Legacy of Land-Use Evident in Soils of Western Australia’s Wheatbelt

Abstract

Native regeneration of old-fields in the wheat-growing region of Western Australia is slow to non-existent. We compared the physio-chemical properties of three old-fields and three woodland remnants adjacent to each old-field to determine if current soil conditions are a barrier to regeneration. Of the variation in soil properties, 17.4% was described by spatial structure, 5.4% by land use (cultivation time and time since abandonment), 3.9% by soil type and 2.6% by vegetation and leaf litter cover. There were differences in individual soil properties between old-field and remnant soils at two sites. Soil compaction, probable erosion as evident by a higher percentage of coarse fragments, increased Colwell phosphate that we interpret as fertiliser residue and reduced organic carbon were evident in one old field, after 60 years of cultivation and 14 years abandonment. Increased Colwell phosphate was evident at the second old field, despite only 1 year in cultivation and 45 years in recovery. The third site showed no evidence of its 4 year period in cultivation 43 years ago despite similar farming practices and soil type to the second. Phosphate fertiliser residues could account for the dominance of non-native annual grasses in the re-assembly of wheatbelt old-fields.

Role of plant functional traits in determining vegetation composition of abandoned grazing land in north‐eastern Victoria, Australia

“…Annual grasses are an example of ruderal type species that can arrest the process of succession through competition with forest species (Davis et al 2005). Despite the removal of degrading processes, degraded Eucalyptus woodlands in New South Wales (Prober et al 2002) and secondary forests in Western Australia (Standish et al 2006) continued to be dominated by introduced annual grasses due to high soil nitrate concentrations. A similar process may operate at the Delatite Peninsula, where annual grasses continue to dominate secondary forests that have greater soil nitrogen concentrations than primary forests (S. Kasel unpubl.…”

“…These species are typically herbaceous perennials with myrmecochorous or barochorous dispersal and large seeds (Bossuyt et al 1999;Hermy et al 1999;Verheyen et al 2003). In Australia, while the vegetation composition of secondary forests is known to differ from that of primary forests (Yates & Hobbs 1997;Standish et al 2006), the role of dispersal mechanisms or other plant traits in determining vegetation composition remains largely unknown.…”

Resource heterogeneity and persistence of exotic annuals in long-ungrazed Mediterranean-climate woodlands

“…This suite of fast-growing annual grasses and forbs threatens native ecological communities in the USA (Huenneke et al 1990;Seabloom et al 2003;Blank and Sforza 2007;Chambers et al 2007), southern Australia (Prober et al 2002b;Lenz et al 2003;Standish et al 2006), Africa (Vlok 1988), Europe and South America (Groves and Di Castri 1991;Gaertner et al 2009). In regions with a Mediterranean climate they form a prominent component of the exotic flora, for example in Western Australia, 45% of the 1,098 naturalized exotic species are annuals.…”

Environmental change: prospects for conservation and agriculture in a southwest Australia biodiversity hotspot

“…Although there needs to be a priority for the retention of existing intact natural areas, in previously cleared, abandoned agricultural land, the creation of revegetated, novel communities (Hobbs et al 2013) that buffer high value, intact areas of native vegetation from agricultural lands, and provide linkages between intact areas, is an important management strategy in the SCR. It is important because it is generally not feasible to re-establish the entire original plant community on abandoned cleared farmland, because of the very high diversity of plants and changed soil and hydrology , Standish et al 2006, 2007. Therefore, these newly established novel ecosystems would comprise a subset of species from the intact areas and therefore contain species that have the capacity to exploit the demanding climate and soil properties of the region.…”