Abstract
Results after 8 years at two experimental sites show no productivity advantage for very short rotations of black Cottonwood; in fact, harvest cycles less than 8 years reduced productivity. At one site, the combined yield from two harvests at 4-year intervals was only 75% of the yield from one harvest at 8 years. Mean annual dry biomass increment per hectare was 6.05 t for the former versus 8.05 t for the latter (P ≤ 0.001).At another, more productive site, annual dry biomass increment averaged 5.8 for the first 2-year harvest, 8.9 for the second 2-year harvest, and 9.7 t/ha for the third harvest made after 4 years (total age of the planting at time of the third harvest was 8 years). Productivities for the second and third harvests were significantly higher than for the first harvest (P ≤ 0.05) but were not significantly different from each other.Highest productivity over 8 years for 2- and 4-year harvest cycles was obtained with 30 × 30 to 61 × 122 cm spacings. Productivity from a single 8-year harvest cycle was also highest at 61 × 122 cm spacing. However, data from both studies indicated a declining effect of spacing on productivity with increasing age of the planting.
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Claims 10
Claim · model-written summary
Very short rotations gave no productivity advantage in black Cottonwood.
- Taxon
- black Cottonwood
Populus trichocarpae0 - Treatment
- very short rotationse0
- Outcome
- productivitye0
- Direction
- no productivity advantagee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
Claim · model-written summary
Harvest cycles less than 8 years reduced productivity of black Cottonwood.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- harvest cycles less than 8 yearse1
- Outcome
- productivitye1
- Direction
- reducede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e1“in fact, harvest cycles less than 8 years reduced productivity”
Claim · model-written summary
At one site the combined yield of two 4-year harvests was 75% of one 8-year harvest.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- two harvests at 4-year intervalse2
- Outcome
- combined yielde2
- Direction
- lowerinferrede2
- Value
- 75%e2
- Comparator
- one harvest at 8 yearse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e2“the combined yield from two harvests at 4-year intervals was only 75% of the yield from one harvest at 8 years”
Claim · model-written summary
Mean annual dry biomass increment was 6.05 t/ha for two 4-year harvests versus 8.05 t/ha for one 8-year harvest.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- two harvests at 4-year intervalse2
- Outcome
- Mean annual dry biomass increment per hectaree3
- Direction
- lowerinferrede3
- Value
- 6.05 te3
- Comparator
- one harvest at 8 yearse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e2“the combined yield from two harvests at 4-year intervals was only 75% of the yield from one harvest at 8 years”
e3“Mean annual dry biomass increment per hectare was 6.05 t for the former versus 8.05 t for the latter”
Claim · model-written summary
At the second site the second 2-year harvest had higher annual dry biomass increment (8.9) than the first 2-year harvest (5.8).
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- second 2-year harveste4
- Outcome
- annual dry biomass incremente4
- Direction
- highere5
- Value
- 8.9e4
- Comparator
- first 2-year harveste4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e4“annual dry biomass increment averaged 5.8 for the first 2-year harvest, 8.9 for the second 2-year harvest”
e5“Productivities for the second and third harvests were significantly higher than for the first harvest”
Claim · model-written summary
At the second site the third harvest (9.7 t/ha) had higher annual dry biomass increment than the first 2-year harvest.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- third harvest made after 4 yearse6
- Outcome
- annual dry biomass incremente4
- Direction
- highere5
- Value
- 9.7 t/hae6
- Comparator
- first 2-year harveste4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e4“annual dry biomass increment averaged 5.8 for the first 2-year harvest, 8.9 for the second 2-year harvest”
e5“Productivities for the second and third harvests were significantly higher than for the first harvest”
e6“9.7 t/ha for the third harvest made after 4 years”
Claim · model-written summary
The second and third harvests at the second site did not differ significantly in productivity.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Outcome
- Productivitiese5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e5“Productivities for the second and third harvests were significantly higher than for the first harvest”
e7“but were not significantly different from each other”
Claim · model-written summary
Highest productivity over 8 years for 2- and 4-year harvest cycles was obtained with 30 x 30 to 61 x 122 cm spacings.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- 30 × 30 to 61 × 122 cm spacingse1
- Outcome
- productivity over 8 yearse1
- Direction
- Higheste1
- Qualifier
- 2- and 4-year harvest cyclese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e1“Highest productivity over 8 years for 2- and 4-year harvest cycles was obtained with 30 × 30 to 61 × 122 cm spacings”
Claim · model-written summary
Productivity from a single 8-year harvest cycle was also highest at 61 x 122 cm spacing.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- 61 × 122 cm spacinge1
- Outcome
- Productivity from a single 8-year harvest cyclee1
- Direction
- higheste1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e1“Productivity from a single 8-year harvest cycle was also highest at 61 × 122 cm spacing”
Claim · model-written summary
The declining effect of spacing on productivity of black Cottonwood increases with the age of the planting.
- Taxon
- black CottonwoodPopulus trichocarpae0
- Treatment
- spacinge1
- Outcome
- productivitye1
- Direction
- declininge1
- Qualifier
- with increasing age of the plantinge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“show no productivity advantage for very short rotations of black Cottonwood”
e1“a declining effect of spacing on productivity with increasing age of the planting”
The same questions in other papers
density · yield · Populus trichocarpa (black cottonwood)Results agree
1 paper in the same direction as this paper
- positive
rotation · yield · Populus trichocarpa (black cottonwood)Results agree
1 paper in the same direction as this paper
- negative
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.