better for the growth of alpine shrubs, however, we found that shrub cover was much lower than we expected.

We were comparing the vegetation cover and composition between two different sites, one that was last burnt in 1947, and one that last burnt in 1962. Our historic data showed that fifty years after fire in the 1947-burn area, shrub cover was at 98%. However, fifty years after fire in the 1962-burn area shrub cover was only at 70% - so definitely not the temperature-induced increase in shrub cover that we predicted. We theorised that the slow recovery of shrubs was also a result of climate change.

As a result of changes to global climate patterns, wind speeds on the mountain have increased by just over 7 km/h since the 60s, which is pretty drastic for an already very windy area. The winds on Kunanyi are known as ’foehn’ winds, which is a phenomenon that occurs when cool, moist wind travelling from one side of a mountain hits the land surface and are transformed into hot, dry winds by the warmer conditions on the mountain’s other side.

Over the past fifty years these increasingly strong, increasingly warm winds are coming in from the west and slamming into the vegetation on the summit of Kunanyi. This can cause abrasion damage to plants from small particles that are picked up by the wind, which particularly impacts smaller shrubs and seedlings. This could explain why cover was much lower in the 1962-burn area – the increases in wind speed correspond with the crucial decades after fire when these slow-growing species were just beginning to establish. Warm winds have a number of other impacts too – they change evaporation and transpiration rates which can essentially dry plants out, and it also dries out the soil which can make it harder for seedlings to establish.

Of course, warmer temperatures and stronger, warmer winds also means greater potential for fire. We therefore end up in this situation where climate change is causing these impacts that prevent recovery from fire, while also creating conditions where fire becomes more likely. It’s a pretty bleak finding, but it also can hopefully be useful. Kunanyi is warmer, drier, and more fire-prone than other alpine areas on the mainland and elsewhere in Tassie, so it’s actually a very effective model for understanding how these other environments might be impacted by warmer temperatures and increases in fire frequency caused by climate change.

That’s so fascinating! I’ve never thought about the specific qualities of the winds on Kunanyi and what it means for the ecosystems there. It’s like a whole new aspect that I hadn’t noticed. Have your findings changed the way you relate to the mountain?
I think it has actually made me realise how little I truly understand about the mountain! I got to hold a microscope up to this one ecosystem and found all these extremely complex processes and dynamics that are constantly shifting and changing and influencing each other all the time – and being influenced by external processes too. The mountain is an incredible mosaic of hundreds of different ecosystems that are all full of these complexities, and it would take a lifetime to understand them all. I think that’s why the mountain is such a compelling place for so many people – you can visit every day and never see the same thing twice.

Field site on Kunanyi

Are there questions you would have liked to answer that didn't get a chance to? 
Absolutely! I think that any time you try to answer a question, about a thousand more questions fall out. A big chunk of my thesis was analysing floristic diversity across time and between fire ages. We expected the vegetation composition to be basically the same between both sites, but there was actually a lot more variation than we thought. This opened up  so many questions – why were some species totally absent from one fire age but flourishing in another? Why were some species dominant in the 1970s but completely absent in 2022? Some of that is explained by succession, that in the stages of recovery from a disturbance certain species are outcompeted by others and vanish from the species mix. But there were some presences and absences that couldn’t be explained by succession alone.

I got really fascinated with seed dispersal mechanisms and how all these different anthropogenic factors could be influencing floristic diversity. For example, Richea scoparia was a lot more abundant in 2022 than it was in previous survey years. There’s research to indicate that Richea scoparia flowers are aided in pollination by snow skinks (Carinascincus microlepidotus) – so could the increase in Richea scoparia be related to warmer temperatures that benefit snow skinks? On the other hand, Trochocarpa thymifolia has declined massively on the mountain since the ‘70s, which could possibly be due to a corresponding decline in the population of currawongs, which spread Trochocarpa seeds by eating their fruit. There were so many of these interactions that I just didn’t have the time or the word count to cover in my thesis, but regardless I think that it demonstrates that ecological questions always have more than one answer!

It's so incredible thinking of all those connections and all the exciting paths you can go down for future thinking and research. Did learning all this teach you lessons beyond the mountain too?
I think it taught me a lot about time, and how some environments are operating at time scales kind of beyond human comprehension. It’s crazy to look at a landscape and be able to read the impacts of a fire that happened almost eighty years ago written across the vegetation.

That also does highlight that the damage humans are doing is happening way faster than the environment can cope with, but in a weird way it also makes me feel hopeful – we might be able to see the scars on the environment for a long time, but eventually they will recover after we’re gone.

Richea scoparia

What are you up to now?
I just started working at the Wellington Park Management Trust as the Natural and Heritage Values Coordinator, living the absolute dream and getting paid to poke around at the flora of Kunanyi! When I’m not on the mountain I’m usually out and about with the UTAS Landcare Society working on ecological restoration projects across Tasmania – come along!

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