Ancient and mysterious. Here is a picture of the planet’s ancient past and if we are very good: a vision of our future.
When I discovered this group of lichens I couldn’t help but feel wonder. This tiny ecosystem is the end result of a whole lot of tricky connections. A lichen isn’t one organism but a perfect marriage of algae/cyanobacteria and fungi. How do tiny compatible organisms manage to find each other in a big world without an online dating service?
Yet, somehow they do find each other. And then they find a way to meld and cooperate to create something bigger and better than each alone could ever be. The process is mysterious. People try to grow lichens in labs and often fail miserably ending up with gross looking blobs instead of the amazing structures anyone can find growing wild.
As a complete newb I can only guess at what is growing in the photo above. I think the orange parasols are Teloschistes. The black circle with a white outline might be Tephomela or Lecanora. Maybe Phaeophysica? shrug Anyone know a good lichenologist?
Mixed in is the leafy-like stuff and paint-splotchy stuff that I have seen often enough but typically overlook.
More of the orange parasols below. I found these communities at Willowbrook Reach growing on living trees.
Many lichens are not pollution tolerant and our neighbourhood has seen a substantial increase in traffic. It isn’t my paranoid imagination speaking. Not only does it take longer to cross the road as a steady stream of traffic flows by but I have seen chemical changes too. Limestone surfaces that were clean when I moved here are collecting that characteristic black stain created by car pollution. These stains are different from the soot I can wash off my house; they are the product of a chemical reaction involving nitrogen dioxide and sulphur dioxide from car emissions. In some places the rock surfaces are pitted showing where they are starting to dissolve.
Limestone blocks are more than an expensive pieces of cut rock. I kind of think of them as compressed fossils. Limestone forms when calcite from ancient corals and tiny microscopic skeletons accumulates in warm shallow seas over an unthinkable stretch of time. It is kind of like rock made from bones and sea shells.
Have you ever seen what happens to a chicken bone stored in a vinegar solution?
First you’ll see bubbles rise as trapped carbon escapes. Let the bone sit and it will become so soft you can twist it — sometimes even tie it into a knot. That is kind of what is happening to this limestone wall. Our oceans. And soil.
What This Means for Gardeners
Gardening in Austin is already really difficult. When I first moved here I thought I was a good gardener with a decent skill set. Apparently not. I had more failures than successes and if it wasn’t for my insanely stubborn nature I would have given up long ago.
I used to think that the problem was in learning how to adjust to working with extreme heat and summer drought. But I think I just discovered a new layer to the problem. The problem isn’t ‘merely’ increasing temperatures — I need to add air and soil acidification into the mix.
That discolouration on limestone surfaces is evidence that the air here is already acidic. The increase in traffic suggests it will become worse. This means the sweet (basic pH) clay soil on this side of the city is probably also undergoing big changes.
For people living on the west side dealing with caliche soil acidification means an already difficult situation can only get drastically worse.
How much of a pH change will the native plants tolerate? Change the chemistry of the air and soil and you change everything.
I already knew I’d need to choose plants that can cope with extremes in moisture and temperature. But now I see that if I want my garden to last I will need to find plants that will tolerate a range in soil pH too. And air pollution. That sounds like big trouble over the long term. Acid loving plants tend to have evolved in forests with a lot of water and cool temperatures. Hmmm.
Meanwhile I think I will continue to seek out and appreciate our local lichen colonies while they last. Some lichens grow at a rate of .5 mm every year. I am from Canada. I know just how small one mm is. The next time I visit the cemetery I am going to bring along a ruler. I remember seeing lichens growing on the tombstones there. The dates on those tombstones could come in handy for appreciating the growth rate of these organisms.
How old are lichens in general? One source said they were already present about 400 million years ago. I am going to start calling that period of time The Age of Cooperation. That is when the leaf cutter ants also created a mutually beneficial relationship with fungi.
No wonder people are so bad at this cooperating business! Modern humans have only been around for about 50,000 years. We are as clumsy as toddlers. As terrible as a two year old. And somehow we’ve found ourselves in charge of the place …