Explore the Benefits of the Hackberry Tree for Shade & Soil

I’ve been looking into trees that offer a lot of bang for your buck, and the hackberry tree stands out. It’s not just about the shade, which is pretty great, but it also does wonders for the soil and supports a ton of wildlife. I wanted to share what I’ve learned about this often-underappreciated tree, covering everything from how it grows to why it’s a solid choice for almost any yard or park.

Key Takeaways

• The hackberry tree provides excellent shade with its wide canopy, helping to cool homes and outdoor areas.
• Its deep root system helps prevent soil erosion, making it useful for stabilizing banks.
• Hackberry trees are very adaptable and can grow in various soil types, including poor or dry conditions.
• These trees are tough, tolerating urban pollution, drought, and salt, and they support a lot of wildlife with their fruit and shelter.
• While they can have some minor issues like weak branches or galls, their overall benefits for shade, soil, and wildlife make them a strong landscape choice.

What Is the Hackberry Tree? 

When I first started looking into trees that offer good shade and help the soil, the Hackberry tree, or Celtis occidentalis, kept popping up. It’s a native North American tree, and honestly, it’s one of those plants that’s tough and useful but doesn’t always get the spotlight it deserves. It’s not as flashy as some other trees, but it gets the job done, providing shade and helping out the environment in its quiet way.

Identifying the Hackberry

One of the easiest ways I learned to spot a Hackberry is by its bark. Younger trees have smoother, grayish bark, but as they mature, it develops this really distinctive corky, warty, and ridged texture. It kind of looks like it’s covered in little bumps or even popcorn. It’s a great way to tell it apart from other trees, especially something like an American Elm, which can look similar in shape. You can often find good descriptions and pictures of this unique bark on sites dedicated totree identification.

Growth and Size

Hackberry trees are pretty adaptable when it comes to where they grow. They can handle a range of soil types, from rich stuff to pretty poor or dry conditions, which is a big plus. They typically grow to be medium to large trees, usually reaching heights of about 40 to 60 feet, with a spread that can be just as wide. They grow at a decent pace, too, adding a couple of feet in height each year, so you get that shade coverage fairly quickly.

Lifespan and Varieties

These trees are known for sticking around for a long time. Under good conditions, a Hackberry can live for 150 to 200 years, which is pretty impressive. It makes them a solid, long-term investment for any landscape. There are also a few different varieties that have been selected for specific traits, like better disease resistance or a more upright growth habit, which can be helpful if you have limited space.

Quick Facts Table

Here’s a quick rundown of what I found

Feature	Details
Scientific	Celtis occidentalis
Native Range	Eastern and central North America
Height	40-60 feet
Spread	30-50 feet
Lifespan	150-200 years
Growth Rate	1-2 feet per year
Bark	Grayish, develops corky, warty texture

While not the most showy tree in the landscape, the Hackberry offers a quiet strength and a host of benefits that make it a truly valuable addition to many environments. Its ability to thrive in tough conditions and support local wildlife makes it a tree worth knowing.

Growth Habit and Canopy

When I think about getting good shade quickly, the hackberry tree comes to mind. It’s not just about how fast it grows, though that’s a big part of it. I’ve noticed that these trees tend to develop a full, wide canopy. This means they spread out nicely, creating a generous amount of shade.

It’s pretty impressive how they grow, usually adding about 1 to 2 feet in height each year. This quick growth is a real advantage if you’re planting a new yard or just want to get some shade established without waiting forever. The branches tend to spread out, giving it that classic shade tree shape.

Canopy Structure and Spread

The hackberry typically grows into a broad, rounded shape. As it matures, its branches spread outwards, often with a graceful arch. This open, expansive canopy is what makes it effective for providing shade. It’s not a skinny, upright tree; it’s built to spread its leaves and branches wide.

Growth Rate and Shade Development

I’ve found that the hackberry’s growth rate is quite good, usually around 1 to 2 feet per year. This means you get shade much faster than with many other tree species. It’s a solid choice if you’re looking for immediate impact in your landscape. This quick coverage is a major plus for anyone wanting to cool down their yard or outdoor living areas without a long wait. For a tree that grows this fast, it’s surprisingly tough, handling all sorts of conditions. You can find more information on fast-growing trees at the native tree species.

