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Frequently Asked Questions

Part 2: How Pando Works

Q & A

Physical Characteristics

Pando is the world's largest tree, but how big is it?

Pando spans 106 acres. Today, around 103 acres is visible to naked eye.

outline of the pando tree

What species of tree is Pando?

Populus temuloides Michx. Sometimes this species is called Trembling Aspen because of how the tree’s leaves tremble in the wind. Others call aspen like Pando, Quaking Aspen because of how their bodies shake, shudder and moan in heavy winds. Locals call aspen “quakies“.

Is Pando all one tree trunk?

No. Pando features over 40,000 ramets (aka stems, branches etc. see below) which looks like individual tree trunks, but are in fact, parts of a single tree interconnected by a massive root system.

Has the shape of Pando remained the same all its life?

No. Pando is constantly changing its shape and form moving in any direction the sun and soil conditions create advantage. Any place a branch comes up, is a new hub that can send the tree in a new direction. If you visit the tree and see new stems, you are witnessing the tree moving or “spreading” out in that direction.

The confusing language of Pando: Rhizome, Trunk, Stem, Raments, Suckers and Branches

Pando defies both scientific and common sense descriptions most people use when they think or, talk about trees. A quick review of some key terms working from the ground up.

  • Rhizome: The root system of the tree. Pando’s rhizome came from a single seed that started spreading out some 9,000 years ago.
  • Genet:The term for a genetic clone. Pando is a single genet.
  • Ramet: A part of the larger genet. These look like tree trunks to us, but are part of the larger tree. Each ramet helps balance energy production, defense and regeneration. Today Pando has an estimated 47,000 ramets.
  • Sucker: Term for fresh growth triggered by a hormone fluctuations in the tree. The hormone cycle that sends regeneration continues today which is why we say Pando is not dying.

With so many ways to describe the tree, and most of those technical terms  beyond what most folks know about trees,  Aspen Trees in specific or, asexual reproduction, for simplicity’s sake, we choose to use two terms to generally describe Pando. One term for what is above ground, “Branches”, as they are parts of a larger tree and behave like branches on a more typical trees; gathering energy.  One word for what is below ground, “Root”.

You can wade into the larger body of language on the Science of Pando Page.

Root and Branches: A less confusing way to understand Pando

For general education purposes, we use the term “root” to describe the part of the Pando tree that is below ground and primarily involved in distributing energy and regeneration. We use the term “branch” to describe any part of the tree that is visible and involved in gathering energy above ground.

How many Branches make up Pando?

Pando has an estimated 47,000 branches.

Is every branch connected to every other branch?

Generally speaking, yes. Each of Pando’s branches is connected to the others through a shared root system.

Can one part of the tree get disconnected from the larger tree?

Yes. Pando’s roots build up and fan out. Sometimes, one outlying part of the tree can get isolated from the rest. Despite this, that section its still part of Pando. What’s more, it is possible that the newly isolated part of Pando can become the basis for an new structure of the larger tree. If all else were lost, that part could also continue Pando’s genetic line.

How big is Pando's root system?

Today, we know little about the underground workings of Pando, but our field crews and independent scientists estimate the root system spans across at least 106 acres (42.89 hectares, 0.17 square miles) and based on our field observations along a road cut through the tree before Pando’s discovery, could reach 30 feet in depth. 

How long is Pando's root system?

Pando’s root system is a tangle of roots built up over thousands of years. A rapid field estimate by Aspen Ecologist Paul Rogers suggests Pando’s roots could span 12,000 miles if laid end to end. That would be nearly half way around the world!

I am having a hard time visualizing the roots. Help me out...

Gather a ball of yarn or string and unravel a few feet and cut it.

Now, unravel the yarn randomly back and forth over the floor.

Once you are done, push the edges of the pile inward until you can just barely see through the gaps between strands of string through to the floor.

1. The layers of the string represents the root systems built up over time.

2. The random paths going back and forth across the floor, are how the root system might look if we could see through the ground.

What does a typical branch of Pando look like?

It varies.

  • New Growth: A small plant body about as big around as a drinking straw with a few small leaves, sometimes a few shade leaves and a primary bud. New growth lacks the white bark, but  is highly flexible, which provides defense against trampling.
  • An Unsustainable “Bushy” Stem: This is new growth almost sure to fail as the tree can only grow around, but not upward. In this case, the higher apical buds have been clipped off by foraging or, have been damaged or broken off by wind or falling debris. These “bushes”, tend to be less than 4 feet tall, spread around about 3-5 feet and feature small leaves. They add little energy to the larger system as Aspen grow quickly to into the sky to gather the most sunlight.
  • A Sustainable Branch: Long and straight, about 5-8 inches in diameter, and at least 8 foot tall with a crown that reaches around 6 feet in diameter. At this stage, the characteristic white bark is thin, but and quite pliable. The bark also features small black “eyes”, which are in fact, branch scars where smaller less productive branches have fallen off the body.
  • A Mature Branch: Between 18-36 inches in diameter and able to reach heights of up to 80 feet with a crown that spans outward up to 30 feet. The bark is thicker, features large branch scars (aka “eyes”). The  base of the branch body often features “elephant toes” at the base; long gray furrows in the bark where the skin has stretched out as the tree increased in diameter over time.

Longevity

Is Pando 80,000 years old?

No. At most, Pando is between 9,000 and 12,000 years old because the land it calls home was dominated by glacial weather patterns until that time.

Most Aspen tend to die out after a while, how does Pando keep going?

Scientists call an aspen clone like Pando, a “stable” clone because they set up and take over their land mass’s dominating the water and nutrient supply.

If I visit Pando, would I be able to see the part that is 9,000 years old?

