Which is better: spruce or beech? Research indicates that mixed forests are more stable than monocultures.

A recent study published in the journal “Zprávy lesnického výzkumu” (3/2025) demonstrates that mixed and structurally diverse stands of spruce and beech exhibit greater stability and resilience compared to monoculture forests. Dendrochronological analyses from research trials at the Křtiny School Forest Enterprise, part of Masaryk’s Forest, confirm that diversity in species and age enhances the trees’ ability to respond to climate extremes and promotes their growth. This study offers valuable insights for the adaptive management of spruce and beech forests in Central Europe.

Photo: natural regeneration of European beech and Norway spruce, author Jan Řezáč

The research conducted for the project „Bohatě strukturované smíšené porosty jako klíčová forma adaptace lesního hospodářství na probíhající změny klimatu“ (Richly Structured Mixed Stands as a Key Adaptive Strategy for Forestry in Response to Climate Change) was based on long-term data collected from tree rings of spruce and beech trees spanning from 1867 to 2022. The study focused on assessing the annual basal area at breast height increment (BAI).

Research scientists compared spruce monocultures, even-aged spruce-beech mixtures, and uneven-aged, richly structured mixed stands. The analysis revealed that while spruce monocultures exhibit higher average tree thickness, they also demonstrate lower stability and greater sensitivity to climate fluctuations.

Photo: beech growing under spruce contributes to a diverse and uneven-aged mixed forest structure, author Jan Řezáč

Mixed stands, particularly those with uneven ages, demonstrated greater stability and more uniform radial growth compared to other types. The presence of beech positively influenced spruce by reducing competition for water and allowing for more efficient resource use due to their complementary characteristics. Additionally, beech contributed to improved growth stability and higher basal area increment (BAI) in stands during droughts and other extreme conditions.

Practice Recommendations:

• Promote mixed stands of spruce and beech, as increased species diversity enhances stability and long-term productivity.
• Favour uneven-aged and multi-layered stands, which are better able to withstand climate extremes.
• In spruce monocultures, anticipate higher variability in growth and a greater risk of destabilisation.
• Including beech in the mixture encourages spruce growth and improves the efficient use of water and nutrients from the soil.
• Adaptive forestry strategies should integrate economic and ecological goals and be founded on long-term research experiments.

Photo: the mixed forest stand consists of a diverse array of trees of varying ages and species, author Jan Řezáč

Scientists from the Forestry and Game Management Research Institute and Mendel University in Brno have confirmed through a study that mixed, and structurally diverse stands of spruce and beech are a promising approach to sustainable management in a changing climate. Supporting diversity is both ecologically beneficial and economically advantageous, as more stable stands are better equipped to withstand disturbances and ensure long-term production.

The paper titled „Konkurenční vztahy dřevin v porostech buku lesního a smrku ztepilého a jejich vliv na produkci v různých typech a stupních smíšení“ (Trees competitive interactions in European beech and Norway spruce stands and their effect on productivity across different types and degrees of mixture)” can be downloaded here.

Authors: Martin Kománek, Eliška Žižková, Petra Jablonická, Pavel Horák, Robert Knott, Kateřina Macháčková (Mendelova univerzita v Brně, Lesnická a dřevařská fakulta); Jakub Černý (Výzkumný ústav lesního hospodářství a myslivosti, v. v. i.; Mendelova univerzita v Brně, Lesnická a dřevařská fakulta)

Prepared according original by Jakub Černý, VÚLHM, v. v. i., e-mail: cerny@vulhmop.cz