Originally posted by Mharr:

Tame a herd of Lox and take them back to the meadows and dark forest, they'll go nuts and clear-cut the whole thing while hunting deer for sport.

...yep, that's my favorite solution as well. I've got a herd of Lox in a Meadow/Black Forest area and I just hop from Lox to Lox and charge around the meadow area on the outskirts, mowing down trees as I go and then I keep circling the grassy area on the edge, shaving off another layer of trees. I have noticed Lox don't damage some random Birch trees and perhaps Oak. I keep Riding my Lox around the 'racetrack', further bucking the fallen trees down to the individual logs...killing 2 birds with 1 stone. I get Ride XP, while generating the Wood resources to pickup at sundown.

Forced child labor is the answer. Maybe you could hire someone from 3rd world nation for pennies an hour to play your toon while you do real life?

The other alternative is that you don't play valheim as a survival game but as a building game by activating god mode giving you infinite and instant resources.

Using the cart could be an option.

I mined a copper node and ended up with a deep crater, it helps if its at the bottom of a slope, cut down trees to roll into it and you'll have masses of wood, you just run through and collect it all. You can then plant tress all along the ridge of the crater and voila!, endless wood

use the elder power all right :P
Go to the elder, and summon him. Shoot him in the backside once and then kite him thru the woods, he will blow up every tree in sight.

My rather facetious answer to this is just to bring a lox over, because my entire tree farm was destroyed in minutes by my lox after they broke out of their pen and went on a rampage.
edit: Oops Mharr already had this covered :) Yes, Lox Forestry Team! Very effective. Very annoying!

Spawner + wolfs and then go afk.

Originally posted by Pabllo:

I mined a copper node and ended up with a deep crater, it helps if its at the bottom of a slope, cut down trees to roll into it and you'll have masses of wood, you just run through and collect it all. You can then plant tress all along the ridge of the crater and voila!, endless wood

I did this exact same thing, only I took it one step farther. I ended up terraforming the crater into a large rectangular pit, planted trees along its edge (and the bottom of the pit), and chopped the trees so they'd fall in.

Also, I'm not sure if this still works, but...whenever I'd plant trees too close together, and left the "chunk" for a few days, I would come back to all of the trees fully grown, even the ones that shouldn't have been.

Tame a herd of Lox and take them back to the meadows and dark forest, they'll go nuts and clear-cut the whole thing while hunting deer for sport.

I always look for clusters of trees that are relatively close together to utilize the domino effect. I rarely need to cut down one tree at a time for resource farming using this method. I usually don't have to venture very far from home to gather wood since I replant as many trees as I can, so I just use a cart to carry everything back.

Don't forget to use the Elder Forsaken power (if you've beaten the Elder). It's not that impressive but it will speed you up a bit. I setup a portal near the Altar so I can switch powers easily when needed.

Also be sure to upgrade you Ax to max for greater time between repairs, and use stamina boosters to help the grind. The others gave good tips on using the trees' falling momentum to help.

Plant trees on a slope. When you cut the ones on top of the slopes, they will impact the ones lower down and may even knock those over for you. Or else find a Troll and let them do the work for you!

There are little things you can do. Cut trees that are close together, hoping to get a couple to fall. Roll the logs next to each other so your cutting two at once. Once you have the cultivator, replant as close as allowed and harvest from the crowded middle. I've had 4 come down at once.
But you always need more wood.....

Temporary portal out where the trees are and chest of storing the wood on the base portal. Then load up on high stamina foods, be fully rested and pop the elder skill.

Chop trees as described by stvlepore. When the axe is blunt or you have no more room teleport home dump wood in chests / repair then teleport back to trees and keep on chopping.

When exploring without portals pick up any and all wood and stash it in chests marked on map. Later in the game when you have the belt you can revisit and collect wood with portals / ships.