Soil phosphorus enhancement below stormwater outlets in urban bushland

Spatial and temporal changes and the relationship with invasive plants

Michelle R. Leishman*, Miah T. Hughes, Damian B. Gore

*Corresponding author for this work

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Invasion by exotic plant species is a significant problem in urban bushland remnants and is often associated with nutrient enrichment of soils. A major source of nutrient enrichment in urban areas is stormwater runoff, which is transferred from impervious surfaces in urban catchments and discharged at outlets on the residential/bushland interface. We measured the spatial extent of soil total phosphorus (P) enhancement below stormwater outlets on Hawkesbury Sandstone-derived soils in northern Sydney and examined whether total P concentration has increased with time since urban development and extended laterally beyond the stormwater flow path. The average area of soil P enhancement below outlets was 0.24 ± 0.05 ha and was widest 30-50 m downslope from the outlet, where it extended an average 40 m across slope. Catchment area was not significantly related to average soil total P concentration. There was a significant decline in total P across slope from the centre of the flow path and a significant positive relationship between soil total P and proportion of exotic plant cover, with soil P accounting for 77.5% of variation. We found evidence for a buildup in soil total P concentration over time within the run-on zone below outlets, with the rate of enhancement being ∼68 mg/kg per decade over a 40-year period. Evidence for lateral transfer of soil P out of the run-on area was more equivocal. There was a significant decline in soil total P across slope from the boundary of the run-on zone, with higher concentrations at distances 0.5 m and 1 m from the boundary compared with >1.5 m. However, this could be due to error in locating the boundary between run-on and non run-on areas. There was no significant relationship between soil P in the non run-on zone and age of development, which would be expected if P was being transferred by biological activity beyond the run-on zone over time. It is clear that the primary areas of concern for management must be the run-on areas below outlets.

Original languageEnglish
Pages (from-to)197-202
Number of pages6
JournalAustralian Journal of Soil Research
Volume42
Issue number2
DOIs
Publication statusPublished - 2004

Fingerprint Dive into the research topics of 'Soil phosphorus enhancement below stormwater outlets in urban bushland: Spatial and temporal changes and the relationship with invasive plants'. Together they form a unique fingerprint.

Cite this