Relevance of the Nitrogen Fertilization

1
Relevance of the Nitrogen Fertilization
Literature to the Problem of Critical Loads for
the Georgia Basin. Gordon F. Weetman Dept.
Forest Science. UBC. Vancouver March
2007 Contract Report for Environment Canada. .
Georgia Basin Puget Sound
Research ConferenceMarch 26-29, 2007Vancouver,
British Columbia
2
MOUNTAIN HEMLOCK ZONE
Biogeoclimatic Zones in Georgia Basin
3
What can we learn from experience with forest
fertilization?

• A huge body of literature and experience over 45
  years 11 Sources of intelligence were reviewed
• --------------------------------------------------
  -----------
• Source 1.
• Commercial N fertilization (around 200kgN/ha) in
  N America and Scandinavia with many environmental
  impact assessments and studies.
• e.g. Hogbom L. and Jacobson S. 2002 Nitrogen
  2002-an impact assessment of forest fertilization
  in Sweden. For.Res. Inst Sweden, Redgorelse nr
  6. 42pp

4
What can we learn from experience with forest
fertilization?

• Source 2.
• Optimum nutrition experiments designed to explore
  the upper limits of increased productivity.
• e.g. Jacobson, S. 2001 Fertilization to increase
  and sustain tree growth in coniferous stands in
  Sweden. Doctoral Thesis, Swedish Univ. Agr.
  Science., Silvestra 217. Uppsala

5
What can we learn from experience with forest
fertilization?

• Source 3.
• Fear of N staturation experiments designed to
  explore the capacity of the system to contain N.
• e.g. Tamm, C. O. Aransson A. Popovic B. and
  Flower-Ellis 1999. Optimum nutrition and nitrogen
  saturation in Scots pine stands. Studia
  Forestalia Suecia 206 126pp

6
What can we learn from experience with forest
fertilization?

• Source 3More N saturation work
• e.g. McNulty S.G. et al 2005.
• Red spruce ecosystem changes following 14
  years of chronic N fertilization.
• For. Ecol. Man (in press)

7
What can we learn from experience with forest
fertilization?

• More N saturation work.
• Aber J.D. and Magill A.H. 2004 Chronic nitrogen
  additions at the Harvard Forest (USA) the first
  15 years of a nitrogen saturation experiment
  For .Ecol Man. 196(1)1-5.

8
What can we learn from experience with forest
fertilization?

• Source 4.
• Use of N fertilization as a test of forest
  ecosystem N status under suspected N loading
  situation
• e.g. Rueth H. M., Baron J.S. and Allstoff E.J.
  2003 Responses of Engelmann spruce forests to
  nitrogen fertilization in the Colorado Rocky
  mountains. Ecol. Applic. 13(3) 664-673

9
What can we learn from experience with forest
fertilization?

• Source 5.
• Natural loading of PNW forest ecosystems by N
  fixation under red alder.
• e.g. Compton, J. E., Church, M. R., Larned S. T.
  and Hogsett W. E. 2003. Nitrogen saturation in
  forested watershed of the Oregon Coast Range The
  landscape role of N2 fixing red alder Ecosystems
  6 773-785.

10
What can we learn from experience with forest
fertilization?

• Source 6.
• BC experience with N fertilization in forested
  watersheds.
• e.g. Pike, R and Perrin C. 2005 Fertilization in
  forested watersheds. Streamline Watershed
  Management Bull.9(1)13-20

11
What can we learn from experience with forest
fertilization?

• Source 7.
• Reviews of N deposition effects in the US.
• Work of Fenn and co-authors
• e.g. Fenn M.E., Poth M.A., Aber J.D., Baron J.S.,
  Bormann B.T., Johnson D.A., Lemly A.D., McNully
  S.G., Ryan D.F. and Stottlemyer.R. 1998 Nitrogen
  excess in North American Ecosystems predisposing
  factors, ecosystem responses, and management
  strategies. Ecological Applications 8(3)706-733

12
What can we learn from experience with forest
fertilization?

• Source 8.
• Fundamental science understanding of the N cycle
  in forested ecosystems.
• e.g.
• Tamm C.O. 1991.
• Nitrogen in
• Terrestrial Ecosystems,
• Springer-Verlag.
• Ecol. Studies 81 115pp.

