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Dinsdale
12-20-2007, 11:25 AM
In many parts of the Chicago area it seems that a larger number of deciduous trees have held onto a larger percentage of their leaves well into the winter. One tree in particular is an ornamental in front of our house that we decorate with lights, so we are well aware that this year's leaf retention is different from past years.

Anyone else experiencing anything similar, and anyone know why this might be the case?

ISTM that we had a pretty dry, warm fall, but I'm not sure whether the weather was outside the norm or, if so, by how much.

Duke of Rat
12-20-2007, 12:52 PM
I have one elm tree that did the same thing. After numerous hard freezes, it still had green leaves. They were hard, like freeze dried, but still green colored and on the tree for a good couple of weeks past when the other tree's leaves had changed colors and dropped off.

The only thing different about this tree was that the utility company had trimmed it just a few weeks before the first freeze to clear the power lines. We also had a record warm November, other than that I have no idea.

Dinsdale
12-20-2007, 01:21 PM
It was really noticeable when it got towards the end of the fall's leaf pickup, and we still had a bunch of leaves on the trees.
The final weekend I did a quick rake, noticing that there were still plenty to fall. The very day after the last pickup there was a big rain storm, causing a bunch of leaves to drop (tho many still remain). :p

(Don't want to give the impression I'm nuts about picking up every leaf, but my understanding is that leaving unmulched leaves on the lawn over winter are bad for the grass.)

Squink
12-20-2007, 01:40 PM
Leaf abcission (http://en.wikipedia.org/wiki/Abscission) is a fairly complicated process. While some level of frost damage can speed up ethylen production, and abcission, more severe damage can leave dead leaves hanging on the tree. I'm not finding a good online review of the processes involved, but here's an article that at least gives the flavor of the subject. (http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=396936)

Dinsdale
12-20-2007, 01:45 PM
Leaf abcission is a fairly complicated process.

Thanks. I ran across an article on-line discussing one year in one location where abscission seemed delayed in non-native trees. And the ornamental I mentioned is a parrotia (beautiful tree, BTW). But I also noted abnormal leaf retention (or delayed anscission) in maples, ash, ornamental pear. So it seems more widespread - at least this year in my location.

Jophiel
12-20-2007, 01:52 PM
Chicago's fall was more "summery" than the average (warm, low-moderate rainfall) which also contributed to the lack of brilliant leaf color in many trees. Leaves just kind of went from green to brown. I imagine it's possible that this affected the formation of the abscission zone in some area trees.

My silver maples though dropped their leaves with a fair quickness between the season change and a few storms which blew out the hold-ons.

Aioua
12-20-2007, 01:55 PM
In many parts of the Chicago area it seems that a larger number of deciduous trees have held onto a larger percentage of their leaves well into the winter. One tree in particular is an ornamental in front of our house that we decorate with lights, so we are well aware that this year's leaf retention is different from past years.

Anyone else experiencing anything similar, and anyone know why this might be the case?

ISTM that we had a pretty dry, warm fall, but I'm not sure whether the weather was outside the norm or, if so, by how much.

(bolding mine)
I'm just picking nits, here, but winter doesn't even start untill tomorrow. :D

Dinsdale
12-20-2007, 02:09 PM
I'm just picking nits, here, but winter doesn't even start untill tomorrow. :D

Sure it's as clear cut (http://www.noaanews.noaa.gov/stories2003/s2143.htm) as all that? Next thing you'll be trying to convince me a tomato is a fruit. ;)

yelimS
12-20-2007, 02:12 PM
Green leaves in winter! I guess that's something you can recognize from quite a long way away!

Aioua
12-20-2007, 02:20 PM
Sure it's as clear cut (http://www.noaanews.noaa.gov/stories2003/s2143.htm) as all that? Next thing you'll be trying to convince me a tomato is a fruit. ;)

NOAA? I don't want the gummint telling me when it's winter! I want... um... whoever the other guys are! :p

Philster
12-20-2007, 02:32 PM
NE USA and I never had leaves to deal with this time of year...until now. Surrounded by giant white oaks, this is very late for the leaves to still be falling.

The last vaccuum trucks come around on Dec 15, and there are piles of leaves in front of everyone's house, just bound for the sewers and to cause flooding.

We had periods of dry followed by drenchings, followed by warmth, followed by sudden cold. While it has all been very normal (we came close to breaking a 125 y/o warm month record), it was a funny curve ball that was thrown at the trees. Just timing. Plus, trees know best, especially the old ones. Over the course of their lives, I'm sure it happened every now and then. I'm sure the old fellas would say that.

In my neighborhood, the answer is 'global warming' (run for your lives!), but I want to know what kind of global warming occurred 125 years ago that we can't even beat their warmest October!

Mark Ryle
12-20-2007, 09:11 PM
from NOAA Magazine Dec. 22, 2003 (http://www.noaanews.noaa.gov/stories2003/s2143.htm)
In northern locations, meteorological winter begins long before the winter solstice. Meteorological winter is based on sensible weather, like when snow and ice fall, while astronomical winter is based on the position of the Earth in its orbit around the sun. The start of astronomical winter is the same everywhere, but the start of meteorological winter changes depending on how far north you live. So, donít think winter arrived December 22. Itís been here. It started right on time on December 1.This article isn't clear about which region has its meteorological winter beginning Dec. 1, although a meteorologist with NOAA National Weather Service in Washington, D.C, is quoted at one point.

Dec. 1 rings true for Allentown, PA, but just doesn't seem right for Washington.

I was wondering which cities or regions have their beginning of meteorological winter coinciding with the start of astronomical winter. Where does meteorological winter begin Dec. 21? I would guess Washington DC, for one.

vetbridge
12-21-2007, 09:25 AM
Sorry Dinsdale, the leaf retention may be my fault. Typically, trees hold their leaves until the day after I do a final raking of my yard, which I've neglected to do this year. :(

Dinsdale
12-21-2007, 10:00 AM
I suspected you were in some way responsible!

So, can you tell me when I should wash my car?

redtail23
12-21-2007, 11:29 AM
Trees around here held their leaves until the ice storm last week. They were still green on a lot of them. It caused a lot of damage, because the branches held a lot more ice than they normally would.

I figured it was just the weather. We had a really odd summer - cool and wet - and a very warm autumn. Geez, I picked tomatoes out of the garden on Thanksgiving!

BarnOwl
12-21-2007, 11:44 AM
I don't know if this counts, but looking out my den window, I can see at least 5 trees whose leaves are still attached. Some of these are on my property, others on the neighbor's lot.

The leaves, which resemble those of elm trees, have long since turned pale orange, and the trees seem to be all of the same species. I don't know what that species is.

BarnOwl
12-21-2007, 11:51 AM
[snippet]

Where does meteorological winter begin Dec. 21? I would guess Washington DC, for one.

Isn't Washington the year-long winter of our discontent?

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