ABOVEGROUND ADVENTITIOUS ROOTS AND STEMFLOW CHEMISTRY OF CERATOPETALUM-VIRCHOWII IN AN AUSTRALIAN MONTANE TROPICAL RAIN-FOREST

Aboveground adventitious roots emerging from the stems and branches of the montane tropical rain forest canopy tree species, Ceratopetalum virchowii, do not require epiphyte mats to stimulate their growth. The adventitious roots grow in dense clumps on fully exposed aboveground woody surfaces of this species on Mount Bellenden Ker in northeast Queensland, Australia, where mean annual rainfall exceeds 6000 mm. While the soil at the study site is nutrient-poor, the nutrient content of the rainwater draining from the stems of C. virchowii is unusually high compared to the stemflow of other neighboring canopy tree species. Ceratopetalum virchowii is particularly prone to the leaching of Ca2+, Mg2+, K+, and Na+. The aboveground adventitious roots of C. virchowii, therefore, may serve the adaptive function of nutrient recovery before its nutrient-rich stemflow reaches the ground and becomes available to other plants. I hypothesize that the growth of the aboveground adventitious roots of C. virchowii is influenced by the high nutrient content of its stemflow and branchflow drainage, and by the moist condition of its woody surfaces which remain wetted for relatively long periods after rainfalls.