The impact of environmental drivers on narrow-leaved ash (Fraxinus Angustifolia Vahl) budburst dates

Abstract

Narrow-leaved ash (Fraxinus angustifolia Vahl) is a fast growing and light demanding forest tree species. In Croatia, the largest complexes of this species can be found along the Sava River. The main objective of research was to determine the influence of environmental drivers on budburst dates. Research was carried out in the clonal seed orchard of Nova Gradiška through four vegetation seasons (2012, 2014, 2015 and 2016). In total, 42 clones were involved in this study. The target phase of phenology monitoring was the phase with distinct budburst and partial segregation of bud scales. Three environmental drivers were selected (temperature, precipitation and insolation) with three different summing dates (1st November, 1st December and 1st January). Statistical data processing included the following analyses: Spearman Rank Correlation, Linear Regression, Multiple Regression and Stepwise Multiple Regression. Among three tested environmental drivers in all of the analyses performed in the study, insolation proved to be the most important factor in the description of budburst dates in narrow-leaved ash.