Effects of Intensive Fertilization on the Growth of Interior Spruce Presentation to: Interior Fertilization Working Group February 5/13 (revised March 4/13)

Typical pattern of growth response following “conventional” fertilization Type 1 response Fertilize Unfertilized “Conventional” fertilization (Type 1)

Typical pattern of growth response following “conventional” fertilization Type 1 response Fertilize Unfertilized “Conventional” fertilization (Type 1)

Typical pattern of growth response following “intensive” fertilization Type 2 response Unfertilized “Conventional” fertilization (Type 1) Fertilize “Intensive” fertilization (Type 2)

Effects of yearly fertilization on the growth of Norway spruce in northern Sweden from Bergh et al. (2005)

Relationship between stem wood production and light interception by forest canopy

How can light interception be maximized?

l Increase the length of the growing season

How can light interception be maximized? l Increase the length of the growing season l Increase the amount of leaf area

How can light interception be maximized? l Increase the length of the growing season l Increase the amount of leaf area l Leaf area is strongly influenced by nutrient availability

Relationship between annual volume growth and leaf area

Current

Relationship between annual volume growth and leaf area Current Potential

“Maximum Productivity” fertilization research EP l Objectives  determine the effects of different regimes and frequencies of repeated fertilization on the growth and development of young, managed interior spruce and lodgepole pine forests

“Maximum Productivity” fertilization research EP l Objectives  determine the effects of different regimes and frequencies of repeated fertilization on the growth and development of young, managed interior spruce and lodgepole pine forests  document the long-term effects of intensive, repeated fertilization on above- and below- ground timber and non-timber resources

Interior spruce study sites Crow Creek l SBSmc2 l 10 years old, planted

Interior spruce study sites Crow Creek l SBSmc2 l 10 years old, planted Lodi Lake l SBSwk1 l 11 years old, planted

Interior spruce study sites Crow Creek l SBSmc2 l 10 years old, planted Lodi Lake l SBSwk1 l 11 years old, planted Hand Lake l SBSmk1 l 14 years old, planted

Treatments l Control l N+B l N+S+B l “Complete blend” l Optimum Nutrition 1 (1.3%N) l Optimum Nutrition 2 (1.6%N) every 6 years

Foliar nitrogen by treatment and year Crow Creek (Brockley 2010)

Foliar nitrogen by treatment and year Lodi Lake (Unpubl. data)

Foliar nitrogen by treatment and year Hand Lake (Brockley unpubl.)

Foliar nitrogen by treatment and year Crow Creek (Brockley 2010)

Foliar nitrogen by treatment and year Lodi Lake (Unpubl. data)

18-year tree height increment by treatment Crow Creek (Unpubl. data) a b c

12-year tree height increment by treatment Lodi Lake (Unpubl. data) b

18-year stand volume increment by treatment Crow Creek (Unpubl. data) a b c

12-year stand volume increment by treatment Lodi Lake (Unpubl. data) b c

18-year stand volume development by treatment Crow Creek (Unpubl. data)

12-year stand volume development by treatment Lodi Lake (Unpubl. data)

Effects of yearly fertilization on the growth of Norway spruce in northern Sweden from Bergh et al. (2005)

Effects of 20 years of annual fertilization on the growth of Norway spruce in central Sweden Tamm (1991)

But …

12-year tree height increment by treatment Hand Lake (Unpubl. data) a

12-year stand volume increment by treatment Hand Lake (Unpubl. data) a b

12-year stand volume development by treatment Hand Lake (Unpubl. data)

Relationship between annual volume growth and leaf area Current

Relationship between annual volume growth and leaf area Current Potential

Leaf area index by treatment at year 12 Crow Creek (Brockley 2010)

12-year stand volume increment by treatment Crow Creek (Brockley 2010)

Leaf area index by treatment at year 9 Hand Lake (Unpubl. data)

12-year stand volume increment by treatment Hand Lake (Unpubl. data)

Effects of frequency of fertilization on the growth of Norway spruce in central Sweden – 5-year results Bergh et al. (2008) F1 – kg N every year F2 – kg N every 2 years F3 – kg N every 3 years

