Abstract
Background and Purpose: Turkish hazel (Corylus colurna L.) has been overused because of its valuable wood. Recently, Turkish hazel has been found only in small isolated populations, and very small populations within its natural distribution area, so it has been protected under IUCN with the status "Least Concern (LC)". Therefore, the remaining Turkish hazel populations have a critical importance. Genetic conservation of this tree species plays a key role in sustainable forest development. There have been only a few studies of single populations, but an overview including all countries is still missing. The aim of this publication is to give an overview of ecological and economic importance of Turkish hazel, which is considered as a tolerant tree species to climate change, for dry and warm conditions in Central Europe. Materials and Methods: This review paper has been prepared based on the existing literature such as reports, theses, project documents and publications related to Turkish hazel. This paper applies a literature review of the concepts of: i) Distribution and threats of Turkish hazel, ii) Ecological and economic importance, iii) Regeneration, soil demand and shading tolerance, iv) Seed, seedling, plant production and planting, v) Competitiveness in forest communities, vi) Invasiveness and hybridization, and vii) Future stand mixtures. Results and Conclusions: This review paper should interest forest practitioners and scientists in all countries who work with this important and valuable tree species under climate change. At first, an inventory of all populations in each country is needed. For this purpose, research should focus on the cultivation of convenient provenances of Turkish hazel under climate change. Next, genetic differences should be determined in the laboratory using genetic markers. After the assessment of the phenotype and genotype of different provenances, it would be possible to recommend provenance for each ecological condition and assisted migration (AM). Main recommendations for each country are used for selecting and establishing gene conservation units (in-situ and ex-situ) and seed orchards that will ensure the survival of Turkish hazel, and for building the base for cultivation in the future. In addition, the results might be a basis for future provenance tests, plantations and possibilities of assisted migration attempts.
Highlights
Climate change affects all forest ecosystems, as well as services and goods provided by forests
The origin of the reproductive material of a tree species plays a key role in its adaptation to environmental conditions, and possible cultivation
Turkish hazel can be found in beech and oak forests as a rare mixed tree species in the Caucasus area [13]. This tree species occurs in stands composed of, for example, Quercus frainetto Ten., Fraxinus ornus L., Carpinus orientalis Miller, and Crataegus L. in dry and poor locations [5]
Summary
Climate change affects all forest ecosystems, as well as services and goods provided by forests. Turkish hazel can be found in beech and oak forests as a rare mixed tree species in the Caucasus area [13]. This tree species occurs in stands composed of, for example, Quercus frainetto Ten., Fraxinus ornus L., Carpinus orientalis Miller, and Crataegus L. in dry and poor locations [5]. The height growth of Turkish hazel in its natural area of distribution is decisively dependent on site conditions. In soil and environmental conditions with lower growth capacity, Turkish hazel can cope with mixed tree species including sycamore maple and ash, which occur there and reach similar heights. These protect the seeds against late frost as well as against high-growth and darkening weed growth in the growth cover [37]
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