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The Vertical Distribution of Roots, Mycorrhizal Mycelia and Nutrient Acquisition in Mature Forest Trees

Göransson, Hans LU (2006)
Abstract (Swedish)
Popular Abstract in Swedish

Den vertikala fördelningen av näringsupptaget hos gran (Picea abies (L.) Karst.), bok (Fagus sylvatica L.) och skogsek (Quercus robur L.) och har undersökts i södra Skandinavien. Två olika metoder har används. Med den första metoden uppskattades trädets näsringsupptag på olika markdjup genom att bestämma fördelningen av rötterna och det externa ectomycorrhizamycelet (EEM) samt mäta näringsupptagningskapaciteten hos rötterna på olika markdjup. Finrötternas biomassa och längd (Ø<1mm) bestämdes ner till 55 cm markdjup. Mängden EEM uppskattades genom mätningar av PLFA 18.2w6,9 och en ny inkubationsteknik. Med denna teknik var det möjligt att separera ectomycorrhiza mycel och mycelet från... (More)
Popular Abstract in Swedish

Den vertikala fördelningen av näringsupptaget hos gran (Picea abies (L.) Karst.), bok (Fagus sylvatica L.) och skogsek (Quercus robur L.) och har undersökts i södra Skandinavien. Två olika metoder har används. Med den första metoden uppskattades trädets näsringsupptag på olika markdjup genom att bestämma fördelningen av rötterna och det externa ectomycorrhizamycelet (EEM) samt mäta näringsupptagningskapaciteten hos rötterna på olika markdjup. Finrötternas biomassa och längd (Ø<1mm) bestämdes ner till 55 cm markdjup. Mängden EEM uppskattades genom mätningar av PLFA 18.2w6,9 och en ny inkubationsteknik. Med denna teknik var det möjligt att separera ectomycorrhiza mycel och mycelet från saprofytiska svampar. Upptagningskapaciteten hos finrötterna bestämdes med hjälp av en rotbioassay med 86Rb (en analog till kalium (K)) och ammonium 15NH4. Med den andra metoden mättes trädets relativa upptagningskapaciteten på olika markdjup mha. 15NH4, radioaktivt fosfor (H232PO4- and H233PO4-) och cesium (en annan analog till K) som injicerades i marken på olika djup och för att efter 21-339 dagar kunde återfinnas i löv och barr.



Fördelningen av EEM verkade i stort följa rotfördelningen. Upptagningskapaciteten av 86Rb i ekrötterna avtog med markdjupet men gran och bok rötternas upptag var oberoende av djupet. Då EEM följde rotdistributionen kunde trädets relativa upptagningskapacitet på de olika markdjupen uppskattas genom att rotmängden multiplicerades med rötternas upptagningskapacitet på vart djup. Det uppskattade upptaget av K från 50 cm markdjup, relativt till 5 cm, befanns var lägre hos ek än hos gran och bok pga. ekrötternas dåliga upptagningsförmåga i de djupare marklagren. De direkta mätningarna av trädens K-upptag bekräftade att eken hade en, relativt sett, lägre upptagningskapacitet i djupa jordlager än gran och bok. Det relativa upptaget av K och N från 50 cm djup var större i de direkta mätningarna än vad som uppskattades med den första metoden. Detta berodde troligtvis på en stor överlappning i de översta marklagret av de jordvolymer omkring rötter och hyfer från vilka näring kan diffundera till roten och därmed minskat upptaget per rotlängd. Resultaten visar att i skogsjordar följer inte alltid näringsupptaget rot och EEM distributionen. Detta kan bero på en överkapacitet att ta upp mobila joner i de övre marklagren och/eller skillnader i upptagnings kapaciteten hos rötterna på olika markdjup. (Less)
Abstract
The vertical distribution of the nutrient uptake of Norway spruce (Picea abies (L.) Karst.), European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) has been investigated in southern Scandinavia. Two approaches were employed. The first involved estimation of the nutrient uptake capacity of the trees at different soil depths by determining the distributions of roots, external ectomycorrhizal mycelia (EEM) and the nutrient uptake capacity of the roots located at different soil depths. The fine root biomass and length (Ø<1 mm) were determined down to a soil depth of 55 cm. The amount of EEM was estimated by measurements of the PLFA 18.2w6,9 using a new incubation technique. It was thus possible to separate the... (More)
The vertical distribution of the nutrient uptake of Norway spruce (Picea abies (L.) Karst.), European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) has been investigated in southern Scandinavia. Two approaches were employed. The first involved estimation of the nutrient uptake capacity of the trees at different soil depths by determining the distributions of roots, external ectomycorrhizal mycelia (EEM) and the nutrient uptake capacity of the roots located at different soil depths. The fine root biomass and length (Ø<1 mm) were determined down to a soil depth of 55 cm. The amount of EEM was estimated by measurements of the PLFA 18.2w6,9 using a new incubation technique. It was thus possible to separate the ectomycorrhizal and saprophytic mycelia. The uptake capacity of fine roots was determined by root bioassays using labelled rubidium, 86Rb+ (an analogue to potassium (K)), and ammonium 15NH4+. In the second method, direct measurements of the relative uptake capacity of the trees from different soil depths were made by injection of 15NH4+, labelled phosphorus (H232PO4- and H233PO4-) and caesium (another analogue to K) into the soil, and after 21-339 days the tracers were recovered in the foliage.



