Tree Species - Appalachian vs. European

A number of years ago I heard on some PBS show that there are more species of trees in the Appalachian area of the United States than in all of Europe. I haven’t been able to confirm this on google or other searches, and I’m wondering now if I heard that correctly. So, is this true, and where can I find info on it? It seems possible that at one time there were more species in Europe, but perhaps their numbers have been reduced due to clearing, etc. In any case, thanks for the help.

I suppose that is possible, though it seems unlikely; Europe is a huge place, and you’ll find plants in niches from taiga to tropical. The circumpolar boreal forests contain an immense and varied biomass for instance.

I wonder if what you heard is that there are more types of trees harvested for commercial use?

The Appalachians are known for diversity of species due to the numerous microclimates in the range. Microclimates are separated by differences in elevation, orientation with regards to Sun and wind, water, etc. George Costantz’ book Hollows, Peepers, & Highlanders, An Appalachian Mountain Ecology is an easy, interesting reference. If it’s available online, the first chapter “Origins” has a good explanation.

I remember that the statement specifically mentioned species of trees. While not remembering the exact quote, I do recall telling my mom about it soon after while riding down I-81 and taking note of the trees while going past. I wouldn’t have been able to see other plant species, thus my memory is reinforced by this.

There wouldn’t be more tree species than Europe. Europe has about 500 native tree species, and the Appalachians would be lucky to have even 1/4 of that diversity.

I suspect what they said is more tree species than Western Europe. Western Europe is a handy comparison for this sort of boast because it was scoured clear by glaciers a few thousand years back and still hasn’t recovered. Depending how you define "tree’ and “western Europe” there are only 50-100 tree species in that region. The British Isles only have about 30.

It’s quite common to see comparisons to Western Europe when it comes to woody plant diversity, but it means very little. The dozen acres of scrub around the corner from house contains more tree species than Western Europe. so it’s not much of a a boast to say that an entire mountain range has higher diversity.

It’s well known that the tree diversity in Europe is much less than that in either eastern North America, or eastern Asia. This has often been attributed to many trees having been wiped out of Europe during the Ice Ages, since they would have been blocked from migrating southward by the Alps and Mediterranean. This article, however, suggests that present climatic factors can account for the difference.

Interesting and informative comments, all. Thanks.

I found the PBS show, Appalachia: A History of Mountains and People. According to it “[s]cientific anecdotes about the nature of the region help viewers appreciate Appalachia as an ecological treasure. One acre of cove forest in the Great Smoky Mountains supports more species of trees than all of Europe.” It seems I greatly overestimated, that is to say, mis-remembered, the area of Appalachia needed, at least according to this production.

That’s a claim that I find very, very hard to believe. 100-200 tree species per hectare is the level of diversity found in lowland rainforest. Very difficult to believe there is that level of diversity in a deciduous, temperate forest in mounatinos terrain.

I’d take sch a claim with a grain of salt until someone provides some actual evidence.

I’m having trouble finding actual data on tree diversity in the Appalachians. Long ago I recall being told there might be something like 40 tree species in a cove forest in the southern Appalachians, but I don’t have any cite. This paper gives a figure of 181 tree species in a 2.5x2.5 degree quadrat in western South Carolina, but of course that’s a much much greater area.

Where are you getting your figures on the number of trees in Europe? Here you seem to imply it’s 100-200, while above you say 500 for all of Europe. Do you mean 100-200 species for western Europe?

Not having the data to hand, 200 species sounds in the ballpark for western Europe. On the other hand, 500 species sounds high to me for all of Europe, unless the Caucasus adds a heck of a lot of species not found in western Europe.

In any comparison we need to take into account that some sources may be using different definitions of what constitutes a “tree,” such as the minimum diameter or height required.

That is what I am thinking. Willows for instance are anywhere from tiny shrubs up to small trees. They constitute a lot of species.

wikipedia says 158 species
here: http://en.wikipedia.org/wiki/Appalachian-Blue_Ridge_forests

That’s a remarkable number. I’ve done a small amount of hiking there. You can see easily see thirty different species of trees in a short walk.

I was being generous and assuming they meant “Western Europe”. Assuming an absolute minimum of 50 tree species for that region for that region, then to have more trees in one acre than all of western Europe would require 100 tree species/ha. IOW even with the most generous interpretation of what is meant we still get a figure that is still well within the range expected for lowland tropical rainforest or the more diverse monsoon forests.

If we adopt a literal reading of Europe and assume even 200 species for the continent then the diversity in parts of the the Appalachians must be in excess of 400 species/ha, which is higher than the highest diversity figures I have seen for rainforests. Not really credible.

I don’t have the references to hand for the European diversity figures, they’re just figures I’ve memorised over the years. As you note, and as I noted above, the figures vary depending on how you define “tree” and “western Europe” and whose taxonomy you are using. I would imagine the upper range figure includes a lot of stuff like the junipers and heathers that are only arguably trees.

A 2.5 degree^2 is, to a *very *rough approximation, around 8 million acres.
~180 species an area that big sounds quite credible, though I would have guessed only half that. But 180 species/8 million hectares is still along way from 100 species in 1ha.

As I said, it’s an extraordinary claim that I would treat very lightly until someone produces some evidence.

If we assume that’s correct, then it’s a little implausible that >100 of those species all grow in single 1 acre plot of cove forest.

Still, it’s impressive diversity for a temperate region. I would have guessed 125 species as an absolute maximum.

I also don’t believe the claim that a hectare of Appalachian forest has more trees than Europe. That’s pretty much impossible, and must be due to some garbling or conflation of other figures.

I do find it plausible, however, that the number of tree species in the southern Appalachians as a region might exceed western Europe, or even all of Europe, depending on your definition of tree.

If that Wikipedia figure of ~160 species is accurate, I would agree. It would probably take some careful finagling over the definition of “Europe” and “tree” to get there, but it could plausibly be done.

If you want to take another non-footnoted number into consideration, wikipedia says that “[o]ver 130 species of trees are found among the canopies of the cove hardwood forests in the Smokies.”

Very unlikely that’s correct as stated. The figure of 130 probably applies to the Smokies in general, rather than just to cove forests, which are only one of several forest types in the region. And most tree species do not reach the canopy. I’m sure lots of the trees included in the total are ones of the subcanopy or second growth.

Also, we might want to expand the idea of “diversity” to include larger taxonomic categories than just “species”. For example, there are several tropical families which happen to have just one or two outliers found in the Appalachians – I think pawpaw might be one, and catalpa another. At the family level, perhaps the Appalachian diversity might actually be close to Western Europe’s. (Correct me if I’m wrong about this.)

Is there a historical factor here? I’d guess European trees were classified earlier than N. American trees. Could there be just less examination of European species that might be further distinquished as species instead of sub-species or varieties?

Not much if any. Botany in North America dates back to the 1700s, and lots of North American species were included by Linnaeus in his Systema Naturae. In any case, there was much more splitting of taxa by early botanists than by 20th Century ones. I would expect that the present European and North America lists represent similar taxonomic philosophies. There is certainly not enough of a difference to account for the much higher diversity in North America.