Refresh a mantel for spring with a few branches
A vase, a few cut branches and some breathing room can change the mantel without starting a collection of seasonal ornaments.

A mantel can look ready for spring before a single flower arrives. Remove the small objects that have gradually gathered there and wipe the surface. Leave the mirror or large picture in place while you work; it gives the arrangement a familiar backdrop. Put back only the things you want to see beside the branches, rather than treating every existing ornament as something the new display must accommodate.
Look at the depth of the ledge. A vase that fits sideways but overhangs at the front is not a good candidate, especially above a working fireplace. Choose a stable vessel with a broad enough base, and follow the fireplace manufacturer's clearance requirements. Branches, paper pictures and dried foliage all need to stay away from heat and flame. An unlit decorative fireplace offers different conditions from one used every evening.
Choose the outline of the branches
Three stems with interesting bends can occupy the same visual space as a large bouquet. Stand them in the vase before cutting them shorter. Turn the vessel and see whether one branch reaches across the picture or points toward the ceiling. A little asymmetry often looks more relaxed than matching stems on both sides of a mirror.
Use only material you can identify and are allowed to cut. Purchased stems or cuttings from your own suitable garden plants avoid guessing about public-land rules. If children or pets can reach the arrangement, check the particular plant's suitability for that household. Decorative branches do not need berries, and leaving those out also means fewer things dropping onto the hearth.
Keep the rest low
Set one small frame or shallow bowl at the opposite end, then look from the room's main seat. The branches should still read as a shape, not as a thicket behind a row of objects. If the vase and frame compete, move the frame farther away before adding another object to balance them.
Protect the mantel from the vase with a waterproof barrier that stays hidden beneath its base. Check for drips when changing water, and remove fallen buds promptly. When the stems have finished looking fresh, the arrangement can end. There is no need to replace them immediately; a clear ledge for a few weeks gives the room just as much of a change as a new decoration.