Generally, the amount of EEM seemed to follow the root distribution. The uptake capacity of 86Rb+ by fine roots decreased with soil depth for oak, but was similar in beech and Norway spruce irrespective of soil depth. The nutrient uptake capacity of the tree was estimated by multiplying the root weight by the uptake capacity of the roots at the different soil horizons, as EEM followed the root distribution. In oak, the estimated uptake of K from 50 cm soil depth relative to 5 cm was lower than in beech and Norway spruce due to the low uptake capacity of the oak's fine roots in deep soil layers. Direct measurements of the K uptake capacity of trees confirmed that the oaks had a lower uptake capacity at greater soil depth than beech and Norway spruce. The relative uptake of K and N from 50 cm soil depth was higher using direct measurements than estimates using the first method. This was probably due to extensive overlapping of the soil volumes around the roots and hyphae from which nutrients can diffuse in the top layer, which decreases the uptake per unit root length. The results show that the nutrient uptake dose not always follow the root and EEM distribution in forest soils. This may be due to an overcapacity of nutrient uptake for mobile ions in the top layer and/or differences in the nutrient uptake capacity of roots at different soil depths. (Less)
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author
supervisor
opponent
  • Professor Godbold, Douglas, School of Agricultural and Forest Sciences, University of Wales, UK
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Plant ecology, Växtekologi, isotopes, Root bioassay, Mixed stands, Picea abies, Fagus sylvatica, Nutrient uptake, Quercus robur, PLFA, Root distribution, Ectomycorrhiza
pages
95 pages
publisher
Department of Ecology, Lund University
defense location
Blå Hallen at the department of ecology, Ecology building, Sölvegatan 37
defense date
2006-02-24 10:00
ISBN
91-7105-233-X
language
English
LU publication?
yes
id
cf7765f6-5013-48f6-976a-c1c7d283d21e (old id 546214)
date added to LUP
2007-09-04 15:45:43
date last changed
2016-09-19 08:45:06
@misc{cf7765f6-5013-48f6-976a-c1c7d283d21e,
  abstract     = {The vertical distribution of the nutrient uptake of Norway spruce (Picea abies (L.) Karst.), European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) has been investigated in southern Scandinavia. Two approaches were employed. The first involved estimation of the nutrient uptake capacity of the trees at different soil depths by determining the distributions of roots, external ectomycorrhizal mycelia (EEM) and the nutrient uptake capacity of the roots located at different soil depths. The fine root biomass and length (Ø&lt;1 mm) were determined down to a soil depth of 55 cm. The amount of EEM was estimated by measurements of the PLFA 18.2w6,9 using a new incubation technique. It was thus possible to separate the ectomycorrhizal and saprophytic mycelia. The uptake capacity of fine roots was determined by root bioassays using labelled rubidium, 86Rb+ (an analogue to potassium (K)), and ammonium 15NH4+. In the second method, direct measurements of the relative uptake capacity of the trees from different soil depths were made by injection of 15NH4+, labelled phosphorus (H232PO4- and H233PO4-) and caesium (another analogue to K) into the soil, and after 21-339 days the tracers were recovered in the foliage.<br/><br>
<br/><br>
Generally, the amount of EEM seemed to follow the root distribution. The uptake capacity of 86Rb+ by fine roots decreased with soil depth for oak, but was similar in beech and Norway spruce irrespective of soil depth. The nutrient uptake capacity of the tree was estimated by multiplying the root weight by the uptake capacity of the roots at the different soil horizons, as EEM followed the root distribution. In oak, the estimated uptake of K from 50 cm soil depth relative to 5 cm was lower than in beech and Norway spruce due to the low uptake capacity of the oak's fine roots in deep soil layers. Direct measurements of the K uptake capacity of trees confirmed that the oaks had a lower uptake capacity at greater soil depth than beech and Norway spruce. The relative uptake of K and N from 50 cm soil depth was higher using direct measurements than estimates using the first method. This was probably due to extensive overlapping of the soil volumes around the roots and hyphae from which nutrients can diffuse in the top layer, which decreases the uptake per unit root length. The results show that the nutrient uptake dose not always follow the root and EEM distribution in forest soils. This may be due to an overcapacity of nutrient uptake for mobile ions in the top layer and/or differences in the nutrient uptake capacity of roots at different soil depths.},
  author       = {Göransson, Hans},
  isbn         = {91-7105-233-X},
  keyword      = {Plant ecology,Växtekologi,isotopes,Root bioassay,Mixed stands,Picea abies,Fagus sylvatica,Nutrient uptake,Quercus robur,PLFA,Root distribution,Ectomycorrhiza},
  language     = {eng},
  pages        = {95},
  publisher    = {ARRAY(0x8a04830)},
  title        = {The Vertical Distribution of Roots, Mycorrhizal Mycelia and Nutrient Acquisition in Mature Forest Trees},
  year         = {2006},
}