Roots, mycorrhizas and their external mycelia in carbon dynamics in forest soil
9-13 September 2006, Rovaniemi, Finland
Background, aims and sessions
There is wide consensus in the scientific community that roots of trees and understorey vegetation play an important role in the carbon dynamics of forest soils, but quantitatively, not enough is known about their contribution to the carbon budgets.
Fine roots - due to their fast turnover in comparison with many other plant components - may produce a large part of the soil litter input. Thus, a high proportion of soil organic matter originates from dead and decomposing fine roots. Data on fine root mortality are however scarce, and turnover rates vary in different experiments and between different methods.
In the decomposition process, carbon is either emitted as CO 2, immobilised in the structure of decomposing organisms, or accumulates into physically and chemically stable structures. The chemical characteristics of the litter (e.g. organic compounds such as lignins and polyfenols) affect its decomposition rate. Only a few studies have focused on fine root litter decomposition.
Mycorrhizal symbioses increase the sink strength of roots for carbon, primarily by increasing metabolic activity of the root system but also by increasing the size of the root-hyphal sink. It has also been demonstrated that a large part of soil respiration is derived from roots. The structure of both fine roots and associated mycorrhizas varies greatly in different species and sites and the relationships of structural variation to functioning is a new challenging research area.
Comparison and development of methods for measuring and modelling coarse root systems is also important for evaluating the role of roots in carbon storage and cycling. A further key aspect will be to develop knowledge and methods on how to relate the structure of coarse root systems to fine root distribution and function.
Knowledge about carbon allocation to roots would be important for estimating the role of soils in the global carbon budget under scenarios of increasing atmospheric carbon, for understanding plant productivity under changing climate, or in different silvicultural regimes.
The aim of the international workshop Roots, mycorrhizas and their external mycelia in carbon dynamics in forest soil is to present and discuss research results on the role of roots in carbon dynamics in forest and peatland soils. The second aim is to compare and evaluate methods and models for estimating fine root dynamics and coarse root biomass and structure.
The workshop will be divided into three sessions
The sessions of the workshop relate to the Working Groups of the Cost Action E 38 "Woody Root Processes". This workshop also belongs to the series of Cost E38 workshops, organized in 2004 in Sweden and Greece, 2005 in Estonia and winter 2006 in Israel.
On the behalf of the organisers we are looking forward to see you in Lapland autumn 2006!
Heljä-Sisko Helmisaari and Tarja Lehto