Navigating New Zealand's Dryland Biodiversity Crisis: Past, Present, and Future Strategies

1. New Zealand’s dryland biodiversity situation: How we got there and how we might go forward Grant Norbury Susan Walker Landcare Research Presentation to the Canterbury Biodiversity Steering Group, Ashburton 31 July 2009.

2. What are drylands? 19% New Zealand’s land area 53,000 km2

3. Outline • Current state of biodiversity • Pressures • Science-driven restoration • Community-driven protection and restoration

4. 83% cleared (cf. 44% nationally) 3% protected (cf. 38% nationally) ~50% NZ’s threatened flora

5. Drylands: • Contain some of the most transformed, least protected and most threatened native ecosystems and species in NZ • Unstable, seral, rapidly changing, invaded

6. Protection and restoration are limited by: • Poor knowledge, experience and science to support biodiversity managers • Poor agency and community awareness of dryland biodiversity and its protection needs

7. Land Environments of NZ • Waitaki, Hurunui, Selwyn, Mackenzie and Ashburton districts in top 11 of all territorial authorities for environmental and ecological diversity • Canterbury therefore contributes disproportionately and significantly to the full range of habitats and ecosystems present in NZ

8. LENZ Canterbury % Indigenouscover left % Protected + Threatened Environment Classification + =

9. The slippery slope Proportion of species remaining 0 0.2 0.4 0.6 0.8 1.0 Proportion habitat area remaining

10. Canterbury habitats - habitat loss to 2001/02 >1200 m 800-1200 m 400-800 m (37% remaining) Proportion of species remaining < 400 m(8% remaining) 0 0.2 0.4 0.6 0.8 1.0 Proportion habitat area remaining

11. Proportion of NZThreatened plants (2005) (Acutely and Chronically Threatened) Canterbury(47%)103 species Nationally threatened plants in Canterbury Proportion of NZ land area Canterbury

12. Ecological pressures • Kiore (1150 yr bp) • Burning (800 yr bp) • Burning and livestock grazing (150 yr bp) • Rabbits (150 yr bp) • Ferrets, stoats, weasels, (cats) (130 yr bp) • Exotic pastures and fertiliser (130 yr bp) • Hares, hedgehogs, mice, rats, possums, goats, magpies • Broom, briar, gorse • Cropping, viticulture, horticulture, dairying, forestry • Housing subdivisions

13. Rapid, ongoing habitat loss • Pastoral farming changes • Smaller upland blocks • Intensive developments

14. Mackenzie Basin

15. Use of spray (and fire) to clear ‘scrub’

16. Discretionary consents On pastoral leases: increasing number of discretionary consents granted to clear, spray, increase stock numbers etc

17. Invading weeds

18. Pests : Feral grazers and predators

19. Palatable & fire sensitive species (and their fauna) long gone Now relicts Olearia hectorii Matukituki Kowhai Little Valley, near Alexandra Hebe cupressoides Tekapo military camp Muehlenbeckia astonii on Kaitorete Spit Cabbage tree, Canterbury Plains

20. Seral or secondary woody communities that are expanding Upper Clutha (Central Otago) Molesworth (Marlborough) Cloudy Range (Central Otago) Esk terraces (Canterbury) Remaining natives are a spiny or toxic subset of formerly rich woody flora

21. Dryands also contain a big suite of endemic herbs (many are threatened)

22. ...and a unique, highly endangered fauna What factors are driving species to extinction?

23. Current state of dryland biodiversity • Large variation from upland to lowland • Those indigenous habitats that are retained and protected are “non representative” • Remaining lowlands are much reduced, highly modified and poorly protected • High numbers of threatened plants, particularlyin lowland and montane zones • Woody vegetation in flux: some winners, some losers

24. Overview of research into sustaining and restoring dryland biodiversity

25. Research aims • Build expertise to enhance natural woody successions • Build knowledge of dryland ecological patterns and processes • Work with agencies, communities and private landowners to improve understanding and protection • Total of 8 years’ funding, 4 to go...

26. Program strategy Succession to native woody communities Strand 1 Strand 3 Strand 2 Biodiversity of dryland woody communities Community and agency awareness Technical know-how to achieve it Scientific mandate and vision Community mandate

27. Aligned work on pests Pest–Pest interactions Impacts on some dryland fauna

28. Strand 1 Succession to native woody communities • What limits native woody succession? • What practical, broad scale solutionscan be developed to overcome these?

29. PLOT & POINT locations in drylands (n = 9935) POLYGONS in drylands (n = 1148) (some not digitised) • Gather known data on woody species distributions • Model distributions with respect to environment • Identify potential succession pathways • Identify best native woody species for trials at different sites Distributions Database

30. Marlborough/North Canterbury Ranked probability of occurrence of woody species Species-poor to species-rich communities

31. Gather existing trait data for dryland woody species • Combine with Distribution Database to • Identify spatial pattern of traits syndromes • Identify whether (and if so what) traits predict successful secondary succession and where Traits Database 300 species (200 native, 100 exotic) 20 traits

32. Dispersal Sward density Climate Light Germination Soil water Wavail, BNPP, ANPP, Litter Soils Growth Decomposition Navail Shrub cover BNPP, ANPP, Litter Mortality Herbivore pressure In progress…..modified from Peters 2002 Ecol. Model. 152:5-32 Limitations to establishment • Understand limitations to woody establishment • Test low intensity management tools • Work towards general model

33. 7 soils pallic volcanic lime brown / loess semi-aridschist How do soil characteristics interact with moisture to affect growth in woody seedlings?

34. Role of competition and herbivory in woody seedling establishmentBendigo, Central Otago • +/- water • +/- herbivory • +/- competition (herbicide + hand weeding) • 4 species

35. Conclusions so far…Herbivory always bad, but competition has net benefit in some placesWater (at least last year) made little difference

36. How does grass sward density affect establishment of woody seedlings?A field & glasshouse experiment

37. Still to come… How does shelter and coarse woody debris affect establishment?

38. Strand 2 Biodiversity of dryland woody communities • What are benefits and drawbacks of woody succession for native biodiversity in drylands? • Demonstration of gains and losses associated with woody dominance

39. Woody Intermediate Non-woody

40. No. native plant species No. native plant species

41. No. native bird species No. native bird species

42. Lizards All lizards

43. Partnership with DOC Grand and Otago Skink Recovery Programme

44. Factors affecting native woody establishment in exotic broomEaling Springs Led by DOC (Canterbury) with range of co-funders • Can native woody species establish in exotic woody stands in drylands? • Do woody weeds facilitate native establishment in dryland environments?

45. Treatments Roller crushed Solid broom (control) Root raked Sprayed Mulched

46. We want to be able to provide advice about a biodiverse future: • What could develop through succession? • What is a priority to protect and/or restore? • What can we just leave to its own devices?

47. Pest interactions

50. Superpredators Ferret Cat Stoat Herbivores Mesopredators Insectivore Rabbit Rat Hedgehog Possum Hare Mouse Native lizard Native invert Vegetation Grazing & Burning Climate