Here are the notes from a hike this past weekend up in Allenspark, on the edge of the Rocky Mountain National Park, less than a mile through the woods from where Sara and I used to live last year. Hopefully, I will be able to upload some images to it in the coming week or so.
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Standing on the edge of a dry streambed only two feet wide, my eyes followed dusty elk and moose prints along a heavily used trail from dry yellow aspen and grass fields across the streambed, into the darker conifer forest. Fir trees had long ago taken over the lower land adjoining the perennial spring, leaving the drier Ponderosa stands to take over the slopes uphill from the stream.
As I followed each print along the trail into the forest, the brighter straw color of a freshly snapped aspen trunk caught my eye. Some storm had snapped the twenty, maybe thirty year old off at chest level, just above a large woodpecker hole. After learning how to find flying squirrels in the woods of Pennsylvania during wandering sessions with friends in college, I have since been unable to resist the urge to tap on every tree I see that has a cavity hole along its trunk. Approaching the tree, I noticed brown lumps in the large cavity that looked like oversized elk droppings. Fishing one out of the hole, I was clueless as to what this wrinkly walnut sized brown sponge was until I thought of all the squirrels I noticed carrying mushrooms around this fall. As truffle flashed through my mind, I held the little brown knuckle up to my stuffy nose and took a whiff. It smelled like almond syrup. I looked for bite marks, and bit a spot where there were none. It was dry and spongy, but had a barely noticeable pleasant taste. Thinking of all of the squirrels I saw carrying poisonous Amanitas this fall, I spit it out.
Giggling over my find, I reached back into the cavity; sounding for the depth of this squirrels cache. I couldn’t feel the bottom, but based on the volume of most larger woodpecker’s nests, I guess there was about three quarters of a gallon of truffles in this single dead aspen. I looked around for a minute, as if something else amazing might pop out of the woods, and walked on resuming my search for a well-used elk crossing close to water where I might be able to hunt this winter.
I followed several elk and moose trails into the woods, trying to stick to prints that were only a day old. However, I kept returning to the streambed, unhappy with the amount of travel any of the crossings were getting. I finally arrived downstream to where the spring consistently flowed year round, and pausing at the bottom of one steep embankment to admire a larger fir whose large roots were dipping into the spring, I noticed a basketball size grass nest perched atop the end of one branch some fifteen feet above the ground. Having been spoiled by the aesthetic oak and maple trees of the east, I rarely climb conifer trees, but decided it was time. And I needed a break from searching for a reliable creek crossing. I reached up into the tree, and stepping upon branches an inch or two thick, I began to wriggle my way through the branches.
Taking a break to wipe some bark from my eyes, I noticed a large, white mushroom, with a whitish yellow cap nestled amidst a tuft of needle next to me. A foot away I noticed a smaller, black and yellow mushroom in the next tuft of needles. I followed the branch to its terminal bud, and looked around me to see almost every tuft of needles had at least one mushroom laying within it, bobbing in the cold, dry wind from the divide, which was maybe four miles away. I climbed further, finding that I was surrounded by hundreds of mushrooms. Taking a quick survey, I could count at least five different species of mushrooms, most of which I later found to be Russula,, many of which are edible to humans as well.
By the time I had arrived at the nest it seemed moot to inspect it, since it was apparent this was one of the nests of the squirrel, or family of squirrels, who inhabited this tree, and covered it with their winter stash of dried mushrooms. I gave the branch a shake, hoping a disgruntled squirrel may take a look from inside. After a second uneventful shake, I climbed further up the tree to a few very large masses of mistletoe coming from the trunk of this fir, perhaps almost 20 feet above the ground. There seemed to be many more mushrooms on the branches closer to the mistletoe, and as I climbed closer I noticed this dense tangle of branches were lined with grass. It was full of mushrooms. From the largest cavity, I could have filled a five-gallon bucket. I grabbed a representative of the two most common mushrooms, and dropped them down to the ground by my pack to id them later at home. I inspected a few more nests within the mistletoe, and clung to the swaying tree for a minute, listening to the wind rippling down through the valley, and smirked as it all came together; from the arrangement of the needles on the branch, to the parasitic mistletoe that sprouted like a preeminent tombstone from its host’s trunk, everything in the near silence of the wind whispered perfection through the trees.
