Genetic diversity and adaptive traits of European versus American Douglas-fir seedlings

Tamara Eckhart,Marcela Van Loo,Hubert Hasenauer,Severin Walcher

doi:10.1007/s10342-017-1072-1

Abstract

Due to its productivity and potential to adapt to the expected climate change, the Douglas-fir is one of the most important commercial non-native forest tree species in Europe. Currently, seeds from both non-native European and native American seed stands are used for plantations. In this study, we investigate European seed lots for their native origin (variety and potential geographic origin in America) and assess the adaptability, growth and survival potential of European versus American Douglas-fir seed lots. We compare the genetic diversity, morphological characteristics such as height (h), root collar diameter (rcd) and the ratio of h/rcd, and the timing of bud burst. We investigate 852 1-year-old seedlings from 10 different US and European seed lots representing 5 provenance regions which are sold in Germany and Austria. Seedlings are genotyped for 13 nuclear SSRs and analysed together with reference data set and standard genetic structuring and assignment methods. Adaptive traits of morphological characteristics and timing of bud burst of the seedlings are recorded and statistically analysed. The results show that the investigated European seedlings originate from recommended American native seed sources and represent both varieties and inter-varietal admixed individuals. European seedlings have a lower genetic diversity versus the American seedlings and native populations. They show significant differences in the adaptive traits such as morphological characteristics and timing of bud burst. According to the genetic diversity indices, certified North American Douglas-fir seed sources should be preferred for planting in Central Europe.

Highlights

The Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is the second most cultivated non-native conifer tree species in Europe after the Sitka spruce (Koble and Seufert 2001), which grows in more than 35 European countries
European provenance regions consist of different native origins and represent both varieties of Douglas-fir
The genetic diversity of the European seed lots was lower in comparison with seed lots from America and native populations

Summary

Introduction

The Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is the second most cultivated non-native conifer tree species in Europe after the Sitka spruce (Koble and Seufert 2001), which grows in more than 35 European countries. Within its native distribution range, in western North America, two distinct varieties of the Douglas-fir are known: the coastal variety The coastal variety grows along the Pacific coast and the west facing slopes of the Rocky Mountain range from British Columbia, Canada to California, USA. The interior variety ( called Rocky Mountain variety) grows further east of British Columbia, across the Rocky Mountains to New Mexico (USA) (Eckenwalder 2009). In the contact zone of the two varieties, hybridization is evident (Gugger et al 2010; van Loo et al 2015; Wei et al 2011).

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Discussion

Conclusion