Abstract
To improve our understanding of shade tolerance, I studied responses in survival, growth, morphological characteristics, and physiological behavior to light availability of naturally regenerated saplings and/or planted seedlings of five tree species [ponderosa pine (Pinus ponderosa), western larch (Larix occidentalis), lodgepole pine (Pinus contortd), Douglasfir (Pseudotsuga menziesii), and Engelmann spruce (Picea engelmannii)] in central and southern interior British Columbia. Lodgepole pine saplings had a greater terminal and lateral increment than Douglas-fir saplings in high light environments. With decreasing light availability, (i) terminal increment, mean lateral increment, and total lateral increment decreased in both species and lodgepole pine had a greater decrease in lateral growth than Douglas-fir; (ii) the ratio of mean lateral to terminal increment in lodgepole pine did not change but significantly increased in Douglas-fir; (iii) the ratio of total lateral to terminal increment decreased in lodgepole pine but increased in Douglas-fir; and (iv) specific leaf area in both species increased, with a marginally greater increase in Douglas-fir; however, Douglas-fir always had a greater specific leaf area than lodgepole pine. Comparison of dynamic and steady-state photosynthesis between understory- and open-grown Douglas-fir seedlings indicated that when a PPFD of 200 or 500 µmol m⁻² s⁻¹ was applied (following a 10-min period at a PPFD of 50 µmol m⁻² s⁻¹) induction times required to reach 50 and 90% of steady-state net photosynthetic rates in the understory - grown branches were shorter than those in the open-grown branches. On a per unit leaf area basis, the understory-grown branches had a lower dark respiration rate and higher net photosynthetic rates at low PPFDs, but lower net photosynthetic rates at high PPFDs than the open-grown branches. However, on a dry leaf mass basis, there were no differences in dark respiration rates between the understory-grown and open-grown branches, but net photosynthetic rates of the understory-grown branches were equal to or higher than those of the open-grown branches at all PPFDs. After three growing seasons, survival of planted ponderosa pine and western larch seedlings decreased with decreasing light availability from intermediate to low light environments, whereas survival of Douglas-fir and Engelmann spruce seedlings did not vary with varying light environments. In low light environments, survival increased in order from western larch to ponderosa pine to Douglas-fir to Engelmann spruce. With decreasing light availability, 1) all study species except western larch had decreased height growth and Engelmann spruce had the greatest decrease among all the species; 2) diameter growth decreased for all study species and Douglas-fir had the greatest decrease; and 3) total biomass growth decreased for all study species and there were no difference in the extent of decreases in both absolute and relative biomass growth rates among the three evergreen conifers; however, ponderosa pine had the highest absolute biomass growth rate over three growing seasons in any given light environment. The ratio of absolute above- to below-ground biomass and specific leaf area varied with light environments in Douglas-fir and Engelmann spruce but not in ponderosa pine and western larch seedlings. These findings suggest the occurrence of interspecific differences in survival and growth, morphological, and physiological characteristics in response to light availability. This study finds that shade-tolerant species (i) have higher survival in low light environments but generally a lower growth rate (height, diameter, and biomass) in both high and low light environments, and (ii) are more efficient in capturing limiting light resources in low light environments due to plasticity in specific leaf area, lateral to terminal growth ratio, and above- to below-ground biomass growth ratio. However, more work is needed to determine which characteristics are the best measures of shade tolerance, and more importantly, to determine the causes of shade tolerance.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 20
Claim · model-written summary
In high light environments, lodgepole pine saplings had greater terminal and lateral increment than Douglas-fir saplings.
- Taxon
- Lodgepole pine
Pinus contortae0 - Outcome
- terminal and lateral incremente0
- Direction
- greatere0
- Comparator
- Douglas-fir saplingse0
- Setting
- high light environmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lodgepole pine saplings had a greater terminal and lateral increment than Douglas-fir saplings in high light environments”
Claim · model-written summary
With decreasing light availability, terminal increment, mean lateral increment and total lateral increment decreased in both lodgepole pine and Douglas-fir.
- Taxon
- both speciese0
- Treatment
- decreasing light availabilitye0
- Outcome
- terminal increment, mean lateral increment, and total lateral incremente0
- Direction
- decreasede0
Not reportedComparator
Verbatim
e0“With decreasing light availability, (i) terminal increment, mean lateral increment, and total lateral increment decreased in both species”
Claim · model-written summary
With decreasing light, lodgepole pine had a greater decrease in lateral growth than Douglas-fir.
