Poplar – The Homemaker

Poplars are some of the fastest-growing trees in the world. They can tolerate the worst conditions and are heavily favored by wildlife. In places where land has been degraded or is falling apart, the poplars can rebuild. They produce tremendous amounts of biomass, feed unbelievable numbers of insects, birds, and mammals, and suck tons of carbon out of the sky like gigantic outstretched vacuums.

The following excerpt is from Trees of Power by Akiva Silver. It has been adapted for the web.

(Photography courtesy of Akiva Silver unless otherwise noted.)

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Listen to the following excerpt from the audiobook of Trees of Power.

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There are 35 species of poplars in the temperate world.

On an industrial scale poplars are widely used for paper, biofuels, chipboards, boxes, matchsticks, paneling, furniture, and a host of other products. To the homesteader they can offer a profitable side business. Because they coppice so well, all the poplar species can be used for any project involving biomass.

Quaking Aspen (Populus tremuloides)

Also known as the trembling aspen, quaking aspens grow across a wide range. They are native from Nova Scotia across most of Canada to Alaska, extending south through Pennsylvania in the East and down through the Rockies out west.

Their name comes from the way the leaves move in the wind. Like all poplars, quaking aspens have a flat stem. They flutter back and forth very fast in any breeze. The sound in a grove of aspens on a windy day has got to be one of the best sounds on Earth.

Quaking aspens have a very white bark that is often confused with birch bark. Birch trees have lenticels (horizontal lines) on their bark, however; aspens do not. Quaking aspens also have a white powder on their bark (some trees more than others; western trees seem to have more of this powder). It can be wiped off with a thumb; it feels a bit like chalk powder. Birch bark, on the other hand, is full of lenticels and peels off in strips with no powder.

The trees grow fast, but not very tall, around 40 to 50 feet. Quaking aspen is the most prolific root-suckering tree I know of. Aspens send out horizontal roots that grow like mint, but on the scale of trees. They can form large colonies through their root systems. The most famous of these is in Aspen, Colorado, which is home to a 3,000-acre grove. This grove is one organism—a single tree with a massive root system and many trunks. If you don’t think nature creates clonal monocultures, the aspen may cause you to question that.

Aspen groves can live for a long time. There is one in Utah that has an 80,000-year-old root system. None of the trunks are very old, but the roots continue to send new shoots up.

Quaking Aspen Habitat

These trees create different ecological conditions depending on if they are growing in the western mountains or the eastern forests. They both require abundant sunlight. Out west they form large pure stands and persist for very long periods of time. You can see huge groves of them in the Rockies in the fall, when their yellow color really stands out. In the East it’s a completely different story. Here quaking aspens appear in old fields and disturbed areas. They have only a certain amount of time before bigger hardwoods take over. Quaking aspen creates an outstanding situation for hardwoods to grow.

They will spread into the worst spots—wet, muddy fields, piles of sand—anywhere there is sun. They grow fast and create a lot of biomass. Their leaves and wood decompose rapidly. Their canopies cast a light shade. In the middle of an aspen grove, you will find grasses and shrubs and tree seedlings. This light shade reduces stress for many species that would have a tough time establishing themselves in an open field. After around 50 years, the bigger timber trees will have taken over and the aspens will have died out, their trunks falling over as a massive carbon mulch for the soil. They set the stage for fields to turn into forests. Aspens will persist on the East Coast if there is continued disturbance, but without it they’ll give way to the giants.

In any situation, quaking aspens create some of the best wildlife habitat in the temperate world. Their buds, leaves, bark, and catkins are highly palatable to many species of birds and mammals. While the groves are young or after a large disturbance is the time when groves offer the most. When aspens are cut, burned, or disturbed, they will send up a huge amount of shoots. These can grow very densely, offering great cover and a lot of food at the same time. The buds and catkins are a big winter/spring food, highly sought after by wildlife of many types. Grouse, deer, and beaver are probably the most notable species to thrive off aspen groves, but there are also countless song-birds, elk, moose, porcupines, rabbits, and hares. There are virtually no herbivores that do not feed on poplars, and quaking aspen offers the most food of all the poplars. It grows the most stems with its end-less suckering habit.

Quaking aspens are so tough, they can be cut ruthlessly and repeatedly and show no loss of vigor. I have never raised livestock, but if I did I would have a hedge of aspen somewhere for them. The trees can withstand repeated browse. I have seen groves of aspen establish themselves in areas with absurdly high deer populations.

In a world of degraded soils and dwindling numbers of birds and amphibians, the aspen offers us a low-maintenance approach to healing damaged lands.

Managing Quaking Aspens for Wildlife

Older aspen trees offer the best den sites and woodpecker food. Younger stems offer better cover and easier-to-reach buds, catkins, and leaves. Grouse do especially well in these thickets of young aspen stems. Younger stems also have more tender bark for mice, voles, beavers, and rabbits. It is best if you can have a mix of old stems and young ones.

Young sprouts will not grow under the canopy of older trees. There needs to be an open side that the grove can spread into. You can maintain this open area by cutting it down every few years. After aspens are cut, they will send up a lot of stems the following year. It’s better to cut trees while they are dormant and their reserves are in their root systems. In some parts of the country, aspens are managed with fire to make them productive. Productivity is measured in stems per acre.

