I've become really obsessed with 'Miyawaki Forests' lately - small, dense, urban forests which can reach a mature state in only a few years. I hope they start showing up everywhere. Fuck minimum parking requirements, where are the minimum forest requirements?
For non-human animals? More complicated. These sorts for forests are generally dominated by “edge species”. Edge species generally do relatively well out of habitat fragmentation.
The most sensitive species that need a lot of depth in forest generally don’t do well with these small pockets.
This is not to say that Miyawaki forests aren’t an improvement, just that their “conservation” value is limited and still need to preserve/manage huge amounts of actual contiguous forest with a minimum perimeter compared to the area covered.
I don't disagree but if the choice is between edge forest and species support for species in edge forests, or carparks and species support for carpark friendly species, I would prefer to have edge forest species.
This is not re-wilding. We aren't trying to get urban badgers and lions.
So, in summary I think your critique is true but misplaced. Consider the viable alternatives, not the pipe dream.
When we de-populate on the next virus, we can re-forest for bears.
That's fair. It's definitely a complementary thing, you want both types of forest I'm sure. Small forests don't cover all the needs, and large forests don't fit everywhere.
I'm having a hard time picturing what they look like -- and the photo in that article is unrelated.
Googling them, I can find images of a few proof-of-concept plots in the middle of fields but I can't find a single example of how they might integrate with a city.
It would be nice to see some kind of before-and-after, even if just an illustration, to get a sense of how they would fit into a cityscape aesthetically and practically.
That 3x3m project shown is not realistic. Not for a newbie and probably not easy to keep from falling apart for an expert.
But yes, wild hedgewoods of a mix of useful shrubs are totally doable even in really small spaces. I had designed a few. They are low maintenance, beautiful, useful, funny, and tasty and everybody should have space for one of this wildlife lifesavers in their gardens.
They're surely extremely region-specific—sourcing with native trees is a big part of their sustainability. Do you know anything about where to find local growing guides for different regions?
The idea that everything needs to be a dense forest is a problem. What is more helpful is a variety of ecosystems available. I don't have a lot of space, but I managed to have 4 ecosystems in all of my yards with 200+ species of plants: California chaparral, Coastal forest, Xeriscape and a wildflower meadow. Cities could also build such environments and that would be more positive than just planting Miyawaki Forests everywhere.
If your city cannot afford botanical gardens, then planting trees on sidewalks, more boulevards, and other places not only bestow ecological benefits but is also good for the human psyche and reduces crime.
Or are areas that have planted trees areas that also tend to have reduced crime?
The abstract of that paper indicates an inverse correlation between trees and crime, but stops well short of claiming or proving a causal relationship.
The correlation they saw was after controlling for potentially confounding variables, like income level, housing stock, density, and demographics, as explained in this article: https://caseytrees.org/2023/09/mythbusting-trees-and-crime/.
So of course it's not proof of causation, but reverse causation(nice neighborhoods lead to more trees planted) seems unlikely to explain the effect.
I hope this isn’t a revelation to anyone at this point. Of course greenery reduces heat, but more than anything it means removing concrete, which mitigates the urban heat island effect. (Urban heat islands absorb heat energy during the day, amplifying extremes, and release heat at night, making it impossible for effective cooling.) And yet there is still so much resistance or otherwise apathy to the idea of planting more trees and removing space for vehicles — as if it’s merely some hippy-dippy shit only good for gentrification.
Planting more trees and removing space for vehicles are two different things; it is not necessary to make them dependent. Those who do, usually do it for their anti-vehicle agenda, and planting green is only an excuse / a tool, not the objective or intent to improve the environment.
If you want more space for parks and green, you can do it also other way. For example, like Hausmann did in Paris.
In a hierarchy of urban planning, I’d favor removing space for cars over demolishing precious space for affordable housing. To that effect, I wouldn’t point to Haussmann who bulldozed plenty of homes and neighborhoods for his unified vision of Paris connected by major thoroughfares. As a result, we have few parks and the city lacks any kind of real arboreal shelter except on some of the boulevards. He was a visionary, but he didn’t have scientific papers or the threat of climate change to contend with.
The idea I have in mind is that the control over cities has been wrested from its citizens. A special car commuting class has more comfort moving about a city like Paris than regular inhabitants — but at what cost and borne by whom? Removing space for cars means removing vehicles, which re-empowers city-dwellers, cleans the air, and cools the city.