- Taxon
- lodgepole pinePinus contortae0
- Outcome
- decrease in lateral growthe0
- Direction
- greater decreasee0
- Comparator
- Douglas-fire0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lodgepole pine had a greater decrease in lateral growth than Douglas-fir”
Claim · model-written summary
With decreasing light, the ratio of mean lateral to terminal increment did not change in lodgepole pine but significantly increased in Douglas-fir.
- Taxon
- lodgepole pinePinus contortae0
- Outcome
- ratio of mean lateral to terminal incremente0
- Direction
- did not changee0
- Qualifier
- significantly increased in Douglas-fire0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ratio of mean lateral to terminal increment in lodgepole pine did not change but significantly increased in Douglas-fir”
Claim · model-written summary
With decreasing light, the ratio of total lateral to terminal increment decreased in lodgepole pine but increased in Douglas-fir.
- Taxon
- lodgepole pinePinus contortae0
- Outcome
- ratio of total lateral to terminal incremente0
- Direction
- decreasede0
- Qualifier
- increased in Douglas-fire0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ratio of total lateral to terminal increment decreased in lodgepole pine but increased in Douglas-fir”
Claim · model-written summary
With decreasing light, specific leaf area increased in both lodgepole pine and Douglas-fir, with a marginally greater increase in Douglas-fir.
Verbatim
e0“specific leaf area in both species increased, with a marginally greater increase in Douglas-fir”
Claim · model-written summary
Douglas-fir always had a greater specific leaf area than lodgepole pine.
- Taxon
- Douglas-fir
Pseudotsuga menziesiie0 - Outcome
- specific leaf areae0
- Direction
- greatere0
- Comparator
- lodgepole pinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Douglas-fir always had a greater specific leaf area than lodgepole pine”
Claim · model-written summary
Induction times to reach 50 and 90% of steady-state net photosynthetic rate were shorter in understory-grown than in open-grown Douglas-fir branches.
- Taxon
- Douglas-firPseudotsuga menziesiie0
- Treatment
- understory - grown branchese1
- Outcome
- induction times required to reach 50 and 90% of steady-state net photosynthetic ratese1
- Direction
- shortere1
- Comparator
- open-grown branchese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of dynamic and steady-state photosynthesis between understory- and open-grown Douglas-fir seedlings”
e1“induction times required to reach 50 and 90% of steady-state net photosynthetic rates in the understory - grown branches were shorter than those in the open-grown branches”
Claim · model-written summary
On a per unit leaf area basis, understory-grown Douglas-fir branches had a lower dark respiration rate than open-grown branches.
- Taxon
- Douglas-firPseudotsuga menziesiie0
- Treatment
- understory-grown branchese1
- Outcome
- dark respiration ratee1
- Direction
- lowere1
- Qualifier
- On a per unit leaf area basise1
- Comparator
- open-grown branchese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of dynamic and steady-state photosynthesis between understory- and open-grown Douglas-fir seedlings”
e1“On a per unit leaf area basis, the understory-grown branches had a lower dark respiration rate and higher net photosynthetic rates at low PPFDs, but lower net photosynthetic rates at high PPFDs than the open-grown branches”
Claim · model-written summary
On a per unit leaf area basis, understory-grown Douglas-fir branches had higher net photosynthetic rates at low PPFDs but lower rates at high PPFDs than open-grown branches.
- Taxon
- Douglas-firPseudotsuga menziesiie0
- Treatment
- understory-grown branchese1
- Outcome
- net photosynthetic ratese1
- Direction
- highere1
- Qualifier
- lower net photosynthetic rates at high PPFDse1
- Comparator
- open-grown branchese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of dynamic and steady-state photosynthesis between understory- and open-grown Douglas-fir seedlings”
e1“On a per unit leaf area basis, the understory-grown branches had a lower dark respiration rate and higher net photosynthetic rates at low PPFDs, but lower net photosynthetic rates at high PPFDs than the open-grown branches”
Claim · model-written summary
On a dry leaf mass basis, dark respiration rates did not differ between understory-grown and open-grown Douglas-fir branches.
- Taxon
- Douglas-firPseudotsuga menziesiie0
- Treatment
- understory-growne1
- Outcome
- dark respiration ratese1
- Direction
- no differencese1
- Qualifier
- on a dry leaf mass basise1
- Comparator
- open-grown branchese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of dynamic and steady-state photosynthesis between understory- and open-grown Douglas-fir seedlings”
e1“on a dry leaf mass basis, there were no differences in dark respiration rates between the understory-grown and open-grown branches”
Claim · model-written summary
Net photosynthetic rates of understory-grown Douglas-fir branches were equal to or higher than those of open-grown branches at all PPFDs.
