Climate change increases synchrony in tree growth

Newsroom

The magazine 'Forest Ecology and Management' has just published A study which presents groundbreaking findings indicating that heterogeneity in tree sizes influences how climate change affects tree growth. In particular, forests with more homogeneous tree sizes are more vulnerable to climate disruption.

The research focuses on the analysis of annual growth data of beech trees at the southern limit of their distribution, using dendrochronological techniques. Since the 1970s, synchrony in tree growth has increased due to the greater frequency of extreme weather events.

“We have observed how direct anthropogenic impacts on forests, through changes in land use, and indirect impacts, through climate change, determine the synchrony in growth, with forests with young individuals being the most vulnerable to climate change,” says Julen Astigarraga, lead author of the study and researcher at the University of Alcalá.

The work highlights the importance of maintaining structurally diverse forests to mitigate the effects of climate change. “In general, the most diverse structures are found in mature forests. However, these forests are very rare across the European continent, but at the same time they are extremely valuable for mitigating the impacts of climate change, as this study shows,” says Paloma Ruiz-Benito, a researcher at the UAH.

Surprisingly, the work now published has shown that pollarded beech forests, a cultural and ecological ecosystem characterised by open forests with abundant shoots on the main trunk and very common in Gipuzkoa, the study area, show remarkable resilience to climate change.

"Increasing the structural diversity of forests, in addition to reducing the synchrony in tree growth, can help reduce tree mortality, enhance carbon sequestration and promote biodiversity by increasing habitat availability," adds Asier Herrero, a researcher at the University of the Basque Country.

"Despite the double threat facing forests, both from climate change and from changes in land use, our findings inspire optimism. The implementation of local policies that promote greater diversity in the age and size of trees could reduce the impacts of these environmental changes. This measure is generally easier to implement than strategies to counteract climate change," says Joaquín Calatayud, a researcher at the URJC.

The study has been possible thanks to the collaboration of various researchers from all over the peninsula, as well as the forest rangers and inhabitants of Oñati (Gipuzkoa), who have shown great interest and support in the data collection process. "The generosity we have received from the local community throughout this work is impressive, and we hope that the results of this study will contribute to adapting beech forests to climate change, not only in Oñati, but also throughout the European continent," concludes Astigarraga.

multidisciplinary collaboration

The research group is made up of Julen Astigarraga, Paloma Ruiz-Benito, Julián Tijerín-Triviño and Miguel A. Zavala from the Forest Ecology and Restoration Group (FORECO) of the Department of Life Sciences at the University of Alcalá; Joaquín Calatayud from the Department of Biology and Geology, Physics and Inorganic Chemistry (ESCET) at the Rey Juan Carlos University; Jaime Madrigal-González from EiFAB-iuFOR at the University of Valladolid; Enrique Andivia from the Department of Biodiversity, Ecology and Evolution at the Complutense University of Madrid; and Asier Herrero from the FisioKlima-AgroSosT research group of the Department of Plant Biology and Ecology at the University of the Basque Country.

The work has been supported by the Oñati City Council, the Basque Government (funding to the consolidated FisioKlima-AgroSosT group, IT1682-22), the IB-ForRes project of the Spanish State Research Agency (AEI, No PID2021-123675OB-C41) and the CLIMB-FOREST project of Horizon Europe of the European Union (No 101059888).