Thanks for playing! The trees having a lifecycle was really just a byproduct of trying to simulate the growth process rather than the tree in a single moment. Originally I was hoping to incorporate some bonsai practices, like trimming and pruning. Since that didn't make it into the submission, they 'die' when the weight of their upper segments gets too great.
I'm glad you found the variety in tree type interesting. The code itself doesn't do a lot different, though I hope to expand on it in the future. For now, when an in game year passes the tree sheds it's leaves and its trunk gets a little thicker, just like in real life. But real trees develop their trunks at different rates and some are sturdier than others, so I did my best to include some of that variety, though hopefully in the future I can expand on that.