With metal spatula, lift 1 strip to cutting surface. On 1 long side, mark at 2-inch intervals with a small cut or with toothpicks. On remaining long side, make a mark 1 inch from short side. Make marks every 2 inches. With sharp knife, cut into triangles, using small cuts as guidelines. Frost triangles with 1/3 of frosting. Sprinkle with candy decors. Pull apart slightly before frosting is set. In center of bottom edge of each “tree”, cut small slit with point of sharp knife. Insert pecan half into slit to resemble trunk of tree. (There will be a small piece at each end of each row that will not be a complete tree.) Repeat with remaining 2 rows of brownies and frosting.