Summary of results from the Regional Forest Nutrition Research Project and Stand Management Cooperat...
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Summary of results from the Regional Forest Nutrition Research Project and Stand Management Cooperative Rob Harrison, Dave Briggs, Eric Turnblom, Bob Gonyea, Bert Hasselberg. University of Washington. NUTSUPDM. Nutrient Supply and Use. POTENTIAL USE. SOIL SUPPLY. ACTUAL USE. REMOBILIZED.

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Nutrient supply and use

Summary of results from the Regional Forest Nutrition Research Project and Stand Management Cooperative

Rob Harrison, Dave Briggs, Eric Turnblom, Bob Gonyea, Bert Hasselberg.

University of Washington.


Nutrient supply and use

NUTSUPDM

Nutrient Supply and Use

POTENTIAL USE

SOILSUPPLY

ACTUAL USE

REMOBILIZED

UPTAKE FROM SOIL


Nutrient supply and use

Results:

Pre-RFNRP

1950’s through 1960’s


Nutrient supply and use

N200

N300

Percent volume response

N200-P88-S154

N200-P88-S168+

N100

N52-P12-K220

N rate (lb N/acre)


Nutrient supply and use

N+P

N200-P88-S168+

N200-P88-S154

N100

N100

N300

N200

Percent volume response

N52-P12-K220

N52-P12-K220

N rate (lb N/acre)


Nutrient supply and use

N200-P88-S168+

N200-P88-S154

N100

N100

N300

N200

Percent volume response

N52-P12-K220

N52-P12-K220

N rate (lb N/acre)


Nutrient supply and use

Results of other studies

Hodge-podge of nutrients other than nitrogen makes conclusions difficult. Several studies indicate results similar to the 2nd above, and many indicate the central role of N.

Clearly, both response to N and other nutrients is site controlled. Indicates need for larger scale studies on a wide variety of sites to pin response to site variables.


Nutrient supply and use

Conclusions of early studies

“Nitrogen application evoked a growth response throughout a range of growing conditions. Magnitude of response is related to amount of nitrogen applied and response is still evident in 1975 from a 1962 application”.

“Apparent response to the application of other elements is quite variable and no consistent picture emerges. There is no evidence of an economic response to the other elements”.


Nutrient supply and use

RFNRP

1969-pres.


Nutrient supply and use

Installations of the PNW Stand

Management Cooperative


Rfnrp installations

RFNRP Installations


Rfnrp installations1

RFNRP Installations


Nutrient supply and use

Forest floor C/N ratio


Nutrient supply and use

(1)

Overall results of SMC studies Response vs. N rate. Sidell thesis.


Nutrient supply and use

Table 2. Pilchuck Tree Farm study established 1994, measured through 2002 (8 y growth). Each treatment is replicated 6 times (two each installation).


Nutrient supply and use

Table 1. Oregon Dept. Forestry study established 1995, measured through 1999 (4 y growth). Each treatment is replicated 6 times (two each installation).


Nutrient supply and use

Results of RFNRP studies

N response averaging 20% (unthinned) -30% (thinned) with 400 kg N, highly site dependent.

Clearly, both response to N and other nutrients is site controlled. Indicates need for larger scale studies on a wide variety of sites to pin response to site variables.

Effects of N fertilization appear to be very long-lived.


Nutrient supply and use

SMC (1991+)

No multi-element additions. SMC

Type II, III and IV no fertilizer work at all


Nutrient supply and use

  • SMC Type I Installations

  • plantations with initial stocking 300-680 spa

  • Respace (PCT) before onset of competition

  • 7 core treatments (basic 7)

  • ISPHa, ISPHa/2, ISPHa/4,

  • ISPHa and ISPHa/2 min thin

  • ISPHa repeated thin

  • ISPHa heavy thin

  • 2-8 plots for other work, including fertilization

  • Eric Sucre did his M.S. on 7 fertilized sites


Nutrient supply and use

Location of SMC Type 1 Fertilized Research Installations


Site descriptives

Site Descriptives


Soil site properties examined

Soil & Site Properties Examined

  • Climatic data

  • Elevation

  • % Slope

  • Relative Density (RD)

  • Quadratic Mean Diameter (QMD)

  • Site Index (SI)

  • bulk density (Db)

  • pH

  • C:N ratio

  • cation exchange capacity (CEC)*

  • Inorganic nitrogen (NO3- and NH4+)*

    *Mineral Soil only


Nutrient supply and use

Total volume and 4-year PAI relative response for each treatment regime at the respected treatment intervals (224 kg ha-1 of N as urea every 4 years). Standard errors are shown.


Nutrient supply and use

Multiple regression equations for the relationships between the unstandardized residuals of total volume (m3 ha-1) and 4-year PAI (m3 ha-1 yr-1) response to 224 kg N ha-1 as urea (dependent variables) and various soil, site and stand variables (independent variables).


Nutrient supply and use

Results of SMC studies

too few sites (7) for broad generalizations

Response to N is site and stand controlled. Indicates need to couple fertilization with other silvicultural treatments, particularly stocking, and use RD or other stand properties to drive time of fertilization.


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