Thinning trees in different types of forests in Liaoning Province's mountainous region was studied to see how it affects the growth and yield of the stands. Thinning didn't help much in Pinus koraiensis plantations, but medium intensity thinning worked best. Thinning improved growth in Quercus mongolica forests, with medium intensity being optimal. Thinning also boosted growth in artificially induced broad-leaved Pinus koraiensis forests, with high intensity being most effective. Overall, the right amount of thinning can increase the total stand basal area and yield of the forest.