Branching Habit and Form

Its branching habit is generally upright and spreading, contributing to that desirable vase or rounded shape. While some older trees might develop a more irregular form, the overall structure is well-suited for creating a dense shade canopy. It’s this combination of spread and density that makes it so effective at blocking sunlight and keeping things cool underneath.

The hackberry’s natural growth pattern, with its wide-spreading branches and dense foliage, makes it an excellent candidate for anyone seeking effective shade. It’s a tree that doesn’t just grow tall, but also grows wide, maximizing its cooling potential.

Shade Benefits

When I think about adding a tree to my yard, shade is usually pretty high on my list of priorities. It’s not just about making the yard look nice; it’s about creating a more comfortable space to use. The hackberry tree really shines in this department. Its growth habit means it develops a pretty dense canopy, and that translates directly into some serious shade.

Cooling Your Home

A well-placed hackberry can significantly reduce the amount of direct sunlight hitting your house, which means less heat absorbed by your roof and walls. This can lead to a noticeable difference in your energy bills during the warmer months. Instead of the air conditioner working overtime, you get natural cooling just from the tree’s presence. It’s a simple, effective way to make your home more energy-efficient.

Creating Outdoor Living Areas

Beyond just cooling the house, that shade creates usable outdoor space. I’ve seen hackberries planted over patios or decks, and it completely transforms the area. It’s like having an extra room, but outdoors. You can sit out there without getting baked by the sun, read a book, have a meal, or just relax. It makes the whole yard feel more inviting and functional.

Shade Benefits Summary

• Reduces home cooling costs: By blocking direct sun, it lessens the load on your air conditioning.
• Increases outdoor comfort: Provides a cool, shaded spot for relaxation and activities.
• Improves air quality: Like all trees, it helps filter pollutants from the air.
• Offers visual appeal: The broad canopy adds a mature, established look to the landscape.

The shade provided by a mature hackberry is substantial, creating a cool microclimate beneath its branches. This makes it an ideal spot for outdoor gatherings or simply enjoying a quiet afternoon.

I’ve found that the hackberry is a really practical choice for anyone looking to add shade. It’s not just about aesthetics; it’s about making your living space, both inside and out, more comfortable and efficient. For a tree that offers such significant shade benefits, it’s a surprisingly low-maintenance option, which is always a plus in my book. You can find more information on selecting the right shade trees for your garden if you’re considering adding one.

Soil Stabilization

When I think about trees that hold their ground, the hackberry comes to mind. It’s not just about the shade it casts, though that’s a big part of it. What impresses me is how its root system works to keep soil in place.

The Power of a Strong Root System

The hackberry tree develops a robust, deep root system. This isn’t just a few shallow roots; these go down and spread out, acting like a natural anchor. This extensive network is incredibly effective at preventing soil erosion. Think about areas near rivers or on slopes – places where the soil is easily washed away by rain or wind. A hackberry planted there can make a real difference.

How Hackberry Roots Help

• Anchoring Soil: The main roots spread wide and deep, gripping the soil and holding it together. This is especially important on banks or disturbed ground.
• Improving Soil Structure: As the roots grow and eventually decay, they add organic matter to the soil. This makes the soil healthier and better able to absorb water, which further reduces runoff.
• Water Management: The roots help water soak into the ground rather than just running off the surface, carrying soil with it.

Planting hackberry trees in areas prone to erosion is a smart move. Their root structure is a natural defense against soil loss, helping to maintain the integrity of the land over time. It’s a simple, yet powerful, way to work with nature.

I’ve seen how effective these trees can be in stabilizing banks, and it’s a testament to their natural design. It’s one of the many reasons I consider the hackberry a top choice for landscaping, especially when you need a tree that does more than just look good. It’s a tree that actively contributes to the health of the environment around it, much like the work done by organizations focused on tree planting initiatives.

Adaptability to Soil Types

One of the things I appreciate about the hackberry tree is how forgiving it is when it comes to soil. You don’t need to have that perfect, loamy garden bed for it to do well. I’ve seen them growing in all sorts of places, from sandy patches near the coast to heavier clay soils inland. It just goes to show you how tough this tree is.

