Tiny Forests in the Desert
Like trees in a forest, biological soil crusts play a key role in the ecosystems in which they are found. Listen as Dr. Sasha Reed, research ecologist with the U.S. Geological Survey, explains why damage to soil crust communities can have greater consequences than you might think. Dr. Reed was awarded the Presidential Early Career Award for Scientists and Engineers in 2011.
- Credit/ Author:
- Jennifer Jerrett
- Date created:
[Narrator] You might not associate the sounds of clear cutting with the desert. But something similar is happening around the national parks in southern Utah. And it's right underfoot.
[Narrator] I'm in Arches National Park and I'm on the hunt -- for biological soil crust. This stuff is alive. It's made up of lots of little organisms and it's found all over the world -- almost anywhere that the soil can see the sun. In deserts like this one, the soil sees a lot of sun, so I'm not going to have to go too far to find some really nice specimens...and in fact, here we are.
[Narrator] So, from where I'm standing, it just kind of looks like a dark, well, crusty layer on the top of the soil -- and I suppose that's not too surprising. But if I get closer, I start to see...tiny...sandcastles. And some of them look like they're covered in soot. And if I get really close -- now, I'm actually looking through a magnifying lens -- I see a garden full of mosses and multicolored lichens and cyanobacteria (you can look that one up later). It really is a forest in miniature.
[Narrator] There are other similarities between trees and crust too. Trees photosynthesize. So does crust. In a forest, leaves fall and decompose, boosting soil fertility. Here in the desert, crust organisms help soil fertility too. And just like trees in a forest, crust prevents erosion.
[Sasha Reed] One of the things that makes them very special in these sandy places...
[Narrator] That's Sasha Reed, scientist with the U.S. Geological Survey in Moab, Utah.
[Sasha Reed] ...is that they exude this glue. They'll ooze out these polysaccharides -- these sticky sugars -- and that sticky sugar will hold the soil particles -- the sand grains -- in place and it's incredibly strong.
[Sasha Reed] It holds the place in place is what we like to say.
[Sasha Reed] The crusts are very resilient to a lot of things like high-speed winds and crazy amounts of water, they've really evolved a way to be able to resist that kind of disturbance, but they are incredibly sensitive to disturbance that compresses them: stepping on the crust...riding your bike on the crust...driving your car on the crust...putting cattle on the crust...those things will absolutely bust the crust.
[Narrator] When crusts are disturbed like this, they can't 'hold the place in place' anymore. And because of blowing sand and dust, those initial disturbances can spread.
[Sasha Reed] If that role of holding the soil in place is taken away, that sand is gonna blow. And the thing about dust, it blows next door...it covers the crust next door -- maybe healthy crust -- and because that crust needs to see the sun to survive, to photosynthesize, it will kill that crust as well.
[Narrator] So now we're moving from something localized to something bigger. Much bigger.
[Sasha Reed] There's some really interesting work that's happened here with dust lately to show that dust that's produced from disturbance blows on to the snowpack of the Rocky Mountains. It changes the color of the snow and that changes the energy balance, making the snow melt faster, and that's predicted to result in a five percent decline in the Colorado River flow.
[Narrator] Not so great for a place that's already pretty dry.
[Sasha Reed] So if you have more dust moving around the earth, it's not just changing the place where the dust came from, it's changing the place where the dust goes to.
[Narrator] Who knew that organisms so tiny could be so important.
[Sasha Reed] And when they go away, we just see things blow in ways that are apocalyptic. I mean it's just a really big deal. It's a huge role that they play at the global scale.
[Narrator] And while we're thinking big -- thinking global -- let's go back to that idea of deforestation.
[Narrator] Clear cutting in the rainforest has dramatic effects. It changes local hydrology, species diversity and soil fertility.
[Sasha Reed] Biological soil crust and dryland ecosystems can be the same way. It's just really small. You gotta get on your hands and knees to be able to see the forest.
[Sasha Reed] Everything is connected. If you're cutting down the forests of crust -- if you destroy these areas, you change everything.
[Narrator] So, what do we do? Stay home? Never get out of the car? Or maybe we should only read about the parks online. I mean really, is there any hope?
[Sasha Reed] There's so much hope, absolutely, I mean these are survivors. These organisms just need us to give them the change to either stay healthy or return to health.
[Narrator] If we just watch our step. Because if we pay attention, we stand a much better chance of not missing the forest, for the trees.
[Narrator] At Arches National Park. I'm Jennifer Jerrett.