Tracking sand dune transformation before, during and after sand dune mining, Myall Lakes, NSW, a case study
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Unmodified landscapes are transformed by the removal of vegetation prior to, during sand mining and through restoration, after mining. Bridge Hill Ridge is presented as a case study for the application of a standardised national system (VAST-2) to account for ecological changes before, during and after mining. Bridge Hill Ridge is a high coastal sand dune, part of the Myall Lakes National Park, NSW. A reference state was defined for the unmodified unmined Blackbutt (Eucalyptus pilularis) and smooth barked apple (Angophora costata) open forest, comprising ten ecological characteristics, integrated with 22 indicators. This information provided the basis for assessing change and trend over time in regard to mining and restoration. Relevant sources of ecological data and information pertaining to the ten ecological characteristics and 22 indicators were compiled and analysed relative to the reference states. Key researchers and land managers who had worked on the site were contacted and interviewed. A field visit was conducted in mid-January 2014 to validate assessment of change and trend, almost 40 years after mine restoration. The effects of land management practices, i.e. mining and restoration, upon the unmodified Eucalypt open forest plant community were assessed relative to the reference state to determine the relative change and trend in the ten ecological characteristics and 22 indicators over time. Reporting standardized indicators helps land managers and other decision makers to understand the nature of change and trend in regard to predicted future states; to make adjustments in rehabilitation activities (e.g. hydrological interventions, control of weeds and feral animals, mitigation of wildfire, and management of people). The benefits of integrated monitoring and reporting using a standardised report card provides a simple tool to inform inform stakeholders of progress towards agreed target/s of vegetation structure, species composition and regenerative capacity (landscape function).
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Tracking sand dune transformation before, during and after sand dune mining, Myall Lakes, NSW, a case study
- 1. Tracking sand dune transformation before, during and after sand dune mining, Myall Lakes, NSW, a case study Richard Thackway The 14th Annual Australian Journal Mining's Mineral Sands Conference Rydges, Melbourne, 4th & 5th March 2014
- 2. Outline • VAST-2 system • Case study - Bridge Hill Ridge, Myall Lakes, NSW • Understanding causes and effects = change in condition • Tracking change and trend before, during and after mining • Interpreting ecological change and trend • Lessons from the case study VAST = Vegetation Assets States and Transitions
- 3. VAST – An ecological systems approach • Making the complex simple by: – Accounting for effects land management change over time – Linking ecological change to land management
- 4. Assessing ecological change before, during and after sand dune mining – using VAST
- 5. Definitions - Condition and transformation • Change in a plant community (type) due to effects of land management practices: – Structure – Composition – Regenerative capacity • Resilience = the capacity of an plant community to recover to a reference state following a change/s in land management • Transformation = changes to vegetation condition over time • Condition, resilience and transformation are assessed relative to fully natural a reference state Vegetation condition
- 6. VAST-2 tracks the effects of land management practices over time At the land parcel level on-ground management actions are the primary cause of changes in vegetation condition: • Modifying • Removing and replacing • Enhancing • Restoring • Maintaining • Improving Biodiversity outcomes can be practically tracked and reported using: • Criteria or Key Result Areas and • Indicators or Key Performance Indicators
- 7. 1925 Occupation Relaxation Anthropogenic change Net benefit time 1900 2025 1950 Reference change in vegetation indicator or index 1850 1875 1975 2000 VAST classes VAST-2 model of ecosystem change (causes & effects)
- 8. VAST-2 focuses on tracking effects of land management on key ecological criteria Soil Vegetation Regenerative capacity/ function Vegetation structure & Species composition 1. Soil hydrological status 2. Soil physical status 3. Soil chemical status 4. Soil biological status 5. Fire regime 6. Reproductive potential 7. Overstorey structure 8. Understorey structure 9. Overstorey composition 10. Understorey composition
- 9. VAST = Vegetation Assets States and Transitions NVIS = National Vegetation Information System VI V IV III II I 0 Native vegetation cover Non-native vegetation cover Increasing modification caused by use and management Transitions = trend Vegetation thresholds Reference for each veg type (NVIS) VAST - A framework for assessing & reporting vegetation condition Condition states Residual or unmodified Naturally bare Modified Transformed Replaced - Adventive Replaced - managed Replaced - removed Thackway & Lesslie (2008) Environmental Management, 42, 572-90 Diagnostic attributes of VAST states: • Vegetation structure • Species composition • Regenerative capacity NVIS