The needles themselves, arranged in a spiral along three-inch twigs that reach up like a supplicant’s hand, perfectly cradle the delicate mushrooms. Arranged about every foot or so, these tufts provide a diligent pine squirrel with the pre-organized matrix along which they can meticulously fill the branches with mushrooms. Larger fungi seemed to be placed closer to the trunk of the tree, while smaller, less valuable pieces of fungi were placed closer to the ends of the branches, closer to the wind.
Mistletoe is a parasite. Once it has infiltrated the bark of a tree, death for the tree begins. While many forest managers seek to remove this pest from valuable stands of wood, this organism naturally selects weaker individuals who are more susceptible to its sticky seeds. Thus, the oldest trees in the forest exemplify those with the greatest tolerance to such parasites. This old fir I was perched within, was one of these such trees. The oldest water loving fir along the whole stretch of stream I had found, and here above me were the largest bunches of mistletoe I had ever seen. The fir showed no signs of distress to me, and I would assume many of its progeny stood solidly below prepared to take its place when the mistletoe exacted its toll.
While we classify mistletoe as a pest, and our human emotions and logic lead us to believe it as a bad thing, without the mistletoe’s presence, one harsh winter could, years down the road, mean a sooner death for this fir tree than the mistletoe promises. Let me explain.
Squirrels depend on the mistletoe to hold their winter’s cache of mushrooms. Just as the fir needles provide the perfect drying rack for a portion of the pine squirrel’s booty, these large tangles of mistletoe are essentially large drying baskets, which allow all of the mushrooms cached here to dry quickly before molding of decomposing. Having such a huge supply of mushrooms at the structural center of the tree ensures that even amidst the roughest winter storms, which may strip all of the mushrooms from the fir branches, these squirrels will still have a hardy supply of fungi just a few branches away. Ok, so what part do the mushrooms play?
Scientists are continually learning that the symbiosis existing between fungus and trees is not just a helping hand to each of these organisms’ well being. It is vital to their existence. The thread-like hyphae of fungus, which are similar to plant roots, spread through the soil, and attach to tree roots when they encounter them. At these sites, a partnership is formed in which the trees provide carbon to the fungus, while the fungus provides water, minerals, and protection against disease pathogens. This symbiosis in effect extends their own resource network exponentially, while helping out their neighbor by sharing excess goods. So, back to the mistletoe.
In the late summer and fall months when squirrels hurriedly collect and dry their winter food stores of fungus, the open gills of the mushrooms dangling from the squirrel’s mouth spread millions of spores across the forest floor, some of which will slowly found new colonies of fungus throughout the forest, which will go on to help ensure the health of the trees creating the forest. Remove one piece of the puzzle and a trophic cascade begins.
Without the mistletoe to maintain the most important mass of the squirrel’s winter diet, the squirrels would not make it through the winter. Where squirrels disappear from patches of the forest, the mushrooms no longer have their “bees” to sew their seeds. A few seasons later, the soils slowly become depleted of hyphae, and suddenly the trees have a tougher time receiving their most important nutrients and water from the soil. So, during the most important time of the summer when they usually focus on creating sugars to bide them through the winter, these trees must allot their energies to growing more extensive root systems to seek out these nutrients. Come wintertime, these trees are often more at risk of succumbing to a rough or longer winter. Finally, a dead conifer tree cannot continue to feed its parasitic mistletoe. In this way, nature exhibits a perfect give and take method of existence in which one organism depends on others to fulfill their weaknesses, while they fulfill another’s.
