Whereas I think sports are an intentional device used by people to avoid war. It gives us a non-deadly way to compete.
There was a recent article in the local Seattle paper about Russians in our area who were buying the Putin lies. So, maybe it’s directed to people like that.
As for the issue of “plastic trash,” that seems like very minor issue in the scheme of things. I haven’t seen any of these blue and yellow ribbons, but I can’t imagine they exceed the amount of plastic we throw away every day for countless other useless things. I get ranting about the amount of disposable plastic trash we generate, but signaling out one small example makes me think you have other objections. Perhaps, as you say, it just seems so completely pointless.
It’s a huge issue, but some random ribbons are hardly a blip on the radar of the trash problem. That said, there is nothing stopping anyone from buying cotton or abacá ribbons instead.
That’s what I intended to say.
Yes, agree. It should be no problem if someone is making a statement on their own property by tying ribbons or flying a flag (or adjusting their avatar on an anonymous internet message board 
), but I took the OP to mean trees in public spaces like along streets and in public parks - I would not advocate for that. It’s like if someone wants to fly the Stars and Bars on their truck there is not much you can do (other than judge the person), but if they try to put that up in a city park there will be a fight.
If you (not puzzlegal, but the collective “you”) want to support Ukraine and Ukrainians, as mentioned, donate to the cause however makes sense to you, and do something to welcome refugees to your community by giving them some of your stuff. My metro has a large Ukrainian community and I am doing both. That will make more difference than doing the minimum effort of hanging a ribbon on a tree, IMHO.
The trees I am seeing are along the streets, on what we call the parkway - between the sidewalk and the curb. They are directly in front of a house, but belong to the city. This is not an aspect I was at all concerned about.
Sometimes - like w/ breast cancer awareness walks, I see more widespread ribboning in more clearly public places. Have not seen that WRT pro-Ukr ribbons
This reminds me of the article and photo in The Onion right after 9/11:
“Not Knowing What Else To Do, Woman Bakes American-Flag Cake” (scroll down a little)
I really thought the original had a pic with her holding a pan with an American flag frosted cake but I don’t see that anywhere so…
Maybe that was in the alternate ending of “Big”. 
I suggest the idea of these ribbons, like the avatars and everything else, is as a reminder. Sure, we’re all aware of the Russian war on Ukraine, but we’re not going to be thinking about it all the time. It can be easy to just move on with the day.
Someone who is entirely practically minded might say “What good is just thinking about it?” To them I would say that thinking leads to action. Someone might check up on the Ukrainian situation and find out that that there is some way to help. Or various other little things that might occur because it’s on your mind.
But I would also argue that the practical is not all there is. There is a certain level of respect involved in remembering the situation. I know it constantly gets mocked, but there’s a reason why the whole “thoughts and prayers” thing started. It wasn’t always such a meaningless phrase. It was literal, a way that humans show sympathy. Symbols are also a way we do that.
I suspect that the people who added those ribbons got their intended effect. The OP thought about Ukraine when he saw them. And sometimes that is the goal. You may or may not take an action with that thought (same as if you see any other ribbon). But you at least thought about it.
You are right. The practice of hanging yellow ribbons began during the Iranian Hostage Crisis in 1979 by Penne Laingen, the wife of Bruce Laingen, the American Charges D’Affairs in Iran and the highest ranking American hostage. She started the campaign to make sure that the hostages remained at the front of Americans’ minds and as a visible indicator to the powers that be that Americans cared about getting American hostages home.
The ribbons today serve the same purpose. Reminding Americans that the invasion of Ukraine is ongoing and pressuring politicians to continue to support Ukraine.
Our public library is giving out packets of sunflower seeds (supposedly, sunflowers are the national flower of Ukraine) for us to grow to show solidarity with Ukrainians.
I think I’ll express solidarity in other ways*, rather than try to shoehorn 10-foot tall sunflower stalks into my garden.
*not by eating borscht.