WWP: Gum trees, Hollows & Bushfires
So, I just thought I would make another little video here guys, another Walking With Pete episode where I want to show you these huge gum trees in the middle of Melbourne, so in the middle of the city effectively. (They’re) right across the road but these gum trees have been here for so long in Royal Park, in the park that I’m walking in, that fortunately they haven’t been chopped down. So, the land hasn’t been, well, it’s been cleared a little bit, but it hasn’t been completely cleared of trees. So, to be completely cleared would mean that all the trees have been felled, they’ve been chopped down, and when a tree is chopped down you say the word, the verb, “to fell”, like “fall”, but it’s the past tense of “fall”, it sounds the same as the past tense, “fell”. “To fell”. So, the present tense (infinitive*) of the verb is “to fell” a tree.
Anyway, these trees are huge, and it’s crazy to be walking around in sort of open woodland, I guess. You’ll see them behind me here, open woodland in Melbourne, right near the CBD. I can literally see some of the buildings right across here behind me. And to have these huge huge trees just sitting around.
And, I guess, one thing I wanted to chat to you guys about that I hadn’t got around to it until now, and I just realised it because I think one of these trees had a really big hollow in the tree. Let’s see if I can see it. So, eh kind of. This one up here, let’s see if I can get in the shot as well just to be a bit vain, up here is a hollow. A hollow is where you get a hole in the tree and an animal can crawl in, lay eggs if it’s a bird, if it’s a possum or some kind of other animal like a lizard, well I guess a lizard lays eggs as well, but if it’s a possum it’s going to make a nest in there and it could live in there and have young in there. Hollows are incredibly incredibly important in the Australian ecosystem, and part of the biggest threat, or some of the biggest issues for native Australian animals is that they require these hollows to reproduce, to live, especially things like parrots. All these lorikeets that I’m always talking about around this area actually nest in hollows like that, and you have possums. The possums you will have seen in these videos like the brush-tailed possum, the ring-tailed possum. They all live in these hollows and they rely on them to reproduce and just to shelter, to hide from predators or just humans in general.
And so, the biggest problem is that humans destroy these trees, obviously, especially what we call old-growth trees. So, these hollows in these trees, like this tree behind me, this hollow up here has probably taken decades and decades to form. So, what you’ll have first, you’ll have a tree like this behind me with a branch like this one here where say a thunder storm, some kind of storm has happened, or wind, I’ll see if I can get that in the background, has come through during, you know, a gusty weather event and it’s knocked a branch down. So, this branch up here, which looks like it’s actually been sawn off, but say normally under natural circumstances the wind would come through and push the branch off the tree or break it off, the branch will fall on the ground like you see around me, these small little branches.
There’s a tram going by by the way. You see in the background.
And, it takes a long long long long time for branches like this in the tree to rot, to decompose, to break down, but eventually they break down and they fall out. So, all this you can see is actually quite old. It’s probably tens of years old, and it’s falling out of the tree. Eventually this will break down, disappear, fall out of the tree and what will be least is the base of what was once that branch. And, that base that sort of goes into the tree is what becomes a hollow, and this is what these guys, like these little birds, these little mammals, even goannas, other kinds of lizards use these hollows in order to survive, in order to have shelter, in order to breed. And so, they’re incredibly incredibly important, but a lot of these trees get destroyed and I think that is one of those huge threats for these animals, is that they have no where to nest, no where to get shelter because there are just no old-growth trees left. Even though you see in the background, here, you know, there is the odd big tree like this, all these other trees that you’ll see around them are incredibly small, and a gum tree like these ones behind me here, let’s see if I can work out my orientation, like this one here couldn’t house anything. It’s got no hollow, it’s got no where for any of these animals to hide, they need these massive massive gum trees that are, you know, over a metre and a have thick, and probably, you know, 30-40m tall, and this thing is probably over 100 years old, and they need them to have these kinds of, you know, branches that have been ripped out and the hole that goes down into the tree to become a hollow.
So, anyway, that’s a bit of a long-winded explanation, meaning that I’m talking a lot and taking a long time to explain the importance of hollows to native Australian animals, but yeah. It’s one of those things that you should definitely think about and appreciate when you see these huge trees when and if you come to Australia. So, you see these massive gum trees behind me. Realise that these gum trees could potentially be 100s of years old. Especially if they’ve got a trunk that’s, you know, over 1m thick.
So, just something to think about guys. Hope you enjoyed this Walking With Pete episode. Get some nature in you, get your biology lesson and I’ll chat to you soon. See you later.
Alright, so, I’m back again, I’m back again. I thought I would do another episode of Walking With Pete, and a bit more nature about these trees, these beautiful Eucalypt trees, because there’s a really good example down here a few hundred metres away of… I guess it gets me talking about bushfires, and bushfires are a big issue in Australia, but they’re kind of also required. Especially for a lot of plants, for example, banksias. Banksias are a plant and hopefully I… Peter who’s editing this video, put a photo in of a banksia tree and the seeds. Hopefully I can show you what they look like. And they actually require fire. They require bushfires to come through, to burn the land, to burn the trees, and that is what opens up the seedpods and allows the seeds to come out. And I think part of the reason that this has evolved, without looking it up, doing it off the top of my head and trying to remember from Biology 101 at uni, is that obviously when you’re down low, when all this stuff is here on the ground, you know, grass, small plants, all kinds of other shoots. This is probably not the best example, but whenever you’ve got these other kinds of grasses, plants on the ground, when a bushfire comes through, particularly a powerful bushfire that burns very hot and quickly it destroys all of those plants. And so, not only does it remove all of the competition, so all those plants disappear, they get burnt obviously, but everything that’s burnt turns into nutrients that goes into the soil. So, it’s the perfect time for banksias to open up their seedpods and let their seeds down into the really rich soil that’s now covered in ash and dead animals, dead plants, whatever it is, all this nutrient rich stuff for them to grow (in*). So, it’s a really cool evolutionary adaptation that native Australian plants have and allows them to thrive really really well with bushfires. And, in fact, they require the bushfires. There’s quite a bit of an argument and an issue happening in Australia with regards to the fact that we’ve cleared so much land and the fact that we want to prevent bushfires, because a lot of people have houses in areas where it’s forested. Where it’s dangerous we want to prevent them because we don’t want infrastructure, houses destroyed, and more importantly we don’t want lives lost, we don’t want people to die during bushfires. But, as a result, it makes it harder for nature because there are fewer bushfires in certain areas where the native animals and the native plants might actually require these bushfires to allow them to live. They’re adapted to them, they’re used to having these bushfires every year, every two years, every five years, every ten years. They’re an incredibly important part of these animals’ or plants’ life-cycles. But also, a big problem…
I just noticed that I’ve got seeds poking into my pants from walking through the grass.
