Tenure review, land management, & protecting the biodiversity of the Mackenzie Basin floor Susan...

Tenure review, land management, & protecting the biodiversity of the Mackenzie Basin floor

Susan WalkerTalk prepared for the Canterbury Aoraki Conservation BoardCanterbury Conservancy Office, 195 Hereford Street, ChristchurchThursday 2 September 2010

Thanks!

Information, data, and photographsRichard Allibone, David Barrell, Warren Chinn, Joy Comrie, Marcus Davis, Nick Head, Bill Lee, Di Lucas, Ian Lynn, Colin Meurk, Geoff Rogers, James Shepherd, Ines Stager, Anne

Steven, Marta Treskonova, Emily Weeks, Jamie Wood

‘Above Hawkes Bay’ (www.abovehawkesbay.com) and Geoff Rogers for oblique aerial photographs

Parts of this talk

Part 1. Tenure review: a recapMy past research and newer data

Part 2. The Mackenzie Basin floorEnvironment, evolution and native biodiversity traits

Changes and threats

Part 3. Biodiversity protection and managementKey ecological questions for protection proposals

Changes under conservation management

Part 1. Tenure review: a recap

Walker, Price & Stephens 20081. Assessed patterns of protection or privatisation to May

2005

2. Predicted future protection and clearance (likelihood of loss)

3. Data sources 1. Land environments2. Land cover (assumed binary indigenous/non-

indigenous status for cover classes)

4. Frame: a continuous index of risk to biodiversity, based on the same principles as threatened environments

39% protected (DOC)

55% privatis

ed without

a covenan

t

May 200566 leases since 1992328,350 ha affected

5% privatised with

a covenan

t

1% retained

as Special Lease

39% protected (DOC)

55% privatis

ed without

a covenan

t

May 200566 leases since 1992328,350 ha affected

5% privatised with

a covenan

t

1% retained

as Special Lease

All land allocated in Tenure Review

Threat classification for land environmentsCategory Category Criteria Category Name

1 <10% indigenous cover left

Acutely Threatened

2 10–20% left Chronically Threatened

3 20–30% left At 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 ENVIRONMENT

S”

Threat classification for land environmentsCategory Category Criteria Category Name

1 <10% indigenous cover left

Acutely Threatened

2 10–20% left Chronically Threatened

3 20–30% left At 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

More developable land, more threatened and less well-protected biodiversity

Assumptions

Risk to indigenous biodiversity is highest in land environments where habitats for native species

• have been much reduced in the past and /or

• are poorly protected today

Categorical spatial model of risk to biodiversity

(Threatened Environment Classification)

Original pastoral leases

Richmond Pastoral Lease

Lake

Teka

po

PRIVATISED

LEGALLY PROTECT

ED

Lake

Teka

po

Richmond Pastoral Lease

Haw

kdun

Range

Upper Manuherikia

Valley

Braeside Pastoral Lease

PRIVATISED

LEGALLY PROTECTE

D

Upper Manuherikia

Valley

Haw

kdun

Range

Braeside Pastoral Lease

0

20

40

60

80

100

0 20 40 60 80 100

High probability of

protection

Lowprobability of

protection%

of

ind

igen

ou

s c

over

pro

tecte

d

as p

ub

lic lan

d

% indigenous cover remaining in environments

High Risk << >> Low Risk

actual

modeled

From: Walker, Price & Stephens 2008

% p

rivati

sati

on

loss

% indigenous cover remaining in environments

High Risk << >> Low Risk

0

20

40

60

80

100

0 20 40 60 80 1000

20

40

60

80

100

0-20%20-40%

40-60%

60-80%

80-100%

Leases have retained more indigenous cover than private land

Private land

Pastoral

leases

% p

ost-

pri

vati

sati

on

cle

ara

nce

of

rem

ain

ing

in

dig

en

ou

s

cover

% indigenous cover remaining in environments

High Risk << >> Low Risk

0

20

40

60

80

100

0 20 40 60 80 100

0

20

40

60

80

100

0 20 40 60 80 100

other

Average % of remaining indigenous cover predicted to be cleared following

privatisation

Rogers & Reynolds (DOC unpublished data)

