Establishment and early growth of species in farm plantations near salt seeps

Abstract

Clearing of native forest has caused a rise in soil watertables and increased the salinity of land and streams in south-western Australia. Reforestation is a possible method of increasing the use of water on cleared catchments, lowering watertables and reducing the output of salt from hillside seeps. One of the first needs is evidence of suitable species for such a project. This paper describes the comparative success of twenty-eight species (mainly Eucalyptus spp.) in establishment and early growth when grown on and near saline seeps during 1976–77. Plantations were located in 850, 500 and 420 mm annual rainfall zones of the Hotham River valley about 150 km south-east of Perth, Western Australia. The sites had saline confined aquifers and seasonal perched watertables which were typical of many landscapes in the region. Though rainfall was below average and only one watering was given, nineteen species had greater than 80% establishment in upslope, midslope and downslope positions. In late winter 1977, 15 months after planting, the leading species were 1–2 metres tall and carried leaf area up to 5.5 m2 per tree where current rainfall was highest. The results indicate a high potential for plant establishment and early growth within the rainfall zones. Eucalyptus spp. from many regions of southern Australia were successful at the wettest location. Success at the two driest locations was limited to species from dry climates of southern South Australia and Western Australia. Planting on seep areas decreased the establishment of three species. Eucalyptus wandoo, E. globulus and E. camaldulensis, which performed well on non-seep areas at one or more locations. Implications for a source of further test species and for planting strategy near seeps are discussed.