A decay study of windthrown indigenous trees

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Abstract
The fungal communities within six stems each of matai (Prumnopitys taxifolia (D. Don) Laubenf.) and rimu (Dacrydium cupressinum Lamb.) were studied nearly four years after windthrow in a dense podocarp forest in the central North Island. There was a significant decrease in yield of isolates of all fungi as well as basidiomycetes in particular with increasing radial depth beneath the cambium (P < 0.01). The decrease was greater for matai than for rimu (P < 0.01). Fewer isolates of either group were obtained from heartwood (0-6% of attempts) than from sapwood and rimu transition wood (13-43%; P < 0.01). Among the basidiomycetes 85% of isolates belonged to eight species or generic groups six of which varied significantly in occurrence between trees (P < 0.05). The condition of the root systems in uprooted trees of four species (matai; rimu; miro Prumnopitys ferruginea (D. Don) Laubenf and tawa Beilschmiedia tawa (A. Cunn.) Benth and et Hook f. ex Kirk) was evaluated in the same forest. On matai and rimu trees a greater mean percentage of emergent roots was decayed at the centre of the exposed surface of the root-soil plate than around the margin (P < 0.05). Matai and rimu roots were significantly more decayed in this exposed central zone than were those of miro and tawa (P < 0.05). Rigidoporus catervatus (Berkeley) Corner was shown to be responsible for a white pocket rot in the heartwood and roots of living trees, and sapwood of fallen logs.