Assessed patterns of protection or privatisation to September 2007 (i.e. 2 more years)

39% protected (DOC)

55% privatis

ed without

a covenan

t

May 200566 leases since 1992328,350 ha affected

5% privatised with

a covenan

t

1% retained

as Special Lease

39% protected (DOC)

55% privatis

ed without

a covenan

t

May 200566 leases since 1992328,350 ha affected

5% privatised with

a covenan

t

1% retained

as Special Lease

All land allocated in Tenure Review

Gra

zing

(8%

)

43% protected (DOC)

50% privatis

ed without

a covenan

t

September 200790 leases since 1992490,500 ha affected

6% privatised with

a covenan

t

0

20

40

60

80

100

0 20 40 60 80 100

High probability of

protection

Lowprobability of

protection

% indigenous cover remaining in environments

High Risk << >> Low Risk

actual

modeled(prediction

)

From: Walker, Price & Stephens 2008

% o

f in

dig

en

ou

s c

over

pro

tecte

d

as p

ub

lic lan

d

0

20

40

60

80

100

0 20 40 60 80 100

High probability of

protection

Lowprobability of

protection

% indigenous cover remaining in environments

High Risk << >> Low Risk

Predicted based on(66 leases

to May 2005)

Actual (90 leases to

September 2007)

% o

f in

dig

en

ou

s c

over

pro

tecte

d

as p

ub

lic lan

d

0

10

20

30

40

50

60

70

80

90

100DOC recommended for protection as public land

More developable landMore 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 1992-2007

Recommendations and achievements for significant inherent values in Tenure Review to Sept. 2007

LINZ achieved protection as public land

% o

f id

en

tifi

ed

sig

nifi

can

t in

here

nt

valu

es

<10% indigenous cover left

10–20% left 20–30% left >30% left and <10%

protected

>30% left and 10–20%

protected

>30% left and >20%

protected

0

20

40

60

80

100

0 20 40 60 80 100

High probability of

protection

Lowprobability of

protection

% indigenous cover remaining in environments

High Risk << >> Low Risk

modeled(to May 2005)

% protectio

n including private

covenants%

of

ind

igen

ou

s c

over

pro

tecte

d

as p

ub

lic lan

d

Part 2. The Mackenzie Basin floorEnvironment, evolution and native biodiversity traits

Changes and threats, old and new

The Mackenzie Basin floor

'Foothills' environments (Lenz Level I E)

(mainly moriane landforms)

'Plains' environments (Lenz Level I N)

(much reworked outwash)

Nationally distinctive physical characteristics1) Naturally high-stress environments (temperature, drought

& nutrients)

Extremes of cold and drought, and shallow, porous, nutrient-poor soils

2) (Almost) wholly glacially derived landforms

The Mackenzie Basin Physical characteristicsNaturally stressful environments

Extremes of cold, drought, shallow nutrient-poor soils

Nationally distinctive

Moraine

Tarns and ephemeral wetlands

(kettleholes)

Braided riverbeds & floodplains

Inland outwash surfaces and sand dunes

Distinctive evolutionary drivers

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)

Beak and claw - browsers, grazers, seed dispersers, understorey scratchers, pollinators….

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)

Distinctive evolutionary drivers

Conservative animals

• Slow growth rates • Long time to maturity• Low fecundity• Long-lived

Conservative plants

Tough, cryptic and slowadapted to

low resource availability, infrequent defoliation, and bird herbivory

Unappetising (dead)

Armoured

Inaccessible

Inpenetrable

Bird legacies in the flora?

Big suite of small, endemic, cryptic, non grass herbs

(many now threatened)

No N-fixing herbs!