Tolerates a Wide Range of Conditions

It’s not picky at all. Whether your soil is rich and full of organic matter, or if it’s on the drier, sandier side, the hackberry can handle it. Even soils that aren’t considered ideal, like those that are a bit compacted or have less available nutrients, don’t seem to faze it. This makes it a great choice for areas where you might not have the best soil to start with, or for tough urban environments. I’ve found that its root system is pretty adaptable, which helps it find what it needs even in less-than-perfect conditions. It’s a tree that makes the most of what it’s given.

Benefits of Challenging Sites

Because it can grow in such varied soil types, the hackberry is a solid option for difficult planting spots. Think about areas with poor drainage or places that tend to dry out quickly; this tree can often manage where others might struggle. This resilience means you get shade and stability without having to do a lot of soil amendment beforehand. It’s a real workhorse for landscaping projects, especially if you’re looking for a tree that won’t demand constant attention to its soil needs. For anyone looking to add some green to a less-than-ideal spot, the hackberry is worth considering for shade and stability.

The hackberry’s ability to grow in various soil conditions, from rich to poor and dry to moist, makes it an exceptionally versatile and low-maintenance tree for many landscapes. Its adaptable root system allows it to thrive even in challenging environments where other trees might fail.

Drought Tolerance and Urban Resilience

I’ve found that the hackberry tree is remarkably tough, especially when it comes to dry spells and the general grit of city life. It’s not a tree that demands constant attention or perfect conditions. Once it gets going, it holds its own.

Surviving Dry Spells

One of the things I appreciate most about hackberries is their ability to handle periods without much rain. This drought tolerance means I don’t have to worry as much about watering it, especially after the first year or so when its roots are established. It can really make a difference in areas where water is scarce or during those unusually hot, dry summers. It’s good to know that even when things get tough weather-wise, the hackberry can usually pull through. For more on how trees cope with dry conditions, this guide on drought effects on tree physiology is quite informative.

Thriving in Tough Urban Spots

City environments can be really hard on trees. Think about compacted soil, pollution from cars, and even the salt used on roads in winter. Hackberries, however, seem to shrug off these challenges. They don’t seem to mind the less-than-ideal soil conditions often found in urban planting sites. This makes them a solid choice for street trees or in parks where the ground might be heavily used and disturbed. Their resilience in these settings is a big plus for urban greening efforts.

Wildlife Support

I’ve found that the hackberry tree is a real powerhouse when it comes to supporting local wildlife. It’s not just a tree; it’s practically a bustling ecosystem all on its own. The small, berry-like fruits it produces are a lifeline for so many creatures, especially during those lean months when other food sources are scarce. Birds, from tiny songbirds to larger game birds like quail and grouse, rely on these fruits. I’ve even seen flocks of cedar waxwings descend upon them, which is quite a sight.

Beyond just food, hackberries offer vital shelter. Their dense canopy provides a haven for nesting birds and a hiding spot for smaller mammals. It’s also a host plant for a surprising number of butterfly species, like the American Snout and the Mourning Cloak. This makes it a fantastic choice if you’re looking to boost biodiversity in your yard.

• Food Source: The drupes (fruit) are rich in nutrients, providing energy for birds and mammals throughout fall and winter.
• Shelter: Dense foliage and sturdy branches offer protection from predators and the elements.
• Habitat: Serves as a host plant for various butterfly and moth species, contributing to insect populations.

It’s easy to overlook the hackberry, especially with its sometimes-unusual appearance, but its role in the local environment is significant. It’s a tree that truly gives back to the natural world around it.

Even deer and rabbits will nibble on the twigs and leaves, though mature trees tend to be a bit more resistant. It’s interesting to note that the galls that sometimes appear on the leaves hatch in the fall, providing another food source for insect-eating birds and other critters. It’s a continuous cycle of support. If you’re interested in attracting more wildlife to your property, planting a hackberry is a solid move. You can find out more about planting initiatives and resources for trees like the hackberry at Grow Billion Trees.

Butterfly and Insect Habitat

Supporting Native Butterflies and Insects

It might surprise some people, but the hackberry tree is a real powerhouse for supporting local insect life, especially butterflies. I’ve learned that these trees are host plants for a surprising number of butterfly species. This means that not only do adult butterflies feed on the nectar from hackberry flowers, but their caterpillars also munch on the leaves. It’s a pretty neat cycle to think about.

One of the most well-known butterflies that relies on hackberry is the hackberry emperor. It’s quite a sight to see them flitting around. But it’s not just them; other species like the American snout and the mourning cloak also use hackberry trees. This makes the hackberry a really important piece of the puzzle for maintaining healthy butterfly populations in our area.