- 10. Current datasets are snapshots but not time series Thackway & Lesslie (2008) Environmental Management, 42, 572-90 NB: Input dataset biophysical naturalness reclassified using VAST framework / replaced / unmodified VAST 2009 Veg condition derived by classifying & mapping effects of land management practices Native
- 11. Generate total indices for ‘transformation site’ for each year of the historical record. Validate using Expert Knowledge • Compile and collate effects of land management on criteria (10) and indicators (22) over time. • Evaluate impacts on the plant community over time Transformation site • Compile and collate effects of land management on criteria (10) and indicators (22) Reference state/sites Score all 22 indicators for ‘transformation site’ relative to the ‘reference site’. 0 = major change; 1 = no change Derive weighted indices for the ‘transformation site’ i.e. regenerative capacity (58%), vegetation structure (27%) and species composition (18%) by adding predefined indicators General process for tracking change over time using the VAST-2 system
- 12. Case study – Bridge Hill Ridge Geographical and historical context
- 13. High sand dune case study Sand mining path Bridge Hill Ridge Figure: Barry Fox
- 14. Transformation site Case study site Field visit January 2014 (Lat -32.404, Long 152.496) Smiths Lake 0 1000 2000 Kilometers Sand mining path
- 15. Bridge Hill Ridge, 2011 Case study site - Field visit January 2014 Smiths Lake
- 16. Bridge Hill Ridge, 1976 & 1991 1976 1991 Source: Geoscience Australia, © Australian Titanium Minerals Industry Smiths Lake
- 17. Bridge Hill Ridge 1975 Smiths Lake Regenerating Mine Path Sandmining Dredge Photograph: Barry Fox
- 18. Bridge Hill Ridge 1991 Smiths Lake Regenerated Mine Path Photograph: Barry Fox
- 19. Bridge Hill Ridge 2011 Regenerated Mine Path Smiths Lake
- 20. Establishing and documenting the Reference and Transformation site Plant community Eucalyptus pilularis and Angophora costata Soil landscape unit Upper slopes and crests of the high dune
- 21. Establishing the Reference and Transformation site Source: Bunning Report 1974 Reference Transformation
- 22. Based on Myerscough and Carolin (1986) Reference state plant community (shaded area)
- 23. Eucalyptus pilularis Angophora costata Banksia serrata Source: Coffey and Hollingsworth, 1973. Map. No. 3.1.5 Reference state plant community (shaded area)
- 24. Source: Coffey and Hollingsworth, 1973. Map. No. 2.3.1.4 Reference state plant community Mined area Smiths Lake
- 25. Reference site/ state Photographs: Richard Thackway
- 26. Transformation site Sandmining – land management practices
- 27. Source: Coffey and Hollingsworth, 1973. Map. No. 3.1.5 Unmined Pond Mining surface Reshaped landform Tailings Mining direction 100 0 100 200 300 Meters Sandmining - the process 250m x 150m
- 28. Topsoil briefly stockpiled <10 days Timber harvested and remaining trees and vegetation removed 1974 (-1 years old) Photographs: Barry Fox
- 29. Sand sprayed and dried and re-shaped as a contoured dune Sandmining Dredge Original Eucalypt open forest Dredge Pond Smiths Lake Dredge Pond 1974 (0 years old) Photographs: Barry Fox
- 30. Transformation site Restoration – land management practices
- 31. 1974-75 (0-6 months old) Topsoil spread over reshaped sand dune Sorghum cover crop planted 1974 (One month old) 1975 (< 6 months old) Photograph: Barry Fox
- 32. 1975 (1 year old) Dead and dying sorghum plants < 1% reseeding Photograph: Barry Fox
- 33. 1976-77 (1.5 - 2 years old) Substantial Acacia regrowth begins Isolated Acacia plants in sorghum compartment 1976-77 (2 Years old) 1975-76 (1.5 years old) Photograph: Barry Fox
- 34. 1978 (3 years old) Acacia die-off beginning Substantial Acacia regrowth Photograph: Barry Fox
- 35. 1979 (4 years old) Substantial Acacia die-off Photograph: Barry Fox
- 36. 1981 (6 years old) Increasing abundance of native species growing among dead Acacia and native grasses Photograph: Barry Fox
- 37. Substantial Acacia Regrowth Substantial bare sand and open space between sapling trees with sparse leaf litter 1991 (12 years old) Photograph: Barry Fox
- 38. 2014 (39 years old) Photographs: Richard Thackway
- 40. Normalising the age of regeneration Figure: Barry Fox
- 41. Generate total indices for ‘transformation site’ for each year of the historical record. Validate using Expert Knowledge • Compile and collate effects of land management on criteria (10) and indicators (22) over time. • Evaluate impacts on the plant community over time Transformation site • Compile and collate effects of land management on criteria (10) and indicators (22) Reference state/sites Score all 22 indicators for ‘transformation site’ relative to the ‘reference site’. 0 = major change; 1 = no change Derive weighted indices for the ‘transformation site’ i.e. regenerative capacity (58%), vegetation structure (27%) and species composition (18%) by adding predefined indicators General process for tracking change over time using the VAST-2 system