In much of the US, the two are interdependent: to plant more trees on streets, for example, many US cities will need to trim the arterial roads that swallowed up neighborhood sidewalks half a century ago.
I wonder if they could cool down a desert; let's say, make nuclear reactors and plant them on the edge of Sahara, and do one thing with them: desalinate water from the sea; use the water to irrigate large portions of the desert, and plant them with bamboo; this will cool the desert, sequester CO2, and have global influence on the climate warming.
Back on the envelope calculations: 3.5 kWh/m^3 to desalinate water, 10 nuclear reactors, 1sq meter for a bamboo plant, you can water and grow 5.5 billion bamboo plant; let's say each plant fixes 10kg of CO2 per year, you reduce 10% of world's emissions in one clean sweep, for a total investment of maybe 100 billion USD
Desalination doesn't produce (freshwater + salt), it produces (freshwater + saltier water). Dealing with the waste brine is a challenge if you want to process that much in such a localized area.
There have been a couple attempts to do this previously. In India, there was one version used as a physical barrier on a customs line for 450 miles. Also happened to improve the area.
There's also an attempt in Africa in the Sahara that a bunch of countries signed on to. Unfortunately, their commitments have mostly amounted to talk without much funding or governmental support. Seen a few videos of locals who seems to believe in the idea, its just not getting much large scale help.
I also use Ecosia (https://www.ecosia.org/) as a web browser, and they supposedly plant trees based on number of searches and a percent diversion of search revenue. Seems to at least have some photographic evidence of money actually being spent somewhere.
Senegal's an example with desert work. Seems to have evidence that at least some amount of trees are being planted with videos (harder to falsify).
You need a ton of water just to run the reactors and the droughts have already required ones that are in desert like the Palo Verde plant to reduce output.
Human activity has lead to the Sahara being much larger now than it was in the past. There are ongoing efforts (https://www.youtube.com/watch?v=WCli0gyNwL0) to try and keep the Sahara from growing any more.
well, anybody with a 100 billion can do that; we're in the age of such technology multipliers that private very rich men can undertake planet-scale geological projects without a sweat
I have always been very curious as to why many cities do not push for more forests to cool down the place. I studied in a college with a lot of trees on campus and the temperature was at least 5 C cooler than just outside the college.
In Britain I've seen trees planted in urban spaces. And then local residents come
and pour rock-salt and weed-killer on the saplings there - because it stops them parking.
Street parking in a lot of cities in america is notoriously "free". I think somebody wrote an article about how in SF, their car pays less rent per sqft than they do.
People who live there profit from the trees through quality of life benefits (such as being 5 degrees cooler). Maybe part of the problem is that a lot of landowners tend to not live in the land they own, so they can't see these profits.
Most land that isn’t already a park is privately owned. Most cities can’t afford to buy out a forests worth of real estate let alone clear it and replant it.
That doesn’t mean you can’t have trees: a high-rise building next to a park is quite dense, as are tree-lined streets.
The problem is those streets: the 20th century model focused on maximizing individual vehicle usage, which meant lots of open space for safe operation and subsidized storage. Cars can’t go around trees like pedestrians or bicyclists and owners don’t want branches falling on their parked cars, so anywhere there isn’t enough space for both it tended to result in more heat-amplifying asphalt.
I totally believe that botanical gardens cool the air within them. That's what happens when you have an area full of trees and shade, with denser vegetation than a park.
But I have a hard time believing that they have any significant effect on the city air 5 or 10 blocks away, where the asphalt is baking in the sun.
So I'm not sure what the point of this article is, because it's not like we're going to replace half the blocks in a city with botanical gardens, as nice as that would be.
Meanwhile, the article claims claims planting trees on the street has less effect, but surely is far more important -- because it affects the whole city, rather than a small localized area in and around a botanic garden?
So there seems to be a major flaw in this article, in that it's comparing the cooling effects of various interventions (botanical gardens, street trees, etc.) but without ever specifying how the sizes or densities are being compared.
Honestly, I can't even imagine what a unit of comparison between botanical gardens and street trees would be, since botanical gardens replace streets and buildings, while street trees merely add to them. It's apples and oranges.
