Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Phillip Is, Pacific Ocean: Drivers of landscape degradation and recovery and its effects on bird communities

21 views

Published on

We present an assessment of the modification of the vegetation condition found on Phillip Island relative to a fully natural pre-European (1750) reference state and the current land and sea birds recorded on the Island. The island became denuded between the late 1700s and mid-1850s. Introductions of pigs, goats and rabbits were made to feed to penal colony of the nearby Norfolk Island. Almost complete loss of vegetation types, extent and condition is attributed to a deliberate land management regime: used to feed the pigs and goats. Pigs and goats became extinct with the loss of vegetation on the Island. Rabbits persisted on the Island until 1988, when they were eradicated. Changes in the extent of vegetation cover has been remarkable from a very low level up to 1900-1980 (estimated <1%); it now covers large areas of the island including valleys and gulleys and cliffs (estimated 50%). Our analyses show that the condition of the largely passively recovered vegetation extent is not of a high condition relative to an assumed reference state (1750) for Pine – Hardwood Subtropical Rainforest. A reconstructed pre-European settlement (original) list of sea birds shows that sea birds diversity on the island have changed little in three recent bird surveys (1978-2015). A reconstructed pre-European settlement (original) list of land birds shows that land birds have obviously changed, with many of the current species not represented in the pre-European list. The current list of land birds, which make up most of the current list of species recorded on Phillip Island have invaded from the nearby Norfolk Island. We conclude that current bird species diversity and distribution on the island is a not a function of the condition of the indigenous native vegetation, assessed relative to a pre-European reference state, but rather it appears to be a response to the lack of mammalian grazing mammals and the present of open to dense shrubby vegetation.

Published in: Environment
  • Be the first to comment

  • Be the first to like this

Phillip Is, Pacific Ocean: Drivers of landscape degradation and recovery and its effects on bird communities

