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The Life of a White Pine

blog / By: Louise Wikert Smith and Jeff Smith

January 3, 2019

White pine was originally a key player in the Great Lakes and New England ecosystems. A few little outliers of them also spilled westward into what became northeast Iowa. I know of no evidence that it grew around here in southeast Iowa, within the last millennia. But we now plant it extensively around here because it is fast-growing, attractive, long lived, and useful to wildlife and us. Its main predators are deer when the tree is young, and some sort of blight, which occasionally kills individuals. The wood is brittle, and storms passing through can leave a trail of branches and sometimes tops. But the tree is resilient and often an upper branch will slowly bend upward and become a new top, and as the tree gets older it will have a distinctive little jog in its trunk where this happened.

After the storm

In a previous blog, I mentioned planting of local farm windbreaks more than a century ago. Today let us take a little tour through the life cycle of a white pine.

A new top in future years

When the tree is young, each year’s growth of new branches forms a single radial whorl, like the spokes of a wagon wheel, usually 6-10 branches in each horizontal whorl, with a bare trunk above and below.

The simple single annual whorls can be identified at a distance, especially when silhouetted against the sky.

The spacing between the whorls of branches reveals past growth. If only a few inches between whorls, the tree has had a tough life, perhaps growing in a crack in a granite outcrop with a short growing season in southern Canada. But here in southeast Iowa, with deep soils, adequate rainfall, and lush summer days, it is not uncommon for white pine to put on as much as three feet of main trunk growth in a single year. As they get taller, they stick up into more aggressive winds, and lose small branches and their shape becomes more irregular – often evolving into pagoda-like layers.

This magnificent specimen in Morrison Park, Coralville, might be just slipping past its prime. About 20 feet up, the bole on the south side has a cavity from which squirrels occasionally toss bits of punky wood. This might become the spot where the tree snaps in a violent storm. Its fortunes may lie in how well lesser storms prune the top and reduce its sail area before the big storm arrives.
This elderly individual is fading fast, and within a decade or two will be thoroughly dead. But at this stage of its career, with more sunlight below, it can evolve into a wildlife thicket draped in native vines.
Even when very dead, white pine often disintegrates slowly from the top down because the wood is well saturated with pitch (which under certain circumstances becomes amber in the distant future). The soft deadwood makes for preferred drilling by woodpeckers, which make cavities, then becoming homes for bluebirds, squirrels, bats, etc., and this service life can continue on for another decade or more after photosynthesis has ceased. And for micro-wildlife: the fungi, beetles, millipedes, ants, etc., this continues for several more decades after the dead snag finally lies on the ground. As the log melts down, the soil-forming processes take over, making carbon compounds with lifespans of hundreds to thousands of years. Not quite immortal, but you get a lot for your effort when you spend a few minutes planting a tree, and a few hours taking care of it.
Beginning the cycle anew
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