Trees are one of the living beings that we have created lots of lore about, but as foreign as they are to us, we still try to assign them human-like qualities. There is so much about trees that is so very different, to try to stuff them into a 'people-box' is a shame.
Trees are fascinating, and there is more that we are learning about them all the time. While we have lore and associations with trees that we have learned from our ancestors, I think it would be a shame to ignore the new information we are discovering, and how it can effect our interactions with trees and what they mean to us.
From a very young age, we are taught that trees make air, specifically that we breath in oxygen and release carbon dioxide and that trees do the opposite: breathing in carbon dioxide and breathing out oxygen. I always thought it was amazing how interconnected we all are.
There are a lot of Pagan interactions with trees, from the basic grounding meditation, to meditating with trees, to the different qualities we assign to different types of tress. And when you start to examine the science behind many of these practices, they become even more powerful and amazing!
Let's look at the tree grounding meditation. It's one I struggled with for a long time, I just don't have that strong of a personal connection with trees (and I couldn't quite get the tree imagery to line up in my head). The idea is to pull any excess (or unwanted/dirty) energy and sink it into the earth, where it can be cleansed and renewed.
The thing is, that this is something that trees do, kind of in reverse. The root system of trees (and plants) will pull contaminates from the soil. I also find it really cool that different plants will take and release different things into the soil (often used when planting crops, the crops are rotated to not deplete the soil year after year). And we know that trees also help filter the air itself, even taking tiny particles of harmful substances out of the air!
To me, this is a much more useful visualization, to see myself as the tree, transforming stuff inside me and releasing it in a better state (it always kind of bugged me that the basic grounding was just like dumping stuff into the earth). It also helps to get your brain thinking about not just holding and passing along toxic things, but actually turning them into better stuff.
One of the stranger tree interactions I've seen is one that has you try to sense the gender of the tree. The idea being that trees would have either masculine or feminine energy, and you could learn to feel which was which. (And that is a whole can of words about gendering things that don't need to be gendered...) But again, trees aren't people, and trees don't come in strict male and female. Without getting overly technical, tree reproduction does rely on what are considered 'male' and 'female' parts (often in flowers)...but the same tree can have both (even the same flower can have both!), or it could start off making one and then later make the other. Some trees (and more plants) don't technically reproduce, instead they clone to make more of themselves!
What's even more unusual, is that trees can naturally graft to each other in the wild, causing two (or more) trees to become joined into one! There is also the Pando tree, which is a forest that is considered all one tree (because they are all clones and are assumed to share one massive root system). Along those lines, there are new studies looking into how trees communicate, and the possibility that they not only pass on knowledge to each other, but can actually shift nutrients to other trees. So, while we often look at any given tree and think it's a single being, it could be several or part of a greater whole!
When it comes to thinking of what energies a given type of tree might hold, we often return to nature. Medicinal properties are a huge link, and depending on what a tree might help you with, it will become associated with that part of the body. But, because humans like to link everything, we also build associations through stories and simply how things look. If a tree reminds us of another thing, there's a link. If an event happened near a specific species of tree, that tree is now linked to that event (and any energies it might have). Figuring out what trees are associated with what things is often an organic process of just finding nifty stories that involve the tree, or facts about it.
Ultimately, trees are somewhat foreign to us, and while we can surely come to know them better, trying to attribute human qualities to them is an exercise in frustration. Appreciate trees for what they give us, and perhaps spend some time thinking about how we can help care for them (because if the trees were to go, we would be in a very bad place indeed).