Acacia brumalis

Overview

Acacia brumalis is a Western Australian shrub; Craig et al. tested three-month-old inoculated seedlings from saline soils at Miling. After 12 weeks of salt-only treatment, survival was 100% at final irrigation-water ECw about 9500 mS/m, although height growth had fallen below controls by week 4. The eHALOPH value of 9.5 dS/m differs tenfold from the paper. [S1, S2, S3]

Names and classification

Acacia brumalis Maslin. The relevant seed and seedling material came from particular Western Australian saltland sources. That provenance cannot be generalized to every population or establish the species as an obligate halophyte. [S3]

Morphology and identification

A Western Australian shrub in Acacia with phyllode foliage; its yellow flowers occur in globose heads and it forms pods. Species identification is based on the Flora of Australia-derived morphological description and voucher material. [S94]

Distribution, habitat and phenology

Craig et al. included this taxon among material collected from moderately to highly saline soils in Western Australia. Another flora places A. brumalis with A. pelophila in a salt-creek setting, but this does not establish root-zone salinity at each locality. Available records do not document large natural salt-marsh populations. [S1, S3]

The Western Australian account gives a flowering period from late May to September. [S94]

Salinity in natural habitats

Table 2 of Craig et al. gives source-soil ECe measurements specifically for A. brumalis (“Miling”): 100–2670 mS/m across sampling dates and depths. These describe seed-source soils, not a uniform root-zone exposure or experimental treatment. [S1, S3]

Salinity studies

Craig et al. measured saturated-paste ECe in source soils for A. brumalis at Miling, Western Australia. Table 2 gives values by depth and date: at 0–50 mm, 2670, 110, and 810 mS/m in spring 1984, spring 1986, and autumn 1987, respectively; at 50–200 mm, 1220 mS/m in autumn 1987; at 200–400 mm, 280, 100, and 2090 mS/m; and at 400–600 mm, 1040, 780, and 2220 mS/m. The overall range is 100–2670 mS/m, reflecting variation among seed-source soil depths and sampling dates rather than treatment doses. [S1]

Craig et al. tested three-month-old seedlings inoculated with symbiotic bacteria under salt, waterlogging, and combined salt–waterlogging treatments. The mixed salts were NaCl:MgSO₄:CaCl₂ at a 16:3:1 molar ratio and were increased by 100 mM per week. Drained saline treatment reached 1200 mM salts (irrigation-water ECw about 9500 mS/m); salt waterlogging reached 500 mM (ECw about 3900 mS/m). After 12 weeks of salt-only treatment, A. brumalis survival was 100% at final ECw 9500 mS/m. Across taxa, weekly height increments remained positive through about ECw 7000 mS/m, although growth had fallen below controls by week 4. [S1]

The eHALOPH species record for A. brumalis lists a maximum salinity of 9.5 dS/m but does not specify experimental material, salinity metric, or treatment duration. Craig et al.’s full paper reports irrigation-water ECw of about 9500 mS/m at the end of salt-only treatment, a tenfold numerical discrepancy. The database gives no verifiable conversion basis, so 9.5 dS/m remains a database entry rather than a confirmed tolerance threshold. [S2]

Reported mechanisms and ecological adaptations

Craig et al. measured height and survival, not tissue ions, osmotic adjustment, or salt-exclusion mechanisms. The linked eHALOPH value is a database field without a defined metric or conversion basis and cannot explain this species’ physiological response. [S1, S2, S3]

Conclusions and evidence gaps

The source-soil measurements describe the field setting at Miling, whereas the salt trial was a potted-seedling treatment; they are not the same root-zone exposure. The study measured height and survival but did not follow flowering, seed set, or field recruitment. [S1, S2, S3, S94]