AN AGE ALTITUDE MATRIX ANALYSIS OF HAWAIIAN RAIN-FOREST SUCCESSION

1 Species composition and biomass of vascular plants were determined in a matrix of 29 sites on the wet eastern slope of Mauna Loa volcano, Hawaii. 2 Sites were sampled at five or six altitudes (914 2438 m a.s.l.) on each of five known-age lava flows (5, 47, 137, 300 and 3400 years B P). 3 The resultant age-climate matrix was used to examine patterns of biomass accumulation, species distribution, and diversity during primary succession. 4 Biomass increased with substrate age and ranged from 0 to over 36 000 g m-2 across the matrix. Generally, biomass increased as altitude decreased, although the maximum value was observed at intermediate altitude on the oldest flow. 5 Community composition varied dramatically with substrate age and climate; species richness ranged from 0 to 30 species plot-1, with the maximum at low altitude on the oldest flow. 6 Succession was more rapid at low than at high altitude, but followed distinct compositional trajectories at each altitude. A number of species were found solely or primarily as specialists at a particular altitude and/or successional position, while others exhibited broad niches.