Decomposition of litter and fine roots, microbial biomass and activity on LWF-plots

Litterbag extensively colonized by fungi, LWF plot Beatenberg. Foto: Beat Frey (WSL)

Carbon and nitrogen dynamics in the soil are driven by the input of plant litter to the non-living organic matter pool. Decomposing plant and root litter play a crucial role in the terrestrial global C and N cycle and decomposition rates of litter yield integrated information about the site characteristics of a forest stand. The rate of decomposition is controlled by environmental factors such as climate, litter quality, soil characteristics and microbial activity. Most decomposition studies in forest ecosystems have been carried out on leaf and needle litter, whereas little research has been done on root litter decomposition. The latter should be of special interest since input of dead fine roots to the soil is assumed to be of the same order of magnitude as foliar litterfall and turnover of fine roots is a rapid process.

Objectives

1. To measure the rates of fine roots and litter decomposition on altitudinal transects over ten years.
2. To determine the microbial activity and soil respiration on altitudinal transects.
3. To define important parameters for modelling the C budget in forest ecosystems (e. g. Modell FORCLIM-D).

Methods

• Litterbags with aboveground and root litter on altitudinal transects (mass loss, lignin, nitrogen)
• Soil respiration
• Microbial activity
• Carbon modelling

Study sites

The project have started in autumn 2000 and is planned to end in 2011. Since 2000 we are collecting soil temperature, mass and carbon loss of litter on five different LWF sites with two altitudinal transects in Beatenberg und Schänis. The study sites were:

• Beatenberg (altitudinal transects from 1200 m up to 1800 m)
• Bettlachstock
• Novaggio
• Schänis (altitudinal transects from 500 m up to 1200 m)
• Vordemwald
  

Publications

• Frey B., Hagedorn F., Giudici F. (2006) Girdling of a sweet chestnut forest: Carbon allocation to roots drives soil respiration but has little effect on microbial biomass. Forest, Ecology and Management 225: 271-277.
• Heim A., Frey B. (2004) Predicting litter decomposition rates for Swiss forests. Biogeochemistry 70: 301-315.
• Zimmermann S., Frey B. (2002). Soil respiration and microbial properties in an acid forest soil: the effects of wood ash. Soil Biology and Biochemistry 34: 1727-1737.
• Heim A., Frey B. (2001) Mikrobielle Aktiviäten in nährstoffarmen Waldböden entlang eines Höhentransektes in den Schweizer Voralpen. Mitteilungen Deutsche Bodenkundliche Gesellschaft 96: 337-338.