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Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
Tree regeneration, Fenner School July 2009
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Tree regeneration, Fenner School July 2009

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This is a public seminar I gave at the ANU in July 2009.

This is a public seminar I gave at the ANU in July 2009.

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  • Introduction I’m here to talk about Sustainable Farms, a very new project funded by the Department of Environment, Water, Heritage and the Arts in the last CERF round, and the Australian Research Council. This particular presentation conveys the results of a scoping workshop held to set the research direction of the project, and give you a sense of what we hope to do over the next few years. I am Kate Sherren, research fellow on Sustainable Farms. I’m based at the Fenner School of Environment and Society at ANU, as is the rest of the Sustainable Farms team, which are Stephen Dovers, Joern Fischer, Jacki Schirmer, and – soon – Helena Clayton. Our advisory panel is also mostly local, comprising Neil Gunningham, Libby Robin and Richard Price. To give you some perspective on my background, I am a Geographer by training – specifically spatial science and cartography. I have worked in other resource management settings, including: Forestry in British Columbia, and Urban water issues in New Orleans But I’m quite new to the agricultural context. I completed a PhD last year at the Fenner School where I used numerous methods from the social sciences, including social network analysis, interviews, and questionnaires. This project provides a good opportunity for me to go forward, merging both skill sets.
  • This is all the different sites graphed. If we draw rough polygons around them you can see that all the site of the same type are pretty much clustered.
  • Transcript

    • 1. Reversing paddock tree decline in Australia's temperate grazing zone Joern Fischer, Jenny Stott, Andre Zerger, Garth Warren, Kate Sherren, Robert Forrester (and other collaborators) The Fenner School of Environment and Society The Australian National University 2 July 2009
    • 2. Outline <ul><li>Background on grazing and woodlands </li></ul><ul><li>Problem definition and aims of our recent study </li></ul><ul><li>Methods, results, discussion of our recent study </li></ul><ul><li>The interdisciplinary context of this work Many results presented here were published in early June 2009 in Proceedings of the National Academy of Sciences USA : Fischer, J., Stott, J., Zerger, A., Warren, G., Sherren, K., Forrester, R. (2009). Reversing a tree regeneration crisis in an endangered ecoregion. The paper is open-access – you can download it from anywhere. </li></ul>
    • 3. Livestock grazing globally <ul><li>Demand for agricultural goods projected to more than double between 2000 and 2050 </li></ul><ul><li>Livestock grazing covers more land than any other land use </li></ul>1. Tilman D, Cassman KG, Matson PA, Naylor R, Polasky S (2002) Agricultural sustainability and intensive production practices. Nature 418:671-677. 2. Foley JA, et al. (2005) Global consequences of land use. Science 309:570-574. 3. Asner GP, Elmore AJ, Olander LP, Martin RE, Harris AT (2004) Grazing systems, ecosystem responses, and global change. Annu Rev Environ Resour 29:261-299.
    • 4. Livestock grazing in Australia <ul><li>More than half the continent commercially grazed </li></ul><ul><li>Temperate woodlands internationally recognised as ‘threatened ecoregion’ </li></ul>Left: McIntyre, S., McIvor, J., Heard, K. (2002). Managing and conserving grassy woodlands. CSIRO Publishing. Right: http://www.anra.gov.au/topics/agriculture/beef/index.html
    • 5. Modification levels McIntyre, S., McIvor, J., Heard, K. (2002). Managing and conserving grassy woodlands. CSIRO Publishing.
    • 6.  
