The Undead of Winter

 By Jan Thornhill

Ruby LOVES to "play dead" so we can will bury her in snow!

I love early spring! And no – I’m not talking about tulips and the return of migratory birds, though I have nothing against those things. I’m talking about earlier, in the first weeks of March, when there’s still plenty of snow on the ground, when, for all intents and purposes, it’s still the dead of winter.

Except it’s not dead.

Minute snow fleas appear on warm days in late winter.

In fact, there’s a surprising amount of life in the late winter forest here in Ontario – especially when the temperature squeaks a few degrees above the freezing mark. By early March, tree sap has begun to flow. Within a few days, deciduous crowns in the distance have taken on a haze, as if someone has smeared wet watercolour across the tips of their sharp branches. Their leaf buds are plumping. Male chickadees start using their “Hey, sweetie,” song, which, I think, is self-explanatory. Skunks wake from their winter torpor and amble about briefly – possibly just to stretch their legs – before returning to their dens to wait for real spring to come. On sun-warmed snow patches at the base of trees, snow fleas congregate, sometimes by the tens of thousands (see my post about snow fleas here).

This perennial Red-belted Polypore (Fomitopsis pinicola)
will drop spores on warm winter days.

And, all over the forest—believe it or not—fungi are procreating like crazy.

Amanita frostiana has a mycorrhizal relationship
with oaks and conifers.

These are not your basic ground mushrooms with caps and stems that you see in summer and fall. Most of those are mycorrhizal, and have a mutualistic relationship with trees, trading underground water and nutrients for the sugars that trees produce. But trees shut down sugar production in the late fall, so the underground networks of mycelia of mycorrhizal fungi also shut down during the frozen months.

The Violet-toothed polypore (Trichaptum biforme) is an annual saprobe.

But there are all kinds of other fungi that have a different kind of relationship to trees. They rot them. Many of these tree decayers, or saprobes, are polypores. Polypores develop their spores inside tiny tubes instead of on gills like store-bought mushrooms. 

The Hexagonal-pored Polypore (Neofavolus alveolaris)
 has—surprise!—hexagonal pores.

The most commonly noticed polypores are shelf fungi or conks. Many are perennial – they have skeletal hyphae—tissue than can withstand freezing and thawing—and just keep growing and growing, sometimes for 70 years or more. And during that time, whenever the temperature goes above freezing for a couple of days, these fungi produce spores. 

Yearly growth layers are obvious on this Phellinus that grows
new spore-producing tubes on its underside each year. 

But, why, you might wonder would they send out spores so much earlier than the birds start doing it and the bees start doing it—when the forest is still, in effect, asleep?

The Gilled Polypore, Lenzites betulina, has elongated tubes that almost look like gills.

They do it early because polypores, like all fungi, are opportunistic. Polypores that grow on living trees usually inhabit the heartwood that runs up the core of a tree trunk. To set up shop in this deadwood, a polypore has to get past a tree’s sapwood, the living layer below the tree’s bark. In the winter, deep freezes cause fractures in tree bark. These frost cracks are perfect for catching passing spores. When spring rains moisten the crevices, and before the tree has time to seal these cracks, the spores germinate and their mycelia work their way into the core. Once past the tree's defences, the fungus sets up shop, spreading its mycelia up and down and around. A fungus can secretly live inside a tree—gradually breaking down lignin and cellulose—for many years before it gives us humans a clue of its presence—by producing reproductive organs (shelf fungi, or conks) on the tree’s exterior.

Fomes fomentarius, is commonly called the Hoof Fungus
 (its shape)  or Tinder Fungus (used to carry fire from place to place
before matches were invented; Ötzi was carrying some).

The Cinnabar Polypore (Pycnoporus cinnabarinus) is the colour of dragon's blood!

The common name for Trametes versicolor is Turkey tails—for good reason

Chicken-of-the-Woods is an excellent edible polypore
 that has the unmistakable texture of overcooked
chicken if you miss its succulent stage.

This Artist's Conk (Ganoderma applanatum) is exhibiting geotropism
— the fungus first grew while the tree was still standing, then, after the tree 
fell, added new growth with its pore surface—once again—facing down.