The right mix and planting pattern of trees enhance forest productivity and services

A new paper published in Nature Communications reveals how the way tree species are arranged in a forest can help optimise ecosystem functioning and productivity. The study was conducted using empirical field data combined with advanced computer models and simulations by researchers at the German Centre for Integrative Biodiversity Research (iDiv), Leipzig University, Friedrich Schiller University Jena, and the French National Centre for Scientific Research (CNRS).

The researchers simulated virtual forests with multiple arrangements of tree species, such as block and mini-block designs, plantings in single and double lines, and fully random distributions. These simulations incorporated real data from the BEF-China (Biodiversity-Ecosystem Functioning) experiment, including tree growth models (based on field inventories), litterfall collections, and decomposition rate measurements. This data allowed the researchers to model the effect of spatial arrangement on ecosystem functions, such as tree productivity, nitrogen, and carbon cycling.

If a leaf falls in a randomly arranged forest, there are benefits

The researchers found that the way tree species are arranged in a forest—whether clustered or randomly spread out—impacts productivity. This so-called species spatial heterogeneity, which refers to the patterns of species distribution within a forest, such as block or line planting, affects how nutrients cycle through the ecosystem. 

“For decades, biodiversity research has emphasised the benefits of mixing species for productivity and carbon storage. However, this approach is rarely implemented, largely due to the absence of practical guidelines that account for real-world forestry constraints”, explains first author Rémy Beugnon and postdoc at iDiv. 

The models show that random planting designs increased tree biomass by 11% compared to clustered layouts. A more even spread of tree species helps promote the even distribution of the fallen leaves, boosting nutrients and organic matter recycling, according to the authors.

The rate of carbon decomposition after nine months also increased with greater spatial heterogeneity, rising from 36.5% of carbon being decomposed in block designs to 47.1% in random designs. Notably, line planting — where alternating rows of different tree species are used — provided a middle ground between ecological benefits and ease of forest management, achieving 40.4% of carbon being decomposed after nine months.

Another key factor is the overall diversity and number of species present in a given forest stand, regardless of their arrangement. More diverse forests, with a wide range of species present, showed higher nitrogen and carbon cycling compared to less diverse configurations. This provides a more diverse mix of resources for decomposers and promotes decomposition. 

“The combination of experimental analyses and predictive modelling could be used to evaluate different scenarios of forest management. Besides the experimental validation of these findings, an important next step will be to know how general our conclusions are and whether they apply to different types of forests”, explains co-author Benoit Gauzens of iDiv and the University of Jena.

The perks of line planting

From a practical standpoint, the researchers note the balance required between securing ecological benefits and forest management. While random planting designs maximise ecological outcomes—including more biodiversity, enhanced nutrient cycling, and carbon sequestration—line planting offers a manageable compromise, simplifying tasks like thinning and harvesting.

Looking ahead, researchers envision extending these computer-based findings by conducting long-term field experiments to validate the study’s results in real-world contexts. Such trials would further investigate the interaction between tree species diversity, spatial arrangement, and ecosystem function, helping develop new approaches to reforestation and sustainable forestry.

“This study is an important example of how basic research can inform management applications under field conditions: we can leverage biodiversity in forests if we arrange it in the right way,” says Nico Eisenhauer, professor at Leipzig University and group head at iDiv. “Moreover, we see how local interactions between trees, their microclimate, and soil biodiversity can scale up to enhance multiple ecosystem services in forests”, he concludes.