Abstract
Repression in lodgepole pine is a condition of slow growth in very high-density stands of natural regeneration resulting after wildfire. A factorial thinning and fertilization experiment (two levels of thinning, none and thinned, and two levels of fertilization, none and complete mix) was established on the Chilcotin Plateau in central British Columbia in a 36-year-old repressed lodgepole pine stand. The objectives of this study were to 1) examine the effects of thinning and nutrient addition and their interaction on repressed lodgepole pine tree and stand growth, foliage biomass per hectare, and growth efficiency, and 2) examine these same treatment effects on crown response of foliage and branches at the whole-tree level and by whorl, cohort, and branch order within the crown. Although repression has been considered an irreversible physiological dysfunction, the large increases in growth reported in this study and others indicate that growth of repressed stands was limited primarily by nutrient deficiencies similar to those found in non-repressed lodgepole pine. This suggests that any observed physiological dysfunctions in repressed lodgepole pine are a symptom of repression rather than a cause. Volume growth was increased from 2 to 7 m /ha/year with nutrient additions on non-thinned plots and to 5 m3/ha/year when fertilizer was applied to thinned plots. Thinning produced a tree-level growth response by allocating limited nutrients to fewer trees resulting in increased tree-level foliage biomass and increased growth efficiency. Additions of nitrogen, sulfur, and boron improved both tree-level growth and stand growth through increases in stand-level foliage biomass and growth efficiency. The additive effects of fertilization and thinning on growth indicate that both treatments are needed to achieve the maximum effect. Increased nutrition and growing space resulted in increases in tree-level foliage biomass, but the mechanisms of these increases differed by treatment. Increased number of fascicles contributed more than increased fascicle weight to the foliage biomass response for all treatments. Increases in the number of foliated branches was more important than increases in the amount of foliage on a branch when fertilizer was applied but these mechanisms were almost equally important to the increase in foliage biomass due to thinning. The lack of treatment effects on foliage biomass at the bottom of the live crown, the position of the bottom of the live crown, and the reduction in the number of cohorts toward the base of the live crown, all suggest that greater foliage biomass response is possible.
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Claims 10
Claim · model-written summary
Nutrient addition increased stand volume growth from 2 to 7 m /ha/year on unthinned plots.
- Taxon
- lodgepole pine
Pinus contortat0 - Treatment
- nutrient additionse0
- Outcome
- Volume growthe0
- Direction
- increasede0
- Value
- 2 to 7 m /ha/yeare0
- Comparator
- non-thinned plotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“Volume growth was increased from 2 to 7 m /ha/year with nutrient additions on non-thinned plots”
Claim · model-written summary
Fertilizer raised volume growth on thinned plots to 5 m3/ha/year.
- Taxon
- lodgepole pinePinus contortat0
- Treatment
- fertilizere0
- Outcome
- Volume growthe1
- Direction
- increasede1
- Value
- 5 m3/ha/yeare0
- Comparator
- thinned plotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“to 5 m3/ha/year when fertilizer was applied to thinned plots”
e1“Volume growth was increased from 2 to 7 m /ha/year with nutrient additions on non-thinned plots”
Claim · model-written summary
Thinning increased tree-level foliage biomass and growth efficiency.
- Taxon
- lodgepole pinePinus contortat0
- Treatment
- Thinninge0
- Outcome
- tree-level foliage biomass and increased growth efficiencye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“Thinning produced a tree-level growth response by allocating limited nutrients to fewer trees resulting in increased tree-level foliage biomass and increased growth efficiency”
Claim · model-written summary
Nitrogen, sulfur and boron additions improved tree and stand growth through greater foliage biomass and growth efficiency.
- Taxon
- lodgepole pinePinus contortat0
- Treatment
- Additions of nitrogen, sulfur, and borone0
- Outcome
- tree-level growth and stand growthe0
- Direction
- improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“Additions of nitrogen, sulfur, and boron improved both tree-level growth and stand growth through increases in stand-level foliage biomass and growth efficiency”
Claim · model-written summary
Fertilization and thinning had additive growth effects.
- Taxon
- lodgepole pinePinus contortat0
- Treatment
- fertilization and thinninge0
- Outcome
- growthe0
- Direction
- maximume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“The additive effects of fertilization and thinning on growth indicate that both treatments are needed to achieve the maximum effect”
Claim · model-written summary
More fascicles contributed more than fascicle weight to foliage biomass responses.
- Taxon
- lodgepole pinePinus contortat0
- Outcome
- foliage biomass responsee0
- Direction
- contributed moree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“Increased number of fascicles contributed more than increased fascicle weight to the foliage biomass response for all treatments”
Claim · model-written summary
With fertilizer, more foliated branches contributed more than foliage per branch to the foliage biomass increase.
- Taxon
- lodgepole pinePinus contortat0
- Treatment
- fertilizere0
- Outcome
- foliage biomasse1
- Direction
- more importante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“Increases in the number of foliated branches was more important than increases in the amount of foliage on a branch when fertilizer was applied”
e1“increased tree-level foliage biomass”
Claim · model-written summary
Under thinning, branch number and foliage per branch contributed nearly equally to foliage biomass increase.
- Taxon
- lodgepole pinePinus contortat0
- Treatment
- thinninge0
- Outcome
- foliage biomasse0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“these mechanisms were almost equally important to the increase in foliage biomass due to thinning”
Claim · model-written summary
Treatments had no effect on foliage biomass at the bottom of the live crown or its position.
- Taxon
- lodgepole pinePinus contortat0
- Treatment
- treatmente0
- Outcome
- foliage biomass at the bottom of the live crown, the position of the bottom of the live crowne0
- Direction
- lack of treatment effectse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“The lack of treatment effects on foliage biomass at the bottom of the live crown, the position of the bottom of the live crown”
Claim · model-written summary
The number of cohorts declined toward the base of the live crown.
- Taxon
- lodgepole pinePinus contortat0
- Outcome
- number of cohortse0
- Direction
- reductione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“lodgepole pine”
e0“the reduction in the number of cohorts toward the base of the live crown”
The same questions in other papers
boron atom · growth · Pinus contorta (lodgepole pine)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
nitrogen · growth · Pinus contorta (lodgepole pine)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- positive
- negative
- positive
pruning · growth · Pinus contorta (lodgepole pine)Positive and negative results
3 in the opposite direction
- negative
- negative
- no effect
fertilization · growth · Pinus contorta (lodgepole pine)Results agree
4 papers in the same direction as this paper
- positive
- positive
- positive
1 paper more in this group
See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.