Wood fire — they have plenty of them in Yellowstone National Park
It has been a couple of months since I added something to this blog. There are a few draft posts which I didn’t publish so far. Well, here is one of them!
When I hear about wood fire, my first thought is always that they are a useless waste of energy. The energy stored in the wood is released without making any use of the heat. The only good thing is that wood fires burn only regenerative fuel, but that doesn’t change their uselessness. Until the 1970s, the National Park Service (NPS) had a similar opinion. They didn’t care about the energy, instead they simply didn’t want those fires to destroy their National Park. But when they studied those wood fires in detail, they discovered really interesting processes. Nowadays wood fires are only fought if buildings or men are in danger. So what made the NPS change its mind?
Let’s have a look at two different families of trees that grow in the Yellowstone National Park: the “spruce and fir” and the “lodgepole pine“. At a first glance they might look similar, but there is a qualitative difference. The spruce-fir-trees give much more shadow than the lodgepole pines. The result is that only the (adapted) seeds of the spruce and fir can survive in a spruce-fir forest. With this knowledge you would probably assume that eventually the whole national park would be full of spruce and fir, since its spreading seems to be a one-way road.
However, there are wind damages, diseases and naturally caused wood fires that burn down the Yellowstone forests. This is where the lodgepole pines can play their joker card. They use two kinds of cones for reproduction: The first type grows, falls off the tree after some time and opens normally. The other type of cones is more interesting: it is “serotinous”. It doesn’t open itself at all. In fact, it doesn’t even fall off the trees on its own. However, if there is a fire, then its sealing melts and the seeds are spread. The advantage is obvious: the lodgepole pine seeds are at the right place at the right time. Right when the old trees burn down and no longer shade the ground, they can start their living!
Although the lodgepole pine seems to be only a transient tree which would under ideal circumstances loose again the spruce-and-fir, it’s reproduction mechanism makes it the most common tree in the Yellowstone National Park.
However, besides the fire and the diseases, there are also other natural enemies of the trees in the Yellowstone. During my discovery tour I noticed that at least water and deer try their best to eliminate woodland:
(Please note the height of the snow in May compared to the height of the trees on the next picture!)