Trees "calculate" which branches to drop based on data they gather as they grow. A competent and experienced arborist knows how to read the tree and simply safely cut off the branches that the tree was already intending to drop so that it doesn't fall on your house or whatever. Inexperienced arborists often ignore this key dendrology fact and may totally butcher your tree. In the process they can create an even larger risk of a tree falling over onto your house during a storm

It's called cladoptosis (basically self-pruning) https://en.wikipedia.org/wiki/Cladoptosis

EDIT: since I'm on the topic of bad tree trimming, NEVER TOP YOUR TREES https://www.arborday.org/tree-resources/dont-top-trees

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jamiecurle 44 minutes ago | parent | next [-]

I'm an arborist since 2022 in the UK and yes, never top trees. But...

There's three scenarios that come to mind in which it's somewhere between "acceptable" and "totally fine for some reason".

One, it's conifer hedge (the types popular in the UK) as these typically respond very well to being topped. It's what makes them a nice tidy hedge. I'm specifically referring to hedges above 3 meters in height. If you ever worked a hedge like this you'll quickly realise the topped stems are the platform to work off. These hedges can be maintained like this for years. For some reason, topped hedges are completely fine with being topped.

Two, it's either topping or removing. Arguably neither is ideal, but some retention is better than no retention. Topping puts the tree on senescence pathway and gives the ecology time to transition from alive to dead and dying. Whereas removal just makes the local fauna get confused about where the tree went.

Three, veteranisation in woodland settings. If there's a distinct lack of standing deadwood and age variation in a population of species in a given woodland NVC type, the topping and verteranising could be a positive management approach on a sample of trees.

This advice is very specific to the UK and especially on point three to the NVC woodland types. Generally though, prune properly at the correct locations, using proper technique being mindful of the structural loads and balancing of the tree. Topping generally, "because reasons" isn't an ideal approach at all.

	▲	lexicality 32 minutes ago \| parent [-]
		> Topping puts the tree on senescence pathway and gives the ecology time to transition from alive to dead and dying. Is this why the council recently topped a tree on my road that's been breaking up the pavement? We thought they were cutting it down since they dug up all the tarmac around it, but they just knocked the top off, taking something like 98% of the leaves with it, and then put fresh tarmac over the exposed roots. We've been puzzling over that for a week...

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vlyan 4 hours ago | parent | prev | next [-]

>NEVER TOP YOUR TREES

they do it where I live because the branches bang against apartments' windows when it's windy. I don't think there's another low-maintenance solution.

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culi 4 hours ago | parent [-]

Coppicing or pollarding are both well-historied techniques that can be used to keep trees growing short. They differ significantly from topping and require a lot of expertise. They also have to be started when the tree is young

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ajb an hour ago | parent [-]

This is often not useful advice, as it is common to acquire responsibility for a tree than has been badly managed. The GP's link actually gives a solution for this case: pruning more accurately over a slightly longer period.

More generally, I've found as the maintainer of a building that while mainstream practices (of property generally, not specifically trees) often undershoot good practice, heritage techniques are often impractically expensive, and function more as a status signalling mechanism than really as a way of doing better. Even more generally, economy-wide; there is a tendency to criticise the mainstream but then promote expensive, semi-artisanal products and services, which while better, simply offer an escape valve to pressure for reform. Better techniques can only benefit the populace as a whole if they are cost reduced under the discipline of serving the mass market, not just offered as a premium version for the well-to-do.

	▲	culi an hour ago \| parent [-]
		Well I agree it'd be ideal for our society would be organized in such a way that effective semi-artisanal trades are cheaper than practices that do more harm than good. The real advice I should've given was to construct protection for a window or hire a certified arborist to do a proper thinning of the canopy. But I wanted to remain on the topic of interest dendrology info

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argimenes 3 hours ago | parent | prev | next [-]

Fascinating! Where is this data stored? I love the idea of a Tree DB queried via TreeSQL.

	▲	culi 38 minutes ago \| parent \| next [-]
		It's basically a decentralized algorithm involving sugar defecits, auxin signalling, calcium flooding whenever cells stretch (due to gravity or wind), and ethylene release. Trees can use all these signals to know which branches are being shaded or dealing with a lot of wind, which side it's being pulled towards more, etc. Trees also optimize for their overall wind profile. Dropping branches that cause it more drag than they are worth in the sugar they make. The lower their wind profile, the lower the risk of the whole tree being uprooted during a storm. When humans cut the wrong branches, it throws everything off balance.
	▲	Terr_ an hour ago \| parent \| prev [-]
		Because they B-Trees?

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jalk 2 hours ago | parent | prev | next [-]

>NEVER TOP YOUR TREES

Kind of annoying when all the fruit is several meters out of reach

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mightysashiman 3 hours ago | parent | prev | next [-]

I'd like to grow bonzai. I have zero prior knowledge. I suppose what you mention applies. Would you happen to have any good resource that applies to bonzai science please?

	▲	tshanmu a minute ago \| parent [-]
		https://www.reddit.com/r/Bonsai/wiki/walkthrough/

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4 hours ago | parent | prev [-]

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