Why do leaves fall at different times?

[fattyphatcakes]

On the same species, in the same neighborhood, or yard, I've observed that some trees hold their leaves longer than others. Why is that? Can I infer anything about the health of the tree?

Also, some trees lose their leaves on the bottom branches first others on the top, what's going on there?

 

[SteveBullman]

exhausting the obvious before getting technical, could have something to do with wind shelter, ie tree blocking another tree from the prevailing wind will likely lose its leaves first

 

[Nathan Wreyford]

they may phenotypically look the same but there are genotypical differences. Plus environmental ones like those mentioned earlier.

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[John Paul Sanborn]

Very early leaf drop is a good sign of stress, such as soil compaction that can lead to decline.

Also systemic disease can first show up this way.

Girdling root is another .

IF the trees are cultivars vs a run of the mill species then thier time of change may be bread into them

 

[fattyphatcakes]

I'm aware that early leaf drop can be a sign of stress, but does it follow that a tree that holds it's leaves is relativly stronger than others?

 

[Chucky]

Microclimatic conditions, genetics, and stress are possible contributors.

Another consideration is the provenance of the tree. Where did the parent of the tree come from? Up here in hardiness zone 4 it's easy to spot tree cultivars whose parents grew in warmer climates with longer growing seasons, hence later leaf drop. If a tree with a southern lineage is grown in the north, and allowed to propagate by seed, it would take several generations for the tree to adjust to the northern clock, and begin to drop its leaves at the appropriate time.

This is one of the reasons Norway Maples, which were planted large-scale here in snowy Syracuse, NY, have big problems (among many other problems), even though they are cold hardy to zone 4. They are still on the European clock, which has a longer growing season, and keep their leaves much too late in the season. When we have an early big snowstorm -- which is no rarity here -- because of all the surface area of the leaves, we get a huge amount of branch failure. It would be nice if some thoughtful local nurseryman would select a Norway Maple cultivar for early leaf senescence.

So, it's common to see many trees of the same species in the same locale dropping their leaves at different times, because you don't know from what nursery the parent of the trees were grown.

Or course, the phenomenon could also be attributed to stress or microclimates. Or genetics, providing the tree is not a clone, thus all the trees having the exact same genetic makeup.

 

[MasterBlaster]

I bet it's just personal issues between the leaves, and gravity.

 

[jkrueger]

The white oak, maybe others as well, will often loose leaves in parts, and turn and stay on in other sections of the tree. When a oak holds it's turned leaves it is a sign of imaturity. And when only in sections, something is going on with the tree having it behave in certain areas as if young. It can be a way to point the way to problems already being corrected by the tree and one can assist.

Jack

 

[fattyphatcakes]

I've noticed that on declining cottonwoods the watersprouts still have their leaves and are still green. Is that explained by the tree doing it's best to cling to life?

 

[John Paul Sanborn]

That is called defencive decline. The tree has problems moving the minerals and water up the the tips, leaves are shed, and then twigs. lower down the tree can get it to the epicormics so they will flush out from the reduction of auxin up stream.