I think the article addresses this fairly well. In addition to shade, evaporation from open water and plant leaves contributes, as does the soil acting as a heat sink.
Botanical gardens are only slightly more effective than trees over roadways from their study, so shade is likely the strongest factor, but the others clearly play a part- from cooling down enough overnight compared to roadways and cement to the evaporation from the denser vegetation having a stronger effect.
The thing that I missed was how such a garden compared to an open, grass park. The difference in vegetation density would be clearer, I think, and might better explain the difference measured between trees over roads and gardens.
From an energy perspective it makes sense, since at least some of the solar energy hitting tree leaves is used for photosynthesis, and reducing Carbon out of its oxydized state. So it's not just accumulated/reflected like for pavement.
Interesting how easy it is to mitigate 5C - and yet we think the world is going to end if temps increase another 2C - when we are basically in an Ice Age and the Earth has only been cooler for brief periods of time in the last 500M years: https://www.climate.gov/news-features/climate-qa/whats-hotte...
Luckily, fossil fuels are going to get phazed out massively over the next 50 years strictly due to economics.
Complete anecdote here, but I live on a park that is about two acres big. Its filled with large old (~100 years) trees and lawns, though it does also cram in a basketball court and two tennis courts. In the summer heat, when we walk around our area, the temperature astonishingly drops about 5 degrees once you get within 2-3 blocks of the park. Its striking in how noticeable it is. I have no idea why, but it seems even a bit of green space can have a big impact.
They do have a significant effect. Trees scoop up rain from the soil, lift it through their trunks and up into the leaves where little mouths (stomata) in the leaves deposit that water back into the air in a process called transpiration.
It is actually in this way that places deep inland can still receive rainfall. Without this process clouds wouldn't be able to make it far inland.
High temperature air rises (by expanding and becoming less dense), the void is filled with low temperature air. So a colder forest will start a wind outward of the forest towards the warmer areas, thereby distributing the colder air into the surrounding area.
You can see the same effect mostly in spring in coastal areas, when the land is heated faster than the sea. Hot air over land will rise, colder air from the sea will move in, causing thermal wind, making the coast a lot cooler. This can cause enough wind for kitesurfing or wingfoiling.
I think it's misleading for a worse reason: These trade temperature for humidity. They seem to work great as long as the temperatures don't go too high. They become hot ovens when they would be the most needed.
I don't see anywhere in TFA where it's implied that the temperature drops as an average, or that somehow it extends past the green area. I feel like you've been misled by a strawman that you created yourself.
Empirically, it extends a tiny bit past the green area.
When I go for walks in summer in my city, it's noticeable how the temperature drops while on the sidewalk when I walk past a green area as opposed to past a building.
But it’s probably the easiest and cheapest way. Another plus point would be creating habitat for smaller animals and morale boost for the city inhabitants
Well, both require making land available, and while amenity gardening is manageable, a botanical garden is often a research site that requires a lot of expertise to set up and maintain. Mind you, that's just fine, the county can and should hire people.
Now, if only we can do something about the absolutely endemic heat desert effect we've created by caking our country in massive black asphalt parking lots and 6-lane freeways.
Nope, can't examine that. Parking lots are peak human design. The most logical design solution for our species.
They mention less heat as one of the multiple benefits of pavers / bricks.
I used to dislike them by default - "They're bumpy". They're not bumpy. There's a shopping center in my town, and even a new Taco Bell, that use pavers for their parking lot, and I can't even notice.
We could probably do pavers for new parking lots and keep asphalt / concrete for heavy-duty stuff like interstates and roads over 30 MPH and not lose much except the up-front cost of pavers. (But hey if Taco Bell thinks they're worth it...)
But bumpy is good!!!! A bumpy street is one where you drive slowly and don't run over children riding bikes to school. A bumpy street is one where you pay attention. A bumpy street says "you may drive here but this is not a space _just_ for your car".
If only they were more common outside the Netherlands. I love my bumpy, brick, tree-lined, narrow, street.
Every residential street should be paved with bricks or other paving stones, instead of asphalt. It's safer, because people drive more slowly. The maintenance costs are also lower.
"Bumpiness" could be climate related - I've spent a lot of time in the upper midwest US and Canada, the freeze/thaw cycles mean things move in the earth.
