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How a Lake Becomes a Bog

This is a satellite photo of the area in Wisconsin where I live, courtesy of Google Maps. You can see why it’s called “Land O’ Lakes” (no relation to the butter, though we sometimes call the abandoned lumber mill on the edge of town “the butter factory” to confuse people). We also have a lot of bogs. These two facts are not unrelated.

These are kettle lakes that were formed by retreating glaciers 10,000 years ago. Many of them have Sphagnum moss growing around their edges. Sphagnum is amazingly absorbent, holding up to twenty times its dry weight in water, and the mats it forms eventually grow thick enough that they act as a substrate for a whole community of other plants we associate with bogs – leatherleaf, wild blueberry and cranberry, orchids, carnivorous plants like pitcher plant and sundew, and many more.

Slowly the lake fills with sediment, and the sphagnum eats away more and more at its edges, growing thicker and absorbing more water as it does. As the lower layers of spagnum die, they decompose very slowly due to anaerobic (oxygen-poor), acidic conditions, so that over time you get rich, moist deposits of peat. Below is an old lake on this property that’s been almost completely bog-ified, with only a small area of open water left in the middle.

Eventually the sphagnum and peat build up to the point where they can even support trees, mostly tamarack and black spruce.

This is all just one more example of the powerful process of ecological succession – one natural community transforming into another through time.

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Sugar Maples and Hydraulic Lift

Taken May 7 – the maples have fully leafed out since then.

Never, ever take sugar maples for granted. Not only do they provide us with a sweet and tasty breakfast condiment, they perform a very cool function called hydraulic lift.

All plants take up water through their roots and evaporate it through their leaves. Sugar maples (along with some other plants) take it a step further. During the day, their roots draw water up from deep underground; at night, when water isn’t evaporating from the leaves, the excess is released into soil near the surface. Sugar maples essentially irrigate the soil around their bases. To read more about this phenomenon, check out this article from Cornell.

Are these Canada Mayflowers taking advantage of natural irrigation?

So if you like wildflowers, next time you see a sugar maple… tell it thank you.

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Tamarack Attack!

Jack, who always leaves such lovely comments, asked about tamarack, and I took a couple photos of tamarack a while ago that have been sitting on my hard drive, so the topic of my next post is obvious.

Larix laricina, commonly known as tamarack, American larch, or hackmatack. (Gesundheit on that last one.) Where I am now in northern Wisconsin seems to be a sort of transition zone between the harsh boreal forests to the north and the more diverse forests to the south, with boreal species like tamarack, spruce and aspen found side-by-side with maple, oak, birch and basswood. Some species I was familiar with in Ohio, like sycamores, are missing entirely, and some, including most of the conifers, are new to me. Tamarack ranges north to the very limits of the tree line.

Its needles, which grow in tuft-like bunches, are incredibly soft to the touch. During a portage on my canoe trip over the weekend, I leaned back to let someone pass me on the trail, and when I felt something silky brush my arm I didn’t have to turn around to know the tree behind me was a tamarack. What’s even more interesting is that this is a deciduous conifer. These needles will turn gold in the autumn and then fall.

When old lakes fill in and turn into bogs, like the one above, moisture-loving tamaracks will be one of the pioneering tree species (along with spruce). Although I can’t rationally explain why, I have a lot of fondness for these slightly oddball trees. Come autumn I’ll have to take some photos to show you the color change.

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Sundew

Interesting though they are (see the downward-facing hairs, to keep insects from crawling out and escaping?), the pitchers aren’t the only carnivorous plant in our bog. To spot the other one, though, you’ll practically have to rub your nose against the sphagnum.

This is sundew, its odd, round leaves surrounded by sticky-tipped hairs. (The fact that the sticky glands look like water droplets gives the plant its name.) The secretions are sweet and tempting, but when an insect makes the mistake of landing here, it’s trapped and the leaf curls around it and digests it.

I’ve never witnessed this plant eat. Maybe sometime I’ll catch an insect to feed to it. It would have to be a very small insect, though.

Because I promise I have a normal-sized thumb, and as you can see, this is a very, very small plant.

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Bog Beauty

One of the delights of the Northwoods (that’s how they spell it sometimes, here, with no space) is the abundance of bogs. The forest will suddenly open to a flat area sparsely wooded with spruce and tamarack, with shrubs such as leatherleaf and bog rosemary beneath them.

Instead of soil and leaf litter, you’ll find a spongy, wet green carpet of sphagnum moss.

And if you’re lucky… perhaps a decidedly odd-looking flower.

Recognize it? This is the flower of a pitcher plant, which has a adapted to the nutrient-poor conditions of the bog by catching and digesting insects in its water-holding leaves. Bogs form where the water is acidic, which hinders decomposition, meaning when plants die the nutrients their bodies contain are very slow to be recycled back into the system.

The patch of pitcher plants that produced this flower was in pretty sorry shape.

If I’d ventured further into the squishy sphagnum, I could have found some nicer-looking ones, I’m sure. Perhaps another day.

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Likin’ Lichen

Once there was a fungus and an algae. The fungus had a really big, nice house with way more space than he needed, but he was a really terrible cook. The algae was a great cook, a gourmet chef, and he was looking for somewhere to live. So, they moved in together… and they took a LICHEN to each other!

