Factors contributing to the zonation of Halosarcia (Chenopodiaceae) species on the margins of an ephemeral salt lake in the semi-arid zone of Western Australia were investigated. Germination and survival of seedlings, tissue solute concentrations, and soil properties were monitored for 30 months at Hannan Lake. Soil conditions and germination were also monitored on a highly saline mine rehabilitation site near Hannan Lake. Additionally, glasshouse experiments were conducted to investigate various aspects of the salinity- and waterlogging-tolerance of selected species of Halosarcia. At Hannan Lake, H. indica subsp. bidens (henceforth H. indica) occurred on low dunes bordering the lake playa, H. doleiformis occurred in the dunes and on the foreslope of the first dune bordering the playa, and H. pergranulata subsp. pergranulata (henceforth H. pergranulata) occurred in the dunes and on the playa. Soil salinity was generally higher on the lake playa compared with the dunes, and at times the playa was submerged (for up to 10 months). Germination of Halosarcia at Hannan Lake occurred on soil exposed as lake water receded during spring. Mortality of seedlings coincided with periods of declining soil water content and increasing soil water salinity, but also with periods of submergence. Once established, H. pergranulata were relatively tolerant of submergence, for example 17 month-old seedlings survived 9 months submergence. At the mine rehabilitation site, H. pergranulata and H. doleiformis were applied as part of a halophytic seed mix. Germination of Halosarcia only occurred when waste-water of low salinity was pumped onto the site. Successful germination and establishment of other halophytic species, initiated by rainfall alone, indicates the site may be more suited to species adapted to drier conditions than H. pergranulata and H. doleiformis.
|Qualification||Doctor of Philosophy|
|Publication status||Unpublished - 2004|