Abstract
One concern of short-rotation intensively cultured hardwood plantations is the accelerated loss of nutrients due to removal of large amounts of biomass and short harvest cycles. In this study, we examine simultaneously the nitrogen trends in all the various pools (trees, weeds, soil, and soil water). We compare the N trends and fertilization rates with leaf N status and tree growth on two soil types over 5 years. The data show a gradual transition from an early herbaceous plant dominated system to a tree-dominated system later in the rotation. On the more fertile site, fertilization was not beneficial to tree growth the 1st year, or even the 2nd, if all weeds were kept out. However, when weeds were present, fertilization was very beneficial to tree growth in the 2nd and 3rd years. After crown closure, fertilization declined in importance as herbaceous vegetation was eliminated, tree foliage biomass stabilized, and N cycling increased. Foliar N was strongly related to fertilizer rate during years 2 and 3 on the fertile site and during the entire 5 years on the infertile site. Form these relations and others, we infer possible critical times for N fertilization during the first 5 years of a rapidly growing hybrid poplar plantation from the time of initial planting through complete canopy closure and shading out of the herbaceous competition.
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Claims 10
Claim · model-written summary
The plantation shifted from herbaceous plant dominance to tree dominance over the rotation.
- Outcome
- transition from an early herbaceous plant dominated system to a tree-dominated systeme0
PopulusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a gradual transition from an early herbaceous plant dominated system to a tree-dominated system later in the rotation”
t0“hybrid poplar”
Claim · model-written summary
On the fertile site with weeds excluded, fertilization did not benefit tree growth in the first or second year.
- Treatment
- fertilizatione0
- Outcome
- tree growthe0
- Direction
- not beneficiale0
- Qualifier
- if all weeds were kept oute0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“On the more fertile site, fertilization was not beneficial to tree growth the 1st year, or even the 2nd, if all weeds were kept out.”
t0“hybrid poplar”
Claim · model-written summary
With weeds present, fertilization benefited tree growth in years two and three.
- Treatment
- fertilizatione0
- Interactor
- weedse0weed
- Outcome
- tree growthe0
- Direction
- very beneficiale0
- Qualifier
- when weeds were presente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when weeds were present, fertilization was very beneficial to tree growth in the 2nd and 3rd years”
t0“hybrid poplar”
Claim · model-written summary
After crown closure, fertilization declined in importance.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After crown closure, fertilization declined in importance as herbaceous vegetation was eliminated, tree foliage biomass stabilized, and N cycling increased.”
t0“hybrid poplar”
Claim · model-written summary
Herbaceous vegetation was eliminated after crown closure.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“herbaceous vegetation was eliminated”
t0“hybrid poplar”
Claim · model-written summary
Tree foliage biomass stabilized after crown closure.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tree foliage biomass stabilized”
t0“hybrid poplar”
Claim · model-written summary
Nitrogen cycling increased after crown closure.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N cycling increased”
t0“hybrid poplar”
Claim · model-written summary
Foliar nitrogen was strongly related to fertilizer rate on the fertile site in years two and three.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Foliar N was strongly related to fertilizer rate during years 2 and 3 on the fertile site”
t0“hybrid poplar”
Claim · model-written summary
Foliar nitrogen was strongly related to fertilizer rate throughout five years on the infertile site.
- Treatment
- fertilizer ratee0
- Outcome
- Foliar Ne0
- Qualifier
- during the entire 5 years on the infertile sitee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Foliar N was strongly related to fertilizer rate during years 2 and 3 on the fertile site and during the entire 5 years on the infertile site.”
t0“hybrid poplar”
Claim · model-written summary
The authors infer critical fertilization times across the first five plantation years.
- Outcome
- possible critical times for N fertilization during the first 5 yearse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we infer possible critical times for N fertilization during the first 5 years of a rapidly growing hybrid poplar plantation”
The same questions in other papers
fertilization · growth · Populus (poplar)Results differ
35 papers in the same direction as this paper · 9 in the opposite direction · 1 reporting no difference from an alternative
- positive
- no effect
- negative
42 papers more in this group
See all 46 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.