From Nookipedia, the Animal Crossing wiki
Trees are common flora in the Animal Crossing series. Some trees bear fruit and others are just for decoration. The number of trees will affect the environment of a town and keeping a sustained good environment will allow the player to receive certain items, such as the Golden Watering Can (or Golden Axe in Dōbutsu no Mori and Animal Crossing), as a reward. Fully grown trees do not die until chopped down by the player. After the tree has been chopped, it leaves behind a stump. A few insect species are found only on stumps, and in Animal Crossing: New Leaf, players can sit on the stumps. When the player chops down a tree, special tree stump designs appear occasionally. Silver axes guarantee a special stump. Certain insects can be found in or on trees, depending on the season and time of day.
Saplings are baby trees available for purchase at Tom Nook's stores and the Garden Center. Not all trees grow successfully, due to poor soil quality and placement. If the player plants a tree where a different tree was cut down then it will have a much higher chance to grow. If the player stands on a tree sapling at exactly 6 a.m., the tree grow under and knock out the player.
 Types of Trees
 Cedar Tree
Cedar trees are evergreen trees. During December, particularly around Chrismastime, Cedar trees are decorated with bright lights. Cedar trees will only grow in the northern half of the village, reflecting the fact that their real-life counterparts are found more frequently in the Northern Hemisphere, being adapted to colder temperatures. The player can shake cedar trees in order to find items, such as furniture or Bells. Beehives are also found this way, accompanied by a swarm of bees.
 Oak Tree
Oak trees are generic trees, resembling fruit trees but bear nothing. Their appearance differs seasonally, turning golden brown in the autumn, being snow-laden in the winter, and bearing cherry blossoms during the Cherry Blossom Festival in April. Similar to Cedar trees, the player can shake plain Oak trees to find furniture and Bells, however, beehives can also be found hanging off the branches of an Oak tree.
 Fruit Tree
Fruit trees resemble Oak trees but bear fruit, three at a time. During the Acorn Festival they also bear acorns. There are 5 different varieties of fruit trees (13 in New Leaf), one for each type of fruit (13 types in New Leaf). The player can receive non-native fruits in letters from Mom or from other villagers, after which they can then be grown into a fruit-bearing tree. Bells and furniture cannot be shaken out of empty fruit trees.
 Palm Tree
Palm trees are foreign trees that bear two types of fruit, banana and coconut, growing two at a time. These trees can be planted only on the beach. There are some beetles that appear only on palm trees.
In Animal Crossing, coconuts are obtained only from visiting the island using a Game Boy Advance. In order to grow a palm tree in Wild World and City Folk, the player must find a coconut washed up on the beach, usually showing up at least once a week. In New Leaf, the player can find both coconuts and bananas on Tortimer Island.
 Money Tree
Money trees are a rare variety of tree that bears money as its fruit. They can be grown by burying bells in the ground with a golden shovel. To maximize potential return and minimize expected loss, the ideal amount to bury is 30,000 bells.
 Golden Tree