Beyond butterflies, the tree also provides a home for other beneficial insects. The galls that sometimes appear on the leaves, which might look like a problem, actually hatch in the fall and provide a food source for birds and other insects. It’s a good reminder that what might seem like a flaw can be part of a larger ecological benefit.

The hackberry tree plays a significant role in supporting native biodiversity by providing essential food and habitat for a variety of insects, particularly butterflies. Its leaves serve as a food source for caterpillars, and the tree’s overall structure offers shelter.

Here’s a quick look at some of the insects that benefit:

• Hackberry Emperor Butterfly: Uses hackberry leaves for its caterpillars.
• American Snout Butterfly: Also relies on hackberry for its larval stage.
• Mourning Cloak Butterfly: Another species that finds sustenance on hackberry.
• Tawny Emperor Butterfly: Benefits from the hackberry’s resources.

It’s really quite amazing how much life a single tree can support. Planting a hackberry is a simple way to contribute to the health of our local ecosystems and help out these important pollinators and insects. You can find out more about how these trees support local wildlife on pages like this one about native butterflies.

Longevity and Low Maintenance

When I look at a hackberry tree, one of the first things that strikes me is how long it’s likely to be around. These trees are built to last, often living for over a century, sometimes even reaching 150 years. That’s a serious commitment to a landscape, a real investment that pays off over generations. They grow at a decent pace, usually adding a foot or two each year, so you don’t have to wait forever to see them mature into their full, shady glory. It typically takes about 15 to 20 years for them to reach their maximum height, which is pretty standard for a tree of this size.

What I appreciate, though, is how little fuss they require. Once they’re established, hackberries are incredibly low-maintenance. They don’t need constant watering, and they’re not picky about soil, which is a huge plus in my book. I’ve found that they don’t need much pruning either, just the occasional trim to keep them looking tidy or to remove any dead branches. This makes them a sustainable choice for any yard or park.

The resilience of the hackberry means it can handle a lot of what nature throws at it, from dry spells to strong winds, without much complaint. This toughness translates directly into less work for me and a more reliable presence in the garden.

It’s also worth noting their contribution to the local environment. They provide food and shelter for all sorts of wildlife, especially birds. I’ve seen so many different kinds of birds flock to hackberries, particularly when the berries ripen. It’s a great way to support the local ecosystem just by having a tree in your yard. You can find out more about their role in supporting wildlife on pages about hackberry trees and wildlife.

So, if you’re looking for a tree that gives a lot without asking for much in return, a hackberry is worth considering. It’s a long-term, beautiful, and practical addition to any landscape.

Aesthetic Appeal

When I consider the aesthetic qualities of the hackberry tree, I’m struck by its year-round visual appeal. It’s not just about the shade it provides, though that’s a big part of it. The bark, for instance, is unique. As the tree matures, its bark develops these interesting corky ridges and almost warty-looking bumps. It’s a texture that stands out, especially in winter when the leaves are gone. I’ve seen it compared to elm bark, and I can see that resemblance. It gives the tree a rugged, established look.

Then there’s the foliage. While it might not produce fiery reds or oranges, the hackberry’s leaves do turn a pleasant, warm yellow in the fall. It’s a subtle but lovely transition that adds a touch of color to the landscape before they drop. The leaves themselves are simple, ovate, and have a slightly rough texture, which I find rather appealing. They create a good, dense canopy during the growing season, which is, of course, excellent for shade.

Distinctive Bark

I find the bark to be one of the hackberry’s most defining features. Young trees have smoother, gray bark, but as they age, it becomes rougher, marked by these distinctive corky ridges and tuber-like growths. This texture isn’t just for show; it provides a habitat for insects and offers a visual element that changes with the tree’s age. It’s a characteristic that helps me identify them easily.

Fall Color

While not the most flamboyant tree in autumn, the hackberry offers a pleasing warm yellow hue. This color adds a gentle, consistent warmth to the landscape as the seasons change. It’s a more understated beauty compared to some other trees, but it’s a reliable and attractive part of its seasonal display.

