Decomposing litter; limit values; humus accumulation, locally and regionally

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 2018-02, Vol.123, p.494-508
• Main Author: Berg, Björn
• Format: Article
• Language: English
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2017.06.026

•Litter decomposition rates may decrease until a limit value for decomposition.•Stable fractions may range from 0 to 58% of litter mass.•Carbon sequestration rates may be based on two main factors, namely litter fall and the size of the stable litter fraction formed during decomposition.•In forests there is a positive relationship between humus sequestration rate and temperature.•The concept ‘steady state’ is not a general phenomenon. Decomposition of foliar litter may be complete or proceed at a progressively lower rate to become zero and a limit value for decomposition may be estimated. Limit values for decomposition have been found to range from 100% accumulated mass loss to 42%, resulting in ‘stable’ fractions of 0 and 58%, respectively. A limit value does not necessarily mean a complete stop in decomposition but litter mass loss may proceed at a very low rate. An asymptotic function is used to estimate limit value/stable fraction, separating a readily decomposed and a stable residue. The stabilized litter fraction defined as (100 – limit value)/100 may be used for estimating the accumulation rate of stable carbon (C) in organic layers.