Sustainable cultivation of root suckers regenerated hybrid aspen –  Nutrient extraction and plant available nutrients in soil

Hybrid aspen is a fast-growing deciduous tree that can contribute to increasing the supply of bio-based raw materials to Sweden’s energy system. After felling, hybrid aspen regenerates abundantly through root suckers. This enables management systems that are based on biomass extraction with short felling intervals. For such a system to be able to contribute long-term to Sweden’s fossil-free energy system, biomass extraction must take place without depleting the soil’s nutrient supply. Today, there is a lack of comprehensive knowledge about how management alternatives and felling intervals in coppice stands affect nutrient extraction and the supply of plant-available nutrients in the soil.

The project is based on an experiment in southern Sweden, where 4-, 8- and 16-year rotations have been followed through measurements of growth, production and extracted biomass. The experiment has now been followed for 16 years, which means that four, two and one rotations have been completed in the three different treatments, respectively. Sampling to estimate nutrients in extracted biomass has been carried out in connection with fellings throughout the experimental period. Soil chemical sampling has been carried out before the establishment of the experiment, halfway through and at the end of the experimental period.

The purpose of the project is to compile, analyze and publish data on nutrient extraction and the soil’s nutrient balance over time. This can provide a basis for assessing the need for nutrient compensation and for practical guidelines and decision support for landowners and entrepreneurs. The project contributes to strengthening sustainable value chains and securing the supply of bioenergy.

Photo: Nils Fahlvik, Skogforsk