Year-Round Interest

Beyond the bark and fall color, the hackberry provides interest throughout the year. Its sturdy branching structure is visible in winter, and the persistent fruit, which ripens to a deep purple-brown, offers a food source for birds and a visual accent. Even the galls that sometimes appear on the leaves have a certain natural charm and are part of the tree’s ecological role. I appreciate a tree that offers something to look at in every season, and the hackberry certainly does that. It’s a tree that grows on you, much like the native hackberry itself.

Versatility in Planting Locations

One of the things I appreciate about the hackberry tree is just how adaptable it is. I mean, you can plant it in so many different places, and it usually does just fine. It’s not picky about where it calls home, which makes it a great choice for all sorts of landscaping projects.

Street Tree

For urban environments, hackberries are surprisingly tough. They can handle the pollution that comes with city streets, and they don’t seem to mind the salt that gets spread around in the winter. Plus, their roots are pretty good at dealing with compacted soil, which is common in areas with a lot of foot traffic or construction. This makes them a solid option for lining sidewalks or planting in median strips.

Park and Public Spaces

In parks, hackberries offer that much-needed shade for picnics or just a place to sit and relax. Their broad canopy provides good coverage, and they can grow quite large, becoming a real feature in the landscape. They also provide habitat for local wildlife, which is always a bonus in public green spaces.

Residential Backyards

Homeowners can benefit from hackberries, too. If you’re looking for a tree to shade your house and cut down on cooling costs, or just want a nice spot in the yard to enjoy the outdoors, a hackberry can fit the bill. They’re relatively low-maintenance once established, meaning less work for you.

Riparian Zones and Erosion Control

I’ve also seen hackberries planted along riverbanks and in areas prone to occasional flooding. Their root systems are quite extensive and help hold the soil together, which is important for preventing erosion. They can tolerate wet conditions better than many other trees, making them suitable for these wetter spots. If you’re looking for a tree to help stabilize a bank, this is one to consider. You can find more information on selecting the right tree for your specific needs at the tree selection guide.

Whether you’re dealing with a busy city street, a community park, your backyard, or a damp area near water, the hackberry tree has proven itself to be a versatile and reliable choice.

Potential Drawbacks

While I find the hackberry tree to be a great option for many landscapes, I have to admit it’s not entirely without its quirks. Sometimes, you’ll notice these little bumps on the leaves, which are called hackberry nipple galls. They’re caused by tiny insects, and honestly, they don’t hurt the tree much. They just look a bit odd, like little warts. It’s a common thing, and I’ve seen them on many hackberry trees I’ve worked with.

Then there’s something called witches’-broom. This is where a bunch of twigs grow together in a dense, messy cluster, almost like a bird’s nest or, well, a broom. It can be caused by fungi or mites, and while it doesn’t usually kill the tree, it can make parts of it look pretty strange. I usually just prune those sections out if they become too noticeable. It’s important to keep an eye on this, especially if you’re dealing with high humidity, as that’s when the fungi that cause witches’-broom tend to do best.

Another thing that can happen is aphids. These little guys suck sap from the leaves, and when they do, they leave behind a sticky substance called honeydew. This honeydew can then get covered in a black, sooty mold. It’s not the prettiest sight, and it can make the leaves sticky to the touch. While it doesn’t usually kill the tree, a really bad infestation can weaken it. I’ve found that sometimes beneficial insects can help keep the aphid population in check, but if it gets bad, I might consider a gentle insecticidal soap. It’s a trade-off, I suppose, for having a tree that’s otherwise so tough and adaptable.

Why Hackberry Is an Excellent Shade and Soil Tree

When I look for a tree to plant, I want something that does a lot of good without asking for too much fuss. That’s exactly what the hackberry tree offers. It’s a real workhorse for any landscape, providing shade and helping the ground it grows in.

Shade and Cooling

The hackberry’s growth habit is pretty impressive. It develops a wide, rounded crown with branches that spread out nicely. This means it creates a good amount of shade, which is great for cooling down your house in the summer. I’ve noticed that areas under mature hackberry trees are noticeably cooler, making outdoor spaces much more pleasant. It’s a simple way to make your yard more comfortable.

Soil Stabilization

One thing that stands out about hackberry is its root system. It grows deep, which is fantastic for holding soil in place. This makes it a really good choice for areas prone to erosion, like along riverbanks or on slopes. I think of it as nature’s way of preventing soil from washing away. Its ability to anchor itself helps keep the ground stable.

