A single-tree approach to determine climate-growth patterns of European beech and their seasonality in the species southern distribution area

Dry and warm climate conditions in southern Europe represent clear limits for European beech (Fagus sylvatica) growth near the species southern distribution limit, but it is unclear how aridification and changes in seasonal precipitation regimes will affect these forests at the individual level. We explored climate-growth relationships and the seasonality of peak climate signals in European beech using daily climate data and a large collection of tree-ring width series from southern and southeastern Europe through Generalised Linear Mixed Models (GLMMs). In most cases we found a positive and significant influence of precipitation on tree growth, and a significant negative effect of maximum temperature. Predictions from the GLMMs revealed a positive impact of precipitation during an 88 day window from spring to early summer (mid-April to mid-July), for an average tree across our network. This critical growing time window ranged from 75 days in warmer and drier conditions, and extended up to 100 days in areas with mild temperatures and moderate summer precipitation. Maximum temperatures negatively affected trees for an average of 27 day window in summer (June-July). This period was reduced to <10 days in locations with wetter and colder summers, rising up to 45 days in sites with drier and warmer summers. The positive effect of precipitation on growth was stronger and commenced earlier in larger trees. Similarly, the negative effects of maximum temperatures were more pronounced for larger trees. The use of daily climate data and a tree-centred approach allowed for capturing critical temporal dynamics in climate-growth relationships that are often overlooked by conventional methods. These insights significantly enhance our understanding of climatic factors influencing individual beech growth at the edge of its distribution range and their seasonal variations.

R.S.N., M.d.L. L.A.L., M.A.S. and E.M.d.C. are supported by the Government of Aragón, through the “Programme of research groups” (group S74_23R, “Clima, Agua, Cambio Global y Sistemas Naturales”). R.S.N. is supported by grant RYC2021-034330-I funded by MCIN/AEI/10.13039/501100011033 and by “European Union Next Generation EU/PRTR” and E.M.d.C. by German Science Foundation (DFG project ARiD - 539441548). The Slovenian Research and Innovation Agency (ARIS) funded the work of K.Č., N.Š.D., M.M., A.B. and K.N. by the programme P4-0015, J.G. and P.P. programme P4-0430, and J.J. programme P4-0107. K.N. was also supported by the “Researchers-2.1-UL-BF-952011″, contract no C3330-19-952011 co-financed by the Ministry of Education, Science, and Sport of the Republic of Slovenia and the EU European Regional Development Fund. J.J.C. was funded by Gobierno de Aragón, research group E03_23R. A.P. by FOR-CLIMSOC Programme, Projects ID PN23090101, I.P. by FOR-CLIMSOC Programme, Projects ID PN23090201 and A.M.P. by PN23090301, within FORCLIMSOC program of Ministry of Research, Innovation and Digitization of Romania. T.Z. was funded by LTER-BG - agreement no DО1-320/30.11.2023 - Bulgarian National Roadmap for Scientific Infrastructure and D.P.D. by the National Science Fund of the Bulgarian Ministry of Education and Science, agreement no KП-06-H66/13. F.B. was partly funded by the Experiment Station of the College of Agriculture, Biotechnology, and Natural Resources at the University of Nevada, Reno (USA). I.L. was supported by the Croatian Forest Research Institute, through Diagnosis and Prognosis Service of the Ministry of Agriculture, Forestry and Fishing & Croatian Science Foundation project DIFPEST (7616). R.T.’s research was connected to activities carried out under the COST Action CLIMO (Climate-Smart Forestry in Mountain Regions - CA15226), funded by the EU Horizon 2020 Framework Programme for Research and Innovation. E.T. received funding from the Comunidad de Madrid program Atracción Talento “César Nombela” grant number 2023-T1/ECO-29118. The AMP was supported by the Romanian National Authority for Research (project PN23090301).

Peer reviewed