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Transcript
Grant Norbury Susan Walker Landcare Research New Zealand’s dryland biodiversity situation: How we got there and how we might go Presentation to the Canterbury forward Biodiversity Steering Group, Ashburton 31 July 2009. What are drylands? 19% New Zealand’s land area 53,000 km2 New Zealand Dryland Outline 1. Current state of biodiversity 2. Pressures 3. Science-driven restoration 4. Community-driven protection and restoration 83% cleared (cf. 44% nationally) 3% protected (cf. 38% nationally) ~50% NZ’s threatened flora New Zealand Dryland Drylands: • Contain some of the most transformed, least protected and most threatened native ecosystems and species in NZ • Unstable, seral, rapidly changing, invaded 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 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 LENZ Canterbury % Indigenous cover left % Protected + Threatened Environment Classification + = Proportion of species remaining The slippery slope 0 0.2 0.4 0.6 0.8 Proportion habitat area remaining 1.0 Canterbury habitats - habitat loss to 2001/02 >1200 m Proportion of species remaining 800-1200 m 400-800 m (37% remaining) < 400 m (8% remaining) 0 0.2 0.4 0.6 0.8 Proportion habitat area remaining 1.0 Nationally threatened plants in Canterbury Proportion of NZ land area Proportion of NZ Threatened plants (2005) (Acutely and Chronically Threatened) Canterbury Canterbury (47%) 103 species 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 Rapid, ongoing habitat loss Pastoral farming changes •Smaller upland blocks •Intensive developments Mackenzie Basin Use of spray (and fire) to clear ‘scrub’ Discretionary consents On pastoral leases: increasing number of discretionary consents granted to clear, spray, increase stock numbers etc Number of properties seeking Code 1 consents Percentage seeking Co are in 60 42 40 20 35 17 0 May2002Mar2003 Apr2003Mar2004 Apr2004Mar2005 May2002Mar2003 A M Invading weeds Pests : Feral grazers and predators 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 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 Dryands also contain a big suite of endemic herbs (many are threatened) ...and a unique, highly endangered fauna What factors are driving species to extinction? 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, particularly in lowland and montane zones • Woody vegetation in flux: some winners, some losers Overview of research into sustaining and restoring dryland biodiversity 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... Program strategy Strand 1 Strand 2 Strand 3 Succession to native woody communities Biodiversity of dryland woody communities Community and agency awareness Technical know-how to achieve it Scientific mandate and vision Community mandate Aligned work on pests Pest–Pest interactions Impacts on some dryland fauna Strand 1 Succession to native woody communities 1. What limits native woody succession? 2. What practical, broad scale solutions can be developed to overcome these? 1. Distributions Database 2. 3. 4. PLOT & POINT locations in 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 POLYGONS in drylands Marlborough/North Canterbury Ranked probability of occurrence of woody species Species-poor to species-rich communities Stage I Stage II Stage III Stage IV Rosa rubiginosa* Rosa rubiginosa* Coprosma propinqua Coprosma rotundifolia Melicytus alpinus Melicytus alpinus Kunzea ericoides Clematis forsteri Discaria toumatou Discaria toumatou Coprosma rhamnoides Ripogonum scandens Kunzea ericoides Discaria toumatou Coprosma propinqua Coprosma propinqua Ozothamnus leptophyllus Alectryon excelsus Olearia odorata Melicytus ramiflorus Carpodetus serratus Rubus schmidelioides Coprosma rhamnoides Muehlenbeckia complexa Kunzea ericoides Rosa rubiginosa* Melicytus ramiflorus Carpodetus serratus Pseudopanax crassifolius Myrsine australis Rosa rubiginosa* Traits Database 1. Gather existing trait data for dryland woody species Combine with Distribution Database to 2. – – 300 species Identify spatial pattern of traits syndromes Identify whether (and if so what) traits predict successful secondary succession and where (200 native, 100 exotic) 20 traits Height Seed size Width Seed bank type Leaf longevity Spinosity Sexual reproduction system Toxicity Age till flowering Palatability to animals Pollination agent Resprout after grazing/cutting Dispersal agent N-fixation Number of seeds/plant/crop Shade tolerance Years between crops Fire tolerance Seed mass Frost tolerance Limitations to establishment • Understand limitations to woody establishment • Test low intensity management tools • Work towards general model Dispersal Sward density Climate Light Germination Soil water Wavail, BNPP, ANPP, Litter Growth Navail Soils Decomposition BNPP, ANPP, Litter Mortality In progress…..modified from Peters 2002 Ecol. Model. 152:5-32 Shrub cover Herbivore pressure 7 soils pallic volcanic lime brown / loess semi-arid schist How do soil characteristics interact with moisture to affect growth in woody seedlings? Role of competition and herbivory in woody seedling establishment Bendigo, Central Otago • +/- water • +/- herbivory • +/- competition (herbicide + hand weeding) • 4 species Conclusions so far… Herbivory always bad, but competition has net benefit in some places Water (at least last year) made little difference How does grass sward density affect establishment of woody seedlings? A field & glasshouse experiment Still to come… How does shelter and coarse woody debris affect establishment? 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 Woody Intermediate Non-woody No. native plant species No. native plant species 120 Grassy Intermediate Woody 100 80 60 40 20 0 Region (3 sites) Bendigo Blackstone Hill Cambrian No. native bird species No. native bird species 7 Grassy Intermediate Woody 6 5 4 3 2 1 0 Region (all 3 sites) Bendigo Blackstone Hill Cambrian Lizards All lizards Partnership with DOC Grand and Otago Skink Recovery Programme Factors affecting native woody establishment in exotic broom Ealing Springs Led by DOC (Canterbury) with range of cofunders • Can native woody species establish in exotic woody stands in drylands? • Do woody weeds facilitate native establishment in dryland environments? Treatments Roller crushed Solid broom (control) Root raked Mulched Sprayed 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? Pest interactions Superpredators Ferret Herbivores Stoat Mesopredators Rabbit Possum Cat Rat Hare Insectivore Hedgehog Mouse Native lizard Native invert Vegetation Grazing & Burning Climate Superpredators Ferret Herbivores Mesopredators Rabbit Possum Cat Rat Hare Stoat Insectivore Hedgehog Mouse Native lizard Shrubland Grazing & Burning Native invert Habitat and pests interact 1990 5 km 2003 Community-driven protection and restoration Distribution of community restoration projects Land areas (ha) covered by BCF projects Southland Otago Canter Nel/Marl Wellington Wanganui BoPlenty Tong/Tau E. Coast Waikato Auckland Northland 0 1000 2000 3000 4000 5000 6000 Drivers of biodiversity decline Social a. Historical inertia b. Poor understanding Biological a. Habitat loss and modification b. Invasive species Problems Solutions Social Poor understanding Educate people Involve the community Help management agencies Biological Habitat loss and modification Purchase land for the public Protection on private land Tenure review (?) Invasive species DoC Private ‘sanctuaries’/covenants Community groups Life-stylers Councils have big challenges • • • Dual development and conservation roles Optimum mix of regulation and voluntary approaches Socio-political context Needs (to sustain biodiversity) A bottom line Need to cap indigenous vegetation loss Indigenous vegetation needs to be defined broadly Invest in an aware constituency Work with willing landowners Inform, advise, educate, incentivise, participate in activities Monitor and report losses as well as gains Build in-house biodiversity capability We celebrate weeds!! These are Central Otago’s kiwi ! Public education tours Aldinga Conservation Area Central Stories Thankyou