    • 7. Photo: Jenny Stott
    • 8. Extent and bias in clearing <ul><li>In Australia’s temperate grazing region, often 80-95% of land cleared </li></ul><ul><li>Large patches remain largely on top of hills </li></ul>Here: the Upper Lachlan catchment (Fischer et al. in press. Frontiers in Ecology and the Environment)
    • 9. Many small patches and scattered trees Manning, A., Fischer, J., Lindenmayer, D. (2006). Biological Conservation. Plants tree per se seed source other plants Abiotic stem flow nutrient enrichment hydrology (salinity, infiltration) Landscape functions Continuity through time Animals shelter hollows shade, litter, food <ul><li>Total amount of tree cover </li></ul><ul><li>Connectivity for tree species </li></ul><ul><li>Connectivity for animals </li></ul><ul><li>Restoration nuclei </li></ul><ul><li>Ecosystem function </li></ul><ul><li>Biodiversity </li></ul><ul><li>Resilience </li></ul><ul><li>Biological legacies </li></ul>Local functions
    • 10. Photo: Kate Sherren
    • 11. The living dead? <ul><li>“ There are those that are standing, living and breathing, but as dead as is the litter, since they have no reproductive future. They are the living dead.” (Janzen 1986, Annu Rev Ecol Syst) </li></ul><ul><li>No regeneration at 87% of sites studied (Spooner et al. 2002) </li></ul><ul><li>Not a single tree regenerated since 1920 in the patch studied (Saunders et al. 2003) </li></ul><ul><li>Regeneration absent at the vast majority of sites studied (Manning et al. 2005) </li></ul><ul><li>Eucalypt regeneration absent at 73% of sites in northern VIC (Dorrough et al. 2005) </li></ul><ul><li>Regeneration unlikely at 38% of sites in SW slopes, NSW (across all types of tenure) (Weinberg et al. 2005) </li></ul>
    • 12. The background for our work <ul><li>An over-cleared region </li></ul><ul><li>Much remnant tree cover in small patches and scattered trees </li></ul><ul><li>These areas have been historically ignored </li></ul><ul><li>Under status quo management, trees are not regenerating in these areas </li></ul>
    • 13. Critical knowledge gaps <ul><li>Our work builds on past research, recognising that: </li></ul><ul><li>The extent of the tree regeneration (failure?) must be systematically quantified; </li></ul><ul><li>Management practices conducive to tree regeneration must be identified, preferably at low costs to commodity production; </li></ul><ul><li>Policies must be developed and implemented to enable sustainable management practices. </li></ul>
    • 14. The ‘Sustainable Farms’ project Funded by the Australian Government, via the Australian Research Council (ARC) and the Commonwealth Environment Research Facilities Program (CERF)
    • 15. Some figures about the Lachlan catchment <ul><li>Settled ~1815, population increase following gold in 1850s </li></ul><ul><li>Average landholder age is 51 years </li></ul><ul><li>Average on-property profit $22,000 prior to drought </li></ul><ul><li>Large-scale land clearing after initial settlement, followed by bursts of regeneration in various locations </li></ul><ul><li>Cowra 1964-1993: 0.36 paddock trees/ha vs. 0.27 trees/ha </li></ul><ul><li>Current tree cover ~15% </li></ul><ul><li>Range of biophysical problems (water, soils, biodiversity) </li></ul><ul><li>(Sources: Lachlan Action Plan 2006; Gibbons and Boak 2002; Ozolins et al. 1999; plus various references within these reports) </li></ul>
    • 16. Management factors affecting regeneration Partly based on: Vesk, P. A., and J. W. Dorrough. 2006. Getting trees on farms the easy way? Lessons from a model of eucalypt regeneration on pastures. Australian Journal of Botany 54:509-519.
    • 17. Location and design <ul><li>Upper Lachlan Catchment </li></ul><ul><li>33 farms </li></ul><ul><li>Wide range of grazing regimes </li></ul><ul><li>Four site types: </li></ul><ul><ul><li>Open paddock </li></ul></ul><ul><ul><li>Scattered trees </li></ul></ul><ul><ul><li>Grazed woodland </li></ul></ul><ul><ul><li>Ungrazed woodland </li></ul></ul><ul><li>Soil chemistry as covariates </li></ul>
    • 18. Different ways of grazing <ul><li>In the Upper Lachlan, three broad ways of grazing livestock are apparent: </li></ul><ul><li>Continuous grazing – paddocks stocked year round </li></ul><ul><li>Slow rotation – paddocks stocked most of the year, but with rest periods for several months </li></ul><ul><li>High-intensity short-duration grazing – rotation of livestock from one paddock to another every few days </li></ul><ul><li>All of these can have a high or low average stocking rate </li></ul>
    • 19. Grazing regimes at our sites
    • 20. First major set of results <ul><li>Three steps of analysis: </li></ul><ul><ul><li>Analysis of how much tree cover occurs at different densities (= regional-scale background) </li></ul></ul><ul><ul><li>Analysis of tree diameter distributions at different sites (= indication of age profile of stands of trees) </li></ul></ul><ul><ul><li>Analysis of (i) time since last regeneration and (ii) probability of recent regeneration at different sites (= insights for future management) </li></ul></ul>
    • 21. Tree densities methods <ul><li>Methods </li></ul><ul><li>High-resolution SPOT5 imagery combined with on-ground surveys of tree densities </li></ul><ul><li>SPOT analysis: 10 m resolution tree layer across the region </li></ul><ul><li>On-ground tree measurements: Diameters and densities measured at 126 sites (106 ‘primary’ + 20 ‘validation’ sites) (> 3500 trees identified and measured) </li></ul>
    • 22. Tree densities results <ul><li>Regional tree cover 18% (farm median = 12%) </li></ul><ul><li>Three quarters under 30% tree cover per 2 ha = about 3 million trees </li></ul><ul><li>Two thirds under 10% tree cover per 2 ha = about 1.5 million trees </li></ul>
    • 23. Tree diameters methods <ul><li>Census or representative sampling of diameters of trees in the 126 survey sites </li></ul><ul><li>Diameters of a given species standardised by scaling them against representative ‘very old’ representatives of the species = unit-free diameter index </li></ul><ul><li>All species scaled back to yellow box for graphs </li></ul>Graphs based on: Banks, J. C. G. 1997. Tree ages and ageing in yellow box. Pages 17-28 in J. Dargavel, editor. The coming of age - forest age & heritage values. Environment Australia, Canberra.
