Protecting indigenous biodiversity in the eastern South Island rainshadow zone Susan Walker Lance McCaskill Memorial Lecture Forest & Bird North Canterbury Branch Annual General Meeting WEA, Christchurch 9 June 2010

Structure of my talk 1.South Island drylands: characteristics and challenges 2.Pre-settlement dryland ecology Radiations and endemism The rule and role of birds and reptiles All but fire-free 3. Humans and the transformation of ecosystems Post-settlement period Pastoral period 4. Where to from here? Four trends in drylands today The case for a return to woody dominance Retreating opportunities

Structure of my talk 1.South Island drylands: characteristics and challenges 2.Pre-settlement dryland ecology Radiations and endemism The rule and role of birds and reptiles All but fire-free 3. Humans and the transformation of ecosystems Post-settlement period Pastoral period 4. Where to from here? Four trends in drylands today The case for a return to woody dominance Retreating opportunities

New Zealand drylands East of main axial ranges Annual Penman Moisture Deficit >270 mm (monthly evaporation minus monthly rainfall, in mm, summed across 12 months) Area ~ 53,000 km 2 (20% of NZ)

ENVIRONMENT TYPES Southern and inland environments G: Inland southern South Island basins and valley floors H: Mackenzie Basin and Central Otago hillslopes Canterbury’s drylands Northern and coastal environments B. Dry hill country (characteristic of North Island drylands, more widespread there) D. Coastal Marlborough and Kaikoura Coast low relief alluvium & loess E: Marlborough and North Canterbury hillslopes F: Canterbury Plains, Banks Peninsula and Otago inland basin alluvium and loess

South Island dryland ecosystems Characteristics Remaining native ecosystems and species are some of New Zealand’s most transformed, least protected and most threatened

Threat classification for land environments CategoryCategory CriteriaCategory Name 1<10% indigenous cover leftAcutely Threatened 210–20% leftChronically Threatened 320–30% leftAt Risk 4>30% left and <10% protected Critically Underprotected 5>30% left and 10–20% protected Underprotected 6>30% left and >20% protected Less Reduced and Better Protected “THREATENED ENVIRONMENTS”

Canterbury dryland environments THREATENED ENVIRONMENTS

Canterbury Region (~2005) Distribution of threatened plants % LOSS of indigenous cover since European settlement, by elevation zone % LOSS of indigenous cover in elevation zone No. of Acutely and Chronically Threatened plants to 400m400 to 800m800 to 1200m 1200 to 1600m >1600 m LowlandMontaneSubalpine & Alpine Canterbury’s 103 Acutely and Chronically Threatened plants (2005 threat classification categories)

South Island dryland ecosystems Characteristics Remaining native ecosystems and species are some of New Zealand’s most transformed, least protected and most threatened Ecosystems are unstable (not at equilibrium) and much invaded

South Island dryland ecosystems Characteristics Remaining native ecosystems and species are some of New Zealand’s most transformed, least protected and most threatened Ecosystems are unstable (not at equilibrium) and much invaded Major conservation challenges Extremely low awareness of dryland biodiversity and its protection needs (community and agencies) Limited knowledge, experience and science to support management for biodiversity protection

Kowhai Bush, Kaikoura Kanuka & mixed broadleaved forest and shrubland, with scattered podocarps Some of Canterbury’s dryland communities

Rakaia Island communities Kanuka forest, kowhai remnants, dry shrubland

Riparian kowhai/lowland ribbonwood remnants, South Canterbury

Hector’s tree daisy Olearia hectori Fierce lancewood Pseudopanax ferox South Canterbury shrubland and forest remnants

Limestone communities, North Canterbury

Limestone communities, South Canterbury Gentianella calcis subsp. taiko

Mcleans Island grasslands

Birdlings Flat/ Lake Forsyth shrublands

South Branch Hurunui valley floors and gorge

Ashburton Basin floor grasslands, shrublands and wetlands

Mackenzie Basin foothills

Mackenzie Basin floors

23% of Canterbury’s ‘Threatened’ and ‘At Risk’ plants, and 11% of Canterbury’s ‘Data Deficient’ plants Mackenzie Basin floor

33 species Grassland and shrublands 31 species Wetlands and their margins and turfs Threatened and At Risk flora

Diverse, endemic, threatened invertebrates Moth, grasshopper and beetle faunas especially rich & distinctive Mackenzie Basin floor

