Anecdata: I have a plot of land in the Santa Cruz Mountains and half of it has redwood coverage and the other half is sparsely covered by much smaller species. On hot days I can go to the redwood half and get an easy 10F temperature drop.
Shade is part of the equation and so is retaining water. Once I was introduced to the idea of check dams and their role in water conservation, I started noticing how the redwoods often build their own on hilly terrain.
The landscape in a forest can be quite complex and rich.
efavdb•1h ago
Can feel the same effect here in CA. I’ve heard that in areas with more humidity the effect is much weaker though, presumably because the air has higher heat capacity or something and so doesn’t cool as quickly in the shade.
SoftTalker•1h ago
I live in the Midwest US, plenty humid here in the summer but it’s consistently 5 degrees cooler in my wooded neighborhood than it is in the nearest town about 10 miles away. The effect is real.
efavdb•54m ago
Interesting. I asked a friend from Texas and he said he wasn't even aware that shade was cooler until he moved out. Need more data.
Retric•11m ago
It’s not about shade alone. A cliff or single tree provides shade, but a forest provides evaporative cooling during the heat across a huge area alongside shade, it ends up a noticeably different climate.
There’s some other effects such as photosynthesis converting sunlight into chemical energy which in the short term is like reflecting that energy into the sky. At night plant metabolism warms the environment slightly and blocking the sky reduces radiative cooling to space, but that’s generally a good tradeoff for comfort.
ahartmetz•16m ago
Might also have something to do with the ground and trees evaporating less water into the already humid air, reducing the cooling effect of evaporation.
user3939382•2h ago
Apparently earthworms are a problem here. The saplings need the brush to protect them and the worms which are non native are mulching it. IIRC. If half of what I hear is happening in the Canadian forests or Amazon is true it’s sickening. Of course you have the naive and confused among us who debate or defend this abhorrent and unnecessary exploitation.
kevin_thibedeau•56m ago
There used to be worms before the ice. They're just repopulating. By extension, none of the trees are native either. The natural state of the higher latitudes was mud and rock 10000 years ago.
jandrewrogers•22m ago
North America did not have an extensive earthworm ecology like Eurasia even though they had some worms. They are an invasive animal[0] brought from Europe that creates problems for the many North American plants and ecosystems not adapted to the pervasive effects of such worms. The worms you find in soil are largely non-native.
I recall a factoid from growing up in southern New England: that Connecticut had more forestland in my youth than it had a hundred years earlier, because so much agricultural land had been abandoned to nature. Presumably farmers wanted soil without an annual stone harvest.
imoverclocked•2h ago
Shade is part of the equation and so is retaining water. Once I was introduced to the idea of check dams and their role in water conservation, I started noticing how the redwoods often build their own on hilly terrain.
The landscape in a forest can be quite complex and rich.
efavdb•1h ago
SoftTalker•1h ago
efavdb•54m ago
Retric•11m ago
There’s some other effects such as photosynthesis converting sunlight into chemical energy which in the short term is like reflecting that energy into the sky. At night plant metabolism warms the environment slightly and blocking the sky reduces radiative cooling to space, but that’s generally a good tradeoff for comfort.
ahartmetz•16m ago