Refining a classical proof of Whitney, we show that any $4$-connected planartriangulation can be decomposed into a Hamiltonian path and two trees. Therefore, every $4$-connected planar graph decomposes into three forests,one having maximum degree at most $2$. We use this result to show that any Hamiltonian planar triangulation can bedecomposed into two trees and one spanning tree of maximum degree at most $3$. These decompositions improve the result of Gon\c{c}alves [Covering planargraphs with forests, one having bounded maximum degree. J. Comb. Theory, Ser.B, 100(6):729--739, 2010] that every planar graph can be decomposed into threeforests, one of maximum degree at most $4$. We also show that our results are best-possible.
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