How do you know when a tree is "getting old"?

[Andy B.]

I've been reading through all the forums here, and I'm only back to maybe 2011 so if this topic has been covered before and I didn't get to it yet, I apologize.

I've mentioned in several other posts that I like big trees and I'm not looking to cut anything down around my place unless there is a reason to (lots of things could be reasons of course).  One question I have is how do you tell when a tree is nearing the end of its natural life?  I don't mean one that has been hit with disease or beavers eating the bark off the bottom or something.  I mean at some point I would assume a tree just "gets old", or is that an incorrect assumption?  I also realize that trees in optimum locations with no outside influences can probably live an exceptionally long time.  But say in general, if you have for example a red oak of some variety, do they normally reach a certain height or diameter and after that point don't really grow much or just start entering a stage of decline?  Or is this lifespan measured in a timeframe so long that as a human I have no need to worry about it because my great-grandchildren will be dead long before any tree I own will die a natural death?  As a child I just remember my grandfathers saying things like, "oak trees only live around 100 years or so" and similar things.

Keep in mind I'm not asking when a tree becomes marketable, just when it should be removed because from a certain point on it will start going into decline and losing value to the forest.  Value could be monetary, but it could also be a tree that is preventing any other tree from growing, or an apple tree that is hollow and no longer produces many apples, or a pine tree that no longer produces any seed to reseed the forest floor for the next generation, etc.  I guess the question could also be asked that if a forest has a dense canopy of healthy trees, are small trees always going to be "unhealthy" until a large tree is removed?

This question may not have an answer, and that is an acceptable answer to me.

Andy B.

[Ianab]

Probably a lot of different answers depending on what trees and where you are.

Regarding a trees "age", look up at the crown. In a young and vigorous growing tree there is a lot of healthy growth up there. Lots of leaves, few dead branches.  An old tree will tend to have a lot of dead material in the tops, and sparser leaves. This makes a big difference to the growth, and how much wood it's producing down on the trunk. Eventually the tree runs out of "vigor" and can't keep up with the attacks of pathogens, and dies. Or rot gets to the roots and it falls over in the next storm.

How long? Depends on the species. 100 years is probably about right for some oak species. It's not a fixed time thing, but that would be a good average. Different species, different time spans. Some smaller tree species might go into decline after only 20 years, others can remain vigorous and growing for 500 years, and live for 1,000s.

If you are putting a $$ value on the forest, then there is a certain time when it's best to harvest a tree, and that may actually be earlier than it appears. Reason is that the most growth is in young trees. Harvest after 50 years, regrow and harvest again in another 50 and you are probably way ahead of waiting 100 years, and getting a 50% better return. You've had the money from the first harvest invested for 50 years. This is where accounting meets forestry, but if it's an investment, then you need to consider things like that.

If you are managing for other purposes (wildlife, aesthetics, hunting etc) then priorities might be different, and those big old dying tress may be an important part of the "ecosystem". Nest trees for wildlife etc.

I guess the question could also be asked that if a forest has a dense canopy of healthy trees, are small trees always going to be "unhealthy" until a large tree is removed?

Not necessarily "unhealthy", probably "different". Some tree seedlings are shade tolerant, and even need shade to grow. So you may get succession occurring, where the make up of the forest changes over time. From open growing types, to the more shade tolerant species over many generations. This isn't necessarily good or bad, depending on what those species are. I think if you want more Oaks, then you need to clear decent openings, and let in sunlight, for the seedlings / saplings to grow. If you just remove single trees it may be that other shade tolerant species will start taking over.

"Managing" forest is the "art" of adjusting these natural processes to get the results we want.

But different forests have different make up and different dynamics. So there is no universal rules. What applies to our local rainforest or plantation pines might be very different to a Nth American mixed hardwood forest.

Ian

[Autocar]

Alot of it comes from years of exsperance working in areas of the country. I can cut red oak within a few miles of each other that a twenty inch trees will cut bad but a few miles away four foot reds will cut just fine. I believe it comes down to while the acorn lands to wet, not enough moisture,  just perfect. Or you can let them stand and lose them to a wind storm or let them get so darn big they cover such a area that when you do cut them they wipe two or three trees out when it lands. Here in my country two feet to thirty inches are purfect to cut theres good wood in them and the growns are small enough you can lay them down without alot of damage. Iam working a job right now where the farther wouldn't cut any trees, now hes in the nursing home and the son called me they had a wind storm and theres alot of damaged timber everything Ive cut was bad where it snapped off but landed on thirty inch white oaks breaking the tops out of them some damaged so bad that a 40 foot log was shadered and cutting a eight foot butt log I was only able to get half a log out of it. Just remember there just like a crop of corn or wheat once there ripe its all down hill from there trees it just takes a little longer  ;).

