Miniature marvels: the down-and-dirty crew
Red-banded polypore fungus clings to a blue oak in Round Valley Regional Preserve.
It’s spring, when forests become wonderlands. Tucked enticingly among the damp grasses, hung shelflike on tree trunks and splayed flamboyantly across boulders are fungi, lichens and mosses – miniature marvels of form and color.
There’s a lot to like about lichens, and it’s not odd to be fond of fungi. Those fleshy and scabrous organisms we associate with the monsters of sci-fi horror flicks (“The Toadstool That Ate Tahoe” comes to mind) are essential to the life of the landscapes we admire.
The toadstools that rise from the forest floor are only the tip of the fungal iceberg. Call them the “fruit” of the organism, the structures that hold spores for dissemination by wind, water or animal transport. The true heavy lifting of forest decomposition is done beneath the soil by a network of microscopic fungal threads called hyphae. The hyphae, aided and abetted by other small fungal bodies, plus bacteria and other microbes, can be credited for the decomposition of 80 to 90 percent of the dead plant and animal matter in the forest.
Fungi also provide food for creepy-crawly mites and the slithering, microscopic worm-shaped creatures called nematodes. But some fungi have turned the tables by evolving strategies for preying on small invertebrates. Sci-fi horror writers, take note: One type of fungus preys on nematodes by dangling a series of little nooses, each comprising only three cells, from its filaments. When the unsuspecting nematode slinking through the soil passes through a noose, the friction of its body trips a mechanism in the noose’s cells, inflating them and strangling the nematode. If you’re wondering why the nematode doesn’t have a prayer, well, the noose inflates in a snappy one-tenth of a second. The fungal cells then grow into the worm and digest it. That, I presume, is how the toadstool disposed of the citizens of Tahoe.
Foliose lichen is spattered across a boulder in Round Valley.
The fungal shelves that adorn tree trunks are among the most fascinating and photogenic of all – though we imagine the trees themselves take a less upbeat, aesthetically appreciative view of their partners in parasitism. The lovely (and expensive) Japanese maple in your front yard doesn’t desire disassembly by fungi. But like forest fires, fungi are nature’s way of telling a tree that it’s time to make way – in style. Those banded and multi-hued wedges spiraling up tree trunks testify, like the crimson and saffron leaves of autumn, to the terrible beauty of Earth’s rhythms.
If mushrooms are hard to find, nestled into the dark and damp crannies of the forest floor, lichens are hard to miss, spattered across rocks and trees like Jackson Pollack graffiti. Lichens wear two hats: they’re fungus-alga organisms in one. But unlike mere fungi, which don’t photosynthesize, lichens thrive in sunlight and don’t require much water to survive. They’re efficient little sponges, soaking up as much as 35 times their weight in water from fog, dew, even humid air. And they retain water like camels, enabling them to survive on rocks, deserts and tundra.
Like fungi, lichens play an important role in the nutrient cycling. They intercept air- and rain-borne nutrients, absorbing those they can use and contributing the rest to their host organisms, such as trees. Although they’re among the hardiest living things on the planet, lichens are sensitive to changes in their habitat, especially the intrusion of air pollution. This makes them valuable indicators of ecosystem continuity and helps scientists identify habitats that need protection.
The first mosses appeared around 350 million years ago – before reptiles and flying insects – making them among the most ancient inhabitants of the planet. Like lichens, mosses need external moisture to move nutrients from place to place – thus their penchant for damp habitats protected from direct sunlight. They’re the most luxuriantly textured of the forest’s miniature marvels, adorning rocks and trees like furry archipelagos.
Moss sporangia sweep across a boulder in Round Valley.
Mosses form a vital line of the ecosystem’s defense. Like soldiers kept in reserve at the outset of a battle, they reinforce the lichens’ shock-troop foothold on rocks, eventually creating a layer of topsoil in which more sophisticated flora can take root. On hillsides subject to landslides, mosses provide a mat that keeps loose soil from slip-slidin’ away.
Over the centuries, we humans have gotten pretty creative with mosses. We’ve mined them for use as a soil additive, fuel, home decoration and flavoring (think Scotch whiskey) – even as first-aid dressing for battlefield wounds (mosses contain a mild antibacterial agent and are highly absorbent).
As our grey winter has given way to the chromatic dazzle of spring, as our attention turns to bright blossoms and sweeping vistas, let’s keep an eye peeled for the miniature marvels beneath our feet, the blue-collar crew whose down-and-dirty work makes it possible for the pageant of spring to maintain its blockbuster status.