Behavior of the ´European´ Douglas-fir

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) with its increasing proportion in Europe holds the promise to be the most economical and ecological important non-native European coniferous forest tree. It outcompetes numerous native European species by better growth properties, equal or better quality of timber and the ability to cope effectively with drought. Douglas-fir has a large native distribution range in western North America. In the USA and Canada, this species is represented by two varieties (`coastal` and `interior`), which are geographically largely distinct, but hybridize when in contact. The `coastal` variety possesses better growth properties than the `interior` variety, which in turn is more cold-hardy and more drought resistant however more sensitive to fungal pathogen under humid conditions. In Europe, Douglas-fir was introduced almost two centuries ago. For European forestry, according to 40-years-old- European provenance research, the `coastal` variety from specific American areas is recommended, whereas the `interior` variety is principally a `no go` variety in all but a few European countries. Interestingly, individuals of both varieties as well as their admixed (inter-varietal hybrid and introgressed) individuals were found in imported American seeds from such recommended `coastal` variety areas. In addition, the distribution of Douglas-fir in Europe was shaped for more than 140 years by import of seed of unknown origin as well as mixing of seed sources. This resulted also in variety-mixed stands, which regenerate naturally and where the inter-varietal hybridisation is expected to take place. The presence of both varieties and/or hybrids in imported seed sources and within existing European stands raises pivotal questions: How frequent are inter-varietal hybridisation events in European stands? What impacts do hybridisation and hybrids/introgressed individuals have on the persistence and development of an introduced species such as the `European` Douglas-fir in its new environment? Being of high significance in evolutionary and adaptation ecology these questions are the focal point of the proposed project. The primary aim of the proposed project is to study the occurrence and distribution of inter-varietal hybrids and introgressed individuals within variety-mixed European Douglas-fir stands and their natural regeneration. Moreover, the drought tolerance of inter-varietal hybrids and the two varieties shall be compared. This will allow identifying trends in the development of `European` Douglas-fir within the established stands also with respect to climate change. The secondary aim is to analyse the genetic structure and composition of American Douglas-fir seed areas relevant for seed transfer to Central Europe, and to compare adaptive phenological and growth traits between selected American and European progenies. This not only permits us to recognize how `variety-pure`, and genetically divergent the imported American provenances are, but also to detect and understand similarities/differences in the adaptive traits when progeny is produced outside the distribution range.

No additional funding sources recorded.