How many trees in North America?

This is a purely numerical question, not a question of habitat. Are there more trees growing in North America today than there were 150 years ago?

My brother made a comment to the effect that he believes there are more trees growing in North America today than there were in the 1800s. I have trouble believing that, considering the amount of urban devlopment that’s happened on the east coast of the US alone.

I’ve found some information on deforestation in North America, but it’s mostly concerned with “virgin forest”.

Thanks very much,

– EJ

Given that large swaths of the upper Midwest were completely denuded of forestation during the 1800’s, it would I think depend upon exactly what time periods are under consideration for comparison.

For the sake of argument how about, 1807, 1907, and 2007?

An article in, I believe, Scientific American some years ago pointed out that the reason songbirds are suffering a decline in numbers isn’t the lack of trees. It’s the fragmentation of the forest and that means that there is more edge to the forests. This exposes the birds nests to more predation by other birds like ravens or cukoos.

“Map Showing in Five Degrees of Density the Distribution of Woodland within the Territory of the United States,” 1873 -William H. Brewer
Easier to see version here: Nevada in Maps

There’s considerable argument about deforestation of the Americas in this thread:
Trees - the new world

I’ve seen charts (I’ll see if I can find them online) before that talked about the amount of timber grown in the U.S. decade by decade. From what I remember, the low point for timber in the U.S. was 1920. After that, it has risen every decade. This doesn’t come from more acres having timber (although some farmland has been reconverted back to timber in some areas) but from growing more trees per acre than in the past. Essentially forests are denser than they used to be.

Well, at least tree farms are.

Forest Service land and private forests are generally denser, too, thanks to fire supression activities.

I found a little bit of data, but not exactly what the OP was asking for, from the Forest Service:

"After two centuries of decline, the area of U.S. forestland stabilized around 1920 and has since increased slightly. The forest area of the U.S. is about two-thirds what it was in 1600.

· The area consumed by wildfires each year has fallen 90%; it was between eight and twenty million ha (20-50 million acres) in the early 1900s and is between one and two million ha (2-5 million acres) today.

· Nationally, forest growth has exceeded harvest since the 1940s. By 1997, forest growth exceeded harvest by 42%, and the volume of forest growth was 380% greater than it had been in 1920.

· Nationally, the average standing wood volume per acre in U.S. forests is about one-third greater today than in 1952; in the East, the average volume per acre has almost doubled. About three-quarters of the volume increase is in broadleaved or deciduous trees."

Both my wife and I and my inlaws have antique houses here in New England. We have also seen pictures of the properties around 1900. What is now dense woods looked like the great plains with no a tree in sight. Large parts New Hampshire, Vermont, and parts of Maine were clear-cut. If you went back in time, many areas would look much less quaint and pretty than they do today. Some of this wasn’t new. When the earliest settlers arrived at Jamstown, they found that they could gallop a horse through the woods because the Native Americans set clearing fires every year and the tree density was low.

In the mid to late 1800’s NH was 20% forest, 80% cleared. Now the numbers are reversed, up to a high of 87% in 1983… So at least in some broad areas this is true. Whether it holds true over all of North America I’m not sure, and it has gone down in NH since 1983.

Yes, absolutely. The photos show a completely different place 100 years ago as opposed to today. Here in Massachusetts, I like to wonder randomly in the woods in parks or wherever else I can find. I almost always see vast expanses of stone walls. They didn’t build nice stone walls in the woods. That was once cleared land and there is a whole bunch of it. Even my very suburban work area has them if you look past the parking lot meaning that even a large office complex might have more trees now than it did 100 years ago.

Here’s an AP/Phila. Inquirer article:

Ditto that. Vermont is now the most heavily-forested of the lower 48 states, IIRC, and has many, many more trees than it did a century ago. I’ve seen lots of old pictures, and the difference is striking.

The claim has also been made here (Oregon), that while there are more trees now than in 1900 (a hundred years later than the OP asked about, but you takes what you can gets), the total biomass of trees is lower: In other words, we’re replacing large, old trees with smaller young ones (and cutting them down again before they have a chance to turn into large old trees).

True? Dunno. But from the air, Oregon looks like a quilt: it’s hard to believe that all those bare spots and 2-year-old growth areas don’t add up to a significant amount of missing lumber.

It’s certainly true that there are fewer old trees in the U.S., no matter where you are, than 150 or 200 years ago. However, I’m not sure that means there is less biomass (although I’m unsure why biomass should matter). Younger trees generally grow in a much more dense group than older trees. With 200-year-old trees, you may have ten per acre (educated guess). An acre of trees that are 20 years old today (without any thinning) would have many, many more per acre. So the biomass may, in fact, be very similar between the two.

Biomass matters because it’s a measure of produced lumber, nitrogen fixation, total light blockage, and oxygen production, among other things (for some of these, the total number of leaves matters more, which is only an indirect dependency of biomass). Plus there’s the issue of high sapling mortality in cleared areas for those species whose “natural” inclination is for the saplings to be shaded by larger trees. If it works out to about the same, maybe it doesn’t matter, but the claim has been made that it doesn’t work out to about the same: that biomass is much greater in old growth than even in tree farms.

Note I’m passing on a claim I’ve heard, not making one of my own – I really have no idea if it’s true or not, and finding unbiased cites on this issue is like finding them on issues involving gays or abortion: the noise covers the signal completely.