Car jacks are used primarily to provide roadside assistance to a driver experiencing a flat tire when he can't call a service or manage to make it to a garage. Jacks can also be used in a pinch for some light landscaping, in this case removing an unwanted tree. By following some basic guidelines, removing a small tree using a jack can be done in an afternoon.
Things You'll Need
Point-end shovel, garden spade or landscaping bar
2 plywood squares, 1/2-inch-thick
Dig out the root system around the tree to expose the roots. Dig a small space underneath the trunk that's the same height of the car jack you'll be using. You need just enough to room slide the jack underneath the trunk, but keep in mind you'll need enough clearance to accommodate the boards you'll have to place under the trunk in a later step.
Cut the tree down to around waist height. This places the trunk at a lower center of gravity, which makes extracting the stump less taxing as well as aids in ensuring the tree falls in the direction you want it to. Saw the largest roots of the tree in half. This "frees" the tree and reduces the strain on the jack and the amount of "elbow grease" you'll need to crank the jack.
Slide a square of plywood underneath the newly cut stump into the space you dug. It's advised the plywood be no less than 1/2 an inch thick to keep it from cracking under the pressure of the cranking. The width or length of the board relates to how much space you created by digging under the stump. Slide a similarly sized plywood square underneath the tree, this time pressing the board upward to the underside of the stump.
Position the car jack in the space between the two plywood squares. The top board will rest snugly on the top plate of the jack. Start cranking and stop once the tree rips out of the ground on the side where you're working. Pull out the jack and place it back underneath the stump opposite where you were; for example, if you're jacking the south-facing part of the tree, now crank the north side. Repeat for the east- and west-facing sides until the stump is loose enough to pull out by hand.
A mixture of salt and warm water poured daily over the roots for a period of about a week will keep the tree from rooting again, but be advised this method makes the soil too salty for future plant growth.