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22. Population viability analysis models for better management of lantana (Lantana camara) Project dates July 2008 – June 2012 Project leader Dr Olusegun Osunkoya Ecosciences Precinct Tel: (07) 3255 4474 Email: olusegun.osunkoya@deedi.qld.gov.au Other staff in 2010–11 Christine Perrett and Cameron Clark Objectives • Use size-structured population matrices and mathematical models to examine vital rates of growth, reproduction and survival of lantana under various landscape scenarios to project its population growth into the future. • Identify, from a suite of demographic parameters and with the aid of computer simulations and model predictions, the main driver/s of population growth that could be manipulated for management purposes. • Analyse spatio-temporal changes in stand dynamics of lantana to explore better management of the weed. Rationale Lantana (Lantana camara) is a WONS and a Class 3 declared weed in Queensland. Despite millions of dollars spent on control, research and extension work, there is a dearth of quantitative data encompassing the entire life cycle of the weed. To date, no attempt has been made to carry out population viability analyses on the species, despite the widely held view that such analyses, when done in concert with sensitivity analyses and numerical simulations, could help greatly in finetuning management strategies for control of invasive organisms. This project aims to fill this apparent gap in our understanding of the invasion biology of lantana. Methods We set up and census permanent plots of 50 m × 50 m at each of four infested sites in the Yarraman–Blackbutt area west of Brisbane (Photo 22.1) to determine the parameters of lantana’s vital rates (seed germination and dormancy, seedling, juvenile and adult growth and survival, and adult fecundity) for projection of its population growth. We also use spatial analytical techniques to assess firstorder and second-order spatial patterns of established individuals and recruits. The four field sites (hoop pine plantation, natural forests subject to either periodic burning or grazing regimes, and cattle property) contain, in increasing order, low to moderate infestations of lantana, but differ in soil properties, rainfall intensity, land use type and weed control practices. Frequency 30 25 20 15 10 5 0 0 100 200 30 25 20 15 10 5 Progress in 2010–11 The third and final census of population dynamics across the four field sites—consisting of more than 2000 permanently tagged lantana plants—was completed. We are now using census data to explore spatio-temporal variation in stand dynamics, spatial patterns and population growth of the weed. Populations at most sites exhibited plant height and crown size distributions that are L-shaped, J-shaped or symmetrical and thus unimodal. Bimodality was observed at the farm site only; this suggests that two distinctive cohorts exist (Figure 22.1). Relative growth rate of lantana plants at the farm site was not influenced by size. This contrasts significantly with trends observed in the other three sites, where one-sided (size asymmetric) growth and competition were apparent. Farm Forest (grazing) Forest (burning) Hoop pine plantation 2008 2008 2008 2008 30 120 50 60 25 100 40 50 20 80 30 40 15 10 60 40 20 30 20 5 20 10 10 0 0 100 200 300 0 0 100 200 300 0 0 100 200 300 0 0 100 200 300 400 2009 2010 48 Technical highlights: research projects 2010–11 120 100 80 60 40 20 120 100 80 60 40 20 2009 2009 2009 0 0 0 0 100 200 300 0 100 200 300 0 100 200 300 50 40 30 20 10 0 0 0 300 0 100 200 300 0 100 200 300 0 100 200 300 400 2010 2010 50 40 30 20 10 Plant height (cm) Figure 22.1 Changes in lantana plant height distribution in each of the four populations surveyed over three years: note that the y-axis (frequency) scale varies between sites 60 50 40 30 20 10
