Conifer dominance?

[Lucas]

I have often wondered why conifers dominant the west coast.


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I pulled the above from The Clouded Leopard book by Wade Davis.

https://books.google.ca/books/about/The ... IdAQAAIAAJ

It is not all of the passage but it gives the gist of why conifer dominance in the PNW may occur.

Is this a plausible reason?

[dbhguru]

Lucas,

Hopefully Dr. Lee Frelich will weigh in on your question.

Bob

[Lucas]

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The complete paragraph.

[mdvaden]

I have often wondered why conifers dominant the west coast.

Why they dominate? Or just why there are so many more of certain species there, and not as many elsewhere?

One reason I ask, in a lot of areas, the Sword Ferns, etc., far more dominate and outnumber them.

Take this image for example. And its similar farther north like up here in Oregon, or partly inland like near Portland,


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[Don]

Mario-
You're not the first to wonder about this!

Specific to the forests of the Pacific Northwest, R. H. Waring and J. F. Franklin in Evergreen Coniferous Forests
of the Pacific Northwest [Massive long-lived conifers dominating these forests are adapted to a winter-wet, summer-dry environment.], suggest that there are a significant number of studies on this topic.

Their own paper points to the conifer's superior ability to adapt to wide ranges of temperature, moisture, and nutrient regimes. Not just in the "anthropocene" but as well in paleobotanical records.

So this begs the question, "Why do angiosperms dominate the Eastern US?" Any thoughts?
-Don

[Rand]

So this begs the question, "Why do angiosperms dominate the Eastern US?" Any thoughts?
-Don

I'd assume that broad leaves, open to the sky are more efficient at capturing light than an array of needles, leading to faster growth, and casting deeper shade in the understory -- provided the plant can supply the higher transpiration load.

[mdvaden]

How trees grow is one side to ponder.

But where trees grow is because their seeds germinate there. I'm not sure whether that's a big matter or not for this particular topic. But the Mt. Ash came to mind, which can grow here in low elevations if planted, but it does not germinate well or at all in low land.

If I recall, the seeds need to be below freezing for like 30 days ... and possibly even twice. That only happens up in the mountains at higher elevation in parts of Oregon, etc..

So where the Mt. Ash will grow bigger or older is a different story from where it will germinate and establish naturally.

I know virtually zero about seed germination needs of east coast trees.

[KoutaR]

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Two comments on the last phrase:

1. "Easily four times as great" only applies to redwoods. Otherwise the statements should be: "... the biomass in the best sites is twice as great as that of the best sites in the tropics." Many writers take for a comparison a top value from the Pacific NW and an average value from the tropics. Or they recycle the same comparison. See http://www.ents-bbs.org/viewtopic.php?f=144&t=4966 . Does somebody have greater values?

2. The phrase gives to understand that the high biomass density is an indication of a high productivity. Actually, it is an indication that there is a lot of dead wood locked in the tree boles, which is partly a result of the longevity of the tree species.