I live in a place where we have a Tesco mall with a big parking lot nearby, but then I have to walk a path through a green area with mostly grass, but some trees and bushes as well.
The temperature difference is staggering. In hot summer, the parking lot is unbearable and the green area feels much better. In early spring/late autumn, the parking lot is uhm-okay (though still ugly), while walking through the green area gives you shivers: cool and wet wind.
Only in deep winter, during the freezing days, both areas feel the same.
TBF, my experience of america when I lived there, was that black asphalt was far less common than light grey (and thus higher albedo) concrete for both. Increasing albedo is considered to be one of the geo-engineering solutions to try.
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For people in urban hellscapes? Yes.
For non-human animals? More complicated. These sorts for forests are generally dominated by “edge species”. Edge species generally do relatively well out of habitat fragmentation.
The most sensitive species that need a lot of depth in forest generally don’t do well with these small pockets.
This is not to say that Miyawaki forests aren’t an improvement, just that their “conservation” value is limited and still need to preserve/manage huge amounts of actual contiguous forest with a minimum perimeter compared to the area covered.
This is not re-wilding. We aren't trying to get urban badgers and lions.
So, in summary I think your critique is true but misplaced. Consider the viable alternatives, not the pipe dream.
When we de-populate on the next virus, we can re-forest for bears.
Ok maybe minimum forest requirements is more accurate but had to do it
RaRa.
https://canadiangeographic.ca/articles/the-many-benefits-of-...
Googling them, I can find images of a few proof-of-concept plots in the middle of fields but I can't find a single example of how they might integrate with a city.
It would be nice to see some kind of before-and-after, even if just an illustration, to get a sense of how they would fit into a cityscape aesthetically and practically.
EDIT: Found a great list after a little investigation! https://www.north-norfolk.gov.uk/tasks/projects/miyawaki-for...
Here is an article about her project.
https://www.abc.net.au/news/2021-07-08/act-micro-forests-in-...
It's been two years, the some of the trees are well over 2m tall already.
But yes, wild hedgewoods of a mix of useful shrubs are totally doable even in really small spaces. I had designed a few. They are low maintenance, beautiful, useful, funny, and tasty and everybody should have space for one of this wildlife lifesavers in their gardens.
"Forests will reach a mature state in only a few years" is just other of this marketing statements that sound nice, but are wrong.
> Fuck minimum parking requirements, where are the minimum forest requirements?
I want a t-shirt with this phrase. Is simply brilliant
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https://www.fs.usda.gov/research/treesearch/40701
Or are areas that have planted trees areas that also tend to have reduced crime?
The abstract of that paper indicates an inverse correlation between trees and crime, but stops well short of claiming or proving a causal relationship.
So of course it's not proof of causation, but reverse causation(nice neighborhoods lead to more trees planted) seems unlikely to explain the effect.
Perhaps fake it till you make it?
Worth a try surely.
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If you want more space for parks and green, you can do it also other way. For example, like Hausmann did in Paris.
The idea I have in mind is that the control over cities has been wrested from its citizens. A special car commuting class has more comfort moving about a city like Paris than regular inhabitants — but at what cost and borne by whom? Removing space for cars means removing vehicles, which re-empowers city-dwellers, cleans the air, and cools the city.
Back on the envelope calculations: 3.5 kWh/m^3 to desalinate water, 10 nuclear reactors, 1sq meter for a bamboo plant, you can water and grow 5.5 billion bamboo plant; let's say each plant fixes 10kg of CO2 per year, you reduce 10% of world's emissions in one clean sweep, for a total investment of maybe 100 billion USD
If you go this route for greening the Sahara, you could allot 5% for the evaporation ponds to turn brine into dry salt.
There are other reasons it will never happen, but this one is solvable! :)
https://en.wikipedia.org/wiki/Inland_Customs_Line#Great_Hedg...
https://amocarroll.com/projects/tracing-the-great-salt-hedge
China has the China's Three-North Shelterbelt Program where they're trying to hold back the desert in North China and Inner Mongollia.
https://en.wikipedia.org/w/index.php?title=Three-North_Shelt...
Based on reports, it has issues with tree survival, yet seems to be making progress based on aerial surveys.
https://www.sciencedirect.com/science/article/pii/S259033221...