Spatial pattern analyses indicated that established and newly recruited individuals are aggregated and that the degree of aggregation decreases with plant size. However, after fire, seedling and juvenile recruitment assume negative association (spatial displacement/ decoupling) in relation to established individuals, perhaps in response to increased lantana litter (fuel load) and thus more intense temperature build-up around existing parent plants during burning. This finding implies that in a landscape where burning is used as a management tool, any follow-up with herbicide that focuses on reducing recruitment can simply concentrate on spaces between established individuals, thereby reducing both herbicide and labour cost. Density and plant size had appreciable effects on the weed’s reproductive capacity and growth, but surprisingly not on survival. The trends in fruit production as a function of plant height were statistically significant at p < 0.05. The intercept but not the slope differed significantly (p < 0.05) between populations (Figure 22.2). On average, lantana populations exhibit reproductive activity at least twice per year, and even more in a good season, when resources (especially moisture) are adequate (Figure 22.3). The lantana population at the hoop pine plantation could only be followed in the first 10 months of the survey due to closing of the canopy and the impenetrable thicket that then developed. Fruit abundance (log) 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 1.5 1.8 2.1 2.4 Plant height (log cm) Part 2 Landscape protection and restoration 49 farm forest (grazing) forest (burning) hoop pine plantation Figure 22.2 Lantana fruit production in 2008 as a function of plant height in the four populations surveyed (a) 100 Lantana plants flowering (%) 80 60 40 20 (b) 100 Lantana plants fruiting (%) 0 Feb. Apr. June Aug. Oct. Dec. Feb. Apr. June Aug. Oct. Dec. Feb. Apr 2009 Date 2010 2011 80 60 40 20 farm forest (grazing) forest (burning) hoop pine plantation 0 Feb. Apr. June Aug. Oct. Dec. Feb. Apr. June Aug. Oct. Dec. Feb. Apr 2009 Date 2010 2011 Figure 22.3 Pattern of (a) flowering and (b) fruiting of lantana over two years in the four populations surveyed
Page 1 and 2: Department of Employment, Economic
Page 3 and 4: Contents Part 1 Integrated weed man
Page 5 and 6: Part 1 Integrated weed management 1
Page 7 and 8: Funding in 2010-11 Queensland Gover
Page 9 and 10: ush (Jatropha gossypiifolia L.)’,
Page 11 and 12: . Pod production (pods per plant) 2
Page 13 and 14: 4. Weed seed dynamics Project dates
Page 15 and 16: Photo 5.1 Experimentalist Laura Rod
Page 17 and 18: Table 6.1 Mortality of Captain Cook
Page 19 and 20: 7. Evaluating the effectiveness of
Page 21 and 22: 8. Biological control of bellyache
Page 23 and 24: 9. Biological control of parthenium
Page 25 and 26: Funding in 2010-11 • Queensland G
Page 27 and 28: Plant height (cm) Number of branche
Page 29 and 30: 11. Biological control of Hudson pe
Page 31 and 32: Part 2 Landscape protection and res
Page 33 and 34: 14. Biological control of Madeira v
Page 35 and 36: 15. Biological control of lantana (
Page 37 and 38: 16. Biological control of mikania v
Page 39 and 40: 17. Weed eradication and containmen
Page 41 and 42: 18. Ecology and control of national
Page 43 and 44: Table 18.1 Number, distribution and
Page 45 and 46: Photo 19.1 (a) Inflorescence, (b) p
Page 47 and 48: 21. Ecology and control of wet trop
Page 49: Navua sedge The foliar herbicide sc
Page 53 and 54: 23. Impacts of environmental weeds
Page 55 and 56: (S, Mn) Axis II [32%] (pH, P, Mg, K
Page 57 and 58: 24. Cabomba (Cabomba caroliniana) e
Page 59 and 60: Cabomba regeneration— substrate q
Page 61 and 62: Figure 25.1 Wild dog GPS locations
Page 63 and 64: Activity index of abundance Activit
Page 65 and 66: Feral pigs have long been establish
Page 67 and 68: Furthermore, the capture process as
Page 69 and 70: Photo 28.1 An Australian raven insp
Page 71 and 72: 30. Adaptive management of rabbits
Page 73 and 74: 31. Mapping the distribution and de
Page 75 and 76: 32. Resistance to rabbit haemorrhag
Page 77 and 78: Part 4 Research services 33. Pest m
Page 79 and 80: Appendixes 1. Abbreviations ANOVA A
Page 81 and 82: Scientific name Common name Dactylo

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