Urban areas as native habitat

1. Urban areas as native habitat

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

3. 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 $ • It’s practical, do-able, often fits in with other uses and is more sustainable (resilient and cheaper in the medium term).

4. Why not? – we’re in NZ, it’s easy to increase natives in cities… especially mobile species

5. How are cities different? • Climate amplified • People but no grazing • Flattened topography • High weed pressures • High disturbance

6. ‘Natural’ Ultic soils:old, famous • Teeming humus layers and shallow, nutrient-supplying topsoils, • Impoverished fertility • Structurally vulnerable; clay sediment runoff • Undisturbed: no surface casting fauna; low fire frequency

7. 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

9. 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

10. 2. Tread gentlyA. avoid, B. nurture, C. rehabilitate

11. Bigger is often better Patch size (least edge) Canopy height Coarse wood

12. Big patches – minimise edge

13. Big wood for insects.. food and hiding places

14. Big (untreated) wood for animals

15. Big wood for little plants – epiphytes, refuges, fungae

16. Big wood for erosion control

17. Big wood for erosion control

18. 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

19. Beetle assemblages in planted bush and unmanaged bush similar 20 Unmanaged bush 96 species 49 22 24 4 4 30

20. 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

21. No dense, long-lived weedmat

22. 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

23. 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 Topsoil removed Litter removed Control Treatment

24. Plants need water & organic matter… so connect flows

25. What about exotics?

26. We have the colours

27. We have toughness

28. 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)

29. Fabulous free NZ resources • www.doc.nz/regional-info/010Canterbury/005Publications/ • Protecting-and-Restoring-Our-Natural-Heritage • www.bush.org.nz/planterguide • www.landcareresearch.co.nz • Hewitt 2004 ‘Soil Properties for plant growth’