Thank you for your question Piper. I shall ask my friends to contribute later.
Humans and animals die because our bodies stop reproducing cells – cells are the building blocks of our body. Amazingly about 40 billion of them die every day…and our body replaces them. However as we get older the replacement process is reduced and eventually it stops, so we die.
However for trees this does not happen, the replacement process continues and the tree keeps on living. Some trees that you might see around you are hundreds of years old.
These are my early thoughts on your interesting question. My friends will add to this when they are ready.