There's also an attempt in Africa in the Sahara that a bunch of countries signed on to. Unfortunately, their commitments have mostly amounted to talk without much funding or governmental support. Seen a few videos of locals who seems to believe in the idea, its just not getting much large scale help.
https://en.wikipedia.org/wiki/Great_Green_Wall_(Africa)
I also use Ecosia (https://www.ecosia.org/) as a web browser, and they supposedly plant trees based on number of searches and a percent diversion of search revenue. Seems to at least have some photographic evidence of money actually being spent somewhere.
Senegal's an example with desert work. Seems to have evidence that at least some amount of trees are being planted with videos (harder to falsify).
https://blog.ecosia.org/senegal/
https://blog.ecosia.org/tag/senegal/
https://www.youtube.com/watch?v=-13bKIS75Gk&ab_channel=TheIm...
Nobody can monetarily profit from trees, unless you were to charge people money for time spent under their shade.
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The problem is those streets: the 20th century model focused on maximizing individual vehicle usage, which meant lots of open space for safe operation and subsidized storage. Cars can’t go around trees like pedestrians or bicyclists and owners don’t want branches falling on their parked cars, so anywhere there isn’t enough space for both it tended to result in more heat-amplifying asphalt.
I totally believe that botanical gardens cool the air within them. That's what happens when you have an area full of trees and shade, with denser vegetation than a park.
But I have a hard time believing that they have any significant effect on the city air 5 or 10 blocks away, where the asphalt is baking in the sun.
So I'm not sure what the point of this article is, because it's not like we're going to replace half the blocks in a city with botanical gardens, as nice as that would be.
Meanwhile, the article claims claims planting trees on the street has less effect, but surely is far more important -- because it affects the whole city, rather than a small localized area in and around a botanic garden?
So there seems to be a major flaw in this article, in that it's comparing the cooling effects of various interventions (botanical gardens, street trees, etc.) but without ever specifying how the sizes or densities are being compared.
Honestly, I can't even imagine what a unit of comparison between botanical gardens and street trees would be, since botanical gardens replace streets and buildings, while street trees merely add to them. It's apples and oranges.
Botanical gardens are only slightly more effective than trees over roadways from their study, so shade is likely the strongest factor, but the others clearly play a part- from cooling down enough overnight compared to roadways and cement to the evaporation from the denser vegetation having a stronger effect.
The thing that I missed was how such a garden compared to an open, grass park. The difference in vegetation density would be clearer, I think, and might better explain the difference measured between trees over roads and gardens.
Luckily, fossil fuels are going to get phazed out massively over the next 50 years strictly due to economics.
It is actually in this way that places deep inland can still receive rainfall. Without this process clouds wouldn't be able to make it far inland.
You can see the same effect mostly in spring in coastal areas, when the land is heated faster than the sea. Hot air over land will rise, colder air from the sea will move in, causing thermal wind, making the coast a lot cooler. This can cause enough wind for kitesurfing or wingfoiling.
Have you built your argument against the study on belief?
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When I go for walks in summer in my city, it's noticeable how the temperature drops while on the sidewalk when I walk past a green area as opposed to past a building.
Dead Comment
You don't need any actual botanical gardens.
It takes little space away from pedestrians, but provides a lot of shade. That seems both easier, cheaper and better that taking up whole city blocks.
Nope, can't examine that. Parking lots are peak human design. The most logical design solution for our species.
They mention less heat as one of the multiple benefits of pavers / bricks.
I used to dislike them by default - "They're bumpy". They're not bumpy. There's a shopping center in my town, and even a new Taco Bell, that use pavers for their parking lot, and I can't even notice.
We could probably do pavers for new parking lots and keep asphalt / concrete for heavy-duty stuff like interstates and roads over 30 MPH and not lose much except the up-front cost of pavers. (But hey if Taco Bell thinks they're worth it...)
If only they were more common outside the Netherlands. I love my bumpy, brick, tree-lined, narrow, street.
The temperature difference is staggering. In hot summer, the parking lot is unbearable and the green area feels much better. In early spring/late autumn, the parking lot is uhm-okay (though still ugly), while walking through the green area gives you shivers: cool and wet wind.
Only in deep winter, during the freezing days, both areas feel the same.
https://www.youtube.com/@NotJustBikes/videos