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Temperature sensitivity of soil organic matter decomposition in boreal soils

Thesis/Dissertation:

Abstract

The temperature sensitivity of decomposition of different soil organic matter (SOM) fractions was studied with laboratory incubations using C-13 and C-14 isotopes to differentiate between SOM of different age. The quality of SOM and the functionality and composition of microbial communities in soils formed under different climatic conditions were also studied. Transferring of organic layers from a colder to a warmer climate was used to assess how changing climate, litter input and soil biology will affect soil respiration and its temperature sensitivity. Together, these studies gave a consistent picture on how warming climate will affect the decomposition of different SOM fractions in Finnish forest soils: the most labile C was least temperature sensitive, indicating that it is utilized irrespective of temperature. The decomposition of intermediate C, with mean residence times from some years to decades, was found to be highly temperature sensitive. Even older, centennially cycling C was again less temperature sensitive, indicating that different stabilizing mechanisms were limiting its decomposition even at higher temperatures. Because the highly temperature sensitive, decadally cycling C, forms a major part of SOM stock in the organic layers of the studied forest soils, these results mean that these soils could lose more carbon during  More>>
Authors:
Publication Date:
Jul 01, 2010
Product Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis or Dissertation; TH: Thesis (Ph.D.); 155 refs. Dissertationes forestales 107. The thesis includes also 6 previous publications published elsewhere
Subject:
54 ENVIRONMENTAL SCIENCES; SOILS; ORGANIC MATTER; DECOMPOSITION; FORESTS; BOREAL REGIONS; CLIMATIC CHANGE; CARBON CYCLE; TEMPERATURE DEPENDENCE; RESPIRATION
OSTI ID:
1008046
Research Organizations:
Helsinki Univ. (Finland). Dept. of Forest Sciences, Forest Soil Science; Finnish Environment Institute, Helsinki (Finland), Research Programme for Global Change
Country of Origin:
Finland
Language:
English
Other Identifying Numbers:
Other: ISBN 978-951-651-304-4; ISBN 978-951-651-303-7; TRN: FI1103014
Availability:
Available in fulltext at http://www.metla.fi/dissertationes/df107.htm
Submitting Site:
FI
Size:
59 p. pages
Announcement Date:
Mar 14, 2011

Thesis/Dissertation:

Citation Formats

Karhu, K. Temperature sensitivity of soil organic matter decomposition in boreal soils. Finland: N. p., 2010. Web.
Karhu, K. Temperature sensitivity of soil organic matter decomposition in boreal soils. Finland.
Karhu, K. 2010. "Temperature sensitivity of soil organic matter decomposition in boreal soils." Finland.
@misc{etde_1008046,
title = {Temperature sensitivity of soil organic matter decomposition in boreal soils}
author = {Karhu, K}
abstractNote = {The temperature sensitivity of decomposition of different soil organic matter (SOM) fractions was studied with laboratory incubations using C-13 and C-14 isotopes to differentiate between SOM of different age. The quality of SOM and the functionality and composition of microbial communities in soils formed under different climatic conditions were also studied. Transferring of organic layers from a colder to a warmer climate was used to assess how changing climate, litter input and soil biology will affect soil respiration and its temperature sensitivity. Together, these studies gave a consistent picture on how warming climate will affect the decomposition of different SOM fractions in Finnish forest soils: the most labile C was least temperature sensitive, indicating that it is utilized irrespective of temperature. The decomposition of intermediate C, with mean residence times from some years to decades, was found to be highly temperature sensitive. Even older, centennially cycling C was again less temperature sensitive, indicating that different stabilizing mechanisms were limiting its decomposition even at higher temperatures. Because the highly temperature sensitive, decadally cycling C, forms a major part of SOM stock in the organic layers of the studied forest soils, these results mean that these soils could lose more carbon during the coming years and decades than estimated earlier. SOM decomposition in boreal forest soils is likely to increase more in response to climate warming, compared to temperate or tropical soils, also because the Q10 is temperature dependent. In the northern soils the warming will occur at a lower temperature range, where Q10 is higher, and a similar increase in temperature causes a higher relative increase in respiration rates. The Q10 at low temperatures was found to be inversely related to SOM quality. At higher temperatures respiration was increasingly limited by low substrate availability. (orig.)}
place = {Finland}
year = {2010}
month = {Jul}
}