I restore degraded lands for a living.

As such, I have a lot to say about the article; most negative, but not all of it. A realist perspective, I suppose. I apologize in advance for all the line breaks but I want to separate my thoughts into palatable little snippets.

The first thing I want to point out is that abandoned lines will not be as productive as predisturbed lands. Further, they will not recover the same climax community unless guided to do so or their distributes was minimal. The principle behind this is that natural ecosystems have a balance to them. Once you upset that a balance things get all wonky and there are a ton of knock on effects. That doesn’t mean that these disturbed areas do not have value, it’s just a different value and if it’s recovery is left unguided, then you could well end up with an entirely different ecosystem than what you started with. For instance if you plough a bunch of native prairie and thistle colonizes, you might get some vegetative spp. that can compete with thistle and it’s rhizotomous growth habit, but most will not be there. You end up with some Frankenstein ecosystem. Other times it’s entirely different.

These forests are similarly underexplored by ecologists as reservoirs of biodiversity.

Yes, in some cases, like selectively logged areas, the abandoned lands themselves can offer sources of spp. For recovery. On top of that, disturbed areas create a lot of edge effects, which can bump biodiversity, but it is not always the spp. You want (e.g. you get the Frankenstein communities I mentioned earlier)

Nature pays little regard to exclusion zones, however. Despite the radiation, wolves, bears, wild boar, lynx, and other large animals are reclaiming their former terrain, forests are encroaching, and carbon is being captured.

Yes, but those megafauna are irradiated most likely and their populations likely suffer as a result.

And even when the war ends, minefields could leave the land unused and unproductive for decades

This is honestly tragic. Ukraine has some of the best soils in the world. Topsoils usually average 60 cm or more. In Canada, the most productive soils will have 30 cm, typically. These soils are the same classification as their Ukrainian counterparts.

Irina Kurganova, a soil scientist with the Russian Academy of Sciences, estimates that the collapse of collective farming there has led to the sequestering annually of more than 40 million tons of carbon in natural vegetation and improved soils

I am also a soil scientist.While Irina is correct, I would like to point out that this carbon is labile in that it cycles thought the carbon cycle, and is not usually long-term (e.g. centuries like biochar or geological binding with carbonate minerals or soil humus). In particular the rate of humus formation is really slow, and requires cold temperatures (climate change breathes heavily over my shoulder). I particularly don’t like how people seem to think that this a fast process (though I concede she is likely aware of how long this takes).

That “half the size of Australia” stat is for global abandoned farm land, in case you were initially confused as I was that they were saying Bulgaria had that much abandoned farm land while being less than a tenth the size of Australia.

Edit: removed redundant words that were unnecessary