One thing I love about the Pacific Northwest is the endless scale of life. Douglas firs stretch 250 feet into the air, but if you kneel at the base of its trunk you’re likely to see a forest in miniature: green fronds tickling the air, slender red sporophytes nodding over them, and perhaps a spider climbing out of the thicket with tiny, translucent legs.

I wanted to create a way for children to engage in this miniature world, so I went out to collect moss and lichen for terrariums. A good terrarium is a closed ecosystem, which means it has everything it needs to survive. I spread gravel and some activated charcoal along the bottom of a glass to provide drainage and discourage bacteria. Then I added some soil and wood chips to provide nutrients. I sprinkled in a little water, a little oxygen, a little light. Now all I needed was a little plant to keep it going.

Zumdiek Park is quiet little forest plot on 108th that reminds us that fewer than 70 years past, Bellevue was a forested wetland. The footpaths were flooded from the morning’s rain and the air was fragrant with pine needles. Chickadees, robins, finches, and towhees sang from the branches, but I kept my head down, searching the wet ground.

Bingo! At the base of a spreading big-leaf maple I found moss city: Peat moss with soft hillocks, step moss drooping over its base, waxy liverwort, and hairy lichen. Snails and beetles crept over the tree as I carefully pried a little bit of this, a little bit of that into my canvas bag, taking care not to gather more than I needed. I took it all back to the museum and spread it out on the glass table with my hand lens. Leaning close I could still smell the forest.

Mosses have no roots, leaves, or stems, so they rely on small hairs called rhyzoids that trap water and anchor them to larger surfaces. Thanks to the rhyzoids, mosses can grow in areas with little or no soil at all, like stone or fallen trees. They have a complicated life cycle, but you can identify the tall sporophytes that will drop the next generation of spores by their slender stalk.

Lichens are even more interesting. They are a symbiosis between a fungus (like a mushroom) and algae (the gunk that grows on a pond). Usually the fungus creates the body of the lichen, and the algae creates energy by photosynthesizing, or using the sun to create energy. They come in all shapes, textures, and colors. My favorite is the sunburst lichen, which is bright orange and takes its nutrients from pika pee as well as sunlight! Scientists haven’t figured out why the algae has evolved to be trapped inside the host fungus, since it can survive quite well on its own. But crouched at the base of the big tree, I’m just glad that it exists in all its colorful glory.

I keep my terrarium sealed tight in a sunny place during the day, so the plants can use the sun’s energy to absorb carbon dioxide and release oxygen. At night, the system reverses and the plants breathe like we do: they absorb oxygen and release CO2. As water is taken up and released, it condenses on the top of my jar, then rains back down onto the plants. Sound familiar?

Join us every Thursday for Naturalist Hour. Or, if you prefer, find a nice mossy tree and take a good look.

Contributed by Daniela Garvue