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Cities need more trees

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Re: Cities need more trees

#131

Post by benfortuna »

huevosabio wrote: post #26

One of my biggest complains for American cities is the risk adversity with respect to trees. In SF, the city went in a rampage to prune and tear down trees (mostly ficus) because of the risk of the branches falling. There are lots of rules for where you can and can't plant trees based on road visibility, signage, electric cables etc. Result is that you have a lot of tree-less spaces in a city where basically anything…

In Australia power companies will butcher any tree that gets close to overhead powerlines. Understandable, but result is an ugly streetscape and very little opportunity for green spaces outside parks.

Re: Cities need more trees

#132

Post by HermanMartinus »

lordgrenville wrote: post #74

I also grew up in Johannesburg, and really miss those trees. When you drive a little bit out of the city you see a completely different landscape. However I'm sceptical about the author's claim that there's no downside. I would assume that most of the trees are not native, and in any case definitely don't grow natively at that density. Feels like there's no free lunch in ecology: is mass tree-planting an exception?

Author here :)

You're correct that very few of them are native. That being said, when comparing to a city with no trees vs a city with non-native trees, I think the latter is still superior.

Re: Cities need more trees

#133

Post by BSDobelix »

danaris wrote: post #129
Xylakant wrote: post #109

Earlier quoted context omitted.

It's a relatively novel concept, though the problems of replacing open surfaces with stone slabs and asphalt could have been obvious decades ago :(

Ah, but you see, stone slabs and asphalt cost nothing to maintain. /s (...Even this is, of course, untrue, but it seems true when you're only paying attention to the next year or so.)

Just 17 milion swiss franks made out of "Valser Quarzit" and a "fountain" that needs constant maintenance because it has to be drinking quality instead of lake-water, just look at that sh*t:

https://aquatransform.ch/projects/sechselaeutenplatz-opernha...

EDIT: But please don't waste energy otherwise (your politician)

Re: Cities need more trees

#134

Post by kkfx »

Cities have too much thermal mass exposed to the Sun, that's is. As a result they makes heat domes between buildings and you can't reduce much the thermal mass with trees because you still have all the buildings.

A solution is new buildings "coated" with light air-gapped panels where air between them and the core structure of the building is free to slowly climb and going outside in the atmosphere. Of course you can't do so on glass facade walls. And it's hard to do on most existing buildings. Also you can't do much for the large asphalted area.

Like it or not, cities and global heating are incompatible, as cities and many other aspects of the modernity.

Re: Cities need more trees

#135

Post by ochre-ogre »

CuriouslyC wrote: post #94
XorNot wrote: post #69

Earlier quoted context omitted.

Root penetration of buried services is a serious problem. While roots generally chase water, they will surround and crush any services which get in the way. Trenching and conduiting is also a lot more expensive. Which is to say: you're looking at a huge amount of cost for what could be described as a very marginal gain because it's already a city.

Tell you what, you enjoy your Mumbai style wire canopy, I'll pay more to live in a place where they bury the lines and tree branches and sky are the only things over my head.

Mumbai has mostly underground utilities, only broadband lines tend to be strung from building to building.

Re: Cities need more trees

#136

Post by agumonkey »

jajko wrote: post #106
agumonkey wrote: post #78

Earlier quoted context omitted.

I live at the boundary between city and forests and in summer the temperature drop is really 'incredible'. The amount of energy wasted by urban areas is as much so. But at the same time it's nice because we can restore more trees for shade easily

I live in foothills of a lower range of hills (European Jura), and it has numerous effects. The air is normally blowing down the mountains towards us in the evening (katabatic wind), so it doesn't matter how hot the day was, evenings are pleasantly cool and night gets colder than expected. This wind also cools hot surfaces pretty effectively. Even just entering a dense natural forest during the day, one can sense dro…

> katabatic wind

I've noticed this while doing evening walk, I didn't know it was a named phenomenon.

Re: Cities need more trees

#137

Post by agumonkey »

wongarsu wrote: post #55
agumonkey wrote: post #36

Earlier quoted context omitted.

Mostly urban density ideas were incompatible with green space in the decades prior. The more you want to fit people to "lower" rent, the less you can allocate for grass or trees.

I don't know. When thinking about "urban density in decades prior" the first thing that comes to my mind are the "commie blocks" of the 50s-80s. The thinking of those often explicitly included green space: put people in denser higher buildings and you have space for green spaces in between. The execution wasn't always stellar, but it was in no way incompatible with trees.

There were a lot of open spaces in the 60s and 70s, but over the years, "every" space has been converted into utility or new buildings.

Re: Cities need more trees

#138

Post by kjkjadksj »

JoshGG wrote: post #76
MrGilbert wrote: post #66

Earlier quoted context omitted.

Albeit being a valid datapoint, the conclusion could as well be that it might be better to put electric power down in the ground, get better insurance, don't park under a tree, and so on…

This is the standard for many cities in the northeast. Power lines are underground.

I’ve only seen it done for suburban tract development, never retrofitted to an existing large city. Do you have examples that aren’t a suburban tract? Just curious how it was implemented as the expenses are usually quoted to be astronomical

Re: Cities need more trees

#139

Post by kjkjadksj »

jajko wrote: post #111
XorNot wrote: post #69

Earlier quoted context omitted.

Root penetration of buried services is a serious problem. While roots generally chase water, they will surround and crush any services which get in the way. Trenching and conduiting is also a lot more expensive. Which is to say: you're looking at a huge amount of cost for what could be described as a very marginal gain because it's already a city.

This is a non-issue in all of Europe maybe apart from south, even poor countries can afford this and root damage is negligent. Its not a serious-enough problem to change your city planning around.

Chances are they did it decades ago when labor was far cheaper and continued to expand the system the entire time.

Re: Cities need more trees

#140

Post by kjkjadksj »

inferiorhuman wrote: post #103
FactolSarin wrote: post #75

Earlier quoted context omitted.

Mexico City is one of the largest cities in the world. Five people out of 21 million is nothing. Sure, every death is tragic, but there are a lot more efficient ways to spend time and money preventing deaths than tree trimming.

Five deaths in the Bay Area from one storm, two in San Francisco (with a population around 800,000). There were other tree related deaths last year. More to the point, the trees that the city is actively removing are old, mature ficus trees that present a variety of risks (e.g. sidewalks, sewer and other underground utilities), overhead (e.g. public transit) wires.

Too bad ficus are easily the densest canopy tree I’ve seen in california
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