Abstract
Tropospheric ozone (O(3)) triggers physiological changes in leaves that affect carbon source strength leading to decreased carbon allocation below-ground, thus affecting roots and root symbionts. The effects of O(3) depend on the maturity-related physiological state of the plant, therefore adult and young forest trees might react differently. To test the applicability of young beech plants for studying the effects of O(3) on forest trees and forest stands, beech seedlings were planted in containers and exposed for two years in the Kranzberg forest FACOS experiment (Free-Air Canopy O(3) Exposure System, http://www.casiroz.de ) to enhanced ozone concentration regime (ambient [control] and double ambient concentration, not exceeding 150 ppb) under different light conditions (sun and shade). After two growing seasons the biomass of the above- and below-ground parts, beech roots (using WinRhizo programme), anatomical and molecular (ITS-RFLP and sequencing) identification of ectomycorrhizal types and nutrient concentrations were assessed. The mycorrhization of beech seedlings was very low ( CA. 5 % in shade, 10 % in sun-grown plants), no trends were observed in mycorrhization (%) due to ozone treatment. The number of Cenococcum geophilum type of ectomycorrhiza, as an indicator of stress in the forest stands, was not significantly different under different ozone treatments. It was predominantly occurring in sun-exposed plants, while its majority share was replaced by Genea hispidula in shade-grown plants. Different light regimes significantly influenced all parameters except shoot/root ratio and number of ectomycorrhizal types. In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants. Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index, concentration of Zn, and Ca/Al ratio. Due to the general reduction in root growth indices and nutrient cycling in ozone-fumigated plants, alterations in soil carbon pools could be predicted.
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Claims 16
Claim · model-written summary
Beech seedling mycorrhization was about 5% in shade.
Verbatim
e0“The mycorrhization of beech seedlings was very low ( CA. 5 % in shade, 10 % in sun-grown plants)”
Claim · model-written summary
Beech seedling mycorrhization was 10% in sun-grown plants.
Verbatim
e0“The mycorrhization of beech seedlings was very low ( CA. 5 % in shade, 10 % in sun-grown plants)”
Claim · model-written summary
No ozone-related trends were observed in beech mycorrhization percentage.
Not reportedComparator
Verbatim
e0“no trends were observed in mycorrhization (%) due to ozone treatment”
t0“Beech”
Claim · model-written summary
Cenococcum geophilum ectomycorrhiza numbers did not differ significantly among ozone treatments.
- Taxon
- Cenococcum geophilum
Cenococcum geophilume0 - Treatment
- different ozone treatmentse0
- Outcome
- number of Cenococcum geophilum type of ectomycorrhizae0
- Direction
- not significantly differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The number of Cenococcum geophilum type of ectomycorrhiza, as an indicator of stress in the forest stands, was not significantly different under different ozone treatments.”
Claim · model-written summary
Cenococcum geophilum predominated in sun-exposed beech plants.
- Taxon
- Cenococcum geophilumCenococcum geophilume0
- Interactor
- Beecht0host
- Outcome
- predominantly occurringe1
- Qualifier
- sun-exposed plantse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cenococcum geophilum type of ectomycorrhiza”
e1“It was predominantly occurring in sun-exposed plants”
t0“Beech”
Claim · model-written summary
Genea hispidula replaced the majority share of Cenococcum in shade-grown beech.
- Taxon
- Genea hispidula
Genea hispidulae0 - Interactor
- Beecht0host
- Outcome
- majority share was replaced by Genea hispidulae0
- Qualifier
- shade-grown plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while its majority share was replaced by Genea hispidula in shade-grown plants”
t0“Beech”
Claim · model-written summary
Light regimes significantly influenced all assessed parameters except shoot/root ratio and ectomycorrhizal type number.
- Taxon
- Beecht0
- Treatment
- Different light regimese0
- Outcome
- all parameterse0
- Qualifier
- except shoot/root ratio and number of ectomycorrhizal typese0
Not reportedComparatorDirection
Verbatim
e0“Different light regimes significantly influenced all parameters except shoot/root ratio and number of ectomycorrhizal types.”
t0“Beech”
Claim · model-written summary
Ozone fumigation significantly lowered ectomycorrhizal type number relative to controls.
Verbatim
e0“In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants.”
t0“Beech”
Claim · model-written summary
Ozone significantly lowered root tip numbers per length of 1 to 2 mm root diameter and root length density per soil volume.
Verbatim
e0“In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants.”
t0“Beech”
Claim · model-written summary
Ozone significantly lowered Mg concentration relative to controls.
Verbatim
e0“In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants.”
t0“Beech”
Claim · model-written summary
Root, shoot and leaf dry weights tended to decrease under ozone.
- Taxon
- Beecht0
- Treatment
- ozone-fumigatede1
- Outcome
- root, shoot, leaf, and total dry weightse0
- Direction
- decreasee0
- Qualifier
- Trendse0
Not reportedComparator
Verbatim
e0“Trends to a decrease were found in root, shoot, leaf, and total dry weights”
e1“ozone-fumigated plants”
t0“Beech”
Claim · model-written summary
Total dry weight tended to decrease under ozone.
- Taxon
- Beecht0
- Treatment
- ozone-fumigatede1
- Outcome
- total dry weightse0
- Direction
- decreasee0
- Qualifier
- Trendse0
Not reportedComparator
Verbatim
e0“Trends to a decrease were found in root, shoot, leaf, and total dry weights”
e1“ozone-fumigated plants”
t0“Beech”
Claim · model-written summary
Total root tip number, vital mycorrhizal root tip number and fine root mass density tended to decrease under ozone.
- Taxon
- Beecht0
- Treatment
- ozone-fumigatede1
- Outcome
- total number of root tips, number of vital mycorrhizal root tips, fine root (mass) densitye0
- Direction
- decreasee0
- Qualifier
- Trendse0
Not reportedComparator
Verbatim
e0“Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density”
e1“ozone-fumigated plants”
t0“Beech”
Claim · model-written summary
Root tip density per surface and root area index tended to decrease under ozone.
- Taxon
- Beecht0
- Treatment
- ozone-fumigatede1
- Outcome
- root tip density per surface, root area indexe0
- Direction
- decreasee0
- Qualifier
- Trendse0
Not reportedComparator
Verbatim
e0“Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index”
e1“ozone-fumigated plants”
t0“Beech”
Claim · model-written summary
Zn concentration and Ca/Al ratio tended to decrease under ozone.
- Taxon
- Beecht0
- Treatment
- ozone-fumigatede1
- Outcome
- concentration of Zn, and Ca/Al ratioe0
- Direction
- decreasee0
- Qualifier
- Trendse0
Not reportedComparator
Verbatim
e0“Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index, concentration of Zn, and Ca/Al ratio.”
e1“ozone-fumigated plants”
t0“Beech”
Claim · model-written summary
Reduced root growth and nutrient cycling in ozone-fumigated plants could alter soil carbon pools.
- Outcome
- alterations in soil carbon poolse0
- Qualifier
- general reduction in root growth indices and nutrient cycling in ozone-fumigated plantse0
Not reportedTaxon
Verbatim
e0“Due to the general reduction in root growth indices and nutrient cycling in ozone-fumigated plants, alterations in soil carbon pools could be predicted.”