bend wood xD

that's really weird, but i'll just say Earth since you could use it with the roots and stuff *shrugs*

both sort of

water could be use to bend the plant from within, except, if the plant is dead, it's probably dried up

earth could be used if it's deep in the ground, or if the plant is dead, and it's begun it's decay process, dirt is basically a miz of long dead plants and animals

well I'm thinking neither of the two have any connection to wood so...none.

It was just a joke. I figured all the crazed Azula fans around here would appreciate it. I couldn't resist!

I believe the airbenders would be the most likely to bend wood. In all seriousness, I find it dubious that earth would be able to bend wood. Water could possibly bend trees but not lumber.

Definitely not earth. Earth refers to inanimate things. Plants are technically alive. Therefore, it's more likely that the water could bend the water inside it.

maybe plant/tree bending should be a bending skill in its own

Well waterbenders can already bend the water in plants. But what if the plant is drier like a tree? Who knowns, I consider it a complex mixture of both elements so maybe only the Avatar can truly bend plants.

But why would earth bend trees? Trees have no physical earth components.

I'm not saying plants are made of earth, I don't think they belong to any element. Technically Waterbenders can only the water in plants and its not earth either for obvious reasons. The question was which element "should bend wood" not that it actually can. So I'm just speculating and I think it would be interesting if it was an elemental mixture.