Decomposition of tree root litter in a climatic transect of coniferous forests in northern Europe: A synthesis

Abstract

The purpose of this study was to understand the variation in root litter mass‐loss rates in a climatic transect across a large region ranging from the Arctic Circle (66°N) in Scandinavia to Berlin (52°N) in north‐east Germany, dominated by coniferous monocultural forests. To investigate the combined influence of litter quality and climate, data were used from 37 sites and plots at which root litters of three coniferous species (Pinus sylvestris, Pinus contorta and Picea abies) had been incubated. In spite of the considerable climatic differences among sites, there were no strong relationships between any climatic variable and the lst‐yr mass loss (range 17.0–40.9%). For the lst‐yr mass loss, the average annual temperature was the most rate‐regulating factor for all litter combined, with a value for R ² _adj of 0.186. Substrate quality also had an influence. Thus, for the whole region lignin concentration was significant, with a value for R ² _adj of 0.142. For the separated groups of pine and spruce stands the value for r ² increased but the factor average temperature still dominated and for pine the R ² _adj reached a value of 0.346. Over the region N concentration in the fresh pine root litter was significant (R² _adj = 0.232). For the root litter of P. abies the average temperature in July was the strongest rate‐regulating climatic factor, with a value for R ² _adj of 0.381. A combination of temperature in July and the initial P concentration in the litter gave an R ² _adj value of 0.713 for P. abies litter, thus explaining about 71% of the variation.

Key words:

• climate
• decomposition
• lignin
• nitrogen. Norway spruce
• Scots pine