Sonoran desert lichens
What makes a ‘discovery’? Recently a lichen species was discovered, in a digitized collection of lichens that had already been collected and misidentified in the past. The digital databases for scientific collections of field samples allow researchers anywhere in the world to explore samples of lichens, and add new information learned since the time the specimen was collected.
I apologize for not providing an image of the new lichen species; I can’t figure out how to manage some of the new aspects of this blog. However, the lichen image above is one of my ‘discoveries’. It is new to me; a discovery made on a slow mosey across a gravelly, cactus and creosote filled flat below Picacho Peak on a warm February evening. Finding a lichen I’ve never seen gives me all the good feelings of discovery; it matters not one tiny bit that others may have already looked at and identified this lichen.
The beautiful cactus above is about two inches tall, seen through a hand lens. This is the first rainbow hedgehog cactus I’ve found and it is a beauty. Unlike many of her kind, there are no pinkish bands of color, only the lace-like white net of spines. Accidentally finding this cactus while looking at lichens in a small rocky outcropping was the best moment of a day filled with excellent sightings and discoveries in a new place. I wonder how many other people wandering very close by on a well used trail have ever seen this tiny beautiful cactus. This was a discovery for me that feels very special.
The black lichen in the above image was a flat dark crust on the rock until I took a look through the hand lens. A multitude of tiny, leafy layers appeared, some with mahogany colors and some with pale edges. Neighbor to the hedgehog cactus, and part of the miniature garden that flourishes at the edge of a busy hiking trail, this lichen and so many others sharing the boulders scattered through the forest are easy to discover by anyone. Slow down, stop for a while and look around. Curiosity is the most effective ‘tool’ for discovering something new.
While idly wandering across gravel flats at Picacho Peak, wondering what might be on seemingly empty ground, I found not only several extremely tiny lichen colonies (see first image), but also found translucent, pale ants making mud tunnels the size of matchsticks, pack rat dens, bird nests, a butterfly new to me, and watched ravens play games with twigs on top of a saguaro. Lichens led me to everything else.
It doesn’t matter what interests you. Everything you find with curiosity becomes new. No matter how many times a familiar lichen is seen, or a bird sighted that you’ve come to overlook because they are so common, there is something new to learn. Discovery doesn’t only happen far away, on Mars or in a distant jungle, it happens in our own backyards and on our favorite walking trails.
I love lichens because their tiny size and inconspicuous ways encourage a slower, more careful observation. Noticing Lichen’s neighbors becomes easy, and before you know it, the forest or meadow is full of color and life you never noticed before. Discovery is not only finding what has never been known by humans, discovery occurs whenever we recognize something amazing or beautiful about the world around us. So next time you are out for a walk, be curious!
I am sitting on a carefully checked rock (cactus spines? rattlesnake?), munching on lunch and letting my eyes focus on the rocks that make up most of the surface of the earth here in this dry arroyo. Two friends and I are spending the day meandering with the water way, smelling and watching and feeling our way into a tiny part of this lush land.
When we pass through this desert in a car, we notice nothing. When we hike a trail at our usual rapid and noisy pace, we notice some of the larger, most unusual residents such as the iconic Saguaro cactus that everyone recognizes. If you are very lucky and observant you may see a roadrunner scoot between the cactuses. But there is more here, more than you can imagine.
I love lichens for many reasons, and so will begin telling of desert wonders by introducing you to a very few of the lichen residents. For they are one of the foundations of all life in the desert.
This blue green foliose lives near the floor of the arroyo, so when water moves through from the summer storms it probably gets very wet. Otherwise life is either very hot and dry or quite cold on this rock. These lichens hold moisture, provide food and shelter and add nitrogen to the land, and moderate surface temperatures, just as they do in the greener hills of the Midwest. They help form the biofilm crust that makes a healthy desert ground surface.