ENVIRONMENT TYPES Southern and inland environments G: Inland southern South Island basins and valley floors H: Mackenzie Basin and Central Otago hillslopes Canterbury’s drylands

Remaining opportunities for dryland biodiversity conservation Dryland Types ABCDEFGH Dryland type Area (km 2 ) Woody Grassy Intensively developed mixed native-exotic

Structure of my talk 1.South Island drylands: characteristics and challenges 2.Pre-settlement dryland ecology Radiations and endemism The rule and role of birds and reptiles All but fire-free 3. Humans and the transformation of ecosystems Post-settlement period Pastoral period 4. Where to from here? Four trends in drylands today The case for a return to woody dominance Retreating opportunities

Radiations and endemism Pleistocene Likely drivers Absence of forest New habitats & vacant niches Isolation ‘Permanent’ barriers (mountains, geological islands) Temporary barriers i.e. glaciations

Dryland radiations & endemism Native brooms Brachaspis grasshoppers “The species exhibit remarkable diversity, from trees to prostrate forms a few centimetres high” (Bevan Weir, NZ Rhizobia)

‘Non- diadromous’ galaxiid fishes

Lowland longjaw Upland longjaw Bignose galaxiid Pencil galaxiids of the Mackenzie Basin

On land, birds and lizards ruled “No where else had birds evolved to become the ecological equivalent of giraffes, kangaroos, sheep, striped possums, long- beaked echidnas, and tigers ” (Tim Flannery, The Future Eaters)

Mega-bird herbivory Diversity of moa sizes and feeding habits

Grazers Finschs duck Takahe Teal

Browsers

Tree munchers Pachyornis Olearia gizzard twigs Gizzard stones

Arboreal defoliators

Frugivores and seed dispersers

Lizards too!

Pollinators

Understorey scratchers and bashers

Turf- maintenance crews

Turfs Bird legacies in the flora

Unappetising (dead) Armoured Inaccessible Inpenetrable Bird defense mechanisms?

fleshy-fruited shrubs

and their imitators!

Big suite of endemic (non grass) herbs (many now threatened) No N-fixing herbs!

Pre-settlement ecosystems All but fire-free “... a bioclimatic zone, possibly unique on a global scale, which was dry, drought-prone but free of all but infrequent fire. The anomalous result is that New Zealand possesses a suite of shrubs and trees tolerant of dry, droughty conditions but highly sensitive to fire and slow to recover in its wake” (McGlone 2001, NZJ Ecol)

Weeping matipo, Myrsine divaricata Mountain wineberry, Aristotelia fruticosa Tough and slow woody plants

No weedy northern hemisphere conifers to march across the landscape

Tough and slow grasses Slow nutrient acquisition Slow nutrient use Slow growth (Craine & Lee 2004, Oecologia) North America New Zealand Australia South Africa Tough (high tissue density) leaves and roots Low in nitrogen Few nutritious, fast- growing sward-forming grasses

Conservative birds and lizards Slow growth rates Long time to maturity Low fecundity Long-lived

North Island Brown Kiwi: slowest growth rate of any bird anywhere! (McLennan et al. 2007) The slowest bird on earth

Structure of my talk 1.South Island drylands: characteristics and challenges 2.Pre-settlement dryland ecology Radiations and endemism The rule and role of birds and reptiles All but fire-free 3. Humans and the transformation of ecosystems Post-settlement period – creation of the grasslands Pastoral period – transformation of the grasslands 4. Where to from here? Four trends in drylands today The case for a return to woody dominance Retreating opportunities

The arrival of humans Clarks Junction fossil pollen trends through the Holocene (from McGlone 2001, NZ Jecol) Beech Grasses Time, warming >> Podocarps (bird dispersed) Shrubs and small trees (wind, then bird dispersed)

Eastern South Island fire history Frequency of dates from subfossil charcoals, South Island (summed in 100-year intervals): Years before present (BP) References: McGlone (2001) NZJ Ecol; Rogers, Walker & Lee (2005) Science for Conservation Frequency (n = 242) Time to to to to to to to to to to to to to to to to to to to to to to to to to to 10400

Enormous post- settlement increase in SI dryland grass pollen percentages Pre-settlement Post-settlement 25-75% 15-25% 10-15% 5-10% 0-5% Grass pollen %s in cores Rogers, Walker & Lee 2005 Science for Conservation

