Nutrient balance as a tool in multi-objective forest management aiming at climate change mitigation and other ecosystem services

Forests are expected to provide several ecosystem services, such as wood production, clean water and carbon sequestration and storage, simultaneously. The basic aerial unit of forest management is gradually changing from stand to catchment scale. Catchment scale management of forest nutrient balance is an important part of modern forestry. A leap towards holistic management of ecosystem services through customised forest management strategies has become possible when high resolution forest, terrain, and soil data can be combined with detailed process-based ecosystem models. We have developed catchment level, spatially distributed nutrient balance and hydrology models, which calculate location-specific forest growth, carbon and nutrient dynamics, and the nutrient export to water courses. Model applications have shown that the nutrient export is very unevenly distributed throughout catchments: 5 % of the catchment area can produce 25% of the nitrogen export. This identification of nutrient export hotspots facilitates knowledge-based planning of forest operations and cost-efficient locating of water protection. We have found that catchments may also contain locations where the stand growth is nutrient limited. This opens the possibility for precision fertilization in which the quality, dose and timing of the fertilization can be adjusted so that the site-specific nutrient supply meets the nutrient demand. Our simulations indicate that especially in peatland forests, fertilization together with water and forest management can effectively improve wood production, decrease carbon emissions and control nutrient export to watercourses.  Furthermore, these models can be used to compare different harvesting methods and forest management strategies with respect to multiple ecosystem services. Process-based ecosystem models including nutrient balance and geospatial high-resolution data are particularly useful in forecasting the effects of climate change allowing development of pro-active adaptation schemes in a specific catchment.