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Hydraulic traits underlying ecohydrological niche separation in semi-arid woody species
Partitioning of water resources amongst plant species within a single biome is possible if these species differ in key hydraulic traits. We examined 12 bivariate trait relationships across nine woody species in a semi-arid biome in central Australia. We found that species with limited access to soil moisture, evidenced by low pre-dawn leaf water potential, displayed anisohydric behaviour (large fluctuations in seasonal minimum leaf water potential), maintained greater sapwood density, smaller specific leaf area (SLA) and a lower osmotic potential at full turgor. The latter was positively correlated with the leaf water potential at turgor loss, which was in turn positively correlated with the water potential at the point of incipient stomatal closure. We also observed divergent behaviour in several trait associations for two sub-groups of species. Specifically, the non-Acacia spp. (Eucayptus camaldulensis, Corymbia opaca and Hakea macrocarpa) had SLA which was an order of magnitude larger than the Acacias; while the Mulga species (Acacia aptaneura and Acacia kempeana) differed from all other spp. across a range of bivariate trait relationships. We conclude that traits related to water transport and leaf water status differ across species that experience differences in soil water availability and that this supports ecohydrological niche separation.
FP16323 Accepted 22 December 2016
© CSIRO 2016