Radial Increment of Beech (Fagus sylvatica L.) Is under a Strong Impact of Climate in the Continental Biogeographical Region of Croatia

Tom Levanič; Damir Ugarković; Ivan Seletković; Mladen Ognjenović; Mia Marušić; Robert Bogdanić; Nenad Potočić

doi:10.3390/plants12132427

Radial Increment of Beech (Fagus sylvatica L.) Is under a Strong Impact of Climate in the Continental Biogeographical Region of Croatia

Plants (Basel). 2023 Jun 23;12(13):2427. doi: 10.3390/plants12132427.

Authors

Tom Levanič^{1

2}, Damir Ugarković³, Ivan Seletković⁴, Mladen Ognjenović^{4

5}, Mia Marušić⁴, Robert Bogdanić⁴, Nenad Potočić⁴

Affiliations

¹ Department for Forest Yield and Silviculture, Slovenian Forestry Institute, Večna pot 2, SI-1000 Ljubljana, Slovenia.
² Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, SI-6000 Koper, Slovenia.
³ Faculty of Forestry and Wood Technology, Institute of Forest Ecology and Silviculture, University of Zagreb, Svetošimunska Cesta 23, HR-10002 Zagreb, Croatia.
⁴ Croatian Forest Research Institute, Division for Forest Ecology, Cvjetno naselje 41, HR-10450 Jastrebarsko, Croatia.
⁵ Department of BI, Analytics and Research, Njuškalo Ltd., Miroslava Miholića 2, HR-10000 Zagreb, Croatia.

Abstract

European beech (Fagus sylvatica L.) is an important component of forests in the alpine and continental biogeographical regions of Croatia. This study aimed to (1) analyze the long-term response of beech to climate, (2) identify potentially critical climatic conditions that could negatively affect the radial increment (RI) and vitality of beech, and (3) evaluate differences in the response of beech between the two biogeographical regions in Croatia. We used the 16 × 16 km Croatian ICP Forests Level 1 network. On a total of 25 plots, we cored between 5 and 24 trees for dendrochronological analysis. Tree-ring widths (TRW) were measured and standardized using cubic spline. TRW chronologies for the two regions were calculated and correlated to the temperature and precipitation data and Standardized Precipitation and Evapotranspiration Index (SPEI) using bootstrapped correlations. Continental region precipitation from April to August and alpine region precipitation from June to August were significantly important for RI. Temperature was less important for RI than precipitation in both regions, but the importance of the negative impact of above-average temperatures in the continental region and the positive impact of above-average precipitation in the alpine region has increased over the last two decades. A comparison with the 3-month SPEI confirmed the significant influence of high temperatures and the lack of precipitation in August on the RI of beech trees in both regions.

Keywords: European beech; climate change; drought; forest productivity; tree growth.

Grants and funding

T.L. was in part funded by the Slovenian Research Agency—research core funding No. P4-0107, program research group “Forest Biology, Ecology and Technology”. T.L., N.P., I.S., M.O., M.M. and R.B. were in part funded by the bilateral Croatian–Slovenian project “Interrelationship of vitality indicators of common beech (Fagus sylvatica L.)” financed by the Slovenian Research Agency and Ministry of Science of the Republic of Croatia. N.P., I.S., M.O., M.M. and R.B. were in part funded by the Croatian Science Foundation under the project HRZZ-IP-2018-01-5222 (VitaClim). D.U. was in part funded by support from the University of Zagreb project “Contribution to the knowledge of carbon stocks in the forest soil in the forest ecosystems of Croatia”.