Vegetation and soil patterning in semi‐arid mulga lands of Eastern Australia

摘要

AbstractVegetation and soil patterns across a 200 ha semi‐arid site 40 km north‐west of Louth, NSW, are described using plant cover data from line transects and soils data from points, sampled systematically (50 m intervals) across the site. A patterned sequence of alternating groves and intergroves with three vegetation types was identified: anEragrostis eriopodasavanna occurring on runoff slopes (<0.5) from low ridges, with aMonachather paradoxasavanna occurring at the toe of these runoff slopes (intergroves), followed by anAcacia anuerawoodland occurring on runon areas (groves, either as discrete islands or more continuous along drainage lines). Data on landform, micro‐topography, and hydrological features indicate that the grove‐intergrove pattern is maintained by differential erosion–deposition processes similar to the dynamic erosion–transfer–sink geomorphic systems described for Central Australia.This vegetation grove–intergrove patterning in Eastern Australia is similar to, but differs in detail from, such patterns reported for arid and semi‐arid Western and Central Australia. Groves or ‘bands’ ofA. anuerain the Centre and the West tend to occur on the downslope side of ‘risers’ or on ‘convex slope‐breaks’ where in the East such groves occur in distinct 'steps’ or ‘flats’ in the landscape; there is a drop into the grove and a sharp ‘erosion‐scarp’ below the grove. A prominent ‘grass band’, identified by cluster analysis as theM. paradoxacommunity type, occurs immediately upslope of A.anueragroves in the East. TheA. anueragroves in the East are also fertile’ patches as soils data demonstrate that groves have much higher levels of organic and exchangeable nutrients (and plant cover) than soils in the intergroves. This paper demonstrates that patterning in mulga lands is more extensive geographically, and has