    • 24. Tree diameters results <ul><li>Distribution characteristic of undisturbed systems only in ungrazed sites </li></ul><ul><li>Strong evidence of insufficient recruitment in low density areas </li></ul><ul><li>Typical diameters of 100 cm or more (well over 120 years old) </li></ul>
    • 25. Regression methods <ul><li>Generalised linear mixed modelling </li></ul><ul><ul><li>Random effect: ‘Farm’ </li></ul></ul><ul><ul><li>Fixed effects: Grazing regimes, tree cover, soil nutrients </li></ul></ul><ul><li>Response variables </li></ul><ul><ul><li>Minimum diameter at the site (= proxy for time since last regeneration) </li></ul></ul><ul><ul><li>Presence/absence of seedlings (= proxy for recent regeneration) </li></ul></ul><ul><li>Models fitted first using subset of all data, then validated on the whole dataset </li></ul>
    • 26. Regression results <ul><li>Significant variables related to regeneration: </li></ul><ul><li>Tree density </li></ul><ul><li>Phosphorus, nitrogen </li></ul><ul><li>Grazing regime: </li></ul><ul><li>Ungrazed or fast rotation significantly ‘better’ than continuous or slow rotation </li></ul>
    • 27. Parallels to other parts of the world <ul><li>Holm oak dehesas in Spain </li></ul>Pulido FJ, Diaz M, de Trucios SJH (2001) Size structure and regeneration of Spanish holm oak Quercus ilex forests and dehesas: effects of agroforestry use on their long-term sustainability. For Ecol Manag 146:1-13.
    • 28. Parallels to other parts of the world <ul><li>Cattle pastures in Nicaragua: </li></ul><ul><li>37 of 85 tree species regenerated under commercial grazing </li></ul>Esquivel MJ, Harvey CA, Finegan B, Casanoves F, Skarpe C (2008) Effects of pasture management on the natural regeneration of neotropical trees. J Appl Ecol 45:371-380.
    • 29. A tree regeneration crisis <ul><li>The region is already over-cleared from the perspective of many species and ecological processes </li></ul><ul><li>Conventional practices are incompatible with the maintenance of tree cover: Fertiliser + continuous grazing = no regeneration </li></ul><ul><li>Under conventional practices, millions of hectares of land currently supporting tens of millions of trees will be treeless </li></ul>
    • 30. Likely rates of tree decline <ul><li>In the Cowra region: 2% per year mortality Ozolins, A., C. Brack, and D. Freudenberger. 2001. Pacific Conservation Biology 7 :195-203. </li></ul><ul><li>Status quo prediction for scattered yellow box: 50% decline over the next 50 years Gibbons, P., D. B. Lindenmayer, J. Fischer, A. D. Manning, A. Weinberg, J. Seddon, P. Ryan, and G. Barrett. 2008. Conservation Biology 22:1309-1319. </li></ul>100% 50% 0% Years into the future
    • 31. Likely consequences <ul><li>Trees are important for many animal species: </li></ul><ul><ul><li>Over 100 bird species </li></ul></ul><ul><ul><li>Over 25 reptile species </li></ul></ul><ul><ul><li>Over 25 mammal species (including bats) </li></ul></ul><ul><ul><li>Over half of all of these use scattered trees! </li></ul></ul><ul><li>Potential for thresholds, cumulative effects, disproportionate effects of scattered trees </li></ul><ul><li>Also lost ecosystem services (= lost $$$): </li></ul><ul><ul><li>Water infiltration, shade for livestock </li></ul></ul>
    • 32. Trees and water infiltration “… both sorptivity and steady-state infiltration were significantly greater (approximately fivefold) under the timbered strata compared with the grassy slopes or cultivation …” D. J. Eldridge, D. Freudenberger, Austral Ecology 30, 336 (May, 2005).