Another big problem is the fact that when we put fires out and prevent them from burning… I’m trying to look for a good example… a lot of stuff, a lot of trees, a lot of sticks, a lot bark, a lot of grass, builds up on the ground, and it actually leads to the potential of there being an even worse bushfire in the future. And so, people are coming around now and they’re starting to realise the importance of bushfires and having potentially more frequent bushfires that are less intense. So, having them more often but as a result having less intense bushfires than trying to prevent all bushfires all the time, and allowing all the stuff to build up on the ground, and then potentially have that one in fifty year, one in a hundred year awful awful bushfire.
So, anyway, Eucalypts are incredibly well adapted to bushfires, and a cool thing that they can do, they have what’s called eucalyptus oil in their leaves. And again I’m just doing this off the top of my head. I don’t know the specifics, but eucalyptus oil, not only is it antiseptic, so you can actually buy it and use it to clean wounds, and eucalyptus leaves where the oil is found are the leaves that the koala eats. So, you’ll see them in the trees and they actually… it’s toxic. I think it’s actually a poison. So, these guys are adapted to eating poisonous leaves.
I’m just trying to get close to show you guys some of these lorikeets. Let’s see if I can get one eating in the background. Hopefully, I got a good shot of that.
So, koalas eat these leaves. These leaves are also incredibly flammable, this is what I was going to get to, because of the oil in the leaves. And you might be thinking, “how is this a good thing if you live in a country that has bushfires all the time? Why on earth would you effectively be wanting to produce leaves that are just going to allow you to go up in flames, literally, to go up in flames so easily?”. And the reason is, because these leaves are flammable they burn fast. They burn hot, they burn fast, and the fire’s gone through. So, by the time the fire’s gone through the tree truck or the base of the tree is not actually that damaged. It might be a little black on the outside, but because the fire went through all the fuel and burnt hard and fast it’s over, it’s gone, but the tree survived, the tree actually survived. Whereas, if it was a less intense slow burn the tree risks dying. And so, that’s why they actually have flammable leaves.
And so, another cool thing that I want to show you guys is the fact that when a bushfire goes through, and I’ll walk forward so that you can see this tree as I get… as I walk forward, the leaves can get burnt off, the branches can get burnt off, but they’ve got an adaptation called epicormic shoots that shoot out of all parts of the tree. So, the trunk, the branches, and even obviously down near the base of the tree, and you’ll see next to me as well… oh the sun. Bugger! You’ll see next to me there’s three trees here that look like bushes. They’re huge huge trees but they looks like bushes, because they… the people came through and obviously decided for one reason or another, the people from the city here, to chop off all the excess branches, and you’ll see that they’ve almost gone fluffy that’s how much all of these branches have just pumped out what are called epicormic shoots, these tiny tiny tiny little shoots full of leaves, they’ve all come out. So, this one right next to me, you’ll see, is just a thick thick thick bush. Look at it. See, and you can see it all coming out of the branch here. All of these shoots are coming out of the branch. And so, even though all of the entirety of this trunk, when the top of the tree was chopped off by the city council here, had no leaves, as a result, it effectively thought it had gone through a bushfire. “No leaves? Oh crap! What do we do? We push out all of the epicormic shoots and produce a crap-ton, a heap, a shit-load of leaves. And so, that’s why these trees behind me are just absolutely covered in these leaves.
And another thing that I wanted to show you was that when the eucalypt is young, or when the shoots are young, the leaves look like this, they’re incredibly thick, and they’re really really round, but then as the tree either gets older, or as the shoots get older, they start to take on this more stereotypical shape more like an arrowhead. And they tend to always point to one side like this. So, you’ll see… this is pretty much how you know that it’s a eucalypt. It’s got leaves that are shaped like this. And they often curl to one side.
Anyway, the sun’s actually quite nice at the moment. It’s going down. I think I’m going to walk home thought. It’s time to get some food. I’m fricken starving, I’m starving. But yeah, anyway, I hope you guys enjoy these episodes. It just comes to my mind and I think this is another one of those cool things that I can explain to you guys and tell you a little bit about nature and Australia. And, you know, actually use the degrees that I got at university.
So, here’s another example, these shoots down low have got incredibly fat round leaves, whereas the leaves further up the tree right at the top are going to be shaped like this, much more sharp. And, I’ve got to give you a shot of this behind me. The sun’s setting and I’ll give you a good shot of the trees just to say bye. Enjoy guys! I bet you can hear those lorikeets as well. Those fricken lorikeets. (There’re) heaps of them, heaps of them! See you!