[Andy B.]

Thanks, that is the kind of info I was looking for.

I'm in southeastern, PA.  There is a stream through the property, so a lot of it gets wet, and there are several areas where the water table is high enough that there is almost always a small patch of standing water.  During the few large rain storms we've had over the past 15 years (storms classified as 100-year-storms) only the stream banks within about 5'-20' get flooded, so it isn't like it is a 200' wide flood plain that floods every spring.  Is there a reference that lists tree species that grow well in this type of habitat as well as the shade-tolerance of them?

I'm a relative newbie at all of this, so any info is helpful.

Andy B.

[WDH]

You might want to read this book, but I warn you, you will learn some big words, and it you use them on here, you will catch some grief  :D.

http://www.amazon.com/Harlow-Harrars-Textbook-Dendrology-Hardin/dp/0073661716

In conjunction to this text, you might get a tree book for PA.  Check with this link as a starting point to search for publications on forest management for the species in your area. 

http://ecosystems.psu.edu/extension

[Andy B.]

You might want to read this book, but I warn you, you will learn some big words, and it you use them on here, you will catch some grief  :D.

http://www.amazon.com/Harlow-Harrars-Textbook-Dendrology-Hardin/dp/0073661716

In conjunction to this text, you might get a tree book for PA.  Check with this link as a starting point to search for publications on forest management for the species in your area. 

http://ecosystems.psu.edu/extension

I like it!  Keep it coming!!

I guess a bit more of an intro about myself that may be pertinent.  For more then 20 years I've had salt water aquariums (for more than 30 years I've had either a salt water or fresh water aquarium).  I have textbooks on coral taxonomy, fish taxonomy, ocean ecosystems and habitats, etc.  Big words and scientific names don't scare me.  :D  I find this entire forest ecosystem extremely interesting and am not afraid to learn all I can about it.  I'll never have a coral reef in my backyard, but I can hopefully have a cool forest.

My current interest is heirloom apples and tomatoes, along with strange and obscure peppers.  Toss in a few odd trees that I can get growing out back, and I'll be a happy man. ;D

Andy B.

[terry f]

    Andy, you seem to be in the same boat as me, in that making money off the timber isn't the primary concern. Forest health, aesthetics and wildlife are my concerns, even if they don't always go hand in hand. Aside from the lodge pole pine, every tree on my place could still be alive 10 generations from now. The larch, ponderosa and doug fir all live hundreds of years here. I have a few trees die every year, but I don't think any die if old age. Good luck on making your little piece of heaven the best you can, managing a mixed age forest can be tough, especially deciding which one to cut and which one to leave when you are thinning.

[Ron Wenrich]

Your trying to define tree vigor, not necessarily its age.  When vigor declines, the tree is more susceptible to disease.  Size isn't necessarily an indicator of vigor.

For trees to grow, you need to allow for crown expansion.  Those trees stuck in the understory have little opportunity for crown expansion, since it can't get the light needed.  This also affects the vigor.  A small tree in the understory may be just as old as a large tree in the overstory.  Your options are to remove the tree in the understory, cut the tree in the overstory to release the small tree, or do nothing.  Most often, the landowner is advised to cut the tree in the overstory to release the small tree.  Not always the best move.  You could also kill the tree by girdling and allow it to remain as a wildlife tree.

Ian has given a good indicator of with the amount of dead material.  You just have to keep in mind that some trees prune easier than other trees.  Tulip poplar rarely has dead branches, where pin oak holds on to them for a very long time. 

Bark is a good indicator.  Its much like the skin on a person.  If you're seeing flat areas on red oak, for example, its a good indicator that the tree is in decline.  The color will also look different from a healthier tree.  Old trees usually have thick plates and the fissures are deep. 

Seams often lead to rot. Not always, but its often an avenue for insects (mainly ants) to invade and take up residency.  Swollen branches are also an indicator of rot.  Once the rot sets in, the tree will start to decline.  You'll see this more often in the oaks then in some of the other species. 