  1. 1. Phillip Is, Pacific Ocean Drivers of landscape degradation and recovery and its effects on bird communities Richard Thackway and Chris Davey Australian National Botanic Gardens 1 March 2018
  2. 2. Outline • Phillip Island became a transformed landscape because of anthropogenic & natural drivers – these include – Social, economic and ecological • Present a framework used to assess and report on the degree of modification of Phillip Island’s plant communities – Criteria and indicators of function, structure and composition • Show how the degradation and restoration of Phillip Island’s bird habitat and diversity of plant communities relates to – deliberate and unintentional land management decisions
  3. 3. Accounting for changes in native veg type, extent and condition LMP deliberately &/or unintentionally do this by: • Modifying • Removing and replacing • Enhancing • Restoring • Maintaining • Improving * * Natural disturbances Function Structure & Composition LMP = land management practices
  4. 4. 1925 Occupation Relaxation Anthropogenic change Net gain time 1900 20251950 Reference changeinvegetation indicatororindex 1850 1875 1975 2000 Model of ecosystem change (causes & effects) Baseline VASTclasses
  5. 5. VIVIVIIIIII0 Native vegetation cover Non-native vegetation cover Increasing modification caused by use and management Transitions = trend Vegetation thresholds Reference for each veg type A framework for assessing modification of native vegetation extent and condition Condition states Residual or unmodified Naturally bare Modified Transformed Replaced - Adventive Replaced - managed Replaced - removed Thackway & Lesslie (2008) Diagnostic attributes of VAST (classes): • Vegetation structure • Species composition • Function /Regenerative capacity
  6. 6. VAST I: Unmodified /residual native Photographs: Richard Thackway & Ross Peacock
  7. 7. VAST II: Modified native Photographs: Richard Thackway
  8. 8. VAST III: Transformed native Photographs: Richard Thackway
  9. 9. VAST IV: Replaced (Adventive ) Photograph: Richard Thackway
  10. 10. VAST V: Replaced (Managed) Photographs: Richard Thackway
  11. 11. VAST VI: Removed Photographs: Richard Thackway
  12. 12. Phillip Island Google earth ~1900 kms
  13. 13. Phillip Island Norfolk Island ~ 6km
  14. 14. Photograph: Peter Coyne ~1750 2015 Phillip Island, South Pacific Photograph: Peter Coyne Reference Pine – Hardwood Subtropical Rainforest
  15. 15. 1906 1979 2008 2015 1906 State Library of NSW to use the Beattie photo 1979 Peter Coyne. Used with permission 2008 Peter Coyne. Used with permission 2015 Peter Coyne. Used with permission
  16. 16. 1981 2008 Photographs: Peter Coyne
  17. 17. Intent of LMRs on criteria & indicators of function, structure and composition: Examples No active interventions Protecting biodiversity; restricting access; imposing minimal use Harvest products Removing biomass, fibre, flowers, fruit and nuts Enhance or improve Rehydrating soils; controlling invasive species; reestablishing a natural fire regime; broadcasting seed hays Extirpate or remove Continuously grazing; intensive cropping, improving pasture production; removing a natural fire regime; draining natural wetlands Reconstruct Revegetating; Rehydrating soils; stabilizing eroding top soil Source: Thackway 2017 Tracking change and trends - effects of land management regimes
  18. 18. Create systematic and comprehensive chronology to assess where, when and how landscapes are transformed relative to a reference LU = Land Use, LMP = Land Management Practices VAST Diagnostic attributes Time
  19. 19. Pine – Hardwood Subtropical Rainforest, Phillip Island, Site 3
  20. 20. Site 3 Photograph: Peter Coyne 2015
  21. 21. 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
  22. 22. 1 3 10 22 Diagnostic attributes Vegetation Transformation score Attribute groups Vegetation Structure (27%) Overstorey (3) Understorey (3) Species Composition (18%) (2) UnderstoreyOverstorey (2) Regenerative Capacity (55%) Fire (2) Reprod potent (2) Soil Hydrology (2) Biology (2) Nutrients (2) Structure (2) Indicators VAST-2 – benchmark scoring of the effects of use and management of native veg (indicators) over time Source: Thackway 2017
  23. 23. Components (3) Function Regenerativecapacity Vegetationstructure Species Composition
  24. 24. Components (3) Criteria (10) Function Regenerativecapacity Major natural disturbances Soil hydrology Soil physical state Soil nutrient state Soil biological state Reproductive potential Vegetationstructure Overstorey structure Understorey structure Species Composition Overstorey composition Understorey composition
  25. 25. Components (3) Criteria (10) Description of loss or gain relative to pre settlement indicator reference state (22) Function Regenerativecapacity Major natural disturbances Change in the area /size of major natural disturbances foot prints Change in the number of major natural disturbances foot prints Soil hydrology Change in the soil surface water availability Change in the ground water availability Soil physical state Change in the depth of the A horizon Change in soil structure. Soil nutrient state Nutrient stress – rundown (deficiency) relative to soil fertility Nutrient stress – excess (toxicity) relative to soil fertility Soil biological state Change in the recyclers responsible for maintaining soil porosity and nutrient recycling Change in surface organic matter, soil crusts Reproductive potential Change in the reproductive potential of overstorey structuring species Change in the reproductive potential of understorey structuring species Vegetationstructure Overstorey structure Change in the overstorey top height (mean) of the plant community Change in the overstorey foliage projective cover (mean) of the plant community Change in the overstorey structural diversity (i.e. a diversity of age classes) of the stand Understorey structure Change in the understorey top height (mean) of the plant community Change in the understorey ground cover (mean) of the plant community Change in the understorey structural diversity (i.e. a diversity of age classes) of the plant Species Composition Overstorey composition Change in the densities of overstorey species functional groups Change in no.s of indigenous overstorey species relative to the number of exotic species Understorey composition Change in the densities of understorey species functional groups Change in no.s of indigenous understorey species relative to the number of exotic species
