I've seen quite a few comments here (+ previous thread) about how Germany's landscape has been so thoroughly battered and poisoned that its environment is a mess even 50 years later and indeed "may never recover". I think this in the short term this is correct, large parts of Germany in 1965 will probably look like the surface of the moon, and be utterly uninhabitable for the forseeable future. Longer term, however, this could be the best thing to happen to the local environments, if our admittedly limited experience with involuntary parks* such as the OTL Chernobyl Exclusion Zone (or even the Korean DMZ) is to be followed - over the medium term (i.e. a few generations), the short-term massive damage to the local ecology is, ironically, more than made up by the complete lack of human presence. Even the Verdun battlefield, which was as utterly destroyed as any place on Earth can be, and will be off-limits for hundreds of years, looks like this today:
Which is not exactly barren wasteland.
The A4 stance towards any sort of real economic development and reindustrialisation in Germany, probably helps. I would not be at all surprised if, by the 2010s, we were seeing the early stages of natural reforestation in large parts of Germany and especially in the exclusion zones, despite the toxins, pathogens, unexploded bombs, and other assorted nasties that make them quite lethal to higher forms of life. A cliche, but Nature's resillience is not to be underestimated when left alone to do its thing.
*A particularly apt term in this case as it was originally coined as a description for parts of the natural world that had either been so messed up or had lost all value to human exploitation and were left to grow wild again. Sterling's original prediction was that these places would be overrun with weeds and have a highly "unnatural" ecology. Instead what we've observed is that these places more or less revert to their pre-human ecological state within a generation or so.