Episodic seedling growth in Allosyncarpia ternata, a lignotuberous, monsoon rainforest tree in northern Australia

On the western Arnhem Land Plateau, Northern Territory, Australia, seedling s of the canopy tree Allosyncarpia ternata S.T. Blake typically spend many years (perhaps decades) as small (< 1 m), multistemmed plants on the forest floor. In this establishment phase, long periods of apparent inactivity ar e interrupted by episodes of rapid growth. This paper describes a 5-year fi eld-monitoring program to examine the pattern of seedling growth and surviv al in allosyncarpia forest, and field and shadehouse measurements of lignot uber size. Individual seedlings may produce, each wet season, a number of f ast-growing stems, which then die back in the following dry season. As a re sult, mean annual above-ground growth during this life stage is negligible. With each wet season, however, the seedling extends its below ground parts - a large lignotuber and a deep root system. After a number of years, when the lignotuber has grown large enough to sustain massive shoot growth, whe n a suitable light gap becomes available, and presumably when roots reach r eliable dry-season water supplies, the seedling grows rapidly. Thus, the sh ortage of saplings in allosyncarpia forest is due to the short time that in dividual plants spend at that particular growth-stage, rather than to any d ysfunction in recruitment.