The ornamental design for a decorativecenterpiece, as shown and described.
FIG. 1 shows a perspective view of the decorative centerpiece with a flower within its body interior, a flower on its base, and a candle in its upper candleholder shown in broken line showing my new design.
FIG. 2 shows a front side elevation view of the decorative centerpiece.
FIG. 3 shows a rear side elevation view of the decorative centerpiece.
FIG. 4 shows a right side elevation view of the decorative centerpiece.
FIG. 5 shows a left side elevation view of the decorative centerpiece.
FIG. 6 shows an overhead view of the decorative centerpiece; and,
FIG. 7 shows an underside view of the decorative centerpiece.
The broken lines shown in FIG. 1 are for the purpose of illustrating unclaimed environment and form no part of the claimed design.