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Invasive Geophytes of south west Australia; Recent Studies on Biology, Ecology and Management
Kate Brown & Grazyna Paczkowska
Urban Nature Program, Department of Environment and Conservation, Swan Region •Around 53 species of invasive geophytes in south-west Australia
•40 species come from the family Iridaceae
•98% are from the Cape Province of South Africa
•All have been introduced for horticulture and have escaped from gardens
•The ability to move into relatively undisturbed native plant communities make geophytes one of the most serious groups of weeds in south-west Australia Watsonia meriana Native geophytes, Meelon Nature Reserve
•How selective is the herbicide 2-2 DPA for Watsonia meriana among the flora of a clay based ephemeral wetland?
•Does the native flora of these wetlands have the capacity to regenerate following control of an invasive geophyte?
•Is there a role for fire in that restoration process? Watsonia meriana invasion of a clay based ephemeral wetland •5 transects, 30 1x 1m quadrats
September •Recorded 2005 cover of native and (before introduced treatment) taxa in each quadrat September 2006 (one year after treatment) ANOSIM Comparing 2005 with 2006
Global R = 0.501 P < 0.01
Average Bray-Curtis dissimilarity measure = 87%
2005 2006
Species Av.Abund Av.Abund
Watsonia bulbillifera 70.0 0.3
Cyathochaeta avenacea 9.0 10.0
Chorizandra enodis 2.0 2.0
Caesia micrantha 2.7 1.4
Viminaria juncea 2.0 1.1
*Briza sp. 3.2 0.2
Drosera rosulata 1.2 0.3
Tribonanthes sp. 0.8 0.2 Following wildfire in February 2007 September 2007
(2 years after initial treatment) •The herbicide 2-2 DPA is reasonably selective and the communities of our clay based wetlands do have the capacity to regenerate once Watsonia meriana has been controlled
•Fire may be a useful tool in the restoration process •Does corm exhaustion coincide with flowering?
•Does wildfire fire offer an opportunity for control of G.undulatus?
Gladiolus undulatus April May June July August
September October November December January December 2004 February 2005 February 2005 July 2005 December 2005 (10 months after fire) Lachenalia reflexa
•How long can seed remain viable in the soil?
Sparaxis bulbifera •Rapid and profuse seeding emergence plays an important role in naturalization
Lachenalia reflexa
Sparaxis bulbifera
Average viability of soil seed bank
600
500
400 Lach 1cm Lach 10cm 300 Spar 1 cm 200 Spar 10cm Numberseed of
100
0
5 5 6 6 7 7 5 0 5 6 0 6 7 0 -0 0 l- -0 -0 0 l- -0 -0 0 l- n r- u t n r- u t n r- u a p J c a p J c a p J J A O J A O J A Conclusions
•The herbicide 2-2 DPA is reasonably selective and the communities of our clay based wetlands do have the capacity to regenerate once Watsonia meriana has been controlled
•Fire may play a role in the restoration process
•For Gladiolus undulatus corm exhaustion does not coincide with flowering
•There maybe a very small window of opportunity to control Gladiolus undulatus following fire
•Soil seed bank of a number of species is relatively short lived
Tribonanthes