Can selection harvesting balance the needs for forest production and enhanced carbon storage?
Short description
Improved forest management is a tool for climate mitigation, but questions remain if continuous cover forestry with selective cutting is beneficial compared to the common rotation forestry with clear cutting. In this project we study the carbon flows and stocks at two sites in SW Sweden, Skogaryd and Remningstorp, to determine if a selectively cut stand can compensate for the carbon stock lost following clearcutting by increased growth and, if so, how. The project also addresses the question if old forests, beyond the assumed economically optimum age, continue to grow and sequester carbon at rates comparable to young forests.
Research background
Forests are both affected by and affecting global climate change. In the Anthropocene, the era of human dominance on the Earth System, there is a need to optimize forest management for contributing to climate change mitigation by enhanced ecosystem carbon storage.
Rotation forestry with clear cutting is the most common silvicultural practice in Sweden, but questions have been raised about its ability to contribute to long-term carbon sequestration. Due to the urgent need for nature-based climate change mitigation options, there is now considerable social and scientific interest in the use of selective cutting, or continuous-cover forestry, but its effects on carbon sequestration are largely unknown.
This project compares carbon flows and stocks in forest subjected to clear-cutting and selective cutting at two locations in SW-Sweden, Skogaryd Research Catchment and Remningstop.
The purpose of this research
The overall aim of the project is to quantify gross primary production (GPP), the flux of CO2 from the atmosphere to the forest, in Norway spruce stands of varying age and management strategies. Novel methodologies based on sap flux and stable isotopes are used to study the carbon fluxes in Norway spruce stands. The goal is to determine whether and by how much carbon uptake capacity is sacrificed as forests grow older. We will also investigate if a selectively cut stand is able to compensate for the carbon stock lost following clearcutting by increased growth and, if so, how.
Research questions
- Do old forests, beyond the assumed economically optimum age, continue to grow and sequester C at rates comparable to young forests or do they shift to lower photosynthetic rates as a result of the difficulty of lifting water to the crowns?
- Does selection harvesting of a forest at the end of the assumed economically optimum rotation length lead to increased growth in the remaining trees, i.e. do the trees compensate with additional growth for the trees that are missing? If so, do they do it by increased photosynthesis per tree? Is it all the trees that respond so or some size classes in particular?
- What is the trajectory of GPP and biomass C stocks in spruce at key points during a rotation period?
