Soil and landscape studies in Western Australia

Mulcahy, M. J.; Bettenay, E.

doi:10.1080/00167617208728773

Cited by 29 publications

(10 citation statements)

References 10 publications

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“…The region consists of many ancient, steep-sided mountain ranges that are heavily dissected by riverfloodplain systems that reliably discharge surface water into the coastal marine zone. Regional geology is complex and contains some of the oldest rock deposits (e.g., Phanerozoic, Proterozoic, and Archaean sedimentary, granite, and volcanic rocks and Devonian limestone) in the world, some as old as 3.7 yr BP (Mulcahy and Bettenay 1972). Soils are generally heavily weathered vertisols with low organic matter contents.…”

Section: Methodsmentioning

confidence: 99%

Dissolved organic carbon biolability decreases along with its modernization in fluvial networks in an ancient landscape

Fellman

Spencer

Raymond

et al. 2014

Ecology

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The metabolism of dissolved organic carbon (DOC) along fluvial networks determines what fraction of organic matter is exported to the ocean. Although it is thought fresh rather than older DOC is preferred by bacteria, old DOC can also be highly bioavailable to stream bacterial communities. In strongly seasonal and oligotrophic regions, we argue that groundwater inputs of old DOC may increase the bioavailability of stream organic matter. We sampled 22 streams along a gradient of size (wetted widths from 1 to 60 m) and one groundwater spring in the Kimberley region of northwest Australia to determine how the age and bioavailability of streamwater DOC varied with stream size. Our hypothesis was that stream DOC would become more enriched in 14C (younger) and less bioavailable as streams increased in size and depleted 14C‐DOC was metabolized by stream microbial communities. We also used fluorescence characterization of DOC, ultraviolet absorbance at 254nm (SUVA254), δ13C‐DOC and lignin phenol yields to assess how these indicators of DOC character influenced the bioavailability and age of stream DOC. Stream evaporation/inflow ratios (E/I, used as a proxy for catchment water residence time), determined from changes in stream δ18O along the gradient of stream size, were positively related to DOC concentration and carbon‐normalized lignin yields, while δ13C‐DOC became more depleted with increasing E/I. Stream Δ14C‐DOC varied from −452.1‰ (groundwater) to 48.9‰ and showed progressive enrichment as streams increased in size and accumulated DOC mainly from terrestrial plant material. Older DOC corresponded to higher bioavailability (R2 = 0.67, P < 0.01), suggesting that old bioavailable DOC, which has escaped from subterranean food webs utilizing 14C‐depleted carbon, is common to one of the oldest landscapes on earth. Therefore, rapid biotic uptake of old bioavailable DOC originating in groundwater springs and the accumulation of modern, terrestrially derived DOC work in opposite directions affecting DOC dynamics along fluvial networks. We suggest the metabolism of old DOC along fluvial networks provides a biogeochemical link between non‐contemporary carbon fixation and modern river productivity.

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Section: Methodsmentioning

confidence: 99%

Dissolved organic carbon biolability decreases along with its modernization in fluvial networks in an ancient landscape

Fellman

Spencer

Raymond

et al. 2014

Ecology

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“…Approximately 67% of the native forest has been cleared for farmland (Loh et al 1989). The landscape and soils of these sites are typical of the Beraking valley form, with slopes dominated by gravelly, sandy soils and some ferruginous duricrust on the hilltops (Mulcahy & Bettenay 1972). The sites are at the eastern extent of the northern jarrah forest where jarrah ( E. marginata ) and to a lesser extent marri ( E. calophylla ) and wandoo ( Eucalyptus wandoo ) form woodland or open forest (Dell & Havel 1989).…”

Section: Methodsmentioning

confidence: 99%

Long‐term changes in the vegetation after the cessation of livestock grazing in Eucalyptus marginata (jarrah) woodland remnants

