Mostly because it is so hugely variable. There are some trends (e.g. oaks usually live longer than birches), but try to put a hard figure on anything, and most individuals will live much less, except for a few which buck the predictions and live much longer than they are 'supposed' to.

Resin

OK - let's shrink the question down.

We are putting in a Donald Wyman Crabapple, three clumps of river birch and an Autumn Blaze Maple.

I assume the Maple will live the longest but ???? how long do they generally live 40 years? 100 years? 200 years?

Birchs ??? same question - My knowledge base only has long and short but I can't put numbers on those words LOL

Well I can try some figures . . . but there's a greater than 99% probability they'll prove wrong with time . . .

Crabapple: 20-40 years
River Birch: 40-80 years
Autumn Blaze Maple: 80-150 years

Resin

but there's a greater than 99% probability they'll prove wrong with time . . .

Anyone want to take bets?

Let's meet back here in . . .2157 and see if my autumn Blaze Maple is still around!

I think there is a 400 year old pear in the US somewhere that i've read about.

"but there's a greater than 99% probability they'll prove wrong with time"

Yep...as normal, plants, bugs and diseases don't read our books:-)............

IMO, a lot of the life span of a tree has to do with where it is planted. Example; the planting of urban forests in small city lots results in trees growing together resulting in over prunning and eventual thinning of trees. On the other hand, there are live oaks on the LBJ ranch that are over 200 years old shading where the President is burried. Then of course, there are the redwoods and sequios that are many centuries old. Then again, at 66, the potential life span of new planted trees is of little consiquence.

There is a quote somewhere that I am not getting right that basically says to plant a tree you have to be an optimist.

Especially something other than junk fast growers.

If you make a good choice on variety and location, planting a tree is mostly a donation to the next and future generations right?

Pretty rewarding all by itself.

RC, the idea that fast growers=low quality trees has some basis in fact but there are exceptions. Several conifers come immediately to mind: White pine, Norway spruce, Green Giant arborvitae, redwood, dawn redwood. All quality trees and fast growers.

I've heard that quote before myself but I think it distorts the truth a bit. If anything, people tend to underestimate the rapidity of development of their young trees. And of course, if a person is an extreme tree geek (like me!) watching them grow is anything but slow and frustrating.

+oM

hmmmmm - Redwoods are fast growers??

Heck with Maples - I'm planting Redwoods! LOL

Just thought I would add to my thoughts here about how you have to be an optimist to plant a tree that I recently saw and article on a guy that is REALLY an optimist when it comes to planting trees. He is working for NASA and is getting paid to study trees growing on Mexico's highest mtn/volcano to see if in about ONE HUNDRED years we might be able to get trees to grow on MARS. HA.

The article also mentioned that trees were the key to creating our atmosphere, that is why they want to see if they can figure out how to grow them on mars, to start creating an atmosphere we might use up there.

Just another reason to do what we like to do around here and hug a tree, eh?

They surely can't be serious!

Mars' atmosphere is only 0.6% of the density of that of the Earth, equivalent to the Earth's atmosphere at 35km above ground level (4 times the height of Everest). Far too thin to sustain the more complex terrestrial plants.

And even if some terrestrial plants could survive there (the best options would be algae, not trees), permission to introduce them to Mars would not be given, for fear of harming any possible indigenous life forms. The various spacecraft sent to Mars have all been subject to extremely strict biosecurity to prevent even a single bacterium reaching Mars.

Resin

You are of course right about current conditions. But, hey, you know NASA. Always have their head in the sky.

But, to address your point, the "plan" is to introduce gasses that will thicken the atmosphere (ala our greenhouse gasses but even more of the ones that capture most) and then introduce trees.

Sorry for no link, I think I saw it on CNN or Yahoo over the weekend.

I have always heard the faster growing trees are usually the bigger trees, and its often very true. Tulip poplars, American chestnuts, white pines, redwoods, and Ash are all very fast growing trees and all of them are capable of attaining massive sizes. (aside from the american chestnut because of the blight) But as a figure of how old some trees get i have heard of:
Oaks: some to 400 years
Redwoods and sequoias get from 2000 to 3000 years old
There are Bristle cone pines nearing 5000 years old
There are individual creosote bushes in the mojave desert that are over 12,000 years old.
and in tasmania there is a plant called kings holly. it is estimated to be over 43,000 years old. it however is a cloning plant, it reproduces vegetatively, however it flowers, but never produces viable seeds.

There are a good number of fast growing and long-lived trees out there - even the American Chestnut may return to its old glory once blight-resistant cultivators are released to the public (hopefully in 5 to 10 years).

As for growing trees on Mars, that would have to happen after Terra-forming the planet had already begun and the atmosphere was loaded with greenhouse gases. It is probably not an impossibility, though it is not practical at the moment.

"There are individual creosote bushes in the mojave desert that are over 12,000 years old.
and in tasmania there is a plant called kings holly. it is estimated to be over 43,000 years old"

Both unsubstantiated claims with no hard datable evidence!

"As for growing trees on Mars, that would have to happen after Terra-forming the planet had already begun and the atmosphere was loaded with greenhouse gases. It is probably not an impossibility"

Actually, it is an impossibility - first and foremost because Mars has no iron core like the Earth, and therefore no magnetic field; this allows solar radiation to stip away atmospheric gasses much more easily in addition to the lower gravity not being able to hold them well. I'm afraid anyone who says it is possible (even in the very long term), is writing science fiction ;-)

Resin

Here's the article for what its worth

By Catherine Bremer
Updated: 1:11 p.m. CT July 16, 2007

MEXICO CITY - Scientists are using the pine-forested slopes of a Mexican volcano as a test bed to see if trees could grow on a heated-up Mars, part of a vision of making the chilly and barren red planet habitable for humans one day.

