Comment by beachy | Hacker News Reader

Comment by beachy | Hacker News Reader

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> The seedlings are planted very densely—20,000 to 30,000 per hectares as opposed to 1,000 per hectare in commercial forestry. For a period of two to three years, the site is monitored, watered, and weeded, to give the nascent forest every chance to establish itself.

Any planting of new forest is to be applauded, but(at least where I live) this is an unrealistic approach.

We have 10 acres (about 4 acres) of land that we have mostly replanted. I've learnt a bit in the process.

1) watering everything is not feasible. We're on tank water, and each summer ends with me policing the lengths of family showers. This southern hemisphere summer, we added one more 25kl tank (several $k) just for plant watering. It barely scratches the surface.

2) weeding is unpleasant and hard work.I struggle to get any help with it. In practice, spraying is the only practical approach, not ideal environmentally.

3) the profile of species that thrive is changing, right before our eyes last summer was brutal and we lost several big trees probably 50+years old in the heat.

While this article's approach is an interesting one, I would say it's is suited to a very compact environment, such as one might find in japan.

At a larger scale, a less intensive approach is to plant semi-intensively mainly in pioneer species. Planted in the autumn or spring, these will survive without watering.

These form a thick forest that prevents weed growth underneath. You have now reached a stable point - you can now leave your forest to nature. Birds will drop seeds, and those seeds will germinate beneath the pioneer canopy, letting the larger species come through and eventually replace the pioneer species.

If you want you can accelerate the process by planting large trees here and there within the pioneer canopy. But again, that won't require watering or weeding.

Key to it is using native species, and picking species that will survive at higher temperatures.

Being in the southern hemisphere, that means species that are commonly found in the north, where it is hotter already.

There is some interesting thinking to be done on "native" versus "adapted" when it comes to planning new forest. It's a reality that the climate is changing and there are many introduced pest species that are all drastically changing the landscapes. On the Pacific coast, the combination of drought, sudden oak death disease and pine beetles are rapidly changing the flora and also the fauna when food and shelter disappears.

When you plant a new forest today, do you try to preserve the native species or do you anticipate what species will thrive in the area 20-50 years from now?

Yes, this is something larger groups are starting to realize and try to work with. Look up the Nature Conservancy's climate change corridors.

They are trying to preserve/conserve land in strips as a priority. This way as climate changes, plants and animals will have a path to migrate unimpeded (or at least impeded less than if there were large roads/developments in the way!).

"Assisted migration" provides ongoing ethical dilemmas, but things seem to be moving in that direction. See, for example, https://www.climatehubs.usda.gov/hubs/northern-forests/topic...

So I think the current consensus is something like: help forests migrate faster than their natural rate, but don't wormhole species across the planet.

That's a fascinating question. We hear a lot of talk about planting forests to combat climate change.

But it seems very feasible that just planting whatever is thriving today will backfire in 20 years time when that species becomes unviable due to temperature rise, reduced rainfall or arrival of some exotic bio pest.

> Birds will drop seeds, and those seeds will germinate beneath the pioneer canopy, letting the larger species come through and eventually replace the pioneer species.

FYI This can actually be a huge problem if you live in Washington State, because Himalayan Blackberry spreads through bird droppings. You have to aggressively weed it or it will choke out everything else in the area within a matter of years, including saplings, mature brush, grass, native blackberry, and other invasives like Scotch Broom.

That blackberry is an insane (kind of scary) species. It grows so fast and has immortal roots that will just sprout up somewhere else. Huge thorns to protect itself from animals and people, delicious big berries to help it propagate. How do you even try to outcompete that as a plant?

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