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

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Presentation on theme: "A 10 year love-hate relationship with CNG: lessons learnt Mark Gardener EWL Sciences, Darwin, NT."— Presentation transcript:

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

2 How it all started…… July 1994 Australian newspaper Wanted PhD student to look at biology of Chile an needle grass. * Marks thoughts

3 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

4 Reproductively successful Can produce 20,000 seeds/ year/ m 2 Has 3 types of breeding systems –Panicle seeds (cross and self fertilised) –Stem seeds (self or cleistogamous) –Basal seeds (self or cleistogamous)

5 Seeds per tiller Basal node nd node rd node th node Total cleistogene seeds Total panicle seeds

6 Long lived seed bank One years seeding seven years weeding (10 seeds/ m 2 after 12.4 years)

7 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

8 Why I hate CNG Gets around Has few friends

9 Good dispersal mechanisms Barbed seeds adhere to clothing, machinery and animals e.g. 10 % of seeds still in sheeps wool after 3 months Wind dispersal up to 3 m Hygroscopic awn (self drilling seed)

10 Seed dispersal by sheep

11 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 doesnt like waterlogging

12 Distribution Current 3 million ha Potential 40 million ha

13 In summary… CNG is widespread and well established in Australia It is highly persistent and well suited to temperate Australias variable climate Its biology mitigates against control at a broad scale

14 Landholder views of CNG 80 % believed CNG has negative economic impacts 95 % of respondents to survey said CNG is not beneficial

15 Cost of CNG Cost of control estimated at $60-$120/ ha/ year Returns for grazing/cropping enterprises $24- $112 ha/ year Probable negative return plus ongoing cost because of reinfestation!

16 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

17 What I learnt in Australia CNG as a pasture plant in Northern NSW

18 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

19 Management options Depends on land use High cost –Crop rotation –Pasture sowing –Herbicide control –Slashing/ mechanical control Low cost –Burning –Biological control –Grazing management *

20 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

21 How to favour desirable pasture species 2 Increased cost of fencing paddocks and more intensive management

22 Conclusion Dont get emotionally involved with CNG but look for ways to manage it appropriately for your land use


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