Leave a tree's stump behind if you want the tree to grow back.
Sunshine Alley turns supported tree stumps into growing plants. Beech, birch, fir, oak and pine stumps regrow their tree species; swamp-tree, Yggdrasil-shoot and supported Ashlands-tree stumps also regrow in their allowed biomes. Growth still takes time and depends on a suitable biome, but these stump plants do not require normal sapling spacing or an open sky.