Next Article in Journal
Spatio-Temporal Configurations of Human-Caused Fires in Spain through Point Patterns
Next Article in Special Issue
Long-Term (13 Years) Decomposition Rates of Forest Floor Organic Matter on Paired Coniferous and Deciduous Watersheds with Contrasting Temperature Regimes
Previous Article in Journal
Ecosystem Services and Disservices of Mangrove Forests: Insights from Historical Colonial Observations
Previous Article in Special Issue
C Stocks in Forest Floor and Mineral Soil of Two Mediterranean Beech Forests
Article Menu
Issue 9 (September) cover image

Export Article

Open AccessReview
Forests 2016, 7(9), 186;

From Litter to Humus in a Norwegian Spruce Forest: Long-Term Studies on the Decomposition of Needles and Cones

Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, 1432 Aas, Norway
Academic Editor: Björn Berg
Received: 5 June 2016 / Revised: 10 August 2016 / Accepted: 11 August 2016 / Published: 25 August 2016
Full-Text   |   PDF [6522 KB, uploaded 25 August 2016]   |  


The aim of this review and synthesis is to illustrate the gradual transformation of needles and cones from litter to humus. Individual needles may follow quite different decomposition pathways, which contributes to a diverse humus structure. In the litter layer (Oi), about 40% of the needles were excavated by special mites that produced slowly decomposable excrements. In the fermentation layer (Oe), needles which happened to be in close contact with fine roots decomposed more rapidly. Cones decomposed slower than needles during the first 3–5 years, so the role of cones in carbon (C) storage may be greater than indicated by their fraction of fresh litter. Over a 13 years period, potassium (K), magnesium (Mg) and phosphorus (P) in cones was released, while the total amount of calcium (Ca), manganese (Mn), iron (Fe) and aluminium (Al) increased strongly. Nitrogen concentration increased but the total nitrogen content remained rather constant. After 13 years, the cones had sunk about 6 cm into the soil and lost 60% of their dry weight but were morphologically intact. A cone monitored for 28 years was fully recognizable and had not yet reached the stable Oa layer. The most inert decomposition products in the Oa layer were fragments of needles and cone scales, microarthropod excrements and chitinous insect remains. View Full-Text
Keywords: decomposition; spruce needles; cones; long-term; soil profile; microarthropods decomposition; spruce needles; cones; long-term; soil profile; microarthropods

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Hågvar, S. From Litter to Humus in a Norwegian Spruce Forest: Long-Term Studies on the Decomposition of Needles and Cones. Forests 2016, 7, 186.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Forests EISSN 1999-4907 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top