13
What can we learn from experience with forest
fertilization?

• Source 9.
• Reviews of literature by other agencies and
  organizations when setting critical N loads
• e.g. SAEFL 2003 Empirical critical loads for
  nitrogen expert workshop. Swiss Agency for the
  Enviroment, Forests and Landscape (SAEFL) Enviro.
  Doc.164. 18pp. http//www.umwelt-schweiz.ch/buwal/
  shop/files/pdf/phpDQvvMp.pdf

14
What can we learn from experience with forest
fertilization?

• Source 10.
• Attempts to model the effects of N fertilization.
• e.g.
• Lillemagi M.2002 Modeling the effects of forest
  fertilization on the N balance in a pine stand in
  northern Sweden
• www.mv.slu/bg/Examensarb/Abstract.

15
What can we learn from experience with forest
fertilization?

• Source 11.
• Our understanding of the most N sensitive
  ecosystems in the Georgia Basin based on the work
  behind the BC Biogeoclimatic Ecosystem
  Classification (BEC).
• E.g. Klinka,K. and Chourmouzis The Mountian
  Hemlock Zone of BC and Brett.R.B.,Klinka K. and
  Qian H.2002 Classification of high elevation
  non-forested plant communities in Coastal BC.
• www.forestry.ubc.ca/klinka/sci_sil/ssesr028
• Scientia Silvica Extension Series.( Not formally
  published but it is the only classification and
  it is very thorough).

16
What does all this work suggest about N impacts
in the Georgia Basin?

• 1.At current low rates of N input (2 to 6 kg
  N/ha/yr) in the Georgia Strait present forested
  ecosystems it appears that no significant
  detrimental effects on ecosystem functions can be
  expected because of the ability of the humus and
  soil to absorb and immobilize added N.

17
What does all this work suggest about N impacts
in the Georgia Basin?

• 2.At higher input rates of 100 to 300 kg N/ha, in
  single one time doses, used in operational forest
  fertilization, experience from similar temperate
  forest ecosystems suggests that no serious
  detrimental effects have been found provided
  guidelines about applications to lakes and water
  courses are respected. Operational forest
  fertilization has been applied to second growth
  stands in the Georgia Basin for over 30 years and
  is ongoing

18
What does all this work suggest about N impacts
in the Georgia Basin?

• 3.Repeated applications of N fertilizer, in
  experiments designed to approximate N saturation,
  have indicated a surprising ability of forested
  ecosystems to absorb added N.

19
What does all this work suggest about N impacts
in the Georgia Basin?

• 4.European empirical critical N loads for natural
  and semi-natural ecosystems in 2002 are in the
  range of 5 to 20 kg N/ha/yr for forest and
  subalpine habitats. Coastal, inland surface water
  and bog and fen habitats are in the range of 5 to
  25 kg N/ha/yr. Given the similarity of ecosystem
  structure and function these are reasonable
  values for the Georgia Basin. US values are in
  the same range

20
What does all this work suggest about N impacts
in the Georgia Basin?

• 5.N fertilization has been used to test the
  degree of N saturation of forested ecosystems.
  This review suggests it be used in the Mountain
  Hemlock biogeoclimatic zone of the Georgia Basin
  where the greatest impacts of N inputs might be
  expected.(An assessment of the Mountain Hemlock
  Zone situation has been done by Anliang Zhong as
  a separate contract.)

21
What does all this work suggest about N impacts
in the Georgia Basin?

• Recommendation.
• Even though current N inputs are assumed to be
  very low there is an almost complete lack of data
  on the Georgia Basin high elevation forest
  ecosystems. monitoring is needed. These
  ecosystems are the ones expected to first show
  symptoms of N saturation. N fertilizer should be
  added experimentally to some sensitive high
  elevation forest sites in the Mountain Hemlock
  Zone of the Georgia Basin followed by monitoring
  .
• .
• .
• In spite of all the research done so far, the
  European critical nitrogen loads expert panel
  suggested in 2002 at the Berne workshop that more
  N addition experiments are needed in areas with
  low deposition (Thats us!)

22

• Monitoring needed in Mt. Hemlock Zone
  fertilization
• the changes in tree needle sizes and N uptake
• changes in the natural ground vegetation as
  classified by K. Klinka
• changes in the humus and soil properties similar
  to the Engelmann-Spruce Subalpine Fir Zone (
  ESSF) N addition trial in Colorado
• changes in the macrofungi sporocarp production as
  suggested by Trudell and Edmonds.

23

• In spite of all the research done so far, the
  European critical nitrogen loads expert panel
  suggested in 2002 at the Berne workshop that more
  N addition experiments are needed in areas with
  low deposition (Thats us!)

24
Mountain Hemlock Zone. Most N input sensitive
in Georgia Basin?
25
What was not considered
26
THANK YOU