No. Each branch of Pando only lives between 110-150 years. The root itself is constantly spreading and building up, extending the system, and spreading out again. This means it is unlikely any part of the “original” root system remains for testing we can do today.

It may be helpful to think about in this way; every part of Pando, is genetically identical to the Pando seed, which set down thousands of years ago.

Health

What kind of soil does Pando like?

Pando, like most aspen, enjoys  moist, well-drained soils. As aspen are one of the most prolific tree species in North America, they can be found in acidic, loamy, sandy or clay soils. In addition, a study in 1987 suggests that an aspen clone can produce 900 pounds of biomass per acre; that is leaf material, tree material etc. In this way, the tree can feed itself and helps sustain soil conditions it thrives in.

How much sunlight does Pando need?

Pando’s is light hungry and very competitive reaching upwards of 80 feet into the sky to maximize light gatehring. An estimate by scientists who research solar radiation, suggests Pando’s land mass receives enough sunlight to power 210 homes a day.

If I had to water Pando, how much water would I need?

Quick estimate: 8.46 Million Gallons every three weeks

 

The Math
As a gardener’s rule of thumb, you should give a mature tree about 10 gallons of water for each inch of diameter of the trunk. Since Pando has around 47,000 branches (trunks, see above), each of which can reach up to 36 inches in diameter, we are talking about a lot of water.


47,000 Branches x 18 inches (conservative diameter of a mature tree) X 10 gallons
=8,460,000 gallons of water every three weeks. 

If Pando needs that much water, where is it getting it from?

Natural Springs, snow melt and summer rain. Pando lives along the lower edges of Fishlake Basin, a steep, high-mountain watershed that feeds Fish Lake. Fish Lake spans nearly 6 miles and reaches depths of 120 feet. We know 70% of Fish Lake is fed by springs. While we still have much to learn about hydrology in Pando, it is arguable, Pando is getting most of it water as the water moves through its steep mountain basin homeland.

What kinds of diseases would I have to treat if I had to take care of Pando?

Fungal and Insect Borne. Pando, like all aspen, is susceptible to fungal diseases, and diseases precipitated by insect activity. We still have a lot to learn about diseases in Pando and the role they play in its health.

How drought tolerant is Pando?

Aspen are drought tolerant. We also know from historical records that Pando has survived droughts that have spanned 300 years.  What’s more, Pando’s homeland near the bottom of a large large watershed probably give some advantage to Pando during dry spells.

Reproduction

How does Pando reproduce?

Pando self-propagates from suckering, a hormonal process.

How Suckering Works: When growth hormones build up along the edge of a root, they spur the creation of a ramet. If conditions are right, the ramet will send up a new stem called a “sucker”. Given time to grow, that sucker will mature and the roots of that branch will also spread outward so that the process can begin again.

Is there a limit to how long Pando can re-produce by suckering?

None that we know of today. Each new stem that becomes a branch, can send out roots that will repeat the process indefinitely as long as the tree remains healthy.

Does Pando makes seeds?

Pando is male, and so, only produces pollen. It can, (and likely has) mated with female aspen in its homeland meaning Pando could have sons and daughters. 

Environment

Is Pando's land mass all just the Pando tree?

Generally speaking, yes. Others trees can take up inside Pando including Spruce, Juniper Bushes and other Aspen. Those trees don’t tend to do well because Pando dominates available water, nutrients and sunshine. 

Can Pando survive a wildfire?

Aspen, including Pando, are fire tolerant for low to medium intensity ground fires as their branches hold enormous amounts of water while the crowns reach high into the sky. In some cases, fire is used to help stimulate regeneration.

If a fire was hot enough to burn Pando down, would that be the end of Pando?

No. The growth hormones that spur regeneration are concentrated in the root system, but spread out in each branch. If a branch is burned, cut, knocked over, the hormones blance in the roots shifts starting the process all over again. You may be surprised to learn that fire has been used to purposefully shift the hormone balance to spur regeneration. 

Animal Interaction

I've heard that deer are a problem in Pando, help me understand...?

The problem with deer, and elk  is their preference for eating the stems of new growth. This hinders Pando’s ability to keep energy production and regeneration in balance as the new growth either dies, or is unproductive throwing energy production out of balance.   When deer or elk eat at the bark of mature trees, they can leave scars which create pathways for diseases and other animals to destroy healthy branches.

How do we keep Deer out of Pando?

Fencing, and a lot of it. Today, the Forest Service uses about 10,000 feet of 8 foot tall fencing to keep deer from over-browsing on Pando. Today, that fence encloses over 53 acres of the tree with more work planned.

Are all deer bad?

No. Deer play a role in the nutrient cycles are and have been part of Pando’s ecology since its birth

What about Cattle Grazing?

Cattle Grazing is not allowed in fenced in areas (53 acres). In fact, cattle grazing is only allowed in one small unfenced part of the tree for 10 days a year after peak growing season,  if weather permits. It’s important to note, leaders from local grazer groups have stated publicly, they want to see more of Pando fenced in and protected because the massive yearly leaf fall, feeds the land.

Friends of Pando is dedicated and working to educate the public, support research and preservation efforts and inspire stewardship of Pando, the world’s largest tree.

 

Friends of Pando is a proud partner of Pando’s public land stewards, Fishlake National Forest of the U.S. Forest Service, Department of Agriculture. Learn more about our partnership.

 

Friends of Pando and its partners are equal opportunity employers.

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Just $14 a month supports work to ensure Pando can be enjoyed for generations to come. Make a one-time or, recurring tax deductible donation today.

Friends of Pando
PO Box 12
Richfield, UT, 84701
Phone: 435-633-1893
IRS EIN: 87-3958681