Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Monitoring carbon stock changes after disturbances and changes in forest management - inventory requirements

If the instrument of sink management within forests is to be used there is a need to account for 2 groups of processes that reduce C stocks in forests, namely disturbances and forest harvesting activities. Disturbances induce important changes in biogeochemical cycling and population dynamics. In spite of a growing body of information on these processes the current state of knowledge does not allow to set up a monitoring scheme that would allow for tracing all effects caused by the wide array of potential disturbances. However, with respect to lasting major changes in carbon stocks in forests, it is recommendable to focus on stand replacing disturbance events, that lead to a sudden transfer of carbon from live trees to litter or from live trees and soil to the atmosphere. Under European conditions these are mainly fires and wind-throw events.

In order to capture C stock changes following fires it is necessary to monitor weather and climate variables that can be measured at a nearby weather station. Together with additional post-disturbance measurements on flame height as well as litter and O-horizon carbon content, carbon lost from living vegetation and soils during the fire can be modelled. Beyond this point the monitoring requirements for fire and wind-throw effects are the same: amount and quality of wood removed from the site and left on-site after the disturbance. The variables to be measured and ways to assess them are reported in the final reports to WP 5.1 and 5.4. A questionnaire sent to researchers and forest managers revealed that interest in and knowledge about carbon dynamics following disturbances are developed in different intensity across Europe. Up to today no country in Europe seems to have a forest inventory in place that can deliver the full range of data needed to assess post-disturbance carbon stock changes. However, in some countries, additional information sources, as e.g. records of disturbance events including location, area affected and effect size existed. These can be combined with classical inventories in order to extract the information needed for Kyoto monitoring.

The release of CO2 from decaying wood is one of the main fluxes that need to be quantified when substantial amount of wood is left on site after disturbances. There is little information available on decay constants and the variation with environmental conditions for European forests and tree species. The literature contains some studies conducted in boreal forests; a small number only is available for the rest of Europe. Therefore, a method to estimate decomposition rate constants from published sources has been proposed and is included in the appendices' to the final report of WP 5.4. A database on dead wood dynamics was acquired from M. Harmon, amended with results on European tree species, and is available on the project's result web page at JRC.

With regard to changes in forest management the main challenge was to define how "forest management" can be defined and to distinguish management options that in praxis often have shifting boundaries. Two levels of management that need to be distinguished: Forest management in a wide sense (actions that shape external influences and legal constraints that frame the decisions taken at the individual forest management unit level) and forest management in a narrow sense (treatment schedule which best meets the objectives set for forest stands). A list of forest management measures that can be applied at the stand level can be found in the WP5.5 report. The most prominent effects can be expected on changes in rotation length and fertilisation of forests that stock on nutrient poor soils.

If forest management effects are to be assessed for detailed actions (e. g. different cutting regimes), it is of paramount importance to define and delimit such actions in a consistent way to be able to distinguish between different categories of FM activities (see final report of WP 5.5 for details). For the estimation of effects the technical systems used for conducting a specific activity and the area subject to this activity must be known. This information has thus to be included in reporting schemes.

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