I do, and I've seen it in others, but from the limited data points I've seen there's no causal relationship with age. I.e. what I've seen is people largely oblivious of nature/ecosystems/flora/fauna sudenly becoming very invested in it, for various reasons, but this doesn't happen at or only beyond a certain age. For me it was around 30 but that's simply because of a series of coincidences (new house, large garden, needed solution for mowing, happened to see a 2nd hand scythe, looked into grassland ecology, etc). But I know people whos obsession started at 16 and at 60 and like everything in between.