| Tropical dry forests occur on the water-mediated, ecological cusp between closed canopy forests and open savannas. This research was designed to assess the mechanisms which enable eight woody Hawaiian dry forest species to co-exist under water limited conditions. Three primary goals were to: (1) identify patterns of water resource partitioning; (2) evaluate the functional significance of stem water storage capacity and water transport systems, and (3) identify whether there are consistent relationships between growth, carbon assimilation and water and nutrient use efficiency among evergreen species. Water resources are partitioned temporally (through four different leaf phenological patterns), vertically (rooting depth) and spatially (mean distance between species). Three species have clearly defined positions along these partitioning gradients. Reynoldsia sandwicensis, a stem succulent, drought-deciduous species stored water to support a late dry season reproductive and foliar flush. Metrosideros polymorpha, the dominant canopy tree in Hawaiian wet forests, was deeply rooted and supported leaf flushes into the dry season and high minimum leaf water potentials (... |
