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Plant-microbe-soil interactions and soil nitrogen dynamics in boreal forests

development of nitrogen limitation

Blaško, Róbert (2014). Plant-microbe-soil interactions and soil nitrogen dynamics in boreal forests. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2014:103
ISBN 978-91-576-8154-6
eISBN 978-91-576-8155-3
[Doctoral thesis]

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Widespread nitrogen (N) limitation of plant growth in boreal forests is a well recognized phenomenon. Yet, the mechanisms responsible for the development of N limitation are unknown. By exploring the linkage between N cycling and microbial community structure, this thesis examines the role of soil microorganisms in N limitation development.

The first part of the thesis addresses effects of long-term N additions on microbial communities and N cycling in Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) forests and if the effects are reversible after termination of N addition. The second part of the thesis explores the role soil microbes play in the development of N limitation in primary forest ecosystems. The general structure and biomass of soil microbial communities was assessed by phospholipid fatty acid analyses. Soil and ecosystem N cycling were inferred from gross N mineralisation measurements and 15N natural abundance in soil and foliage. Retention of the 15N label by soil microorganisms was used to infer N retention capacity of the ecosystems.

Despite unique responses in microbial communities and gross N mineralisation to long-term N additions between the two studies, some common patterns emerged. Gross N mineralisation, microbial community structure, and N retention were strongly linked. Microbial biomass decreased but gross N mineralisation increased after N addition. The increased biotic N retention after termination of N addition coincided with increased functional role ectomycorrhizal fungi play in ecosystem N cycle as inferred from changes in 15N natural abundance.

In the land uplift chronosequence, large inputs of N through N2-fixation resulted in soil N accumulation but a decline in N supply rates. This coincided with increasing microbial N-immobilisation and increasing abundance of ectomycorrhizal fungi suggesting their importance in N retention. I suggest that the strong N limitation typical of boreal forests can develop in about 150 years.

This thesis provides strong evidence that ectomycorrhizal fungi played an important role both in the return of N limitation two decades after termination of N addition and in the development of N limitation in a primary boreal forest.

Authors/Creators:Blaško, Róbert
Title:Plant-microbe-soil interactions and soil nitrogen dynamics in boreal forests
Subtitle:development of nitrogen limitation
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :20 November 2014
Depositing date:20 November 2014
Number of Pages:63
I.Blaško, R., Högberg, P., Bach, L.H., Högberg, M.N. (2013). Relations among soil microbial community composition, nitrogen turnover, and tree growth in N-loaded and previously N-loaded boreal spruce forest. Forest Ecology and Management 302, 319-328.
II.Högberg, M., Blaško, R., Bach, L., Hasselquist, N., Egnell, G., Näsholm, T., Högberg, P., (2014). The return of an experimentally N-saturated boreal forest to an N-limited state: observations on the soil microbial community structure, biotic N retention capacity and gross N mineralisation. Plant and Soil 381, 45-60.
III.Blaško R., Holm Bach L., Yarwood S., Trumbore S., Högberg P., Högberg M.N. (20XX). Shifts in soil microbial community structure, nitrogen cycling and the concomitant declining nitrogen availability in ageing primary boreal forest ecosystems. Manuscript.
Place of Publication:Umeå
Publisher:Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8154-6
ISBN for electronic version:978-91-576-8155-3
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F61 Plant physiology - Nutrition
K Forestry > K01 Forestry - General aspects
P Natural resources > P34 Soil biology
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Other Earth and Related Environmental Sciences
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Forest Science
Obsolete subject words > NATURAL SCIENCES > Biology > Terrestrial, freshwater and marine ecology > Terrestrial ecology
Agrovoc terms:soil microorganisms, nitrogen mineralization, nitrogen retention, ectomycorrhizae, fungi, phospholipids, fatty acids, boreal forests, sweden
Keywords:gross nitrogen mineralisation, phospholipid fatty acids, ectomycorrhizal fungi, N limitation, boreal forest, land uplift, long-term N addition, N retention
Permanent URL:
ID Code:11665
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
External funders:Swedish Research Council
Deposited By: Robert Blasko
Deposited On:21 Nov 2014 14:37
Metadata Last Modified:02 Dec 2014 11:09

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