Vertical Position-Based Resistance of Teak Wood (Tectona grandis Linn.f.) Against Wood-Decay Fungi

In the humid tropics of Indonesia, the durability of traditional wooden structures is challenged by pervasive fungal decay.This study investigated the decay resistance of teak wood (Tectona grandis Linn.f.) as influenced by the stem's vertical position against various wood-decay fungi.Employing a completely randomized factorial design, the research delineated two primary factors: vertical position within the log (bottom, middle, top) and fungal species (control, Schizophyllum commune, Pycnoporus sanguineus, Dacryopinax spathularia).These fungi were selected due to their dual significance as both decomposers and potential threats to wood-based materials.A total of 12 treatment combinations were tested, with each replicated thrice, culminating in 36 experimental wood samples.Results indicated a significant effect of both the log's vertical position and the species of fungus on teak wood weight reduction.A gradation in weight loss was observed vertically along the log, with the least at the bottom (1.84%), increasing at the middle (3%), and peaking at the top (5.38%).Among the fungi, the control exhibited negligible weight loss (0.07%), with D. spathularia (3.56%), P. sanguineus (4.99%), and S. commune (5.04%) contributing to progressive increments in decay.The interaction between the bottom log position and S. commune resulted in the most pronounced weight reduction (7.53%), while the top log position without fungal exposure exhibited the slightest change (0.02%).According to the Indonesian National Standard for wood resistance to rot fungi, teak wood demonstrated a resistance class II against D. spathularia and P. sanguineus, and a lower class III against S. commune.It is recommended that for construction purposes, teak sourced from lower stem positions should be prioritized and maintained under dry conditions with moisture content below the fiber saturation point to mitigate fungal degradation and extend the material's longevity.