Benefits, costs, priorities for improvement

Transcription

1 Plantation Productivity Symposium - Mt Gambier Weed Management Benefits, costs, priorities for improvement Paul Adams Forestry Tasmania

2 Overview Weed management Importance of herbicides Benefits and Costs Opportunities for improvement Suggested priorities Plantation Productivity Symposium - Mt Gambier

3 Adding value productivity enhancement Reducing physical impacts (fire, wind, insects, disease) Improving growth (weed management, nutrition, silviculture, genetics) More wood per hectare Higher quality wood Increased value Applying new technologies (information systems, harvest & transport, processing, new products) Plantation Productivity Symposium - Mt Gambier

4 Weed management More than weed control Improve establishment and productivity (by reducing competition for site resources - light, water and nutrients) Improve access for operations Coppice and wilding management Improving health and disease risk Managing fire risk Vegetation management Plantation Productivity Symposium - Mt Gambier

5 Weed management improving productivity A key component of silviculture Resource management: Know your sites know your weeds manage the resources interactions opportunities for integration Major gains have been achieved Lessons from agriculture Plantation Productivity Symposium - Mt Gambier

6 Importance of herbicides Aerial or ground-based application Plantation Productivity Symposium - Mt Gambier

7 Herbicides Used extensively world-wide Very effective and relatively low cost Ability to control a large number of competitive species Management systems reliant upon continued availability Risks: off-site movement, resistance, regulation Plantation Productivity Symposium - Mt Gambier

8 Alternative methods Manual cutting Slashing Mulching Cultivation Cover crops Biological control Expensive, partially effective Plantation Productivity Symposium - Mt Gambier

9 Weed management plantation establishment Crucial in first 1 2 years of growth Leads to fast early growth, healthy, uniform, vigorous plantations Rapid domination of the site, shading of the weeds Enables fertilisation and tree breeding benefits to be realised Allows more attention on less predictable issues (eg. pests and diseases) Plantation Productivity Symposium - Mt Gambier

10 Plantation establishment - eucalypts Mainly pre plant Plantation Productivity Symposium - Mt Gambier

11 Plantation establishment - pines Pre plant and post plant Courtesy Forestry SA Plantation Productivity Symposium - Mt Gambier

12 The impact of weeds eucalypts Plantation Productivity Symposium - Mt Gambier

13 The impact of weeds - pines Courtesy Forestry SA Courtesy Forestry SA Plantation Productivity Symposium - Mt Gambier

14 Impact of weeds: Site history (ex farmland, ex forest, 2R, 3R) Site productivity and resource availability (water, nutrients) Weed species (grasses, herbaceous, woody) Site preparation techniques (soil tillage and residue management) Tree species planted Planting density (time to canopy closure, thinning) Stage of growth/management Plantation Productivity Symposium - Mt Gambier

15 Weed management R&D effort Significant development of management through R&D Quantifying responses Crop response timing, duration, intensity of competition Methods Herbicides products, formulations, additives, rate, timing, frequency Alternatives cover crops, slashing, mulching, cultivation Area/pattern spot, strip, broadcast Application aerial and application technology Plantation Productivity Symposium - Mt Gambier

16 Weed management R&D effort Specific weeds ecology, grasses, bracken, gorse, broom Environmental herbicide fate/leaching, drift, buffer width, resistance Mechanisms competition for light, water and nutrients, physiology Interactions fertiliser, insect control, stand density, site productivity Modelling/DSS eg. VMAN, Cabala weeds Plantation Productivity Symposium - Mt Gambier

17 Tree crop response Survival, early growth Height (m) a. I Low N High I Low N Zero I High N High I High N Zero WF N High W 1 N Zero E. globulus growth to 2 years 0 80 b. WF D 15 (mm) N High W 20 N Zero Months since planting Adams et al Plantation Productivity Symposium - Mt Gambier

18 Long term effects A 40 Responses to complete weed control Stem volume difference between treatments at 8.5 years Difference in stem volume averages (m 3 ha -1 ) B C N-N Sp-N St-N C-N N-C Sp-Sp Sp-C St-St St-C C-C 20 Patterns: Nil Spot Strip Broadcast Plantation Productivity Symposium - Mt Gambier Time after planting (years) Shaw, Mattay and Adams 2002 Figure 2. Differences in average stem volume 18

19 Long term effects Paired plot network (38 pairs) Understand the impacts of weed competition on productivity across broad biogeographically region Understand drivers of stand productivity/size class distribution Weed free (m 3 ha -1 ) Eucalypts age 5 years NF pasture Provide validation data sets for model development Control (m 3 ha -1 ) O Grady (unpublished) Plantation Productivity Symposium - Mt Gambier

20 Interactions Weed competition and response to fertilisers Basal area incr P. radiata response to weed control and fertiliser Grass Grass free Grass + fertiliser Grass free + fert Year1 Year2 (Squire 1977) Plantation Productivity Symposium - Mt Gambier

