It's a pleasure to be here today and I'd like to thank the Royal Society of Victoria for inviting me to come and talk about what I think is an important issue around the role of climate change and how it might impact our native forests to state. Australia is a cultural landscape. There have been people here for tens of millennia and traditional owners of these lands and landscapes have shaped them. They are custodians in every sense of that word. They have worked and they have lived on these landscapes and have had impacts on them. The notion, however, that these areas are pristine, untouched by humans, that if we just leave them, they will return to some idyllic state. I think ignores the very rich tradition of the traditional owners here on this continent. And I think we've seen this all over the world. We've seen it in the Brazilian Amazon. We've seen it in Central and South America. We've seen it in parts of North America. There is a long history of human involvement in landscapes. I think we need to acknowledge it and I think there's a lot that we can learn from it. So the main message of my talk is that climate change is impacting our forests. That forest management can buffer these impacts, but not forest management as we know it. This is annual main temperature anomalies in South-East Australia. And as you can see over the course of the past century, temperatures have been increasing over time. A more concerning image is this one. This is the global ocean heat content in the top two kilometers of the oceans of the world. And what you can see here is that since the early 1980s, the amount of heat in the ocean has been increasing steadily. And that heat is effectively the future warming in the world. That over time, even if we were to stop emissions today, that there is an enormous amount of heat that is banked up in the ocean. And as a consequence, warming of the earth is effectively baked in for decades to come if not longer. I think it's really important to recognize that Australia, South-East Australian particular, is probably at the forefront of the world in bearing the brunt of climate change in the native forest estate. And we're probably at the back of the pack in the world in terms of doing the research for how we should manage our forests. And so I think really thinking about how we invest in research that focuses on adapting our management to climate change is long overdue and is fundamentally important if we want to move forward in a constructive way. How are forests impacted by climate change? There's a couple of different ways that this happens. The first one is climate as a disturbance itself. The most obvious version of this is drought. The second way we think about climate and how it will impact forests is as a driver of disturbance. The obvious place that we see this is in fires. Now one of the things that we have found is that the fire regimes themselves are changing. So this is some work that my colleague, Scott Mooney, from UNSW and I have done in Cosiasco National Park. And we looked at sediment cores from bogs and the presence of macro charcoal in them. And the key takeaway from this work is that while there has been fire in the past, we don't see that across the whole landscape. What we see that really stands out in these sediment cores is that this big spike of charcoal right at the very top of the sediment cores shows that basically since the latter part of the 20th century there have been lots of big fires. And that those are fires that have occurred across the entire landscape. So we're really changing the fire regimes comprehensively. So the third part of my talk and what I'll spend most of the time on is how can force management help? There are three things that are obvious for us to do. We can reduce the density of overcrowded stands. We can grow trees bigger, faster, and we can shift to more fire resistant species. So I want to start with reducing stand density. We did some early work in the 2000s looking at the impacts of stand density on the response to the millennium drought. And what you see on the left in the high density stand is lots of dead trees on the ground. Most of the trees are pretty small and the crowns aren't terribly vigorous. On the right hand side, the low density stand with 600 trees per hectare, the trees are much larger, there's very few dead trees on the ground, and the crowns are quite vigorous. The next thing I'd like to talk about is growing big trees faster. So I'm going to start with this figure. And what they showed in this study was that the period of high risk for these forests is between roughly seven years after disturbance to about 36 years. And that older forests are much less at risk of loss of canopy. So what we need to be thinking about is how do we move trees out of this period of high risk more quickly? Fire mortality or the probability of mortality is related to tree size. The third point that I'll make with regards to stand level management is that we can shift to more fire resistant species, thinking carefully about which species and what sizes we have of those trees in the forest and across the landscape is important for trying to buffer some of the impacts of fires in these types of stands. The last thing I'm going to talk about is managing the forest. So this is the broader scale perspective. So one of the things particularly in South East Australia we should be thinking about is shifting towards uneven aged forests. One I think really need example is this pilot project from a site near a bucken. And so this is a site prior to the harvest. And this is a site immediately after the harvest two months later. And what you'll notice of course is that a lot of trees are still here. This is the forest three years after the harvest. And the thing that really jumps out at me here is this area here where you can see how vigorous those crowns are. And then the last picture here is after a fire in 2017 that burnt through this site. Now this fire was beginning to peter out as it reached this site. But what you'll notice is it had very little effect on the forest per se. This is likely because amongst other things breaking up the forest by taking out groups of trees throughout the management unit breaks up the continuity of the fuels, the canopy fuels in this site. So the last thing I'll talk about for the stand level management is emulating natural disturbances at the landscape scale. So this is the central highlands. We use clearfelling the clearfell burn and sew system historically because it emulates the conditions after a catastrophic bushfire which we take as the natural disturbance in these types of forests. The question though is is that really what catastrophic bushfires look like? And so as PhD student of mine Katie Hammond is doing some really neat work using some of the remarkable remote sensing data sets that are becoming available to us. To look at what happened after the 2009 bushfire. And so on the left hand side you see a 2 kilometer by 2 kilometer tile with 20 by 20 every 20 by 20 meter pixel that has mountain ash forest in it within the 2009 fire footprint. What she then did was to take the data from this of canopy cover after the 2009 bushfires and ask the question what would be the silvicultural analog to what we see happening from the fire. And so she grouped the 20 by 20 meter pixels into one hectare pixels. And the image on the right, the obvious thing you'll notice here is that clearfelling in yellow is not the majority. So this raises some important questions about how we think about the application of different silvicultural systems across a landscape. So this is a picture from the silvicultural systems trial from Tandell Brenn that Katie Hammond, my PhD student, is also working on. And there are a suite of different treatments. They include clearfells, they include small gaps, various flavors of retention of the overstory. We can then begin to ask the question which of these different silvicultural systems best aligns with different parts of the landscape. And how should we think about balancing those things across a landscape. Climate, as I've said, is going to shape these forests. And that climate change is baked into the system and it's going to continue for decades if not a century or more. And we need to think about that very, very carefully. One way that we can address this threat is to reduce the density of overcrowded forestry. We also need to be thinking about natural disturbances as analogues. We've talked about this for decades, but I don't think we've had the data or the wherewithal to really understand very carefully what a natural disturbance looks like in particular in terms of the heterogeneity of natural disturbances on the landscapes. If we can spread the variability in stand composition and structure, we will be spreading the risk of these long-term impacts from climate across the broader landscape. Forest management has a role and I think it has an important role in the native forest state in the context of climate change. But, and I respect that there are many views about forest management and that is based on 50 or more years of certain types of forest management. I think we really need to have a nuanced debate about what is the role of forest management and what pieces of our forest management toolkit we can use to positive effect in these forests. Because I think doing nothing in the face of rapid climate change is going to lead to many, many more problems.