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Nutrient Limitations to Growth of Westside Douglas-fir Forests: A Look Beyond Nitrogen

Nutrient Limitations to Growth of Westside Douglas-fir Forests: A Look Beyond Nitrogen. Doug Maguire Department of Forest Science Oregon State University   Steve Perakis FRESC USGS   Rick Fletcher Department of Forest Resources Oregon State University Doug Mainwaring

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Nutrient Limitations to Growth of Westside Douglas-fir Forests: A Look Beyond Nitrogen

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  1. Nutrient Limitations to Growth of Westside Douglas-fir Forests: A Look Beyond Nitrogen Doug Maguire Department of Forest Science Oregon State University   Steve Perakis FRESC USGS   Rick Fletcher Department of Forest Resources Oregon State University Doug Mainwaring Department of Forest Science Oregon State University

  2. Background • Trials originally of interest to members of the Swiss needle cast cooperative • Fertilization has been investigated as one of the tools to combat SNC • Previous SNC fert studies have generally included N, either as single-nutrient treatments or blends: • Menasha trials • Plum Creek trials • VMRC trials • Balanced Fertilizer trials

  3. Background • Studies suggest that nitrogen may be problematic in SNC-infected stands • Lack of response to N in previous fert trials • Negative correlation between foliage retention and foliar N • N from fertilization was found to be directly responsible for increased the fungal nitrogen levels and fungal fruiting, and thus, disease severity

  4. Background • Studies suggest that nitrogen may be problematic in SNC-infected stands • Lack of response to N in previous fert trials • Negative correlation between foliage retention and foliar N • N from fertilization was found to be directly responsible for increased the fungal nitrogen levels and fungal fruiting, and thus, disease severity

  5. Background • Proposed study went through several iterations to meet the needs of participants • How to include non-SNC Coop members • Fixed area vs. individual tree plots • Treatments

  6. Fertilization Trials 16 locations, 12 landowners Cascade Timber Giustina Green Diamond (2) Hampton (2) Lone Rock Menasha (2) ODF OSU Port Blakely Starker West Fork Timber Weyerhaeuser (2)

  7. Study design • Individual tree plots (1/40th acre) • 10 plots per treatment • 5, 7, or 8 treatments per site • 50, 70, or 80 plots per site 18.6 ft

  8. Target stands • Target stands • 20 yrs of age (+/- 5 yrs) • 300 tpa (+/- 100 tpa) • No pct or fertilization in last 8 years • < 20% salal cover • Good road access • Relatively flat • Limited brush cover • Nearby donut source

  9. Target stands • Target stands • 20 yrs of age (+/- 5 yrs) • 300 tpa (+/- 100 tpa) • No pct or fertilization in last 8 years • < 20% salal cover

  10. Treatments

  11. Treatments, Kinsey Values given in lbs/acre

  12. Treatments, Fenn Values given in lbs/acre

  13. Installation Choose appropriate dom/codom measure tree on 1 chain grid Subject tree measurements: Dbh Ht Hllb Sapwood width Diameter @ 5.5 m Fifth-whorl foliage retention

  14. Installation 1/40-ac plots centered on measure tree (radius=18.6 ft) Plot-level measurements: Dbh of all trees within plot

  15. Installation Each treatment randomly assigned to 10 plots Treatment-level data (composite from 10 plots): Foliage (needles from current shoots) Soil (from 2 soil cores)

  16. Schedule • 2006-07 • Install and measure plots • Sample soil and foliage • Fertilize (February-March) • 2007-08 • Sample soil and foliage • Apply lime to Kinsey treatments • 2009-10 • Measure plots • Sample soil and foliage • 2012-13 • Measure plots

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