Speciation does not occur in human timespans. If 3 species of seed bearing plants out of 330,000 went extinct per year, we could expect to live on a barren planet within 110,000 years. This is a very rapid rate, given that plant life has existed for 5,000 times longer than that.
Who knows what chemical and medicinal discoveries we shut ourselves away from as species are dying out. Consider a single poppy species that gave medicine 4 or 5 chemicals that turn out to be the basis of the vast majority of medicine's strong pain relief repertoire.
This is far more of a problem than a solution.
1) Many of the bred/GMO cultivars are sterile and/or unable to survive in the wild. They actively work against biodiversity.
2) Many of the bred/GMO strains are used in monocultures either in agriculture or gardens. These both displace the native plants, steal resources, and are also far more vulnerable to pests, disease, etc. Again, not improving, but destroying biodiversity.
3) Much of human activity in addition to breeding new species/cultivars is also deliberately or inadvertently moving species into new ecosystems. Some of these become rapidly spreading invasives that damage or destroy the local ecosystem, both plants and insects, animals, and birds that feed on the now damaged ecosystem (& no, they usually cannot just eat the new plant, nevermind if it's not toxic).
4) Many of the bred/GMO variants, even if planted in their native habitat, are incapable of providing sustenance to native insects & birds. While they may still have the external characteristics to attract them (odor, UV spectrum colors, etc.), they lack the actual nutrients, e.g., because they are sterile. So, not only do the human breeding/GMO activities damage biodiversity in plants, they are also damaging the other ecosystems.
So, if you are going to count human bred/GMO'd cultivars, they need to be counted against biodiversity.
Between these disruptions of the plant ecosystem, pesticides, habitat destruction, climate change, and other effects, we are much more dangerously close to breaking the food chain than people imagine.
This is invisible because of ignorance, normalcy bias, and the fact that these are enormously complex ecological webs, and they are very resilient until they aren't -- at which point the system collapses and it is too late to repair.
Numerous civilizations and indeed ecosystems have collapsed because of this sort of problem (see e.g., Permian Extinction which nearly extinguished life on the planet).
We are now causing this on a global scale and, except for the asteroid ~65MM years ago, at a pace unprecedented in geologic history.
The problem from a mass extinction of plants is that we don't know what the reverberating effects of those eradications can mean. There are many animal, insect etc species which may be reliant on said plants for primary nutrition which then percolates all the way up the food chain and potentially decimating other animal populations.
It is not hard to imagine the potential side effects of say, the resulting plant extinction resulting in massive bee population losses for example. But that's just one prominent example of what lost biodiversity can potentially cause. This lost biodiversity can then further contribute to the rise of invasive species and the result is a destabilization of multiple biomes which have been relatively stable for a long period of time.
However, that's unlikely. Well before that, human society and population will likely collapse, due to climate change.
GMOs and cultivars grown in labs not only have no positive effect on biodiversity, they have significant negative effects. See more detailed post above.
I'm no biologist, but surely that is a Pandora's Box of a claim. There isn't even one clear definition of what a 'species' actually is [0].
I can't find a source, but I'm guessing most species are small, short lived creatures with a lifespan of ~1 year; such as mice or insects. That is 70+ generations per human lifespan - 70 generations probably is long enough to get a new species if there is evolutionary pressure.
It's a subjective description of a factual conclusion of the study. Extinction rates that are "500 times faster than they would naturally [be]" are certainly alarming to me as well.
Why do you think that sounds too good to be true? Why would a species become extinct naturally? Nature seems pretty good at maintaining a species once its evolved to be viable. Obviously things do die out naturally, but to me (a non-botanist) it seems like something that would be very unusual without external factors (eg meteorites, global floods, climate change..)
Also, there are diseases that can target specific plants, when unchecked, can wipe out an entire plant population (see Panama disease for bananas for an example)
Extinction level blights similar to these are not often found in the natural world. They're only a thing because we (humans) eliminated genetic diversity from crops through grafts and clones. If the plants reproduced naturally its likely that a range of genetically diverse children would have been resistant to the fungus.
Based on what?
Why would I expect that? Because of all the "sky is falling" rhetoric. I don't expect that to mean the sky is falling over the next 10,000 years; I expect it to mean that the sky is falling now.
[Edit: Note that I am not saying that this is good news - just that it is considerably less bad than I expected.]
10 000 years is a lot of time. Compared to other climate issues, with consequences expected in decades, this deserves at best a "cool, we'll fix that in a century or two, if technological civilization still exists by that time".
On the other hand, I do agree with your practical assessment:
> "cool, we'll fix that in a century or two, if technological civilization still exists by that time".
Because, if for no other reason, it probably won't.
And there's also the fact that it's a human impact that can't likely be mitigated in any other way than collapse of the human population.
So since 1900, that's 357 species disappearing, out of 330,000 (~0.1%)
How did they arrive at the conclusion that this is an "alarming rate"? Also, "up to 500 times higher" means, the expected rate is less than 1 plant going extinct out of 330,000 species, which sounds way too good to be true.