Grass pollen percentages (same data) Pre-settlement Post-settlement Percentage of pollen sum (%) Otago sitesCanterbury sites Marlborough Rogers, Walker & Lee Science for Conservation

Creation of the grasslands

A few tussock species spread far and wide Those with most rapid growth rates! enabled by ‘mast’ seeding: periodic massive seed production longish (>decades?) fire return times Midribbed snow tussock Red tussock Narrow- leaved snow tussock Slim snow tussock Lloyd, Lee & Wilson (2002) Conservation Biology

Gitay, Lee, Allen & Wilson (1992) Journal of Environmental Management Recovery following burning Chionochloa rigida 13 Otago sites with known fire history, Measurements taken in 1989 at 1 to 26 years since burning TIME SINCE LAST BURNING>>> Some characteristics have not fully recovered in 30 years New Zealand grasses recover slowly from disturbance

Payton, Lee, Dolby & Mark (1986) NZJ Botany UNBURNED New Zealand grasses recover slowly from disturbance

Bracken (for the first time) and scrub on steeper land Different stages of recovery from infrequent Maori fires Abundance of palatable plants Herbivore vacuum

Creation of the grasslands: summary A one-off ! Unique combination of circumstances Infrequent (>decades?) but massive fires: a radical new disturbance –A few species were pre-adapted and did well (most didn’t) No weeds 500 years of (virtually) no herbivores

Transformation of the grasslands Began with European settlement Late 19th century over-enthusiasm “exploitative pastoralism” More frequent burning High stocking rates New plants The period of pastoralism O’Connor (1986) TGML Journal

Transformation of the grasslands Changes in grassland structure and composition continue today (perhaps especially in short tussock grasslands) e.g. Connor 1964; O’Connor 1982; Treskonova 1991; Rose et al. 1995; Hunter & Scott 1997; Jensen et al. 1997; Walker & Lee 2000; 2002, Duncan et al Major transitions Tall tussock grasslands to short tussock grasslands Short tussock grasslands to degraded herbfields with much bare ground Stature and density of the tussocks reduced Decreased diversity and abundance of native species Increase in non-native plants No evidence of equilibrium with pastoral management! The period of pastoralism

Three synergies in the transformation of the dryland grasslands 1. Burning + grazing 2. Domestic + feral grazers 3. Reduced native dominance + exotic invasion

Grazing-only effects: experimental evidence Chionochloa rigida (narrow-leaved snow tussock) Carrick Range, Otago Grazing affects tussock regeneration: a)reduced overall recruitment b)reduced proportions small seedlings c)reduced seedling height d)reduced proportion of seedlings distant from plant small tussocks large tussocks “LIGHT” grazing (control) “HEAVY” grazing Immature tussocks Lee, Fenner & Duncan (1993) NZJ Botany

Synergy 1. Burning + grazing synergy Kevin O’Connor’s depiction Burning alone Burning + constant grazing Burning + increasing grazing O’Connor (1982) NZJ Ecology

Burning + grazing synergy: experimental evidence Mark (1965) NZJ Botany Mean number of new tillers emerged in the 2 years following spring and autumn fires Spring Autumn Burned onlyBurned and then regrowth clipped

Synergy 2. Domestic + feral grazers

Survey evidence 957 quadrats in 47 alluvial systems Walker & Lee (2000; 2002; 2003) Synergy 3: Reduced native dominance + exotic invasion

Number ( n ) of exotic plant species >> Native dominance Average native dominance score (for quadrats with n exotic species) Fewer exotic species where structural dominance of native species is greater

Main invaders are perennial forbs and grasses Relatively few woody invaders NATIVE EXOTIC TOTAL FLORA ANNUALS Dicot (non-grass!) herbs 4 12 Grasses 2 6 N-FIXERS Herbaceous 0 7 Woody 5 2 PERENNIALS Dicot (non-grass!) herbs116 34* Grasses 28 14* Sedges Orchids Trees n* = significantly more, n - = significantly fewer than expected (P<0.05 by chi-squared)

Major ecological shifts (post-settlement and pastoral periods) Slow bird herbivore fauna, to boom-bust mammal fauna Slow woody/shrubby communities with numerous cryptic non-grass herbs, to new open grasslands invaded by ‘fast’ light-demanding exotic plants –sward-forming grasses & N-fixing herbs, –northern hemisphere postglacial tree “superweeds”

