Urban areas as native habitat

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Urban areas as native habitat
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Outline

• Why create native habitats in urban areas?
• Five principles to increase functioning native
  habitat biodiversity

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Why create urban habitats?

• Scientific biodiversity hotspots at
  environmental cross-roads, under-protected and
  vulnerable
• Social create sense of place (most people live
  in cities and have limited wild exposure)
• Available resources people and
• Its practical, do-able, often fits in with other
  uses and is more sustainable (resilient and
  cheaper in the medium term).

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Why not? were in NZ, its easy to increase
natives in cities especially mobile species
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How are cities different?

• Climate amplified
• People but no grazing

• Flattened topography
• High weed pressures
• High disturbance

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Natural Ultic soilsold, famous

• Teeming humus layers and shallow,
  nutrient-supplying topsoils,
• Impoverished fertility
• Structurally vulnerable clay sediment runoff
• Undisturbed no surface casting fauna low fire
  frequency

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City soils

• Increased runoff surface water flow less
  infiltration, less storage, removal of
  watercourses, subsurface water flows cut
• Stressed plants shallow rooting, less oxygen and
  water, warmer
• damaged soil biota, mowing removing leaves
  disrupts carbon cycling (N) elevated P
  (anti-myc), sometimes N

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Five principles

• Tread gently minimise impact isolation
• Bigger is often better logs, area
• Natives like natives - use native plants
• Structurally complex, tall, dense is best
• Plan for low maintenance connectivity
  minimise disturbance, connect water and organic
  cycles for resilient systems

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2. Tread gentlyA. avoid, B. nurture, C.
rehabilitate
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Bigger is often better

• Patch size (least edge)
• Canopy height
• Coarse wood

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Big patches minimise edge
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Big wood for insects.. food and hiding places
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Big (untreated) wood for animals
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Big wood for little plants epiphytes, refuges,
fungae
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Big wood for erosion control
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Big wood for erosion control
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Structurally complex tall denseRichard Toft
(Chch), Robin Gardner-Gee (Motuora)
1600
1400
1200
1000
Number of native beetles
800
600
400
200
0
Unmanaged A
Planted A
Pasture B
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Beetle assemblages in planted bush and unmanaged
bush similar
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Unmanaged bush 96 species
49
22
24
4
4
30
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Plan for low maintenance

• Let sleeping logs (and leaves) lie
• Weed removal at ground level ( herbicide)
• Natural water flows and connectivity minimise
  need for irrigation and drainage

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No dense, long-lived weedmat
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How to heal soil

• Loosen let air in
• Avoid traffic, especially when wet
• Maximise plant growth and cover (avoid direct
  rain drop contact erosion)
• Use organic mulches
• Connect leaves and invertebrates to humus and soil

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Removing litter and topsoil reduces growth soil
recovers slowly
100
4 year-old trees
15 year-old trees
80
60
Tree volume ( of control)
40
20
0
Control
Litter removed
Topsoil removed
Treatment
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Plants need water organic matter so connect
flows
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What about exotics?
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We have the colours
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We have toughness
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Principles

• Tread gently minimise impact isolation
• Bigger is better logs, area
• Natives like natives
• Structurally complex is best
• Plan for low maintenance connectivity (water
  and leaf litter)

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Fabulous free NZ resources

• www.doc.nz/regional-info/010Canterbury/005Publicat
  ions/
• Protecting-and-Restoring-Our-Natural-Heritage
• www.bush.org.nz/planterguide
• www.landcareresearch.co.nz
• Hewitt 2004 Soil Properties for plant growth