21 Interactions Weed competition and response to fertilisers (Squire 1977) Plantation Productivity Symposium - Mt Gambier

22 Interactions Weed competition and response to fertilisers 80.0 E. globulus age 7 years 70.0 Fert + WC Volume (m3 / ha) Fert Nil fert + WC Nil fert Plantation Productivity Symposium - Mt Gambier

23 Site quality effects Shaw, Mattay and Adams 2002 Total Stem Volume (m 3 ha -1 ) N-N C-N N-C Sp-Sp St-St C-C 0 Penola Mt Gambier Mt Burr Plantation Productivity Symposium - Mt Gambier Figure 1. Total stem volume at age 8.5 years 23

24 Weed management R&D effort R&D (Australia and New Zealand) forest growers chemical companies contractors universities CSIRO/FRI/Ensis/Scion CRC s consultants Significant work by Tomkins et al. since 2000 Forest Industry Herbicide Research Consortium (FIHRC) since 2010 Plantation Productivity Symposium - Mt Gambier

25 The economics of weed management Need more economic analysis (Benefit, Cost, NPV s) Long-term crop responses (rotation length trials) Costs for establishment: using herbicide (< $250 / ha) < 20% of establishment costs (to age 2 years) < 10% total costs for pulpwood regimes (10 12 yr) < 5 % total costs for solid wood regimes (20 30 yr) Costs pre canopy closure (<$250 / ha) Alternative methods: slashing, mulching ($200 $700 / ha) Plantation Productivity Symposium - Mt Gambier

26 The economics of weed management Example: Wilkinson, Neilsen and Edwards 1993 Hexazinone for grass and woody weed control Trial Strip spraying Broadcast spraying Strip spraying ROI NPV ($) NPV ($) % Ex-pasture Grasses Ex-native forest Dolly bush Ex-native forest Woody weeds Projected returns to age 25 years Hexazinone at planting Plantation Productivity Symposium - Mt Gambier

27 Other factors affecting weed management Landscape diversity Terrain / access Neighbours Environmental (eg. soil, water, biodiversity) Forest Certification Demonstrate commitment to reduce chemical use where possible Plantation Productivity Symposium - Mt Gambier

28 Reducing herbicide use Approach: continued use of appropriate herbicides (lower rates in combination with alternative control methods) (Little et al 2004) Using more active herbicides, increased precision, etc However: Trend towards intensification of management To improve economic returns To make every hectare count How to do this sustainably? What other opportunities for weed management? Plantation Productivity Symposium - Mt Gambier

29 Other opportunities to apply weed management Post-planting (including rescue) Pre-canopy closure (including rescue) Post-thinning (to increase response to thinning, post-thin fertilisation) Pre-harvest (pre establishment treatment for next crop) Plantation Productivity Symposium - Mt Gambier

30 Other opportunities eg. eucalypt plantations Pre harvest PULPWOOD SOLID WOOD Pre plant Post plant Post thin Fertilisation Pre harvest Plantation Productivity Symposium - Mt Gambier

31 Plantation Productivity Symposium - Mt Gambier

32 Plantation Productivity Symposium - Mt Gambier

33 Cassotti Plantation Productivity Symposium - Mt Gambier Courtesy Forestry 33 SA

34 Post-thinning weed management Woody weeds, gorse, bracken, blackberry, native grasses Weed regrowth after thinning Competitive for water, nutrients? Need to verify. Fertiliser + weed control > Fertiliser or Weed control Ground-based application limited by access, terrain, conditions Successful application in South Australia (also overseas) Plantation Productivity Symposium - Mt Gambier

35 But only apply where needed and economic Plantation Productivity Symposium - Mt Gambier

36 Weed Management Priorities for improvement RWG5 (2003,2007), Potter 2008, Tomkins 2010 Optimise management regimes for existing weed species Improve herbicide formulations / additives / mixes Registration of effective alternative herbicides Suitable post-planting herbicides for eucalypts Risk management: off-site impacts, resistance Calculate long-term productivity gains (to define economics) Alternative methods (insect biological control and myco-herbicides) Plantation Productivity Symposium - Mt Gambier

37 Weed management Adding value / improving productivity Concluding comments Continuing importance of weed management and herbicides Significant advances through R&D (it pays) Continue (establishment, pre-canopy closure) R&D Improve integration, understand interactions Where suitable: post-thinning weed management (+ fert) Effective coordination needed Plantation Productivity Symposium - Mt Gambier

38 Acknowledgements Don McGuire (FSA) Ross Gillies (HVP) Gavin Matthews (AFPA) Anthony O Grady (CSIRO) Plantation Productivity Symposium - Mt Gambier

39 Thank you Plantation Productivity Symposium - Mt Gambier