Structure of my talk 1.South Island drylands: characteristics and challenges 2.Pre-settlement dryland ecology Radiations and endemism The rule and role of birds and reptiles All but fire-free Herbs and wood 3. Humans and the transformation of ecosystems Post-settlement period Pastoral period 4. Where to from here? Four trends in drylands today The case for a return to woody dominance Retreating opportunities

Trends in dryland landscapes today Intensive agriculture: complete transformation Continued pastoral use: native grassland dominance reduced, consolidation of exotic species (especially mammal grazing-adapted light-demanding forbs and grasses) Reduced fire-frequency with relict shrubs: expansion of mixed unpalatable native-exotic woody vegetation Grazing and fire reduced: race between residual native species and new exotic species

Intensive agriculture

Trends in dryland landscapes today Intensive agriculture: complete transformation Continued pastoral use: native grassland dominance reduced, consolidation of exotic species (especially mammal grazing-adapted light-demanding forbs and grasses) Reduced fire-frequency with relict shrubs: expansion of mixed unpalatable native-exotic woody vegetation Grazing and fire reduced: race between residual native species and new exotic species

Trends in dryland landscapes today Intensive agriculture: complete transformation Continued pastoral use: native grassland dominance reduced, consolidation of exotic species (especially mammal grazing-adapted light-demanding forbs and grasses) Reduced fire-frequency with relict shrubs: expansion of mixed unpalatable native-exotic woody vegetation Grazing and fire reduced: race between residual native species and new exotic species

Expansion of mixed, native-exotic woody vegetation

Trends in dryland landscapes today Intensive agriculture: complete transformation Continued pastoral use: native grassland dominance reduced, consolidation of exotic species (especially mammal grazing-adapted light-demanding forbs and grasses) Reduced fire-frequency with relict shrubs: expansion of mixed unpalatable native-exotic woody vegetation Grazing and fire reduced: race between residual native species and new exotic species

Tekapo Scientific Reserve, Mackenzie Basin 1992 to 2009 Monitoring Plots

Flat Top Hill Conservation Area, Central Otago (retired & reserved 1993) 2009

Pragmatic dryland conservation goals? Return to past states is impractical Today’s grasslands are unstable, and difficult to maintain as grasslands “Ecological Integrity” (Lee et al. 2005) Species occupancy –“native species that could and should be present, are present” Native dominance –“native species dominate structure, composition and function” Environmental representation –“across a full range of environments”

The case for a return to woody dominance in drylands Former widespread ecosystems were slow, woody, fire-free –wood overstorey, non-grass herb understorey Major exotic plant invaders and competitors are light- demanding Focus of 8-year FRST-funded ‘dryland’ research programme Facilitating transitions to native woody communities, understanding associated biodiversity benefits/changes, building understanding and awareness

Retreating opportunities for dryland protection Land use intensification Land reform (Tenure Review) ABCDEFGH Dryland type Area (km 2 ) Wood Grass Intensively developed

DOC recommended for protection as public land More developable land More threatened biodiversity Threat categories from the Threatened Environment Classification (Walker et al. 2007) Data source: Department of Conservation, unpublished data for 69 of the 90 leases reviewed Recommendations and achievements for significant inherent values in Tenure Review to 2007 LINZ achieved protection % of identified significant inherent values <10% indigenous cover left 10–20% left20–30% left>30% left and <10% protected >30% left and 10–20% protected >30% left and >20% protected

Leases retain more indigenous cover than private land in the same environments % indigenous cover remaining in environments Indigenous cover retained (%) Private land Leases

A: 1990B: 2009 Converted by 1990 Converted between 1990 and 2009 Mackenzie Basin floor

B: 2009 Converted by 1990 Converted between 1990 and 2009 Grays Hills Sawdon Simons Pass Glenmore Mackenzie Basin floor leases

Conclusion Restoring dryland ecological integrity through woody dominance may be possible BUT only if the habitat remains

Thanks! Ideas, information and photos Nick Head, Peter Johnson, Jamie Wood, Marieke Lettink, Geoff Rogers, Di Lucas, Bill Lee, Kelvin Lloyd, Ines Stager, Emily Weeks Paul Martinson for his extinct bird portaits from Tennyson & Martinson, Extinct Birds of New Zealand, Te Papa Press (available from Manaaki Whenua Press)