Climate is definitely a factor wrt length of growing season. More carbon is sequestered in high USDA zones than in lower ones.

Yep^. Good that you allowed for water availability, as in the actual world, that comes into play. But taking that out of the equation, longer growing season def. leads to increased growth.

+oM

Don't most trees have a sweet spot where they grow best?

I am thinking Larix laricina vs Metasequoia. The Larix will out perform Metasequoia up north but not here with my longer growing season.

Right?

The American Pacific Northwest has the highest Net Primary Productivity in the lower 48, the Sitka-Tongass in temperate North America (rainforests).

Doug-fir in the PacNW are unbelievably large, here not so much. In the Tongass Doug-fir are outcompeted by spruce-hemlock; in the Hoh Doug-fir outcompetes the spruce-hemlock.

Anyhoo, a hypothetical tree will be larger in a warmer, wetter area but tornado adds important detail for specifics: Many texts will specify 'best in zone x-z'.

IMHO, much will depend upon the species. Many species produce one flush of growth per year, and that is that. Those are probable going to less affected. Those that are capable of producing multiple flushes if time permits (possible associated with whether the days are still lengthening or not), likely benefit from longer growing seasons. But as with anything, there are limits.

Arktrees

branches keep growing all season long.. ????

as compared to say... conifers .. that bud out and set buds for the following season.. after one great spurt in spring??? [for the most part?]

ken

No one's mentioned the role of provenance, which is probably the more important factor.

Plant X has a large native range. Could be anything, oak, maple, dogwood, you name it. Look it up in a nursery catalog and it provides has a hardiness zone 4-8 (this is a hypothetical example). Take seed from down south and try to grow the resulting plant up north, and it leafs out too early and is susceptible to early frosts. It also doesn't abscise early enough in the fall and gets hit by frost damage again. On the other hand, take seed from up north and grow it down south, and the resulting plant will leaf out later and abscise earlier than the surrounding southern plants of the same species, and thereby give up many of the advantages of the longer growing season. In the end, it will look more similar in size to the tree grown up north than the southern trees (of the same species) around it.

Ken,
Our Sugar Maples push one quick flush in the spring, and then photosynthesis the rest of the summer. They do not continue growing lengthwise, but do in caliper. Our freeman maples flush growth until about summer solstice, then are done for the rest of the summer. Same with the redbuds, and many others. Those that grow until solstice would certainly seem to benefit from the longer growing season, while Sugar Maple seemingly would not. However, none continue to elongate for the full summer period, at least here they don't.

Arktrees

No one's mentioned the role of provenance, which is probably the more important factor.
o Don't most trees have a sweet spot where they grow best?

o Doug-fir in the PacNW are unbelievably large, here not so much.

o In the Tongass Doug-fir are outcompeted by spruce-hemlock; in the Hoh Doug-fir outcompetes the spruce-hemlock.

o tornado adds important detail for specifics: Many texts will specify 'best in zone x-z'.

;o)

Ah, I can see I was not as clear as I had hoped...

Seed provenance refers to the specified area in which plants that produced seed are located or were derived. Local provenancing is a position maintained by ecologists that suggests that seeds should be planted of local provenance only. The idea is that within species variability reflects adaptation to the local environment. IOW, not simply 'species X performs best here' (how I read your quoted statements), but species X trees from location Y are adapted to that site and have different characteristics than species X trees from location Z'.

I brought this up because I think it's a very interesting phenomenon. I suppose it's a bit off topic if the question is 'Will this particular specimen put on more growth when grown somewhere with a longer growing season.' But it is relevant if you're asking 'why does species X put on more annual growth down south'? The implication is, it's not because they're grown down south but because the local population is adapted to a longer warm season, and such individuals will exhibit a longer growing season wherever they're grown. In other words, it's not so much the environment per se but the intrinsic genetics of the local sub-species population that causes the longer growing season. That's the idea anyway.

This post was edited by maple_grove on Tue, Apr 16, 13 at 15:20

I've noticed that Quercus polymorpha and Taxodium mucronatum will continue to grow well into the fall while other trees shut down and getting ready for the winter despite the fact both are not from around here. I suspect that genetically, they are used to having a long growing season from their native area. I wonder if they'd adapt to shorter growing seasons over here eventually via seedlings??? The late growth on these trees don't seem to be harmed at all once cold weather comes.

In my parts catalpa speciosa keeps growing until stoped by the frost. It does get harmed though, but most of the years growth will survive

I've noticed multiple flushes of new growth on both an oak and several red maples or silver/red maples I have in my yard. In fact, we had an October Glory put out new growth as late as August of last year. I remember being concerned it wouldn't harden off well before frost time.

Maple_Grove has got it. Nuff said.

In other words, it's not so much the environment per se but the intrinsic genetics of the local sub-species population that causes the longer growing season. That's the idea anyway.

Sure its the environment. The local population has adapted to the environmental conditions - the environmental conditions haven't changed because of genetics of the local tree population.

Degree days are degree days are degree days - that's why they are tracked; the more degree days you have, the longer your growing season.

I agree that tree provenance matters for local climate adaptation, but ultimately it is length of growing season (and water) that drives size, which is why I brought up Douglas-fir.

That is why the temperate rain forests grow bigger trees than the cold continental interior - they have a longer growing season (and are not moisture-limited). The tallest Doug-fir here are well over a hundred feet shorter than in Washington state. And again - each tree is optimized in a climate zone.

WxDano, I completely agree with you that a longer growing season can result in faster growth. I wanted to bring up provenance (local adaptation and genetics) as a separate and distinct factor that can also influence growth rates, and help to explain why trees in different locations have different growth rates.

Remember, the environment does not bring about changes in genotype. The idea that it does, espoused by Lamarck, was disproved by Charles Darwin in the 1850s. Rather, the environment can select from existing phenotypes by altering the odds of reproductive success. To take it back to my original example, Acer rubrum seed from local stands in Minnesota, when grown in Georgia, will have a shorter growing season (later leaf out and earlier abscision) than the local Georgian Acer rubrum, as a function of the plant's genetics not the environment. Calling it simply "the environment" ignores this, and there is a (perhaps subtle) difference between the environment and provenance which is an expression of the environment through natural selection over many generations. Sorry to belabor the point.

Best regards,
Alex

And finally, as a practical consideration, the hypothetical person interested in growing plant A, whatever its provenance, will also do well to understand the influence of a warmer and longer growing season on pest and disease organisms. This factor can alone dictate what will grow where, and how fast. For an example, we're looking at the possibility of loosing species in the indigenous plant communities if and when warming continues, as pest species formerly unable to survive our winters, are increasingly able to do so.

So just as in the nuanced discussion about provenance, this entire subject is complex. And we hardly ever really know what we're doing!

+oM

Sometimes the longer growing season equates to hotter temperatures and drier summers that the species cannot tolerate well. In those cases the trees are stunted and the extra growing season didn't help.
In general however the answer is yes.
One item not mentioned that I have noticed is that the xtended growing seasons of the south equate to earlier maturity of certain trees in bearing nuts : Bur Oak bearing earlier than northern trees. Suspect this will hold true for other species but have not checked others.

Has anyone in zone 6 or there-abouts noticed their trees waking up sooner by a couple weeks, compared to the 5-6 years before now? It seems to me that some trees are too early. My Comptons oak and Durand oak went into leaf around April 9. No big deal I guess, but just unusual.