One Very Big Tree

I spent Wednesday through Friday of last week canoeing the Willamette River over on the coastal side of the state (for work – yes, be jealous). Marked on the map of one of the state parks we camped at, Willamette Mission, was the nation’s largest black cottonwood tree. Who could possibly resist?

It was…

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…a very…

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…big tree.

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This is the “Willamette Mission Cottonwood,” which is 155 feet tall, has a circumference of over 26 feet, and is approximately 270 years old. For scale, here’s a poorly-lit shot with a couple people standing next to the trunk:

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I wish I’d had more time to take better pictures and enjoy it properly, but alas, we were only passing by. Still, it’s always fun to encounter a giant.

More information:

A Walk in an Aspen Stand

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Back in Wisconsin, aspen suckers grew like weeds after an area was logged. It came as a surprise to learn, when I moved out West, that here aspens are in serious decline and the focus of conservation efforts. Above is a stand that we’re going to be building a fence around soon at work, to protect it from damage from cattle, deer, and elk.

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It’s doubtful that elk actually spend much time in this pasture anymore (though they’re definitely around in the hills), but the dark scars on the trunks of the trees come from elk scraping at the bark with their teeth to get at the nutritious, photosynthetic layer of bark under the white outer layer.

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While aspen trees do produce flowers, most of their reproduction is vegetative, in the form of new shoots or “suckers” growing from existing root systems. Young, tender suckers are super tasty food for deer – the ones in the photo above, growing in the shelter of a fallen adult, have been heavily browsed. Fencing the deer out of the stand will help young trees get established.

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The way suckering works is actually pretty interesting – the crown of the tree produces a hormone called auxin that inhibits the production of suckers. When the tree falls and auxin is no longer produced, the growth of new suckers increases in response to keep the stand going. An aspen stand is really one big organism, interconnected by the root system that keeps on living even as individual trees die and are replaced. One particular aspen clone in Utah is a candidate for the world’s largest, oldest organism.

There are multiple reasons for aspen decline in the West, including the removal of top predators from ecosystems (no wolves -> more elk and deer -> more browsing of aspen) and the suppression of natural wildfires, which allows other trees like junipers to become established and crowd out aspen. Climate change is almost certainly playing a role, as well. More information:

Nobody Likes Junipers

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Juniper trees are the nemesis of many ranchers around here. As a result of the region’s altered fire regime – no more wildfires sweeping through and keeping trees from establishing themselves – Western Junipers (Juniperus occidentalis – I like literal Latin names like this) are encroaching more and more onto rangeland, sucking up water with their taproots and outcompeting understory plants.

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But the truth is, I kind of like ‘em, these tough, scrubby little trees. They’re survivors. And they’re not an exotic invasive species – they were always here, it’s just that now there are even more of them, in more places.

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The female cones don’t look like cones at all, but like fleshy little silvery-blue berries. They’re an important food source for fruit-eating birds like robins and waxwings. They’re also where the flavoring in gin comes from. Someone I met at a conference recently told a story about mistaking a bag of juniper berries her boyfriend had left in their freezer for blueberries and baking them into a pie, but I wouldn’t recommend trying that at home.

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The rugged individuals of the tree world. Really, they fit right in around here. And since me secretly liking them won’t actually change whether efforts to eradicate them from rangeland are successful, I’m going to go right on doing it.

The Butterscotch Tree

Across large areas of the American West, one tree is the undisputed king of dry montane forests: the Ponderosa Pine, Pinus ponderosa. “Ponderosa” is literally Spanish for “ponderous,” a name which reflects the size and majesty of these trees. However, it isn’t only their beauty (or their value as timber) that makes me fond of Ponderosas. It’s their scent.

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Why Does Snow Melt Around the Bases of Trees?

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I’m sure you’ve all noticed this if you’ve been in the woods in winter: as the season goes on (and on and on, if you live where I do), the first place snow starts to retreat a little is often around the bases of the trees. Why?

The answer is actually not all that exciting. A few plants, such as skunk cabbage, actually do generate their own heat early in the spring, but as far as I know that’s not the case for the sugar maples and other common trees here. The most likely explanation is just that the relatively dark color of the tree bark absorbs more heat and, as a result, melts the surrounding snow. Still, any sign of spring is cause for celebration at this point!

The Natural History of Maple Syruping

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We started tapping maple trees on campus this week. I would guess that most of my readers are familiar with the general process of making maple syrup – you tap the trees to collect their sap and boil it down to get rid of the excess liquid and concentrate the sugar. The Ojibwa Indians in this area were already collecting sap to make syrup and sugar before the first European settlers arrived, and there’s even a town south of here called “Sugar Camp” because the site was known as a center of maple tapping activity. But why do we tap the trees at a specific time of year? What exactly is going on with the sap?

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Marcescence

Red oak in September:

Red oak in October:

Red oak today:

See all the dead leaves still clinging to its branches? This is called marcescence. A lot of oaks and beeches, especially younger ones (and especially on lower branches, as seen here), hang onto the past season’s old dead leaves throughout the winter. The dead leaves finally drop off in the spring when new ones grow in their place. No one is quite sure why some trees do this, but there are a few theories – well, a lot of theories.

  • Dropping dead leaves at the beginning of spring could provide a burst of fertilizer to start off the growing season as the leaves decompose.
  • Keeping the leaves in the winter could help trap more snow around the bases of the trees, giving them extra moisture when the snow melts in the spring.
  • The dead leaves could even provide some protection from cold and frost for the tree’s buds or even deter browsing by herbivores.

For more information, check out this great article on marcescence by a professional forester in Vermont. Are any trees marcescing (did I just make up a word?) in your area?