CONDITION OF ROADSIDE VEGETATION IN RELATION TO NUTRIENT STATUS

This article presents work which studied the effects of soil nutrient status on degradation of roadside vegetation in the wheatbelt of Western Australia. In particular, we studied the effects on weed invasion and insect herbivores. Road verges in the Kellerberrin district of Western Australia are severely affected by nutrient enrichment presumably from adjacent agricultural areas. In road verges dominated by the mallee, Eucalyptus erythronema, the percentage cover and diversity of exotic species of annuals and perennials show significant increases that correspond to increases in soil phosphorous. There are gradients in soil nutrients across road verges from high levels on the paddock side of the verge to low levels on the road side, and these correspond to similar gradients in the percentage cover and diversity of exotic species. The influence of the observed nutrient enrichment and the resultant increases in weed invasion on the native annuals and perennials is unclear. It appears that nutrient enrichment may increase the percentage cover of native species, but may also increase the competitiveness of exotic species, and so ultimately be to the detriment of the native species. Considerable methodological problems were encountered while investigating defoliation by insects in road verges. This made reliable conclusions based on the findings difficult, but some trends were apparent. The levels of defoliation of Eucalyptus erythronema in road verges (10+/- 1%) were low compared to the findings of other studies. Defoliation levels within reserves (8+/- 1%) were not significantly different to those in road verges. There were no correlations between insect defoliation of E. erythronema and either foliar nitrogen or soil nitrate and ammonium levels. Nor was there any correlation between foliar nitrogen and soil nitrate and ammonium levels. Some recommendations for methods to reduce the nutrient enrichment, and hence decrease the level of vegetation degradation on road verges, are discussed. For the covering entry of the conference, see IRRD abstract no. 843352.

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  • Corporate Authors:

    SURREY BEATTY

    43 RICKARD ROAD
    CHIPPING NORTON, NEW SOUTH WALES  Australia  2170
  • Authors:
    • CALE, P
    • Hobbs, R
  • Publication Date: 1991

Language

  • English

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Filing Info

  • Accession Number: 00631126
  • Record Type: Publication
  • Source Agency: ARRB
  • ISBN: 0-949324-35-3
  • Files: ITRD, ATRI
  • Created Date: Jul 1 1993 12:00AM