Abstract
Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands. Efficiency was found to decline with increasing crown leaf area (LA). This decrease was associated with a decrease in foliage ratio, that is, the proportion of assimilating tissue in the crown. This ratio has been suggested as an indirect measure of a tree's respiratory demand per unit of LA. A lower ratio implies that a smaller percentage of carbon fixed by the crown is available for stemwood growth, thus reducing E. Efficiency declined more rapidly when only LA on branches assumed to be exporting carbohydrates to the stem (LA,) was considered; even though the percent LA. of crowns increased as total LA increased. The greater proportion of LA. on trees with high LA was attributed to greater crown length, which on large trees results in a greater proportion of LA exposed to a favorable light environment. However, the continued decrease in foliage ratio with increasing crown size appears to more than offset the increase in percent LAX, causing the decrease in E with increasing LA. Efficiency of a tree is also affected by its position within the canopy. In A. lasiocarpa, greater LA is strongly associated with increased height in relatively small trees. I examined efficiency of trees relative to other trees in the same stand and found E to increase with greater LA in small trees. Greater E with increasing LA was attributed to the improved canopy position associated with increased height. In larger trees, greater LA was no longer associated with substantial increases in height and E declined as LA increased, presumably because of the decreasing foliage ratio. The pattern of change in E with increasing LA of A. lasiocarpa was compared with that of Pinus contorta var. latifolia Engelm. Differences between the two species were attributed to differences in canopy structure. Greater canopy stratification in A. lasiocarpa, combined with greater canopy coverage and leaf area index, suggests that the light environment of relatively small trees is strongly affected by canopy position and, therefore, height. In A. lasiocarpa, then, E increases with LA as long as there are associated increases in height. In P. contorta, limited canopy stratification results in few trees being located in a poor light environment. Increased LA is not associated with improved canopy position and, therefore, E decreases with increasing LA, even in relatively small trees, due to the decreasing foliage ratio. A general conceptual model is proposed to explain production-leaf area relations in forest-grown trees, based on changes in relative tree size and differences in canopy structure.
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Claims 8
Claim · model-written summary
Leaf area efficiency of Abies lasiocarpa declined with increasing crown leaf area.
- Taxon
- Abies lasiocarpa
Abies lasiocarpae0 - Organ / stage
- crowne1
- Outcome
- Efficiencye1
- Direction
- declinee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands”
e1“Efficiency was found to decline with increasing crown leaf area (LA)”
Claim · model-written summary
The decrease in efficiency with crown leaf area was associated with a decrease in foliage ratio.
- Taxon
- Abies lasiocarpaAbies lasiocarpae0
- Organ / stage
- crowne1
- Outcome
- foliage ratioe2
- Direction
- decreasee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands”
e1“Efficiency was found to decline with increasing crown leaf area (LA)”
e2“This decrease was associated with a decrease in foliage ratio”
Claim · model-written summary
In relatively small Abies lasiocarpa trees, greater leaf area was associated with increased height.
- Taxon
- Abies lasiocarpaAbies lasiocarpae0
- Material
- relatively small treese3
- Outcome
- heighte3
- Direction
- increasede3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands”
e3“greater LA is strongly associated with increased height in relatively small trees”
Claim · model-written summary
In small Abies lasiocarpa trees, efficiency increased with greater leaf area.
- Taxon
- Abies lasiocarpaAbies lasiocarpae0
- Material
- small treese4
- Outcome
- Ee4
- Direction
- increasee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands”
e4“found E to increase with greater LA in small trees”
Claim · model-written summary
In larger Abies lasiocarpa trees, efficiency declined as leaf area increased.
- Taxon
- Abies lasiocarpaAbies lasiocarpae0
- Material
- larger treese5
- Outcome
- Ee5
- Direction
- declinede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands”
e5“In larger trees, greater LA was no longer associated with substantial increases in height and E declined as LA increased”
Claim · model-written summary
In larger Abies lasiocarpa trees, greater leaf area was no longer associated with substantial increases in height.
- Taxon
- Abies lasiocarpaAbies lasiocarpae0
- Material
- larger treese5
- Outcome
- heighte5
- Direction
- increasese5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands”
e5“In larger trees, greater LA was no longer associated with substantial increases in height and E declined as LA increased”
Claim · model-written summary
The differences in efficiency between Abies lasiocarpa and Pinus contorta were attributed to differences in canopy structure.
- Taxon
- Abies lasiocarpaAbies lasiocarpae0
- Outcome
- Differences between the two speciese6
- Qualifier
- differences in canopy structuree6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area efficiency (E) was examined in 49 destructively sampled Abies lasiocarpa (Hook.) Nutt from several stands”
e6“Differences between the two species were attributed to differences in canopy structure”
e1“The pattern of change in E with increasing LA of A. lasiocarpa was compared with that of Pinus contorta var. latifolia Engelm”
Claim · model-written summary
In Pinus contorta var. latifolia, efficiency decreased with increasing leaf area, even in relatively small trees, due to the decreasing foliage ratio.
- Taxon
- Pinus contorta var. latifolia
Pinus contorta var. latifoliae1 - Material
- relatively small treese2
- Outcome
- Ee2
- Direction
- decreasese2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The pattern of change in E with increasing LA of A. lasiocarpa was compared with that of Pinus contorta var. latifolia Engelm”
e2“E decreases with increasing LA, even in relatively small trees, due to the decreasing foliage ratio”