Condensed tannin, which are in fairly high concentration in bark tissue, is thought to inhibit decomposition [REF].
Analysis of the lignin in bark wall during decay by the white-rot fungi Lentinula edodes (Shiitake mushroom) using 13C NMR revealed that the lignin polymers contained more Guaiacyl lignin units than Syringyl units compared to the interior of the plant [REF].