Long-term dynamics of leaf and root decomposition and nitrogen release in a grey alder (Alnus incana (L.) Moench) and silver birch (Betula pendula Roth.) stands

ABSTRACT

The decomposition of the leaf litter, fine roots (d < 2 mm) and coarser roots (2 ≤ d < 5 mm) of grey alder and silver birch, as well as of α-cellulose sheets using the litterbag method was studied in two experimental stands on Podzoluvisol soils in Southern Estonia. For both tree species, the coarser roots decomposed faster than the fine roots, (p < .05), tree species did not affect the decomposition rate of the roots (p > .5). The nitrogen (N) input to soil from aboveground litter was multiple times higher than the N flux from roots. The remaining relative ash-free mass of the leaves of grey alder and silver birch after three and a half years was similar. After 11 years the remaining relative ash-free mass of the fine and coarser roots of grey alder still accounted for around 10% of the initial value. For silver birch the remaining value was around 20% after 9 years. The litterbag method to underestimates in fertile soils the decomposition of organic matter and thus did not reflect the actual dynamics of decomposition.

KEYWORDS:

• Leaf litter decomposition
• fine root decomposition
• litterbag method
• nitrogen dynamics
• silver birch
• grey alder
• carbon

Acknowledgements

We thank Mrs. Ester Jaigma for revising the English text of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Gunnar Morozov http://orcid.org/0000-0002-9442-9929

Jürgen Aosaar http://orcid.org/0000-0002-7711-2014

Mats Varik http://orcid.org/0000-0002-6633-1967

Hardo Becker http://orcid.org/0000-0002-1150-4808

Additional information

Funding

This study was supported by the Institutional Research Funding IUT21- 04 of the Estonian Ministry of Education and Research and by the Estonian Science Foundation [grant number 5748] as well as by the project of the Estonian University of Life Sciences [T170053MIMK].