Summary of results to date l Young, nutrient deficient Sx plantations apparently respond well to repeated fertilization

Summary of results to date l Young, nutrient deficient Sx plantations apparently respond well to repeated fertilization l Potentially large effects on rotation length or harvest volume

Summary of results to date l Young, nutrient deficient Sx plantations apparently respond well to repeated fertilization l Potentially large effects on rotation length or harvest volume l Magnitude of gains directly related to frequency of application

Modelling the effects of repeatedly fertilizing interior spruce l Age of unfertilized and fertilized stands at minimum operability (e.g., 200 m 3 /ha merchantable volume)

Modelling the effects of repeatedly fertilizing interior spruce l Age of unfertilized and fertilized stands at minimum operability (e.g., 200 m 3 /ha merchantable volume) l Merchantable volume of unfertilized and fertilized stand at a given stand age (e.g., 20 years in future)

Modelled effects of fertilization at 5-year intervals SI=20 Fertilize every 5 years, age 20 50% total volume response per fertilization Fertilize

Modelled effects of fertilization at 5-year intervals SI=20 Fertilize every 5 years, age 20 75% total volume response per fertilization Fertilize

Cautionary Notes l Repeated fertilization may negatively impact:  Wood quality

Cautionary Notes l Repeated fertilization may negatively impact:  Wood quality  Forest health

Cautionary Notes l Repeated fertilization may negatively impact:  Wood quality  Forest health  Non-timber values (e.g., understory, water, wildlife)

Cautionary Notes l Repeated fertilization may negatively impact:  Wood quality  Forest health  Non-timber values (e.g., understory, water, wildlife) l Future competition mortality may reduce net volume gains

Cautionary Notes l Repeated fertilization may negatively impact:  Wood quality  Forest health  Non-timber values (e.g., understory, water, wildlife) l Future competition mortality may reduce net volume gains l Only short-term (18-yr) local data available

Cautionary Notes l Repeated fertilization may negatively impact:  Wood quality  Forest health  Non-timber values (e.g., understory, water, wildlife) l Future competition mortality may reduce net volume gains l Only short-term (18-yr) local data available l All stands are not equally responsive

Cautionary Notes l Repeated fertilization may negatively impact:  Wood quality  Forest health  Non-timber values (e.g., understory, water, wildlife) l Future competition mortality may reduce net volume gains l Only short-term (18-yr) local data available l All stands are not equally responsive l Small number of research trials

Recommended approach l Proceed cautiously with repeated fertilization every 4-6 years on select SBS sites

Recommended approach l Proceed cautiously with repeated fertilization every 4-6 years on select SBS sites l Site/stand attributes  young (15-25 yrs)  broadcast burned  N deficient (<1.1% N)

Recommended approach l Proceed cautiously with repeated fertilization every 4-6 years on select SBS sites l Site/stand attributes  young (15-25 yrs)  broadcast burned  N deficient (<1.1% N) l Apply N at ~175 kg/ha

Recommended approach l Proceed cautiously with repeated fertilization every 4-6 years on select SBS sites l Site/stand attributes  Young (15-25 yrs)  Broadcast burned  N deficient (<1.1% N) l Apply N at ~175 kg/ha l Apply other nutrients (S, B) as needed (every 2 nd application?)

Recommended approach l Proceed cautiously with repeated fertilization every 4-6 years on select SBS sites l Site/stand attributes  Young (15-25 yrs)  Broadcast burned  N deficient (<1.1% N) l Apply N at ~175 kg/ha l Apply other nutrients (S, B) as needed (every 2 nd application?) l Monitor foliar nutrients, forest health and water quality

Recommended approach l Proceed cautiously with repeated fertilization every 4-6 years on select SBS sites l Site/stand attributes  Young (15-25 yrs)  Broadcast burned  N deficient (<1.1% N) l Apply N at ~175 kg/ha l Apply other nutrients (S, B) as needed (every 2 nd application?) l Monitor foliar nutrients, forest health and water quality l Continue measurement and re-treatment of existing research trials