If beavers are present in a grove, they will cut every tree within reach. For trees that are farther inland, they will dig canals and get all the aspens they can. The trees respond with abundant sucker shoots. These grow on a rotating basis as the beavers repeatedly harvest them.

I believe quaking aspen creates some of the best wildlife habitat of any plant, offering cover and year-round food. At the same time, aspen groves are some of the most soothing places to walk through as the filtered sunlight and rushing of the wind through their shaking leaves make their way to your senses.

Eastern Cottonwood (Populus deltoides)

These are the giants of the poplars. Eastern cottonwoods can grow to over 100 feet tall. They grow rapidly—enormous trees are often no more than a few decades old. A friend of mine once cut a cottonwood growing too close to his house. The tree was close to 20 feet tall and had a trunk the diameter of an average adult man’s leg. When we counted the rings, it was hard not to laugh. There were only four. They were spaced over an inch apart. This tree can put on wood at a staggering rate.

Cottonwoods can spread clonally like the quaking aspen, but not nearly as prolifically. In general they spread by seed, releasing it on warm sunny days in late spring. The cotton-like u looks like snow as it spreads everywhere. Seeds that land in waterways are carried o until they are washed ashore on some gravel bar or bank. This is how they are most successful at propagating themselves.

Cottonwoods drink copious amounts of water. They are generally found along riverbanks, canals, and abandoned gravel pits. They drink so much water that they can dry wet spots up. Once while working in the tree service, my colleagues and I were taking down a large cottonwood in the summer. My co-worker’s chain saw touched the trunk of this giant—and out came a fountain of water. It looked like a drinking fountain, only about twice as thick a stream of water. It poured out in this fashion for several minutes. I felt compelled to taste it and almost puked when I did.

Trunks over 4 feet in diameter are not rare. These giants only live to be around 70 to 100 years old. As they decline, they leave a wake of biomass behind. Large limbs and trunks become riddled with woodpecker holes as the birds easily tear apart the soft wood to find grubs inside. Denning sites for mammals are common in old cottonwood trunks. The wood breaks down pretty fast, and is an outstanding builder of soil.

The trees coppice well. They can withstand high browse pressure. Their leaves and buds are just as popular among wildlife as the aspens are. Cottonwoods are a supreme biomass tree. They will feed and house an abundance of wildlife while enriching the soil and drinking excess water in wet areas. There are several other species of cottonwood ranging across North America. Most grow along waterways. In some arid regions out west, they will dominate riverbanks.

Bigtooth Aspen (Populus grandidentata)

These trees grow sporadically throughout the eastern woodlands in forests of various ages. I have found them in both young and old woodlots. They are usually found as just a few scattered specimens, but in forests that have seen a lot of logging they are often more common. They provide the same food and habitat as the quaking aspens and cottonwoods, but on a smaller scale since they don’t grow in dense groves.

Bigtooth aspen has possibly the most beautifully colored leaves in fall. Colors can range from iridescent shades of purple and pink to yellow and red, all on the same leaf. The margins of the leaf are covered in big teeth (no kidding).

I thought of bigtooth aspens in the past as low-value trees in the woods, but I have come to see that, scattered throughout the forest, they add an element of diversity. The trees feed an abundance of Lepidoptera and other insects. Birds and mammals use their trunks, leaves, catkins, and buds.

White Poplar (Populus alba)

This tree is native to Eurasia. It was once widely planted as a windbreak and for ornamental reasons. Due to its naturalizing habit, it is rarely planted today; it’s now viewed as a noxious weed. The leaves of white poplar are silver on the underside and very beautiful in the wind. Non-native poplars do not feed native Lepidoptera and other insects the way native trees do.

Hybrid Poplars

These have been bred by crossing European poplar (Populus nigra) with cottonwoods. The trees grow extremely fast, often reaching 30 feet in just three or four years. The wood they produce is harder than the native poplars and is suitable as a fuel wood.

Hybrid poplars grow so fast that they are typically harvested on a seven-year rotational basis. Logs are used for making plywood, biofuels, and paper (yes, at age seven!).

Plantations of hybrid poplar are always made of clones. Some of these large plantations out in the Northwest are thousands of acres and support little wildlife. They are voids for biodiversity. This is not the fault of the tree, but a mistake of management. The difference between clonal blocks of native poplars and hybrid poplars is in the origin of the trees. Native insects have evolved to eat native poplars. There are countless species that will only feed on poplar leaves. These insects are the backbone of a food web that supports birds. Hybrid poplars do not feed insects the way aspens do. In fact, many newer hybrid poplar clones have been genetically engineered to avoid being food for Lepidoptera (butterflies and moths). These trees have had Bt (Bacillus thuringiensis) added to their DNA. Bt is a bacterium that is regularly used to kill Lepidoptera. The result is a silent forest. Transgenic poplars are not available to the public in the United States at this time. They are widely planted in afforestation projects in China.

Hybrid poplars are more suitable in mixed plantings or as hedgerows and windbreaks on diverse farms. They make fast-growing hedges, o er a massive amount of wood at a young age, and can be cut again and again. For details on growing and using hybrid poplars, I recommend Peter Greatbatch’s Practical Guide to Renewable Energy Using Hybridized Hardwoods.

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