Isn't this because humans killed and took the role of large grazing animals and large predators? After some time this can result in a new equilibrium, and when humans move out it's chaos again for a while. Question is not if nature will deal with it, but rather what we humans want — probably not some ecological desert for millenia.

I read the study. The "problem" with it is that it only examines biodiversity before and after abandonment, but without the abandoned areas being rewilded in any way.

Some areas are so destroyed by human activities that they need some help in rewilding, which is definitely possible. Of course, this study does point out that some management of the land that resembles previous human activities could help biodiversity. And of course, as the study mentions, they did not include "Mosses, lichens, mammals and invertebrates—including soil organisms such as nematodes and molluscs".

Keep in mind also that biodiversity is difficult to measure can be counterintuitive. Farmland and managed land creates edge habitats, or a confluence of habitats, where measured biodiversity is higher. Of course, when that edge habitat disappears the measurements can go down. But that does not imply that merging a huge number of farmland back ot a more contiguous wild are won't support biodiversity better in the long run.

Every ecosystem on the planet besides recent settlements like Hawaii or Antarctica are co-evolved with human beings. "Pristine wildness" is almost always a myth.

Before so many people, Japans open wet habitats were mostly floodplains, with rivers that flooded and shifted around the way rivers do. Those rivers are now dammed, channelized, the floodplains are cities and fields, much the same as in the Eastern US. Rice paddies became the wetland for frogs, fireflies, dragonflies,wading birds. If the paddies go to forest, those species don’t return to floodplains, because the floodplains no longer exist.

I suspect this is the opposite in areas of the USA that have seen population declines. There is virtually nowhere in the USA in the 2020s that looks like, say, Ogimachi Village. And even in, say, the 1920s, so much forest had been cut for agriculture, logging, mining, and soon thereafter for the first suburbs, that I can't imagine human development had any positive effects whatsoever on wildlife or biodiversity.

I can't help wondering if their consideration of climate change as a covariate factor has been rigorous enough.

Climate change is happening everywhere but it is quite noticeable in Japan with summers getting hotter and winters getting milder.

Seems counter-intuitive and definitely warrants research to understand the mechanism. The most unintuitive part being local plants not returning.

The problem is apparently the tall bamboo that is taking over and not letting native tree to grow. This bamboo does not have home grown competition although it is a native bamboo. The who thing probably needs some sort of automated tilling and panting or imported workers to remove the the giant bamboo and farm it somehow perhaps.

This is surprising to hear. I lived in very remote kyushu for years and saw an incredible amount of wildlife. Badgers, hare, foxes, wild boar, deer, racoons (tanuki), monkeys. Roadkill everywhere all the time.

Give it 20 more years, it takes time for ecosystems to rebuild.

There are a lot of confounding factors in ecosystems at the edges of urban areas. I live in the Massachusetts exurbs, and have seen fluctuations in the population of deer, wild turkeys, and coyotes.

I've also seen some very well secured trash bins in Tokyo, so Japan clearly has wildlife even in urban areas that's very interested in the contents of trash bins.

I used to have a committee of four farm dogs visit my kitchen scrap pile every morning to sniff around. Now they are all in their separate invisible fence boundaries. So, more coyotes, fewer turkeys? I see more turkeys in some closer in suburbs and the neighborhoods of Boston.

> plant diversity peaked in the medieval era, when small farms created a patchwork of fields, pastures, and forests that supported a greater array of plants than either the closed forests that came before or the industrial farms that would follow.

That seems reasonable from a study from Europe they quoted. If farmed land, garbage left around, or brush clearing was helping certain species thrive it could mean they will struggle once farm plots and that other stuff goes away. It would be rather silly to have someone dump piles of rotting food in the woods to keep up the wild boar biodiversity that’s now declining.

Not so long ago, maybe a couple of years, I heard that the trend was to go back to the countryside. Now it's emptying out again? Which one is it? Or does it change that quickly?

If something is dependent on human intervention for survival in a specific environment, was it ever even wild?

When the environment changes and we convert forests to farms or urban centers, wildlife of course disappears. Then over time the surviving creatures will evolve and adapt to become suited to living around these urban centers.

When you remove these urban centers the same thing happens. You are changing the environment. So of course there is an initial culling as the selection process activates.

We tend to think of depopulating actions in a single unidirectional way. Nature -> Urban = Bad and depopulating. The reality is that nature is neutral. It's Not unidirectional and nothing is bad or good. Believe it or not I'm sure species do go extinct from the conversion from urban to more wild environments. It happens both ways and again, extinction isn't inherently bad either.

I feel like this has been studied before, and lots of times: nature is uncontrolled. Which really leads to constant (like every 10 years or so) disasters of one kind or another (usually an invasive species), destroying plant growth and biodiversity.

Humans built systems to prevent all this from happening, 1000s of little custom ones in 1000s of different little places with 1000s of different functions and kept those systems running. Irrigation. Bringing food (and edible trash). Preventing collapses. Building dams. Removing invasive species from specific areas. Those are probably the big ones. That's why there is the continuous nature across Europe. It's entirely artificial and it's due to farms being so incredibly widespread. Just look at the map. It's absolutely incredible how far and how much there are.

The "natural" Europe is really mostly steppe dotted with swamps and forests, usually next to each other, with vast open spaces, with very few animals, in between. That should be the situation one would expect to return.

Maybe they weren't wildlife but roomates just like the pigeons and the rats.

I'm skeptical. Having been to some areas of rural Japan, I'd suggest that the macro cycle established by humans was irrigation related and the removal of the same causes deep challenges to former human-presence-biome members. A novel and restored biome, more suited to the natural hydrosphere of the area, will likely take decades to a century to re-emerge assuming its species survive and its preconditions haven't been ruined by concrete.

Note also in my limited experience there is typically a severe and sudden difference between flat land and mountains, the former being human managed with extreme prejudice and the latter being typically degraded/unnatural/replanted ("Japan's forests are ~44% dense post-war cedar/hinoki plantations with barren understories"). This is one of the most striking features of the Japanese landscape relative to other nearby countries. I would assume the current study focused only on flatland, as the forests are not going to empty out when proximal humans desist: quite the opposite.

The unstated truth here is that Japan apparently raped its physical environment for its war machine.

https://japansociety.org/news/japans-forests-good-days-and-b...

This is obvious to me in Southern California. I contribute nutrients to the land near me that would otherwise not be here at all. The compost alone has nutrients from fruit and vegetables that don't even grow here. I maintain fruit trees that the squirrels and rabbits eat and in turn the coyotes and red tailed hawks are able to sustain their population. It's pretty simple really. We add more energy into the system and it has more biodiversity in turn.

I wonder if this is somewhat specific to Japan or has been observed elsewhere

In your face depopulators!

this will inevitably prompt the usual litany of "without immigration, Japan will not survive", so I'd like to point out the elephant in the room: no one wants to live in the countryside anymore, for a number of good reasons. those reasons are mostly cultural, and there's nothing any government can do about it.