Beech and pine trees are better together
The Scots pine, an evergreen coniferous tree, mixes well across European forests with the European beech, a common hardwood tree. Generally, these two important European trees grow better together than single-tree forests, creating robust ecosystems for other living organisms. However, the delicate balance and competition between the two tree types, which depends on factors such as CO2 concentrations and climate change, remains poorly understood. Against this backdrop, the EU-funded ECOPYREN3 (Integration of ecological processes in forest models to assess long-term effects of management and global change on forests in southwestern Europe) project researched environmental factors and modelled tree growth to advance research on the topic. Specifically, the project team documented nutrient and water cycles in two research sites and outlined factors that influence competition. It built mathematical relationships of climate-tree growth and water use efficiency by studying tree rings. This led to modelling the particular pine-beech mix and ecosystem to see how it can grow under different climate scenarios. The team worked at two research sites in northern Spain, a Mediterranean forest and a mountain forest. Using state-of-the-art technology, the project extrapolated the longest time series of nutrient circulation for these mixed forests – i.e. over a period of 15 years. It showed how tree growth in these mixed forests can be improved, considering water, shade and geographic factors. Moreover, the project team produced the most accurate projections of species complementarity under future changing climate conditions. It showed for example that under current climate conditions, beech trees can benefit from accompanying species while pine trees show virtually no change when combined. These interactions can shift with the pressures of climate change, underlining the importance of understanding delicate environmental mechanisms to preserve ecosystems. Project outcomes have led to better research on ecological interactions between two major European tree species that grow together. The findings support adaptive forest management in cooler Mediterranean regions based on the beech-pine mix. Lastly, the project created a powerful tool to support decision-making in forest management to evaluate impacts related to timber production, biomass production and water use.