Hidden in the lichens and small plants that grow in rock niches are insects, essential for bird and reptile residents. Hawks, owls and small mammals eat the birds and lizards, and they support the coyote, fox and larger animals. All these animals fertilize the land and leave bones, fur and other inedible parts of their meals to return to the soil, replacing nutrients, and so each resident provides something essential for others in a close web of cooperation.
This moss glows with silver light; it drew our attention from quite a distance away. Around the edges were small crustose lichens. (My photo of them was blurry so we can’t see them, sorry. Cell phone cameras are useful but have big limitations that I am not able to overcome.) Since moss prefers less harsh sunlight and more moisture than many lichens, especially the crustose lichens, there are fewer mosses in the desert. This moss is dry now, but turns more green when watered. Often lichens that are dark colored or black have cyanobacteria that give them the dark color. What causes the moss’s dark color? This is the largest patch of moss I have seen so far. Usually there are only small areas of moss in somewhat shady areas. This moss gets a lot of sunshine.
As we munch through our lunch, we notice many birds flying back and forth across the arroyo. There is much twittering in the bushes. The more we look the more birds we see. We are sitting very close to a tiny water hole, and that is why the birds are gathered here.
This tiny puddle and the damp ground around it supports a great many birds, animals, insects and plants. The water is from a rain two days before; there is probably less than a gallon of water here now. Soon this water will be gone but for now it draws dozens of birds and other residents. We see verdin, rock wrens, black phoebe, gila woodpecker, warblers and more. Ants trail across the sand, bees by the hundreds drink from the damp places, butterflies too. Most need some of the water, but it is also a place where many find a meal.
How many species of lichen can you find in the photo above? There are quite a few! This picture shows an area of about 6 inches of rock. Each lichen has a different chemical composition, and may have a different bacteria partner.
The Sonoran desert has over 2,000 species of plants, and over 1,000 species of bees. One hundred species of reptiles here live nowhere else in the world. This bare and harsh looking land is a rich and complex world. Fragile to some stresses, yet resilient and flexible in many ways, the plants and animals of the desert share the lichen’s long adaptation to not only a very hot land, but a home that also is very cold, very dry and very wet at different times.
Below is a desert fern; its leaves are hard, built to resist losing moisture.
The fern is living in a bed of moss, and within the moss are tiny lichen. Lichen surround the moss, in the cracks of the rock. Eventually the moss and fern will go and larger plants take root.
Each time I see a different resident of the desert, I think about what relationships that resident has with any other being nearby. Some relationships are between residents and those who are only here a short time, such as that of the Ocotillo and hummingbirds. Ocotillo blooms in the spring when the hummingbirds that are migrating pass through the area. Nectar from the flowers may be the only food these long distance flyers have. Ocotillo blooms do not depend on rainfall as many other plants’ blooming time does. What conversations have been going on between hummingbirds and ocotillo, for time beyond human understanding, to develop this delicate dance that both support and both benefit from? This is the ever-present story of the desert, and every place on earth, but in the desert there are few or no backup options if one partner fails to participate. Over and over, each animal, plant, insect, fungi and lichen here have a similar story of mutual responsibility and benefit.
A beautiful rock in Sabino Canyon, that tells a complex story about what went on here over a very long time. But hidden in the cracks and shadows is another story; that of the life that begins with tiny spores, isidea and soridea of lichens. Move close, get out your hand lens and look at the rock. There, almost invisible, are the beginnings of a lichen forest. Many years from now the rock may present a different color, then even later, the shapes of crustose lichens will appear fully grown and visible. Insects and birds and lizards and mammals will benefit in many ways, and life will continue in the desert canyon.
Lunch is over, but our walk is not, so my friends and I will leave you, to wander farther up the arroyo. Thanks for joining us!
(Answer to ‘How many lichen species in this picture?’ = I count six! Do you see more?)
Disclaimer: All identifications are tentative. Lichens are very hard to identify, I am not an expert, and my focus is relationships, beauty, and the whole of life around the lichens. If you know what a lichen’s name is, please let me know.
Remember to Look for Lichens!