Land area has little to do with population as you yourself eloquently show with the examples in your statement. The area's culture, history, and environment are all more relevant factors for demographics. The USSR's population was the hardest hit by WWII and their population 'catch up' hindered by frequent famines.

[–] InvertedParallax@lemm.ee 3 points 1 day ago (1 children)

1947–1991

After 1947 there were no known famines. The drought of 1963 caused panic slaughtering of livestock, but there was no risk of famine. After that year the Soviet Union started importing feed grains for its livestock in increasing amounts.[50]

They lost a ton of population when the USSR broke up, and population growth wasn't that high for Russians since the war due to general nihilism.

[–] Burstar@sopuli.xyz 3 points 1 day ago* (last edited 1 day ago) (1 children)

Yeah 'food shortage not rising to full blown famine' would probably be more accurate. There have been several severe droughts in the USSR/Russia since WWII that impacted food availability.

This chart shows the age distribution:

collapsed inline media

[–] thebestaquaman@lemmy.world 2 points 22 hours ago

The age distribution chart of Russia is fascinating in that you can still see (what I have heard is) the aftermath of an entire generation being decimated in WWII in the form of these population "dips" every 20-30 years.