Weeping matipo, Myrsine divaricata Mountain wineberry, Aristotelia fruticosa

Tough and slow woody plants

Adaptations to Low resource availability

Infrequent defoliation

No weedy northern hemisphere conifers to march across the landscape

Tough and slow grassesNZ grasses in general

•Slow nutrient acquisition •Slow nutrient use

•Slow growth•Tough (high tissue density)

leaves and roots•Low in nitrogen(Craine & Lee 2004, Oecologia)

North America

New Zealand

Australia

South Africa

The ecological opposites of fast-growing, sward-forming pasture

grasses

Tall tussock research shows:•Unusually low root:shoot ratios• Small below-ground nutrient

reserves•Slow replenishment of nutrient

reserves after defoliation(Williams 1977, Meurk 1978, Payton et al. 1986, Mark

1994)

Creation of the grasslands

Clarks Junction fossil pollen trends through the Holocene (from McGlone 2001, NZ Jecol)

Beech

Grasses

Tim

e, w

arm

ing

>>

Podocarps(bird

dispersed)

Shrubs and small trees(wind, then bird dispersed)

Creation of the grasslandsconsolidation with Polynesian fire frequencies (> decades?)

Began with European settlement

Late 19th century over-enthusiasm

“exploitative pastoralism”•More frequent burning•High stocking rates•New plants

Transformation of the grasslands

O’Connor (1986) TGML Journal

Ongoing under pastoral grazing (Treskonova (1991) NZ Journal of Ecology)

Tall tussock grasslands to short tussock grasslands

then

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 dominance of non-native plants, especially

• Exotic sward-forming grasses,

• N-fixing herbs,

• Grazing-resistant flatweeds (esp. mouse-ear hawkweed).

Transformation of the grasslands

Major ecological shifts (post-settlement and pastoral periods)

Slow bird herbivore fauna, toboom-bust mammal fauna

Slow, stress-tolerant, fire-free, woody/shrubby vegetation with numerous cryptic non-grass herbs, tograsslands, depleted by grazing and invaded by ‘fast’ light-demanding exotic plants adapted to mammalian grazing and for rapid growth and spread– sward-forming grasses, N-fixing and resistant herbs– northern hemisphere postglacial tree “superweeds”

Recent trend:IntensificationNew open semi-natural

grasslands invaded by ‘fast’ light-demanding exotic plants

towholly exotic pasturesthrough– Oversowing and

topdressing– Irrigation– Soil cultivation & cropping

1990 2009

Converted by 1990 Converted by 1990Converted between 1990 and 2009

Extent of complete conversion

2009

Converted by 1990Converted between 1990 and 2009

Conversion 1990-2009

Oversowing & topdressing

(41%)

Soil cultivation

and/or irrigation

(50%)

ForestryUrban/ Infrastructure

Flora includes:

23% of Canterbury’s ‘Threatened’ and ‘At Risk’ plants,

and 11% of Canterbury’s ‘Data Deficient’plants

Remaining biodiversity of the Basin floor

Threatened and At Risk flora

33 species Grassland and shrublands

31 species Wetlands and their margins and turfs

Diverse, endemic, threatened

Moth, grasshopper and beetle faunas especially rich & distinctive

Invertebrates

Birds

Lowland longjaw

Upland longjaw

Bignose galaxiid

Pencil galaxiids of

the Mackenzie

Basin

Mackenzie Basin floor

2009

Converted by 1990Converted between 1990 and 2009

Proposed 2010 on…

2009 Upper Waitaki Hearing: Irrigation application areas

Southern Mackenzie Basin floor

Wairepo kettleholes – now an island

Ohau Downs outwash plain proposed for

irrigation

B: 2009

Converted by 1990

Converted between 1990 and 2009

Grays Hills

Sawdon

SimonsPass

Glenmore

Foremost remaining

opportunity

Pastoral leases in the north of the Basin

Part 3. Biodiversity protection and management

Key ecological questions for proposals

1. Will the areas that are significant be protected, and will they be large enough?

2. Is this really protection from key threats?

Will grazing be removed or reduced to enable native species persistence and recovery?

Will harmful activities be prohibited? e.g.•Oversowing and topdressing•Increased stocking rates/new stock types •Subdivision, tracking, erection of structures•Exotic tree planting•‘Scrub’ spraying

Ongoing changes (Treskonova (1991) NZ Journal of Ecology)

Tall tussock grasslands to short tussock grasslands

then

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 dominance of non-native plants, especially

• Exotic sward-forming grasses,

• N-fixing herbs,

• Grazing-resistant flatweeds (esp. mouse-ear hawkweed)

What’s the problem with continued grazing?