- 42. Condition components (3) [VAST] Key Result Areas (10) Key Performance Indicators (22) Regenerative capacity Fire regime 1. Area /size of fire foot prints 2. Number of fire starts Soil hydrology 3. Soil surface water availability 4. Ground water availability Soil physical state 5. Depth of the A horizon 6. Soil structure Soil nutrient state 7. Nutrient stress – rundown (deficiency) relative to soil fertility 8. Nutrient stress – excess (toxicity) relative to soil fertility Soil biological state 9. Recyclers responsible for maintaining soil porosity and nutrient recycling 10. Surface organic matter, soil crusts Reproductive potential 11. Reproductive potential of overstorey structuring species 12. Reproductive potential of understorey structuring species Vegetation structure Overstorey structure 13. Overstorey top height (mean) of the plant community 14. Overstorey foliage projective cover (mean) of the plant community 15. Overstorey structural diversity (i.e. a diversity of age classes) of the stand Understorey structure 16. Understorey top height (mean) of the plant community 17. Understorey ground cover (mean) of the plant community 18. Understorey structural diversity (i.e. a diversity of age classes) of the plant Species Composition Overstorey composition 19. Densities of overstorey species functional groups 20. Relative number of overstorey species (richness) of indigenous :exotic spp Understorey composition 21. Densities of understorey species functional groups 22. Relative number of understorey species (richness) of indigenous :exotic spp
- 43. VAST-2 key ecological criteria & indicators Reference state Transformation site Fire regime * * Soil hydrology * * Soil physical state * ** Soil nutrient state ** * Soil biological state * * Reproductive potential *** *** Overstorey vegetation structure *** ** Understorey vegetation structure *** *** Overstorey species composition *** *** Understorey species composition *** *** Populating the VAST-2 criteria *** Quantitative data /info * Qualitative data /info
- 45. Importance of dynamics Rainfall is assumed to be main driver of system dynamics • Period 1900 - 2013 • Average seasonal rainfall (summer, autumn, …) • Rainfall anomaly is calculated above and below the mean • Two year running trend line fitted NB: Must calibrate remote sensing to account for dynamics • e.g. ground cover, greenness and foliage projective cover
- 46. Seasonal rainfall anomaly (Lat -32.404, Long 152.496) -2 -1 0 1 2 3 1901 1904 1907 1910 1913 1916 1919 1922 1925 1928 1931 1934 1937 1940 1943 1946 1949 1952 1955 1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 Spring -3 -2 -1 0 1 2 3 4 5 1901 1904 1907 1910 1913 1916 1919 1922 1925 1928 1931 1934 1937 1940 1943 1946 1949 1952 1955 1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 Winter -4 -2 0 2 4 6 1901 1904 1907 1910 1913 1916 1919 1922 1925 1928 1931 1934 1937 1940 1943 1946 1949 1952 1955 1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 Autumn -2 -1 0 1 2 3 1901 1904 1907 1910 1913 1916 1919 1922 1925 1928 1931 1934 1937 1940 1943 1946 1949 1952 1955 1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 Summer Source: BOM
- 47. Are we there yet? Results
- 48. Key Result Areas – Regenerative capacity
- 49. Key Result Areas – Regenerative capacity
- 50. Key Result Areas – Vegetation structure
- 51. Key Result Areas – Species composition
- 53. Lessons from Bridge Hill Ridge • BHR is atypical of the usual restoration effort and regeneration outcome that follows sand mining • The restoration effort and regeneration outcome at BHR is very good • A great deal more money was spent on BHR than other similar mining paths • The quality of the restoration effort and regeneration outcome is directly related to the amount spent
- 54. What else could be done to improve the site toward the reference state? • Consider establishing an appropriate experimental fire regime checking for weed incursions • Allow more time for incremental change in: – Understorey Species Composition – Overstorey Vegetation Structure – Reproductive Potential (Understorey)
- 55. Conclusions • The VAST-2 report card helps tell the story of change and trend in vegetation condition • The restoration effort and regeneration outcome at BHR is very good • A similar approach could be applied to existing, proposed and future mined sites
- 56. VAST helps in ‘telling the story’
- 57. VAST helps in ‘telling the story’ Predictions of mature forest (Bunning’s Enquiry 1974)
- 58. More info & Acknowledgements More information http://www.vasttransformations.com/ http://portal.tern.org.au/search http://aceas-data.science.uq.edu.au/portal/ Acknowledgements • Matt Bolton, Barry Fox, Mike Dodkin and Shane Cridland assisted with data and assessment • University of Queensland, Department of Geography Planning and Environmental Management for ongoing research support • Many public and private land managers, land management agencies, consultants and researchers have assisted in the development of VAST-2