    • 33. Trees and bats (… and their estimated economic value in the USA …) L. F. Lumsden, A. F. Bennett, Biological Conservation 122, 205 (Mar, 2005). Quote from a study in the USA: “ We estimate the bats' value as pest control for cotton production in an eight county region in south-central Texas. Our calculations show an annual value of $741000 per year, with a range of $121000-$1725000, compared to a $4.6-$6.4 million per year annual cotton harvest.” C. J. Cleveland et al., Frontiers in Ecol. Environm. 5, 238 (Jun, 2006).
    • 34. Trees and the Superb Parrot (threatened in NSW) Manning et al. (2004).Biol. Conserv. 120, 363-374 Superb Parrot (Geoffrey Dabb, photogallery.canberrabirds.org.au)
    • 35.  
    • 36. Reversing the crisis “ Contrary to common wisdom, scattered trees are not doomed to be the living dead. Although low seed supply and a history of intensive land use impose constraints on tree regeneration in heavily cleared areas, reducing nutrient inputs and applying fast rotational grazing can substantially enhance regeneration.” (Fischer et al. 2009 PNAS)
    • 37. Two vital management challenges: Soil nutrients and livestock grazing McIntyre, S., Lavorel, S. (2007). Agric. Ecosys. Environm. 119, 11-21
    • 38. Benefits of low nutrient pastures <ul><li>Benefits for tree regeneration </li></ul><ul><li>Also, low-nutrient environments: </li></ul><ul><ul><li>Have healthier mature trees => Maximising the survival of mature trees is critical to avoid population bottlenecks in the availability of key resources </li></ul></ul><ul><ul><li>Have more native ground cover species </li></ul></ul><ul><ul><li>Have more native arthropod species (for references, see Fischer et al. 2009 PNAS) </li></ul></ul>
    • 39. Benefits of altering livestock grazing <ul><li>Livestock exclusion has ecological benefits, but comes at a high economic cost </li></ul><ul><li>Greening Australia ACT estimates the opportunity costs of complete stock removal at over $10,000 AUD per year per 100 ha </li></ul><ul><li>Fast rotational grazing promises to be a win-win opportunity (at least for tree regeneration) </li></ul><ul><ul><li>Interesting also given rising fertiliser costs and increasingly frequent droughts </li></ul></ul>
    • 40. Management options <ul><li>Considering our results in context: What are the management options? </li></ul><ul><li>Active management: </li></ul><ul><ul><li>The planting or direct seeding of new trees </li></ul></ul><ul><li>Passive management: </li></ul><ul><ul><li>Managing environmental conditions to encourage natural tree regeneration </li></ul></ul><ul><li>(e.g. Dorrough J, Vesk PA, Moll J (2008) Integrating ecological uncertainty and farm-scale economics for planning restoration. J Appl Ecol 45:288-295) </li></ul>
    • 41. Management options <ul><li>Active management (planting or seeding) </li></ul><ul><li>Establish trees along existing fence lines (commonly done, but does nothing for scattered trees) </li></ul><ul><li>Establish trees in scattered pattern (done by some pioneering farmers) </li></ul><ul><li>Exclude livestock from paddocks, prior to re-seeding and resting them for several years (used by Greening Australia ACT) </li></ul><ul><li>Passive management (for natural regeneration) </li></ul><ul><li>Fencing off woodland patches (commonly done, but does nothing for scattered trees) </li></ul><ul><li>Drastically reduce or cease fertiliser use (no institutional support yet, unlike in parts of Europe) </li></ul><ul><li>Take up fast rotational grazing (gaining popularity despite lack of institutional support) </li></ul>
    • 42. Management options <ul><li>Active management (planting or seeding) </li></ul><ul><li>Establish trees along existing fence lines (commonly done, but does nothing for scattered trees) </li></ul><ul><li>Establish trees in scattered pattern (done by some pioneering farmers) </li></ul><ul><li>Exclude livestock from paddocks, prior to re-seeding and resting them for several years (used by Greening Australia ACT) </li></ul><ul><li>Passive management (for natural regeneration) </li></ul><ul><li>Fencing off woodland patches (commonly done, but does nothing for scattered trees) </li></ul><ul><li>Drastically reduce or cease fertiliser use (no institutional support yet, unlike in parts of Europe) </li></ul><ul><li>Take up fast rotational grazing (gaining popularity despite lack of institutional support) </li></ul>