Since you are trying to keep your forest in a fully stocked condition, it might be handy to know some things about basal area measurement.  Its a simple measurement that can be done with angle gauge.  The one I use is about $15.  You would be wanting to keep your stocking at about 110-120 sq ft/acre for fully stocked hardwood stands.  You could go a little heavier with big wood.  When cutting, you don't want to go too much below 60-70 or you run the risk of epicormic branching, which causes defects in the wood.  Keeping your woodlot in those bounds will help maintain the vigor. 

[WDH]

You can also use herbicide to kill undesirable low value trees (from all standpoints like timber value and wildlife value, etc.) or trees that are shading out more desirable trees or saplings.  This creates the opportunity for target species to flourish, you do not have to have logging equipment on site to do it, you can do it yourself, and the woodpeckers will love you.  The simplist way to do this is the hack-n-squirt method.  All you need is a sharp hatchet and a spray bottle like bathroom cleaner comes in, and herbicide to put in the squirt bottle.  The herbicide label will detail how to perform the treatment. 

[Andy B.]

Your trying to define tree vigor, not necessarily its age.  When vigor declines, the tree is more susceptible to disease.  Size isn't necessarily an indicator of vigor.

Ron,

YES, vigor is the term I was searching for!  I realize it is not easily defined, but I'm learning more about the forest every day.  If you would have said to me "you run the risk of epicormic branching" a few months ago I would have given you a blank stare and asked what the heck are you talking about.  Now when I walk along the edges of my yard and look at the trees on the edge of the wooded areas, I know exactly what "epicormic branching" is, and I am starting to understand what causes it.

I'm going to pick up one of those angle gauges and take some photos and post them in a new thread.

WDH,

There are a few standing dead trees the woodpeckers love.  Those trees have lost all "vigor".  :D  They aren't really worth anything for firewood at this point, so I just leave them alone until they fall over.  I'm not ready to start removing any living trees yet.  I need to learn more about what I have and what is worth keeping before moving to the next step.  Well, except for those boxelders that get in my way.

Andy B.

[SwampDonkey]

Yes, knowledge of silvics and of your local forest region is a head start. Take where I live here in NB and look at balsam fir as an example. In the south of NB, fir lives about 60 years, up here further north 90 years and they also grow bigger.

When I look at the bark of a balsam, if the bark is 'dried up', I mean the pitch blisters are no more, and if I see seems, the centre is gone to dung. When I look up, the new growth is very short, lichen in the branches. Then I know I have an old tree here. I have cut many fir with a brush saw that are 50 years old, about 2" on the stump, no pitch blisters, lichen in the branches. Junk trees. How a mill thinks this will make future logs is beyond me, won't even make good pulp.

I have also cut 45 year old fir that is 18" at breast height, chalk white with blisters. The neighbors cut a lot of 50 year old fir (within 5 years of that) last winter and 18-20" dbh. Mature for up north here, but not over mature. But time to harvest before the balance of life tips over the hill.  ;D

[thecfarm]

Andy,look up into the trees, If you can see thorugh the limbs when the leaves are on,it's getting old. No big words with that one.  :D  Those dead trees are called wildllfe trees.A forest is a wonderful thing.

[Clark]

I would agree with most of the above statements and add that when you hear someone claim a tree is past vigor based purely on the size of the tree, watch out!  Trees are amazing things and live so much longer than humans it seems to be the human compulsion to make sure they don't live longer than us.  I don't know how else to explain it but there are many people who believe that a tree XX" in diameter needs to come down.  Especially when it's an urban tree and doesn't show sign of decay or weakness, let it live.

"Managing" forest is the "art" of adjusting these natural processes to get the results we want.

Ian, you had so much good advice but I have to correct you on this one.  The word you are looking for is "craft", unless you want to start defining "art"!

Clark

[JByrd]

A neighbor had a 3 ft diameter oak in his front yard cut down because it was dying - most of the leaves were gone on one side.  I counted 230 rings, so this tree was a baby just after the American revolution.  The tree was over 100 years old when it was less than a foot in diameter.  Then, the rings doubled in thickness the rest of the way out.  I am guessing the faster growth started when Europeans invaded the area (Ohio - early to mid 1800's) and cut down most of the trees. 
The point is, don't judge an oak by it's age, judge it by size and condition.

Feb 2014 update on this oak - I quartersawed these logs and stored the lumber in my barn loft for over a year.  Recently made about 400 bf of tongue and groove flooring from it.  This is the nicest lumber I have ever used.  Lots of radial flecks, boards flat and straight except around the knots.  Since the central part of the log grew over 100 years ago in a dense forest, it has the extremely fine grain normally found only in old growth timber.