thats a big fish ...

i dont understand the premise.. why would alder drop their leaves in spring???

perhaps if you rephrase the question.. ???? ... you dont mention down under in the question.. so i presume you arent there???

ken

Hey

I think its because its a nitrogen fixer but not sure.

II

Alders may have a significant summer leaf drop in dry summer areas. River birch do this as well.

In my northern VA area, we often have flash droughts in Aug/Sept and the cherries and tulip poplars defoliate.

" I know that Alder trees will drop their leaves from the end of april

and onward."

Where do you get the April leaf drop theory from? Is that how Alders behave in your area? Where I am Alders are completely bare in winter and fully clothed in summer. They grow by water so seldom experience drought. Also US and EU is an enormous area comprising wildly different climates. Trees may behave differently in different places.

There are a great many species of alder as well and not all will necessarily behave the same. I live surrounded by red alders, a native species here, and I have never encountered early leaf drop unless the trees are overly stressed by summer drought. But leaf drop beginning in April? No way!!

I am unaware of any other deciduous trees that might display this trait....and that includes any nitrogen fixers.

Is this perhaps a question about marcescense and confusing alder with beech?

Hi all

I'm talking about Black Alder, Alnus glutinosa. I'm reading a book by John Triska on aquatic fungi, and it states that A. glutinosa will drop leaves from the end of april. Thats all i know so far.

I'm writing a book, and i need to find trees that will drop their leaves, not only during fall/autumn, but other months as well. Decidious trees in EU and US. So i'll be making a list.

Divide it into climate regions, which I think i'll have to do

All trees, deciduous and evergreen can shed unneeded and used up leaves, flower bits and bark all year long for all kinds of reasons. It's like mammals shedding skin cells and hair. That is a different thing than going dormant and shedding all the leaves in the fall.

Oh okay. To be more specific i need to pick up leaf litter from streams, ponds, rivers, not only during fall. Leaf litter in fair amounts. Nothing crazy though. Areas around Maryland, New York, Florida

Black Alder does not drop leaves in April around here in the Midwest U.S.. It drops it's leaves in autumn unless it's stressed or there's other problems. The male catkins wither in the spring. While spent leaves do have nitrogen, it's the roots of the Black Alder that has nitrogen fixing symbionts. That's what causes the roots to be nodular.

If you want to pick up leaf litter outside of fall... do so. Go out after a goodly storm and see what's been blown off the trees. In the spring there is often a lot of litter from autumn that has been sitting overwinter. Watch out for drought streaks during the summer for leaf loss on trees. I don't know if you are looking for fresh fallen leaves or stuff that's already starting to get broken down. But most of the time there's something in the water.

What are you doing with the litter? What's the book about?

i need to pick up leaf litter from streams, ponds, rivers,

That is not specific enough. It still is not in the least bit clear what you are asking. Are you wanting to clean the water because it is messy or add organic matter to the water for the aquatic ecosystem? Streams, ponds, lakes and rivers can also have countless aquatic plant species to pick up litter. Falling leaf litter is also not going to be the sole source of organic matter getting into bodies of water.

Any deciduous tree can drop some leaves early if stressed for some reason....such as disease, drought or radical weather changes. But for an otherwise healthy and unstressed tree, it is of NO benefit to the tree to have an early leaf drop. It will affect the ability to photosynthesize successfully to store needed nutrients for winter and to stimulate spring growth. I would not expect many - if any - deciduous trees to demonstrate this trait under any "normal" circumstances.

OTOH, broadleaved evergreen trees like magnolias, live oaks, arbutus, etc. will drop old leaves throughout the year but rarely in a one time, heavy quantity similar to a fall leaf drop with their deciduous cousins.

I was thinking along the same lines as Christopher. Marcescence is a thing, though I only see it on young specimens. It is kind of cool to drive around this time of year and see a 8 ft tall oak completely covered in brown leaves. Those are shed in the spring when the new leaves come out.

Marcescence is very different from what the OP is attempting to describe. That is not an early or spring major leaf drop but rather the opposite - the tree holding onto unproductive dead leaves longer than typical in fall or winter.

Alnus glutinosa can be 'partially marcescent' with a few leaves lingering into spring.

TD, look up trees that are 'Marcescent' if you want leaves that are still on the tree by spring in cold areas.

Ostrya virginiana and northern pin oak (Quercus ellipsoidalis) are two that come to mind.

see previous thread from poaky1 HERE

Shingle Oak was one of her favorites.

Great point about trees that keep their winter coats. We got some oaks here that do that. I suppose those are the only leaves that aren't subjected to the usual processes in the water as litter. Because they are still on the tree. So in a way the spring drop of the dead leaves would probably be the freshest fallen leaf litter in the spring.

I figured the OP meant spring leaf drop, as in the fresh grown leaves of spring dropping off.

A champion of shedding is the London planetree, Platanus x acerifolia.

It continually drops leaves, seed balls and exfoliating shards of bark. When it does get around to the major fall leaf purge, that lasts for weeks and weeks, unlike other trees that do their fall leaf shedding in a relatively short period.

The London planetree is often recommended as an "ideal" city tree because it's fairly tough and withstands pollution. But it's a messy bugger.

The London planetree is often recommended as an "ideal" city tree because it's fairly tough and withstands pollution. But it's a messy bugger.

Huge growing, covered in irritant hairs and susceptible to anthracnose. But most importantly huge growing, not in scale with anything smaller than a mansion or other large building.

Alnus glutinosa is the only native Alder in the British Isles. Here, at least, it is neither marquescent nor does it drop its leaves in Spring.

This thread caused me to go check and see what my Ostrya v. looks like at this time of year.

Still has leaves even with occasional strong bouts of wind. My other tree in the back yard looks about the same. I surmise the colder the climate, the less likely buds will swell and begin pushing at the base of petiole?

Yes, Sam, the several rather young shingle oaks along a stream near me seem to hold on to every single browned leaf. Actually looks attractive because of it.

Bill, I think a callus grows over the petiole connection and that's what literally cuts it off. But then early cold could slow/prevent that too. I think what you say can indeed be the case, like my Shumard oak that holds alot of its leaves overwinter and then they get pushed off in spring.

Tommy, boxelders lose leaves (turn yellow) during much of the growing season. My removed river birch did it some. Tuliptrees and some others can do it prematurely if it's real dry.

Yes, my Quercus ellipsoidalis (NPO) leaves are dense and really stuck right now, even after all that heavy ice and snow events. From what I recall, those seem to release right before new buds begin to push in the spring.