I had thought he was in the taiga when he first escaped because he referred to being in a forest, with no landmarks, etc. "surrounded as we were by trees that were identical in height and girth." In fact the taiga is home to the world's tallest, and hence, I presume, oldest, trees. So when my grandfather described them as being "deep in the bowels of a forest that may not have been touched by human feet since
the Six Days of Creation" he might not have been exaggerating.
Not only does far eastern Siberia have an unforgiving climate (the better to discourage inmates from any thoughts of escaping -- and surviving), but it is also home to the Amur Tiger (aka, the Siberian Tiger), the largest specie of tiger in the world, but also, as the book demonstrates, capable of higher order thinking, particularly when it comes to taking revenge.
Predatory animals don't usually attack humans unless they, themselves, have been or are being attacked, but in one of the incidents described in the book, a hunter stole some meat from an animal that the tiger had killed, which the tiger considered an attack (or at the very least, rude behavior). Not only was this particular tiger pissed off, byut he memorized the particular hunter's scent, and stalked him, camping outside the hunter's cabin for several days, and then returning to the forest to await the hunter whom she knew would return, as if she had some hypnotic power over him. She waited for the hunter (tigers, while having the capability to get very angry, also seem to have a great deal of patience, making them deadlier than even the cattiest <--hmm, wonder why we use that descriptive term? -- high school girl), and when he returned, she attacked and ate him, leaving only the clothing as evidence of his kill and, perhaps, a warning.
So while my grandfather's crazy ideas and occasional charm got him out of a lot of close calls, I'm glad he didn't have to test his charm on a tiger, one with a long memory.