Presentation_by_Mark_Gardener.ppt

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Published on November 27, 2008

Author: aSGuest4240

Source: authorstream.com

A 10 year love-hate relationship with CNG: lessons learntMark GardenerEWL Sciences, Darwin, NT : A 10 year love-hate relationship with CNG: lessons learntMark GardenerEWL Sciences, Darwin, NT How it all started…… : How it all started…… July 1994 Australian newspaper Wanted PhD student to look at biology of Chilean needle grass. * Mark’s thoughts Why I love CNG : Why I love CNG Has an attractive weeping habit with sexy purple glumes Likes to have sex Is good with kids Will stick around through good and bad times Reproductively successful : Reproductively successful Can produce 20,000 seeds/ year/ m2 Has 3 types of breeding systems Panicle seeds (cross and self fertilised) Stem seeds (self or cleistogamous) Basal seeds (self or cleistogamous) Seeds per tiller : Seeds per tiller Long lived seed bankOne years seeding seven years weeding : Long lived seed bankOne years seeding seven years weeding (10 seeds/ m2 after 12.4 years) Long lived tussocks : Long lived tussocks Seedling survival is high Growth is slow but steady even in dry times Survival of tussocks is high - 70% over 3 years Why I hate CNG : Why I hate CNG Gets around Has few friends Good dispersal mechanisms : Good dispersal mechanisms Barbed seeds adhere to clothing, machinery and animals e.g. 10 % of seeds still in sheep’s wool after 3 months Wind dispersal up to 3 m Hygroscopic awn (self drilling seed) Seed dispersal by sheep : Seed dispersal by sheep Widely dispersed : Widely dispersed Found over approximately 3 million ha in Queensland, NSW, Victoria, South Australia and Tasmania Found on all land tenures in grassland and open woodlands Tolerates some shade but doesn’t like waterlogging Distribution : Distribution Current 3 million ha Potential 40 million ha In summary… : In summary… CNG is widespread and well established in Australia It is highly persistent and well suited to temperate Australia’s variable climate Its biology mitigates against control at a broad scale Landholder views of CNG : Landholder views of CNG 80 % believed CNG has negative economic impacts 95 % of respondents to survey said CNG is not beneficial Cost of CNG : Cost of CNG Cost of control estimated at $60-$120/ ha/ year Returns for grazing/cropping enterprises $24- $112 ha/ year Probable negative return plusongoing cost because of reinfestation! Benefits of CNG:what I learnt in South America : Benefits of CNG:what I learnt in South America CNG is widespread in temperate grazing regions CNG often the dominant species in temperate grasslands CNG was considered a beneficial winter growing pasture species What I learnt in AustraliaCNG as a pasture plant in Northern NSW : What I learnt in AustraliaCNG as a pasture plant in Northern NSW My view of CNG : My view of CNG Yes it does have negative economic impacts But MAYBE it could be used as a pasture species even though there is a drop in production Grazing management may result in more productive outcomes Management options : Management options Depends on land use High cost Crop rotation Pasture sowing Herbicide control Slashing/ mechanical control Low cost Burning Biological control Grazing management * How to favour desirable pasture species 1 : How to favour desirable pasture species 1 A short duration- high grazing intensity- long rest system All species are eaten/trampled to similar height during grazing period During rest (up to 90 days) faster growth of desirable pasture species results in competitive advantage How to favour desirable pasture species 2 : How to favour desirable pasture species 2 Increased cost of fencing paddocks and more intensive management Conclusion : Conclusion Don’t get emotionally involved with CNG but look for ways to manage it appropriately for your land use

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A 10 year love hate relationship with CNG: lessons learnt

A 10 year love-hate relationship with CNG: lessons learnt Mark Gardener EWL Sciences, Darwin, NT
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