- Taxon
- Douglas-firPseudotsuga menziesiie0
- Treatment
- understory-grown branchese1
- Outcome
- net photosynthetic ratese1
- Direction
- equal to or highere1
- Qualifier
- at all PPFDse1
- Comparator
- open-grown branchese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of dynamic and steady-state photosynthesis between understory- and open-grown Douglas-fir seedlings”
e1“net photosynthetic rates of the understory-grown branches were equal to or higher than those of the open-grown branches at all PPFDs”
Claim · model-written summary
After three growing seasons, survival of planted ponderosa pine and western larch seedlings decreased with decreasing light availability from intermediate to low light.
- Taxon
- ponderosa pine and western larche0
- Treatment
- decreasing light availabilitye0
- Outcome
- survivale0
- Direction
- decreasede0
Not reportedComparator
Verbatim
e0“survival of planted ponderosa pine and western larch seedlings decreased with decreasing light availability from intermediate to low light environments”
Claim · model-written summary
Survival of Douglas-fir and Engelmann spruce seedlings did not vary among light environments.
- Taxon
- Douglas-fir and Engelmann spruce
Picea engelmanniiPseudotsuga menziesiie0 - Treatment
- varying light environmentse0
- Outcome
- survivale0
- Direction
- did not varye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“survival of Douglas-fir and Engelmann spruce seedlings did not vary with varying light environments”
Claim · model-written summary
In low light environments, survival increased in the order western larch, ponderosa pine, Douglas-fir, Engelmann spruce.
- Taxon
- western larch to ponderosa pine to Douglas-fir to Engelmann sprucePicea engelmanniie0
- Outcome
- survivale0
- Direction
- increasede0
- Setting
- low light environmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In low light environments, survival increased in order from western larch to ponderosa pine to Douglas-fir to Engelmann spruce”
Claim · model-written summary
With decreasing light availability, all study species except western larch had decreased height growth, with Engelmann spruce showing the greatest decrease.
- Taxon
- all study species except western larche0
- Treatment
- decreasing light availabilitye0
- Outcome
- height growthe0
- Direction
- decreasede0
- Qualifier
- Engelmann spruce had the greatest decreasee0
Not reportedComparator
Verbatim
e0“With decreasing light availability, 1) all study species except western larch had decreased height growth and Engelmann spruce had the greatest decrease among all the species”
Claim · model-written summary
With decreasing light availability, diameter growth decreased for all study species, with Douglas-fir showing the greatest decrease.
- Taxon
- all study speciese1
- Treatment
- decreasing light availabilitye2
- Outcome
- diameter growthe1
- Direction
- decreasede1
- Qualifier
- Douglas-fir had the greatest decreasee1
Not reportedComparator
Verbatim
e2“With decreasing light availability, 1)”
e1“diameter growth decreased for all study species and Douglas-fir had the greatest decrease”
Claim · model-written summary
With decreasing light availability, total biomass growth decreased for all study species, with no difference in the extent of decrease in absolute and relative biomass growth rates among the three evergreen conifers.
- Taxon
- all study speciese1
- Treatment
- decreasing light availabilitye2
- Outcome
- total biomass growthe1
- Direction
- decreasede1
- Qualifier
- no difference in the extent of decreases in both absolute and relative biomass growth rates among the three evergreen coniferse1
Not reportedComparator
Verbatim
e2“With decreasing light availability, 1)”
e1“total biomass growth decreased for all study species and there were no difference in the extent of decreases in both absolute and relative biomass growth rates among the three evergreen conifers”
Claim · model-written summary
Ponderosa pine had the highest absolute biomass growth rate over three growing seasons in any given light environment.
Verbatim
e0“ponderosa pine had the highest absolute biomass growth rate over three growing seasons in any given light environment”
Claim · model-written summary
The ratio of absolute above- to below-ground biomass and specific leaf area varied with light environments in Douglas-fir and Engelmann spruce but not in ponderosa pine and western larch seedlings.
- Taxon
- Douglas-fir and Engelmann sprucePicea engelmanniiPseudotsuga menziesiie0
- Treatment
- light environmentse0
- Outcome
- ratio of absolute above- to below-ground biomass and specific leaf areae0
- Direction
- variede0
- Qualifier
- not in ponderosa pine and western larch seedlingse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The ratio of absolute above- to below-ground biomass and specific leaf area varied with light environments in Douglas-fir and Engelmann spruce but not in ponderosa pine and western larch seedlings”
The same questions in other papers
light · survival · Pseudotsuga menziesii (Douglas-fir)Results agree
1 paper in the same direction as this paper
- no effect
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.