this post was submitted on 31 Aug 2023

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Assisted migration of redwoods to Washington state: good or bad idea? (mander.xyz)

submitted 2 years ago by [email protected] to c/[email protected]

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Hello fellow tree huggers,

Question: if I have a plot of land in the Western Washington Cascades, should I plant redwoods and/or sequoias on it on not? I would do this in addition to the obvious douglas firs, western red cedars, western hemlocks and various appropriate ground shrubs/ferns.

I can see a lot of articles about "assisted migration", many of which reference redwoods, but also all of which state that the idea is controversial. The idea is that Northern California is becoming less habitable for these trees, and Washington and BC become more like how California used to be, so the redwood forest will naturally migrate northwards. However, climate change is happening too fast for a slow-moving forest to realistically keep up.

The proponents argue that it's a way to preserve an important species, especially one which is a great carbon sink.

The doubters argue that some species of plants wouldn't survive the process, or could bring pests, or at least be susceptible them.

I can't tell if those drawbacks really pertain to redwoods/sequoias in Washington though. There are hundreds of them around the Seattle area that are doing just fine, more than a hundred years after residents planted them.

What do y'all think? Do it or no?

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[–] [email protected] 4 points 2 years ago (1 children)

Let's find out more about the situation.

You've got access to land for regeneration? And with that, you're going to plant tree species onto that land. You are going to pick mostly endemic species, and the planting will be diverse.

Of the endemic species, will you be provenancing them from distant locales of their range, ones that may match your assumed new climate (or at least be moving that way)?

With the Redwoods, will you be planting enough of them so that they become a Redwood forest 'ecotype' or will they be oddities in your forest, just poking their head out here and there?

If they're present in your area without the issues of bugs/disease, won't be invasive (to the detriment of all species not the fact that they propagate themselves) or harm aspects of the environment, and you like them - I would do it. I personally have vulnerable species from a long way away as garden oddities and have no issues.

But, if you are going to plant a Redwood forest (with understory) then you probably to have to do some due diligence of untoward impacts. If you are regenerating a bare paddock that isn't attached to any native areas, I personally believe what you do, with a few caveats, is fine. But without knowing the purpose i.e. how many, final restoration goal etc, it's hard to say.

I would say though that not doing it and watching climate change destroy large swathes of species (which is already happening, an article from 9 or so days back was a good read), you would be kicking yourself that you didn't do enough. I'd like to believe that building a mostly endemic forest is the goal but within that forest is a foundation of other species that may be able continue the base ecological functions that are required (erosion, canopy, structure etc) if climate change has aggressive impacts on your area. Yours as an insurance policy for an interesting species is something different again.

[–] [email protected] 3 points 2 years ago (1 children)

Wow, thanks for the thorough reply! I'll try to respond to your questions and also add more context...

You've got access to the land for regeneration?

Yes, I own the land.

will you be provenancing them from distance locales of their range?

Honestly haven't thought about this yet, but I figure I'll just go to the nearest nursery!

will you be planting enough of them so that they become a Redwood forest ‘ecotype’ or will they be oddities in your forest, just poking their head out here and there?

Just oddities, mixed together with the endemic species. I should say the lot is only a half acre, so it's really not a forest by any stretch. It's just a little chunk of land I want to care for responsibly. It is right on the edge of the Baker-Snoqualmie National Forest though, so I want to be mindful of what might spread into the "real" forest.

If you are regenerating a bare paddock that isn’t attached to any native areas

The lot is currently in a pretty unnatural state. There are a few western red cedars and native shrubs/ferns, but also a big blackberry patch, lots of English ivy, and a few other species I haven't identified yet. To make things worse, most of those foreign invasives are on a steep hillside that seems like a big erosion risk.

The surrounding forest is a mix. Some of it is nice, old douglas firs, hemlocks, cedars etc with the native undergrowth, and some of it is like mine - blackberries and ivy etc.

final restoration goal

I mainly just want to bring this land back to a mostly natural state so it functions (and feels) like a healthy PNW forest. I also want to put a few fast-growing big trees on the hillside to prevent erosion (this was what got me thinking about redwoods/sequoias). Ideally, the small piece of forest I do have the privilege to steward will be able to help the surrounding area regenerate to how it belongs as well. I'm trying to think ahead 100 years to how the climate will be, and start planting for that now.

Conclusion

This probably won't be a big deal in the grand scheme of the forest anyway, since I have such a small space to work with. I might just do it!

[–] [email protected] 2 points 2 years ago (1 children)

Cheers for the answers. I think it's a goer.

But, I'd implore you to assess the climatic zone movement that may occur (which was alluded to) and make sure your endemic/native plants have some insurance against that.

I wouldn't take the advice of a nursery, I'd be trying to find studies from ecologists and climate experts and see what they are suggesting as possibilities.

Good luck with the invasives! I do that for work and it's one of the hardest jobs I've ever had, naughty plants are fucking relentless.

[–] [email protected] 2 points 2 years ago (1 children)

Haha yeah those invasives are gonna be a few years of work. Any tips for killing them without creating a bigger erosion problem? I was thinking I’d start by just ripping out little circular clearings and plant some medium sized things in the space left behind, then wait a year or two to really go hard on the rest of it, so there’s never any time without roots holding everything together.

Yeah Ive read a bit about how climate change will impact the native plants. I think western red cedar is in the most danger but it’s gonna be a while before they really can’t handle it.

[–] [email protected] 2 points 2 years ago

You'll need a local expert in techniques for those particular weeds. For example, we have developed techniques for certain weeds but if I look those weeds up, not one technique will be listed; they're usually generic and written by people that have never done the work. And these people are sure they know everything.

But the idea you have is right, if the weed allows you to do that. Sometimes, depending on the weed, you literally can't plant anything back in because the weed is hard to remove and doing that makes it even harder. I would consider, without knowing anything about your ecology; grasses and sedges (possibly ferns) are usually a good option as they have fine, fibrous roots, are cheap to propagate, easy to mass plant, and grow relatively quickly. Maybe you have some pioneering trees (native or exotic) that you can remove later, quick growers that are easy to kill or succeed out once you've got the weed out of there.

[–] [email protected] 4 points 2 years ago* (last edited 2 years ago)

Especially since these trees are widely planted in your area already, I don't see much harm in trying. Assisted migration is mainly controversial as it pertains to reforestation of wild areas. For small plots like this in urban areas or even urban fringes, it's hard to image any harm it could do. In fact, I would argue it's a great place to test these ideas and see what problems may exist for more radical assisted migration projects later on, if those become necessary.

Make sure to pick the right spot--both species prefer deep soils with consistent moisture. Coast redwoods in particular do not tolerate drought or extreme cold. Should not be an issue most of the year but if you are on a well-drained slope, you may need to irrigate in dry summer weather to maintain good health. Coast redwoods are also very difficult to remove/eradicate once established because they vigorously sprout from the stump when damaged. So make sure it's in the right place.

A nice thing about these two species is they are very fire resistant, particularly coast redwoods. As this may be an emerging issue in Washington, they could bring extra resilience to your landscape in the case of catastrophe.

If it's not too cold, I would consider some oaks too--they are very crucial for wildlife and insects in North America. I think Q. garryana would be your local species but if you want to try some assisted migration, Q. kelloggii and Q. chrysolepis could be interesting to trial as well.

I'd recommend looking for a nursery that takes phytosanitation seriously. Many serious diseases and pests of plants are being spread by nurseries right now, especially if trees are being moved long distances. If your lot is more urbanized this is less of an issue because they're likely already present but for a more rural plot it would be well worth paying attention to.