  26. 26. Examples of responses of VAST functional criteria Criteria #1 Criteria #2 Criteria #3 Criteria #4
  27. 27. year score% Pine – Hardwood Subtropical Rainforest, Phillip Island, Site 3 Pigs released Uninhabited island Pigs died out Goats and rabbits released Goats died out Rabbits eradicated Rabbit control commenced Commenced passive & active restoration. Minimal ecological monitoring
  28. 28. Transformationscore Years 1800 2016 Reference Developing scenarios for future landscape transformation Modified Transformed Replaced/ managed Residual Replaced/ adventive VAST Classes 1850 19501900 2000 2050 2100 Replaced/ removed Baseline Classes can be modelled as extent and condition Extentnative
  29. 29. Prioritizing land management regimes over time and space Intent of regime on criteria & indicators of function, structure and composition Examples No active interventions Biodiversity protection, minimal use Harvest products Biomass, fibre, flowers, fruit and nuts Enhance or improve Rehydrate soils, control invasive species, reestablish a fire regime, seed hays Extirpate or remove Overgrazing, intensive cropping, pasture improvement, removal of fire regime, draining wetlands Reconstruct Revegetate, rehydrate soils, stabilize soil Source: Thackway 2017
  30. 30. Phillip Island- Past, present and future Chris Davey
  31. 31. Important dates • 1774 Norfolk Island discovered • 1788 Phillip Island names • 1793 Pigs released • 1820s Goats and Rabbits released • 1826 Substantial changes noted. Pigs died out sometime earlier • 1856 Arrival of Pitcairn Islanders • 1862 Island almost barren
  32. 32. Important dates • 1977 Rabbits and CSIRO • 1978 Start of Rabbit eradication • 1978 December, RAOU Congress • 1988 The last Rabbit • 2005 December, NIF&FS bird survey • 2015 December, COG bird survey
  33. 33. Original bird fauna of Phillip Island Seabirds Landbirds Kermadec Petrel (Rail)* (Pycroft’s Petrel)* (New Zealand Snipe)* Providence Petrel (Norfolk Island Wood Pigeon)* White-necked Petrel (Norfolk Island Ground Dove)* (White-faced Storm-Petrel)* (Norfolk Island Kaka)* Little Shearwater (Norfolk Island Green Parrot) Flesh-footed Shearwater (Norfolk Island Starling) Wedge-tailed Shearwater (Long-tailed Triller) Black Noddy (Grey Gerygone) Brown Noddy (Golden Whistler) Sooty Tern (Scarlet Robin) White Tern (Grey Fantail) Grey Ternlet (White-chested White-eye) Masked Booby Sacred Kingfisher Red-tailed Tropicbird () extinct on island, * caused directly by pigs
  34. 34. Bird surveys • 1978 RAOU survey, 10 years pre-rabbit eradication • 2005 NIF&FS survey, 17 years post-rabbit eradication • 2015 COG survey, 27 years post- rabbit eradication
  35. 35. 2015 COG Bird survey • Sixteen paths • Four teams of three • Three sites per path • Site 50 metre radius over 10 minutes • Each site surveyed by three observers
  36. 36. Survey comparisons-Seabirds Seabird 1978 2005 2015 Providence Petrel 0 1 0 Kermadec Petrel 0 2 0 White-necked Petrel 0 2 0 Black-winged Petrel 3 4 7 Wedge-tailed Shearwater 3 0 1 Little Shearwater 2 2 2 Red-tailed Tropicbird 1 4 7 Australasian Gannet 1 1 0 Masked Booby 6 5 7 Brown Noddy 0 3 2 Black Noddy 2 6 6 Grey Ternlet 5 4 3 White Tern 0 2 1 Sooty Tern 5 4 7
  37. 37. Survey comparisons- Landbirds Landbirds 1978 2005 2015 Mallard 0 1 0 White-faced Heron 0 0 1 Swamphen 0 1 7 Feral Pigeon 0 2 2 Shining Bronze-cuckoo 1 0 0 Sacred Kingfisher 0 3 6 Kestrel 1 1 1 Swallow 0 1 5 Silvereye 0 2 5 Starling 2 3 3 Blackbird 0 1 3 House Sparrow 1 2 4 Greenfinch 0 2 5
  38. 38. No. species of Seabirds and Landbirds 0 2 4 6 8 10 12 14 1978 2005 2015 Survey year Seabirds Landbirds
  39. 39. Australasian Gannet
  40. 40. Black-winged Petrel
  41. 41. Red-tailed Tropicbird
  42. 42. Kermadec Petrel
  43. 43. The transformation story in nutshell • Losses and gains – land bird species diversity – bird habitat – shelter and roosting sites – bird nesting sites – food sources
  44. 44. Conclusions • Phillip Island became a transformed landscape because of anthropogenic & natural drivers – these include – Social, economic and ecological • Degradation of bird habitat and diversity occurred because of deliberate and unintentional decisions – Land management regimes • Restoration of Phillip Island’s bird habitat and diversity of deliberate and unintentional decisions – policy and planning – management inventions – monitoring inputs and outcomes – reporting outcomes
  45. 45. Acknowledgements • Peter Coyne, David Freudenberger, Kevin Mills provided information and insights into the transformation of Phillip Island • Members of the Canberra Ornithologists Group and • Craig Doolan, Manager of Norfolk Island Park and Botanic Gardens Peter Coyne (2009). Incredible! : the amazing story of the birth and rebirth of a natural treasure Phillip Island, South Pacific http://www.petaurus.com/PI/
  46. 46. Thank you

×