Planetary scientists at NASA and Mexican universities believe if they can warm Mars using heat-trapping gases, raise the air pressure and start photosynthesis, they could create an atmosphere that would support oxygen-breathing life forms.

Getting trees growing would be a crucial step. The scientists' quest has taken them to the snow-capped Pico de Orizaba a dormant volcano and Mexico's tallest mountain  to examine trees growing at a higher altitude than anywhere else on Earth.
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"It sounds like science fiction, but we think it's feasible," said research professor Rafael Navarro-Gonzalez, who has spent nine years examining Pico de Orizaba's pine forests.

"We have experienced warming our planet with greenhouse gases, but on Mars we could do it faster with more powerful gases," he said in his lab at Mexico City's UNAM university.

The first human mission to Mars is seen 10 to 15 years away, and the warming-up process could start 50 years later, NASA scientist Chris McKay said. There will also be ethical issues to overcome.

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"It's playing gardener more than playing God, but the ethical questions are important," McKay said.

By pumping in highly insulating gases like methane or nitrous oxide, the scientists think they could heat Mars to 41 degrees Fahrenheit from minus 67 F now. That would match temperatures where trees grow at 13,780 feet on Pico de Orizaba.

Having trees on Mars, as opposed to only simple plant forms like algae or lichens, would open the possibility of humans one day being able to breathe Martian air.

The scientists are studying what makes trees refuse to grow above a certain point, where temperatures drop and the air becomes thinner, to see how easily they could grow on Mars.

"Things don't really start cooking from a biological point of view until trees start growing. Trees are the engines of the biosphere," McKay said.

"It's possible Mars could have trees in 100 years. (But first) we need to understand what sets the tree line on Earth," McKay said by telephone from NASA's Ames center in California.

No calls to earthlings
Despite Mars' lifeless rocky surface, burning ultra-violet radiation and its extremely thin, carbon dioxide-loaded air, humans have for long been obsessed with finding life there.

Scientists believe Mars has ice at its polar caps that could melt into seas and that its subsoil contains the key elements needed for life.

Even though none will live to see the fruit of their work, the scientists on the Pico de Orizaba project believe it would be fairly straightforward to pump greenhouse gases into Mars' atmosphere, introduce bacteria to start photosynthesis and finally send up tree seeds with a human mission.

"Nothing that we know rules it out. There's still a lot of uncertainty, but nothing that's a showstopper," McKay said.

The project would be called off if life was found to already exist on Mars.

"The idea is to explore the possibility of colonizing Mars. If there is life, we have no right to destroy it. But if Mars is barren we could take life from Earth to Mars," said Navarro-Gonzalez, spinning a Mars globe that shows ravines 6 miles deep and dizzying 10 mile high mountains.

His "before" and "after" images show the arid planet transformed into a new world of lush green plains, lakes and mineral-rich mountains that could one day supply earth.

Still, that vision is centuries away. For now, anyone braving the six-month flight to Mars would have to live in a pressurized dome, suffer violent dust storms and be cut off from earthlings too far away to easily speak to.

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In the long term, Mars's low gravity could also have odd effects on would-be settlers, causing people to grow alarmingly tall, and cosmic radiation could cause cancers and mutations.

McKay ruled out anything more permanent than short-term research bases for the next century. "I don't have this vision of people moving to Mars the way people settled the New World, setting up homes and bringing their families."

Yes, I just finished a geological ecology course and the iron core aspect was discussed in relation to maintaining an atmosphere. I agree with Pine Resin. I'd like to know how they expected it to stay put. We'd have to duct tape in on.

Thank you philmont for the clarification.

I guess the other question is where are they getting the greenhouse gasses and can they pump out enough often enough to make up for whatever would be lost to solar radiation?

Some pointed headed engineering type (you know, the kind with real answers) will probably save us from further idle speculation. ;)

"where are they getting the greenhouse gasses"

From the SUV's that the astronauts will be driving around in!

Just to get back on topic:

http://www.nativetreesociety.org/newest_updates.htm

Check out the latest Bulletin from the Eastern Native Tree Society, and there's a great article in there regarding coring trees and computing maximum ages.

Creosote bush (Larrea tridentata)and Kings holly (Lomatia tasmanica) are both clonal. The age of the big creosote clone in the Mohave Desert is based on estimates of how rapidly a clone expands as a "fairy ring", wherein the bush dies on the inside while expanding on the outside. There is no objective evidence for the age of the present-day plant body.

Kings holly is also a clone, but with crucial differences. All the known individuals of the species are found in close proximity. They are triploids, unable therefore to reproduce sexually even if another Kings holly appeared on the horizon. All the individual bushes have the same isozyme genotype. Thus this collection of triploid bushes arose from the same ancestor. Finally, a Kings holly leaf fossil that has been carbon-dated at +/- 43,600 yrs has been found in the Kings holly area, and it has the same triploid characters as the living plants.
For these reasons, and others discussed in my forthcoming book "The Bristlecone Book" the claim can't be dismissed offhand. It has a lot to do with what is considered evidence.