No evidence of equilibrium with pastoral grazinge.g. Connor 1964; O’Connor 1982; Treskonova 1991; Rose et al. 1995; Hunter & Scott 1997; Jensen et al. 1997; Walker et al. 2003; Walker & Lee 2000; 2002, Duncan et al. 2001, Meurk et al. 2002.

0

1

2

3

4

5

6

Mackenzie Basin Grazing Trial fescue tussock plots (Meurk et al. 2002)

Ben Ohau MaryburnSawdon Simons Hill

Average fescue tussock cover (%), grazed ‘control’

OUTWASH

Avera

ge %

cover 1990

2000

MORAINE

Nb. Geometric mean used here because of data are not normally distributed

MechanismsDirect

Plant foliage and seedlings are eaten, favouring

•low-growing, less palatable, more toxic/prickly plants

•those able to recover more rapidly from defoliation

Palatable plants progressively restricted or eliminated

small tussocks <- -> large tussocks small tussocks <- -> large tussocks

“LIGHT” grazing(control)

“HEAVY” grazing

Fate of snow tussock seedlingsLee, Fenner & Duncan (1993) NZJ Botany

(Szaro 1989, Huntly 1991, Fleischner 1994, Frank et al. 1998; 2002)

MechanismsDirect cont…

Selective grazing prevents regeneration & successional development

Heavy browse at favoured sites local elimination

Nutrients shifted and redeposited unevenly

Reduced vegetation vigour with gradual nutrient depletion (widespread)

Locally nutrient-enriched weed establishment sites (local)

MechanismsDirect cont…

Trampling

•creates disturbed bare ground

•destroys sensitive habitats

e.g. kettlehole turf margin, streams and flushes

FRST-funded research findings on ephemeral

wetlands and their turfs may be of interest

MechanismsDirect cont…

Grazing and trampling degrades/removes feeding and spawning habitats of native freshwater fish

Oversowing and topdressing

Reduces nutrient stress- exotic pasture grasses, legumes or other crops as seed, - the additional nutrients they require to thrive to the soil

Mackenzie District Plan indigenous vegetation clearance rules

Exemptions …This rule shall not apply to:Any [short tussock grassland/indigenous cushion or mat vegetation] where the site has been oversown, and topdressed at least three times in the last 10 years prior to new clearance so that the inter-tussock vegetation is dominated by clovers and/or exotic grasses

Oversowing and topdressing stripes at

Ohau Downs

Whole-of-government purchased SPOT-5 image 2007/08

Kettlehole tarns and ephemeral wetlands

Lake Ohau

Are the Basin’s modified grasslands resilient?

Tekapo Scientific Reserve, Mackenzie Basin 1992 to 2009

Outwash terrace (3)

Moraine fan (2)

Moraine (3)

Tekapo Scientific Reserve sampling plots1992 to 2009: significant changes

Thanks to Marta Treskonova & DOC for unpublished data

0

1

2

3

4

5

6

Mackenzie Basin Grazing Trial fescue tussock plots (Meurk et al. 2002)

Ben Ohau MaryburnSawdon Simons Hill

Average fescue tussock cover (%), grazed ‘control’

OUTWASH

Avera

ge %

cover 1990

2000

MORAINE

Nb. Geometric mean used here because of data are not normally distributed

Tekapo Scientific Reserve, Mackenzie Basin 1992 to 2009

Monitoring Plot 4: Outwash terrace

1992 2009

Tekapo Scientific Reserve sampling plots1992 to 2009: significant changes

Thanks to Marta Treskonova & DOC for unpublished data

Tekapo Scientific Reserve, Mackenzie Basin 1992 to 2009

Moraine October 2009

Tekapo Scientific Reserve, Mackenzie Basin 1992 to 2009

Sampling area = 0.5% of plot area

20 m

One of eight,50 × 50 cm

permanently marked quadrats

Tekapo Scientific Reserve sampling plots1992 to 2009: significant changes

Thanks to Marta Treskonova & DOC for unpublished data

Tekapo Scientific Reserve, Mackenzie Basin 1992 to 2009

Monitoring Plot 3: Moraine Fan

That’s all!

Happy to answer questions…