Crown symptoms and foliar analysis can guide nutrition management of eucalypt plantations in Tasmania Paul Adams and Karl Wotherspoon

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1 Crown symptoms and foliar analysis can guide nutrition management of eucalypt plantations in Tasmania Paul Adams and Karl Wotherspoon Division of Forest Research and Development

2 Outline FT eucalypt plantation estate Nutrition management Crown shape and symptoms Foliar analysis EucFERT - fertiliser decision tool Summary Questions

3 Forestry Tasmania - plantations E. nitens and E. globulus plantations (~40,000 ha) Solid wood production (20-25 yr rotations) Pruned to 6.4 m, thinned to 350 stems / ha Intensive management aimed at: making every hectare count improved use of operational synergies applying site - specific Precision forestry

4 Nutrition management >15 geology types >80 soil profile types Mostly ex- native forest sites Many with low - moderate soil nutrient status Low Productivity High Four granite soils Fertilising is therefore important

5 Low - moderate fertility soils Failure to apply secondary fertiliser leads to a decline in growth, vigour and leaf area (within 2 3 years) reduced apical dominance with dying lower branches reduced pruning potential economic failure Can t prune dead branches - defect

6 Nutrition management Fertilising targeted at maximising growth responses optimising economics (wood volume and quality) and minimising off-site losses

7 Nutrition strategy Since 2000 Re-vitalise existing young plantations (+ older pruned) Prevent growth decline in new plantations (including 2R) More recently Post - thinning fertilisation Opportunities Boosting growth on more fertile sites

8 Fertiliser decisions are based on: Soil - chemistry, physical, biological, history Site - micro climate, weeds, Trees - health and condition, growth rate (ht, BA, MAI), Management - coupe details, environmental issues, neighbours knowing your site and monitoring your trees

9 Monitoring your trees (for planning inputs and monitoring responses) = critical assessment times

10 Important tree factors : Very High growth - do not fertilise Growth High growth - possibly fertilise height, dbh, volume Low growth - high fertiliser inputs Medium - Std fertiliser regime Height (m) Very Low - do not fertilise Health pests and diseases Tree age (years) Crown development and symptoms crown size, shape, density, colour MAI

11 Crown shape and symptoms (age 1-4 yrs) Shape, density, size, colour

12 Crown shapes Conical Healthy crowns, cone shaped and densely foliated almost to ground Good health, vigour and uniformity

13 Crown shapes Narrow Limiting nutrients affect branch growth producing uniformly short branches leading to a cylindrical crown shape rather than a conical one. Crown density is often reduced and foliar discolouration may be present.

14 Crown shapes Crown lift Leaves in the lower crown are prematurely shed leading to an early lifting of the green crown and branch death. Increased risk of insect attack. No opportunity to successfully prune such trees and growth is slow.

15 Crown shapes Weeping Branches distorted and bent into a weeping form, accompanied by small distorted leaves. Often associated with copper deficiency.

16 Crown shape progression Conical 1 Narrow 2 Crown lift 3 Shape can be used to indicate current tree nutrient status the potential impact on current and / or future growth the need for fertiliser inputs

17 Foliar analysis Foliar analysis successfully used for determining nutrient status in many species, particularly conifers (eg. P. radiata) Good relationships established between nutrient concentrations and future growth

18 However, with E. nitens, E. globulus Foliar analysis much more difficult Many factors influence nutrient concentrations - interpretation is difficult There is some correlation with growth in young plantations (carrying juvenile foliage) But low relationship with growth rate after age 2-3 years In general, tree develops more leaf area rather than increases in foliar nutrient concentrations

19 E. globulus foliar N concentration (age 13 months) related to diameter increment (cm) (Adams 2004)

20 E. globulus nutrition trial - foliar N concentrations (+/- fertiliser) 2.0 Mawbanna N conc (%) Nil fert Fertiliser Age (yrs)

21 Foliar analysis Mainly used to confirm nutritional diagnosis eg. micro-nutrient deficiencies for trees < 2 years old Gross deficiencies (N and P) more indicated by crown shape, leaf area development and symptoms

22 These methods incorporated into EucFERT - fertiliser decision tool Along with soil and site factors To improve nutrition management decisions

23 EucFERT - fertiliser decision tool Guides fertiliser decision making Improves confidence in decisions Formalises decision process (records decision tree) Provides outputs for coupe fertiliser management plans Soil /site management Fertiliser product, rate, application, frequency, timing Environmental risk

24 In summary Importance of tree / stand monitoring ( knowing your site ) Don t rely on early age height growth only Crown shape / symptoms are useful indicators These utilised in EucFERT decision tool Field trials in place to validate these methods

25 Using crown symptoms and foliar analysis to guide nutrition management of eucalypt plantations in Tasmania Questions?