Adaptability to Different Soils

I’ve found that hackberry trees aren’t picky about where they grow. They can handle a variety of soil types, from sandy and dry to richer, moister ground. This adaptability means you can plant them in many different places without worrying too much about soil preparation. They seem to do well even in less-than-ideal conditions, which is a big plus for me.

Drought Tolerance and Urban Resilience

This tree is also tough. Once it’s established, it doesn’t need a lot of water, which is a relief. Plus, it can handle city life pretty well. It tolerates things like pollution and road salt, which many other trees struggle with. This makes it a reliable option for planting along streets or in urban parks. It’s a tree that can really take a beating and keep on growing.

Wildlife Support

I also appreciate how hackberry trees help out local wildlife. The small berries it produces are a food source for birds, especially in the winter. It also provides shelter and is a host plant for certain butterflies. It’s nice to have a tree that contributes to the local ecosystem. It does more than just look good.

Longevity and Low Maintenance

Hackberry trees are known to live a long time, often over 150 years. This means you’re planting something that will be around for a long time, providing benefits for generations. And the best part? They don’t need much care. Minimal pruning is usually all that’s required. It’s a tree that gives a lot without demanding much in return. I like that kind of dependability.

Aesthetic Appeal

Beyond its practical benefits, the hackberry has a unique look. The bark has a rough, corky texture that’s interesting to see, especially in winter. While its fall color isn’t the most dramatic, it still offers year-round interest. It’s a tree that has character.

Versatility in Planting

Because of all these traits, I see hackberry trees used in so many different places. They work well on streets, in parks, in backyards, and even near water. Their ability to handle various conditions makes them a versatile choice for almost any planting project. It’s a tree that fits in almost anywhere.

Overall, the hackberry tree is a solid choice for anyone looking for a tree that provides good shade, helps the soil, and supports wildlife, all while being low-maintenance and adaptable to many environments. It’s a tree that truly earns its place in the landscape.

Looking for a tree that offers great shade and helps your soil? The Hackberry tree is a fantastic choice! It grows well and is tough enough to handle different soil conditions. Want to learn more about why it’s a top pick for your yard? Visit our website today to discover all the benefits of planting a Hackberry tree and how we can help you with your tree needs!

Frequently Asked Questions

What kind of soil and sunlight does a Hackberry tree need to grow well?

I find that the Hackberry tree is quite adaptable. It can grow in many different kinds of soil, whether they are rich, dry, or not very good. It also does well in places that get a lot of sun or just some shade. This makes it a good choice for many different yards and landscapes.

Does the Hackberry tree provide good shade?

Yes, Hackberry trees are known for providing excellent shade. Their branches spread out wide, creating a good amount of shade. This makes them a great option for cooling down your home or making outdoor areas more comfortable, especially during hot weather.

How well do Hackberry trees handle tough conditions like drought or city pollution?

I’ve learned that Hackberry trees are very tough. They can handle dry spells, pollution, and even road salt, which is why they are often planted in cities. They also tend to live a long time, often over 150 years, making them a lasting addition to a landscape.

What kind of wildlife does the Hackberry tree support?

Indeed, Hackberry trees are beneficial for wildlife. They produce berries that birds love, especially in the fall and winter. The tree also offers shelter and nesting spots for birds and is a host plant for different kinds of butterflies.

How does the Hackberry tree help with soil erosion?

I’ve observed that Hackberry trees have deep roots that help hold the soil in place. This is very useful for preventing soil from washing away, particularly on riverbanks or areas where the ground might be disturbed.

Are there any common problems or downsides to planting a Hackberry tree?

While Hackberry trees are generally low-maintenance, I have noticed a few minor issues. Sometimes, their branches can be a bit weak and might break in strong winds. They can also develop galls or have issues with aphids, which can make the leaves look a bit messy, though this usually doesn’t harm the tree.

Where is the best place to plant a Hackberry tree?

I find that the Hackberry tree is a good choice for many places. I’ve seen them planted along streets, in parks, in backyards, and near rivers. Their ability to handle different conditions and provide shade makes them very versatile.

Are Hackberry trees strong and long-lasting?

Yes, I have found that Hackberry trees are quite resilient. They can survive strong winds, dry weather, and even occasional flooding once they are established. This toughness means they often live for a very long time, sometimes over 150 years.