A peek down under: Chris Phillips. structural root architecture of some New Zealand native plants. Mike Marden, Jagath Ekanayake & Alex Watson

Transcription

1 A peek down under: structural root architecture of some New Zealand native plants Chris Phillips Mike Marden, Jagath Ekanayake & Alex Watson

2 Disclaimer We are not botanists! We are not plant ecologists! We are on the edge! We play in the dirt! We are statistically challenged!

3 Wadda ya know?

4 In this talk. Context 3 strands What we ve done 2 trials How we do it What we ve found How we use the information Wrap up

5 Context 1 hillslope stability Plantation forests for erosion control Pinus radiata and other exotics 1980 s s to 1990 s Effectiveness, densities, harvesting etc

6 Context 1 hillslope stability

7 Context 1 hillslope stability

8 Context 1 hillslope stability

9 Context 2 river bank stabilisation Off the hills and into the rivers ICM Riparian restoration/rehabilitation efforts Natives vs exotics, Ecology vs function Performance, build the K base

10 Context 2 river bank stabilisation

11 Context 3 Carbon & SLM MAF Govt policies - convergence Climate change mitigation & Sustainable land management (SLM) >> HCE What to use, how effective, how much C, what rate, where, management etc

12 The Big Question? Can our New Zealand native plants perform E & SC functions as well as introduced plants? In geotechnical terms, how do we quantify the benefits of vegetation to soil stabilisation? With roots Without roots Shear displacement

13 What we ve been doing Exotic species 2 native trials 1 MSc. on Cordyline

14 What we ve been doing - natives Riparian plant trial Common name Karamu Ribbonwood Kowhai Lemonwood Kohuhu Lacebark Mapou Fivefinger Cabbage tree Rewarewa Manuka Tutu Podocarp trial Common name Kauri Rimu Kahikatea Miro Totara Matai Puriri Titoki Sedge grass NZ Mountain flax Toe toe Cabbage trees Marden, Rowan, Phillips (2007; 2005) Phillips & Marden (2006) Still in progress Czernin (2002) Czernin & Phillips (2005)

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16 How we do it The old The hard The new

17 What we ve found General growth patterns Biomass Root length Root depth Site occupancy Root strength

18 Root architecture Root definitions Root bole Lateral Sinker Sinker Taproot

19 Root architecture Tree root forms plateroot heartroot taproot

20 What we ve found growth Cabbage tree (Cordyline australis) Czernin (2002) Czernin & Phillips (2005)

21 What we ve found growth m (Psuedopanax arboreus) 3.35 m m 1 year old 2 year old 3 year old 4 year old

22 What we ve found growth 4 yr old Totara Kauri 1 m 0

23 Toe toe What we ve found growth 3 year olds Flax Carex Kahikatea & Puriri 4m 1m

24 What we ve found root spread 5 year old Pittosporum tenuifolium (kohuhu) Coprosma robusta (karamu)

25 What we ve found root spread Mean max. root spread 5 year old mapou rewarewa five.finger manuka karamu kowhai lacebark cabbage.tree kohuhu ribbonwood tutu lemonwood Root Spread (m)

26 cabbage.tree Mean max. root depth 5 year old mapou five.finger kohuhu kowhai lemonwood manuka rewarewa lacebark tutu karamu ribbonwood (cm) What we ve found root depth

27 What we ve found root depth Ribbonwood Cabbage tree

28 year old rewarewa five.finger manuka kowhai lacebark kohuhu lemonwood karamu ribbonwood tutu cabbage.tree mapou (kg) What we ve found biomass Above-ground Below-ground

29 What we ve found root length 3 year old - woody

30 What we ve found root length 3 year old - all

31 What we ve found root length 3-5 year old - all

32 What we ve found variation

33 What we ve found variation

34 What we ve found variation

35 What we ve found variation 5 year old - woody Data range max, mean, min

36 What we ve found root tensile strength (1-4 mm diameter) Willows MPa Riparian plant trial Old FRI data Exotics 0 Lacebark Hard beech Kowhai Manuka-1 Manuka-2 Red beech Kanuka Kohuhu Kamahi Fivefinger Rewarewa Cabbage tree Mountain beech Douglas fir Ribbonwood Radiata pine Lemmonwood Tutu Karamu Watson & Marden (2005) Rata Mean max. tensile strength (MPa)

37 How we use it Knowledge delivery

38 Watson & Tombleson (2004) How we use it management Planting types radiata pine 3 yr old

39 How we use it Allometry Cabbage tree root depth Rooting depth (cm) y = x r 2 = Gisborne plant trial 11 yr Mean root collar diameter (cm)

40 How we use it relative root reinforcement Window of vulnerability 1. Kanuka spha 2. Radiata 1250 spha 3. Radiata 800 spha 4. Radiata 500 spha Watson, Phillips, Marden (1999)

41 How we use it Models Root site occupancy 100% root site occupancy

42 How we use it Models Root site occupancy What about these bits? 100% root site occupancy

43 5 yr Poplars? Cabbage tree? 7 yr? 4 yr 8 yr 25 yr Czernin & Phillips (2005) Totara 9.5 yr?? McIvor et al (2007) 4 yr Marden & Phillips (unpub.)

44 How we use it root site occupancy model Effective root spread radius 100%?? Site occupancy 0% Mean maximum root length radius Root reinforcement index (RFI) = Root surface area Root spread area

45 Effective root spread measured & predicted using model equation Effective Root Spread distance from stump (cm) Time (years) b y = a x c exp( x) 5-Finger 5-Finger Cabage_Tree Cabage tree Karamau Karamau Kohuh Kohuhu Kowhai Kowhai Lacebark Lacebark Lemonwood Lemonwood manuka Manuka Mapou Mapou Rewarewa Rewarewa Ribbonwood Ribbonwood Tutu

46 How we use it root site occupancy & density Site occupancy (%) Site occupancy (%) for planting density 1m x 1m 5-Finger Cabage tree Karamau Kohuhu Kowhai Lacebark Lemonwood Rewarewa Ribbonwood Tutu Mapou Time (years)

47 How we use it root site occupancy & density Site occupancy (%) for planting density 2m x 2m Site occupancy (%) Finger Cabage tree Karamau Kohuhu Kowhai Lacebark Lemonwood Rewarewa Ribbonwood Tutu Time (years)

48 How we use it Visualisation Avondale Stream, existing channel, May 2004

49 Avondale Stream, Carex added

50 Avondale Stream, Juncus added

51 Avondale Stream, native trees added

52 Existing channel has little in-stream cover

53 Riparian grasses provide cover & spawning habitat

54 Cabbage trees suitable above the wetland grasses

55 Tree ferns also suitable above wetland grasses

56 Chockie fish time What native had the greatest tensile root strength? What do we call the gadget we use to expose the root systems of plants? What s so special about the root systems of cabbage trees? Fivefinger

57 Wrap up We know more than we did before Hard won data Natives can grow quickly Maybe need to look more at function Opportunities for further research Optimisation for site reinforcement Carbon modelling.. Modelling in general

58 The unhealthiness in our world today is in direct proportion to our inability to see it as a whole. Peter Senge