Submitted By: Allison Strauss, Annual Adventure Maven

AB2

See Part 1 here.

April 26, 2011

Ponderosa Pine Forests

Field Example: Black Forest, Colorado

“Of all the pines, this one gives forth the finest music to the winds.” 

—John Muir on Ponderosa Pines

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Young ponderosas hugging at Section 16, Colorado Springs

Introduction to Ponderosa

“The range of ponderosa pine essentially defines the West. From Nebraska to California, and from Southern British Columbia to Northern Mexico, ponderosa pine is the dominant forest tree of the montane zone in Western North America.”

—Audrey Delella Benedict, The Naturalist’s Guide to the Southern Rockies

There are three kinds of ponderosa, the one in the Southern Rockies being the Rocky Mountain Ponderosa Pine.

Ponderosa is the Goldilocks tree. It likes a temperate climate—not too hot, not too cold, not too wet, not too dry.

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Ponderosa Dispersion & Fire

Ponderosa ideally grow in clumps in open grassy areas. American pioneer accounts describe ponderosa forests as “park like” with grass “stirrup-high.”

Trees, like most large species, favor longevity over high reproduction. Ponderosa saplings therefore grow in the open grass, away from the clumps of their mothers, sparing the mature trees competition. Each clump of trees, therefore, is of one generation.

Clumping in the grassland keeps fires regular and low impact. Fire, like water, takes the most direct course, which in this case is through the open channels of grass. Most saplings burn, but those that make it to maturity are then out of harm’s way.

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But Black Forest, like most ponderosa forests today, is not park-like. Europeans brought the practice of fire suppression to North America, and the U.S. Forest Service has followed in this tradition, putting out all fires, not distinguishing between emergencies and regular low-level ones. Without their population control mechanism (channels of grass), ponderosa forests have grown dense so now virtually all fires are emergencies.

Black Forest is in fact named for its density, displaying a random pattern of dispersion. The trees are all about the same age, probably around 100 years old, rather than there being clumps of different generations.

The European perspective sees forest fires as wasted lumber. Ponderosa pine is the second most harvested type of lumber in North America. (#1 is Douglas fir.) The irony is, now there’s nowhere for fires to go without burning these very trees.

This is further perpetuated by aggressive brush clearance, which has also taken a toll on wildflowers.

Ponderosa’s Best Friend

Underground truffles (fungi) are integral to ponderosa and other pines. They wrap around the tree roots, essentially becoming one with them. This combination is called Mycorrhiza (fungi-root). Mycorrhiza increase the tree’s intake of water and nutrients from the soil.

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Being underground, untouched by the wind, truffles rely on animals for dispersion. Animals dig them up, eat them, and poop out the spores elsewhere.

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Abert’s squirrels also eat ponderosa phloem (part of the trunk that transports sap), which they live off exclusively through the winter, making Abert’s squirrels an indicator species of ponderosa forest health.

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Ponderosa’s Enemy

Dwarf mistletoe is a parasite to ponderosa. It can only produce 3-4% of its own energy, so it grows on tree branches, sucking out the carbohydrates (sugar) and water, the tree’s own food. This makes it hard for the tree to photosynthesize, and may render it barren.

Dwarf mistletoe disperses its seeds in summer, when the fruit explodes, shooting gooey seeds as far as 20 feet at up to 50 miles per hour!

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Black Forest is highly infected with dwarf mistletoe.

Gamble’s Oak

There are also Gamble’s oak in Black Forest, the only oak native to Colorado. Like other oaks, Gamble’s mast. Masting species let seed heavily in some years, and little to none in others, but all members of a local population let the same amount at once. For example, one year, a population may drop all of its acorns, but then drop a few to none in the next three years. They’re “irregular and synchronous.”

Black Forest also has a ground cover of delightfully named kinnikinnick, which bears eat.

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