I told this joke in almost every forest ecology class I taught at Jekyll Island. It’s a terrible, horrible, awful joke, but at least it helped the kids understand that lichen is actually fungus and algae living together symbiotically, with the algae providing the fungus with food (photosynthate) in return for living within its structure.

Sometimes I would hand each kid a card with a photo and description of a plant we were going to see and let them do the teaching, telling the rest of the group what their plant was called and some interesting facts about it. Invariably the one who got lichen – not technically a plant, of course, but close enough – would look a bit disappointed at first (and so would you, if you were eleven and your classmates’ cards talked about palm trees and Spanish moss!) but then warm to the subject when they read the card, spending the rest of the hike watching eagerly for bright pink splashes of “bubblegum” lichen, which were prettier but less common than the gray-green ones. The facts on the lichen card explained that, though it’s sensitive to pollution and can be an indicator of ecosystem health, it’s also one of the first organisms to colonize bare rock and can survive in harsh environments like deserts… and tundra.

See, this is going somewhere relevant to the Rocky Mountains after all! The rocks scattered among the alpine tundra in Rocky Mountain National Park were covered in lichens in a variety of colors and textures, and one reason the signs once again warned us sharply to stay on the path was so as not to trample them. There are many types of lichens, and though I may not know how to identify them I can still appreciate their diversity.

So, have you taken a likin’ to lichens to? Sorry, sorry, couldn’t resist!

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On the Tundra

Leave the montane zone behind and climb high enough, and you reach the alpine tundra – “alpine” to distinguish it from arctic tundra, although the two ecosystems are much the same.

After looking up at the treeless tops of the mountains for so long, it was incredible to actually be up in them.

You reach these high places via Trail Ridge Road, which winds up and then down again, from one end of Rocky Mountain National Park to the other. We were relieved that the main walking trail was clear of snow, because the road had only opened for the season a couple weeks before, and in places we drove between towering walls of snow. In late June!

In other places the snow was in the process of melting, creating ephemeral pools and streams of clear, cold, pure water.

I gave a presentation in a college botany class years ago on the adaptations of plants to arctic and alpine environments, so seeing this all in person was fascinating for me. The lichens and wildflowers are each going to get their own post!

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The Mountain Pine Beetle

As you drive through Rocky Mountain National Park you see a lot of mountainsides (started to type hillsides and corrected myself!) that look like this.

I admit to increasing the color saturation on this photo slightly to bring out what I want you to see, but the large swaths of red-brown trees are obvious regardless. Something is attacking and killing large numbers of lodgepole pines. The culprit is the mountain pine beetle, Dendroctonus ponderosae.

The dead and dying trees are everywhere you turn.

Pine beetles are native to North America, but droughts and warm winters (likely due to global warming) have led to an unprecedented explosion in their numbers. They infest a pine tree by laying their eggs under its bark, which introduces a fungus into the tree that blocks water and nutrient transport as well as the flow of the sticky pitch, with which the tree might otherwise defend itself. (This is actually similar to how the invasive ambrosia beetle, which I’ve written about previously, attacks bay trees.) Apparently this leads to characteristic blobs of pitch forming on the surface of the bark, and if I’d known that I’m sure I could have found examples to photograph but I didn’t know what I was looking for while I was there.

One of the more effective management techniques is to remove affected trees before the beetles can spread, and we saw some places in the national park where tree removal had been taking place.

Unless something changes, this epidemic could continue indefinitely. Very sad.

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Elk, Elk Everywhere!

One thing we saw in Rocky Mountain National Park was elk.

Lots of elk.

Lots and lots of elk (click to view full size).

In fact, while at one point there were almost no elk left in this area – in 1913 and 1914 about fifty were transplanted from Yellowstone to repopulate them – today there seems to be a herd grazing in every meadow you pass. Because their natural predators, such as wolves and grizzly bears, have been extirpated from the park and its surroundings, their numbers have exploded dramatically. In order to protect sensitive riparian areas from overgrazing, the park has erected fences to create elk “exclosures” around some of the streams. They’ve also culled individuals periodically.

The park’s elk population is closely studied and monitored, and we spotted a couple with radio collars while we were there. One thing they keep close tabs on is the prevalence of Chronic Wasting Disease, a relative of “mad cow” disease that affects species in the deer family.

These weren’t the only large mammals we saw on our trip – we also spotted several moose, and from a distance a herd of mountain big-horned sheep. No black bears, but I should have plenty of chances to see those once I arrive in Wisconsin!

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What Is Cryptobiotic Crust?

There were signs everywhere at Arches warning people to stay on marked trails, because if you left them you risked stepping on and destroying the soil’s cryptobiotic crust.

Wait, cryptowhat? Isn’t that something to do with bigfoot? No, that’s cryptozoology. Cryptobiotic crust is a black layer that forms on the surface of the soil in arid regions, and as the name suggests, it’s actually alive.

See the black stuff on the ground in this photo? If you do a Google image search, you can find other, better images, but basically it’s made up of a mixture of stuff like bacteria, algae, fungus, lichens, and mosses. It’s delicate enough to be severely damaged by a single footprint or tire track, and depending on conditions it can take as long as a century to re-grow when it’s damaged. Soil crust decreases erosion, alters how water infiltrates the ground, and benefits plants by increasing nutrients in the soil. It can be an important part of desert ecosystems.

Did all the warning signs really stop people from leaving the trails constantly? Well…

Nope.