Pettit¹,

Froend²

2001

Austral Ecology

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This paper documents changes in the floristic composition of Eucalyptus marginata Donn (jarrah) woodlands over 7 years of recovery from continual, intensive livestock grazing. In remnants of native woodland left after agricultural clearing, which have been subjected to livestock grazing, comparisons were made between the floristics of fenced exclosure plots and open plots that continued to be grazed. The vegetation in nearby remnants, which had not been subjected to livestock grazing, was also surveyed. An initial increase in annual exotic pasture species after grazing relief was only temporary and highly influenced by fluctuations in annual climatic patterns, particularly rainfall distribution and abundance. Subsequent years saw a decrease in exotic annuals in exclosure plots and an increase in native perennials, in a trend towards becoming more floristically similar to the ungrazed sites. Germination of overstorey species was observed in the exclosure plots, however, development of seedlings and saplings was sparse. Results indicate that for jarrah woodland in southwestern Australia, natural regeneration is possible after the removal of livestock, with the return (within 6 years) of native species richness to levels similar to those found in ungrazed vegetation. Re-establishment of cover, however, appears to take longer. The floristic dynamics are described in terms of a nonequilibrium model. Two vegetation states exist, degraded remnants with an understorey dominated by annual species, and ungrazed vegetation with an understorey dominated by perennial shrubs and herbs. The former state is maintained by continual heavy grazing by livestock. Upon relief from grazing, the vegetation undergoes a transition towards floristic similarity to ungrazed vegetation. After 6 years, vegetation change in the exclosure plots appears to be continuing and therefore it is still in transition.

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“…The landscape and soils of these sites are typical of the Beraking valley form with slopes dominated by gravelly sandy soils with some ferruginous duricrust on the hilltops (Mulcahy & Bettenay 1972) . The sites are at the eastern extent of the northern jarrah forest where Eucalyptus marginata (jarrah) and to a lesser extent E. calophylla (marri) and E. wandoo (wandoo) form a woodland or open forest (Dell & Havel 1989).…”

Section: Methodsmentioning

confidence: 99%

Grazing in remnant woodland vegetation: changes in species composition and life form groups

Pettit

Froend

Ladd

1995

J Vegetation Science

150

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Abstract. Grazing by domestic livestock in native woodlands can have major effects on ecosystem functioning by the removal of plant species that form important functional groups. This paper documents the changes in floristics in a large group of remnants of native woodland left after agricultural clearing in southwestern Australia. Species richness and diversity were significantly reduced in remnants and the proportion of exotic species increased. Detrended Correspondence Analysis (DCA) was used to identify floristic and environmental patterns among plots and identified two distinct groups based on grazing intensity. This indicated that the significance of the relationship between grazing effects and DCA floristic axes was greater than edaphic characteristics that normally influence floristic patterns. Floristic characteristics of sites that were influencing the position of plots on the ordination diagram included proportion of exotic species and proportion of native perennial shrubs and herbs. Numbers of species of native shrubs and perennial herbs were significantly reduced in grazed plots and numbers of exotic annual grasses and herbs were significantly higher. Other life form groups such as native perennial grasses and geophytes were not significantly affected by grazing. Reproductive strategies of perennial species showed a significant decrease in numbers of resprouters and a significant increase in numbers of facultative seeder/ sprouters. Exclosure plots showed increases in number and cover of perennial shrubs and herbs after three years whereas number and cover of exotic species did not change. Time series DCA showed that the floristic composition of exclosure plots in grazed sites became closer to that of the ungrazed sites.

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Soil and landscape studies in Western Australia

Cited by 29 publications

References 10 publications

Dissolved organic carbon biolability decreases along with its modernization in fluvial networks in an ancient landscape

Dissolved organic carbon biolability decreases along with its modernization in fluvial networks in an ancient landscape

Long‐term changes in the vegetation after the cessation of livestock grazing in Eucalyptus marginata (jarrah) woodland remnants

Grazing in remnant woodland vegetation: changes in species composition and life form groups

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