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Progress report on the grant
Measuring and managing the impact of secondary salinisation on
riparian flora
Principal Researchers
Alan Lymbery, Fish Health Unit, School of Veterinary and Biomedical Sciences,
Murdoch University
Neil Pettit, School of Aquatic and fisheries Sciences, University of Washington
Other Personnel
Michelle Ingram, PhD Student, Fish Health Unit, School of Veterinary and
Biomedical Sciences, Murdoch University
Commencement Date 4 July 2005
Expected Completion Date 29 June 2007 Grant
details
Progress report July 2006
Field surveys in experimental catchments
Surveys were carried out in Ernies catchment (uncleared) and Lemon catchment
(cleared) in November 2005 and March 2006. Dons catchment (partially cleared)
could not be surveyed because of damage from a recent burn in the area.
In each of the two surveyed catchments data were collected on soil salinity,
soil structure, plant cover, plant species diversity, plant species composition,
invertebrate density, invertebrate species diversity and invertebrate
species composition.
Although the data are still being analysed, preliminary results indicate
a clear difference between catchments in both soil salinity and biological
diversity, with the cleared catchment having a greater soil salinity and
a reduced diversity of both riparian plant species and vegetation-dwelling
invertebrates (Table 1).
Table 1 Mean (standard error in parentheses) soil salinity, number of
riparian plant species/quadrat and number of invertebrate species/quadrat
in each catchment.
| Catchment |
Soil salinity (mS/m) |
Number of plant
species/quadrat |
Number of invertebrate
species/quadrat |
| Ernies |
27.7 (1.3) |
10.6 (0.8) |
21.3 (3.1) |
| Lemon |
54.9 (5.2) |
8.2 (0.9) |
13.3 (1.1) |
Detailed studies along a salinity gradient
Twenty permanent quadrats were established along a 6 km salinity gradient
in Lemon catchment in March 2006. Within each quadrat, data were collected
on soil conductivity, soil moisture content, soil organic matter, soil
nitrogen, plant species diversity, plant species composition and biomass.
In addition, individual plants were tagged for ongoing measurements of
growth and seed set.
Although the data are still being analysed, preliminary results show a
strong negative correlation between soil salinity and the diversity of
riparian plants (Figure 1).
Initial analyses have identified a number of species of Hakea
with contrasting responses to salinity. Seeds have been collected from
these species to test the effects of salinity watering treatments on germination,
growth and reproductive characteristics.
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