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Research article - Peer-reviewed, 2021

Species stratification and weather conditions drive tree growth in Scots pine and Norway spruce mixed stands along Europe

Aldea, Jorge; Ruiz-Peinado, Ricardo; del Rio, Miren; Pretzsch, Hans; Heym, Michael; Brazaitis, Gediminas; Jansons, Aris; Metslaid, Marek; Barbeito, Ignacio; Bielak, Kamil; Granhus, Aksel; Holm, Stig-Olof; Nothdurft, Arne; Sitko, Roman; Lof, Magnus


Mixed forests are suggested as a strategic adaptation of forest management to climate change. Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) are tree species of high economic and ecological value for European forestry. Both species coexist naturally in a large part of their distributions but there is a lack of knowledge on the ecological functioning of mixtures of these species and how to manage such stands. This paper analyses these species' intra- and inter-specific competition, including size-symmetric vs. size-asymmetric competition, and explore the effect of weather conditions on tree growth and competition. We studied basal area growth at tree level for Scots pine and Norway spruce in mixed versus pure stands in 22 triplets of fully-stocked plots along a broad range of ecological conditions across Europe. Stand inventory and increment cores provided insights into how species mixing modifies tree growth compared with neighbouring pure stands. Five different competition indices, weather variables and their interactions were included and checked in basal area growth models using a linear mixed model approach. Interspecific size-asymmetric competition strongly influenced growth for both tree species, and was modulated by weather conditions. However, species height stratification in mixed stands resulted in a greater tree basal area growth of Scots pine (10.5 em(2) year(-1)) than in pure stands (9.3 em(2) year(-1)), as this species occupies the upper canopy layer. Scots pine growth depended on temperature and drought, whereas Norway spruce growth was influenced only by drought. Interspecific site-asymmetric competition increased in cold winters for Scots pine, and decreased after a drought year for Norway spruce. Although mixtures of these species may reduce tree size for Norway spruce, our results suggest that this could be offset by faster growth in Scots pine. How inter-specific competition and weather conditions alter tree growth may have strong implications for the management of Scots pine-Norway spruce mixtures along the rotation period into the ongoing climate change scenario.


Mixed stands; Climate change; Competition-weather interaction; Pinus sylvestris; Picea abies

Published in

Forest Ecology and Management
2021, volume: 481, article number: 118697
Publisher: ELSEVIER

Authors' information

Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre
Ruiz-Peinado, Ricardo
Instituto Nacional Investigacion Tecnologia Agraria Alimentaria (INIA)
del Rio, Miren
Instituto Nacional Investigacion Tecnologia Agraria Alimentaria (INIA)
Pretzsch, Hans
Technical University of Munich
Heym, Michael
Technical University of Munich
Brazaitis, Gediminas
Vytautas Magnus University
Jansons, Aris
Latvian State Forest Research Institute Silava
Metslaid, Marek
Estonian University of Life Sciences
Barbeito, Ignacio
Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre
Bielak, Kamil
Warsaw University of Life Sciences
Granhus, Aksel
Norwegian University of Life Sciences (NMBU)
Holm, Stig-Olof
Umea Univ UMU
Nothdurft, Arne
University of Bodenkultur Wien
Sitko, Roman
Technical University in Zvolen
Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre

Sustainable Development Goals

SDG13 Climate action

UKÄ Subject classification

Forest Science

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