Growth-climate relationships at yew and wild service trees on the eastern edge of their range in Europe

Anna Cedro,Bernard Cedro

doi:10.5424/fs/2015243-07480

Abstract

Aim of study: The aim of the study was the construction of regional chronologies for South-Western Poland for yew (Taxus baccata L.) and wild service tree (Sorbus torminalis L.), two of the rarest native tree species on the edge of their range in Europe. The relationships growth-climate and incremental dynamics at both these species were investigated as well.Area of study: The eastern borders of the ranges of yew and wild service trees run across Poland. The majority of the yew occurrence sites are situated in South Poland, within the area of uplands and mountains, whereas the wild service tree grows in the western part of the country. The study plots (5 for yew trees, 4 for wild service trees) were located in nature reserves in SW Poland.Material and Methods: The research materials were cores from 200 trees (115 yew trees and 85 wild service trees). The annual growth widths were measured, then, local chronologies were constructed using classic methods of dating. Regional chronologies were based on yew trees with the Student’test t > 6.0, and wild service trees with t > 5.9. The chronologies were subjected to the indexation and used for dendroclimatological analyses: pointer years, correlation and response function.Main results: The yew chronology, spanning 219 years (1790-2008), was established on the basis of 51 samples, the average width of annual growths amounted to 0.61 mm. The wild service tree chronology, representing the period 1841-2013 (173 years), was produced from 37 samples, the average width of annual growth amounted to 0.60 mm (from 0.27 up to 0.58 mm). Dendroclimatological analyses of the yew indicated thermal conditions of the winter months and beginning of spring (straight correlations) as the predominating factor affecting the annual growth widths. Summer drought was an additional factor limiting growth. For the wild service trees cool and humid summer months in the growing season favour the formation of wide growths.Research highlights: On account of strong dispersion and limited small populations of these two tree species, there are few dendrochronological studies available. Therefore, every piece of information on the ecology of the yew and wild service tree allows us to broaden our knowledge of these rare species enriching the biodiversity of the native tree flora.Keywords: tree-ring width; Taxus baccata L.; Sorbus torminalis L.; dendroclimatology; Poland.

Highlights

Yew (Taxus baccata L.) in Europe occurs in the north to 63°N in Norway and Sweden, the eastern limit of its range runs through Estonia, Poland, Carpathian Mountains and descends to Greece and Turkey
Mean tree-ring width for the population fluctuated from 0.27 mm up to 0.58 mm
The Expressed Population Signal (EPS) values are above the applied threshold of 0.85: from 0.87 for MI chronology to 0.97 for CI chronology (Table 2, Wigley et al, 1984)

Summary

Introduction

Yew (Taxus baccata L.) in Europe occurs in the north to 63°N in Norway and Sweden, the eastern limit of its range runs through Estonia, Poland, Carpathian Mountains and descends to Greece and Turkey. The yew is one of the rarest coniferous trees in Poland; protected legally, written down in the Polish Red List of Threatened Species (Kruszelnicki, 2001), and the majority of its occurrence sites are protected in the form of nature reserves. The eastern border of the range of this species runs across Poland: the yew trees appear in the northern, western and southern parts of the country, but not in the central-eastern areas. Most of the yew sites are situated in southern Poland, in the belt of uplands and mountains: in the Sudetes Mountains and

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