    • 43. Prioritisation and policy options <ul><li>Active planting and seeding most appropriate where natural regeneration is unlikely (e.g. few parent trees or high soil nutrients) </li></ul><ul><li>Passive management for natural regeneration ultimately preferable: to foster a self-perpetuating farm ecosystem </li></ul><ul><li>Which policy tools are appropriate? Financial incentives? Education? Regulation? </li></ul>
    • 44. The ‘Sustainable Farms’ project Funded by the Australian Government, via the Australian Research Council (ARC) and the Commonwealth Environment Research Facilities Program (CERF)
    • 45. Future plans for the ecology component <ul><li>Aims: </li></ul><ul><li>Establish links between fauna and tree cover </li></ul><ul><ul><li>Surveys of birds and bats completed </li></ul></ul><ul><ul><li>Pilot study on bats in press </li></ul></ul><ul><li>Project tree cover into the future under different management scenarios </li></ul><ul><ul><li>To be completed over the next few months </li></ul></ul><ul><li>Project the distribution of selected fauna species into the future </li></ul><ul><ul><li>Preliminary results over the next few months </li></ul></ul>
    • 46. Back to our own data: Bird surveys 2007 and 2008 <ul><li>2007: </li></ul><ul><li>122 bird species </li></ul><ul><li>Paddocks: 56 species </li></ul><ul><li>Scattered Trees: 70 species </li></ul><ul><li>Grazed Woodland: 68 species </li></ul><ul><li>Ungrazed Woodland: 68 species </li></ul><ul><li>Revegetation: 47 species </li></ul><ul><li>Detailed analysis yet to come </li></ul>Brown Treecreeper (Tom Green, photogallery. canberrabirds.org.au)
    • 47. UNGRAZED WOODLAND REVEGETATION PADDOCK SCATTERED TREE GRAZED WOODLAND
    • 48. Welcome Swallow Tree Martin Rainbow Bee-eater Cockatiel Varied Sitella White-browed Scrubwren Eastern Yellow Robin Speckled Warbler Spotted Pardalote Richard’s Pipit Brown Falcon Peaceful Dove Common Blackbird Rufous Songlark White-thr. Treecreeper Brown Treecreeper White-winged Chough Laughing Kookaburra Crimson Rosella Striated Pardalote Eastern Rosella Magpie-lark Crested Pigeon Noisy Miner Sulphur-cr. Cockatoo Grey-crowned Babbler Jacky Winter Superb Fairy-wren Superb Parrot
    • 49. Overview of social science components + policy analysis and economic modelling
    • 50. Conclusion <ul><li>Our temperate grazing systems are internationally recognised as threatened </li></ul><ul><li>Trees will be lost, unless urgent action is taken </li></ul><ul><li>Negative ramifications for key ecosystem services and biodiversity </li></ul><ul><li>Consistent messages are emerging about what needs to be done: </li></ul><ul><ul><li>(1) altered grazing regimes, and </li></ul></ul><ul><ul><li>(2) nutrient management, both at large scales </li></ul></ul>
    • 51. Acknowledgements <ul><li>This work was funded by the Australian Government, via the ARC and CERF programme </li></ul><ul><li>Thanks to all participating farmers and the Lachlan CMA </li></ul><ul><li>Particular thanks to many direct collaborators, especially Jenny Stott, Steve Dovers, Bob Forrester, Kate Sherren, Jacki Schirmer, Andre Zerger, Karen Stagoll, John Stein, Lorna Fitzsimmons, John Field, Garth Warren, Brad Law, Maria Adams… and others! </li></ul><ul><li>Thanks to my ANU colleagues for advice </li></ul>The full paper is FREELY available on the PNAS website: www.pnas.org (search for “Joern Fischer”) Fischer, J., Stott, J., Zerger, A., Warren, G., Sherren, K., Forrester, R. (2009). Reversing a tree regeneration crisis in an endangered ecoregion. Proceedings of the National Academy of Sciences USA.
    • 52. Land sparing or wildlife-friendly farming? Fischer, Brosi, Daily, Ehrlich, et al. (2008). Frontiers in Ecology and the Environment.

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