Dear Colleagues,

Genetic gain is the improvement in average phenotypic or genetic value due to selection in a forest population over cycles of tree breeding. It can be improved through a shortened cycle period by integrated breeding strategies, meaning the level of increase in the performance achieved annually by artificial selection. Gene diversity serves as a way for populations to adapt to changed environments. Seed orchards are a tree improvement delivery system between tree breeding and forest regeneration and are leading suppliers of genetically improved seeds worldwide. The genetic gain of seed orchards is increasing along with the advancement of tree-breeding cycles and the uptake of a lot of accumulated knowledge is available as a result. Advancements in genomics have offered an insight into how DNA information controls all forest tree species’ biological functions and how it has the potential to accelerate the breeding cycle. The management of seed orchards should be fine-tuned accordingly to maximize genetic progress, while maintaining a sufficient adaptive diversity in forest stands, and to improve climate resilience. The tree improvement delivery system encompasses all aspects of tree breeding, starting with phenotypic selection and ending with the production of genetically improved seeds and seedlings. Additionally, this process is paramount in determining the genetic gain and gene diversity trade-off to ensure that the maximum genetic gain and gene diversity in future forests are attained. Our goal is to facilitate the exchange of research and practice information on the progress of tree breeding and its improvement. Therefore, we encourage papers to maximize genetic progress while maintaining a sufficient adaptive diversity in forest populations.

Potential topics include, but are not limited to:

• Breeding strategy;
• Genetic gain estimation;
• Genetics of seed orchards;
• Pollen contamination, flowering and fertility variation;
• Physiology and technology of seeds and seedlings;
• Vegetative propagation techniques, including somatic embryogenesis;
• Forest population genetics and tree genomics.

Prof. Dr. Kyu Suk Kang
Prof. Dr. Nebi Bilir
Dr. Eduardo Pablo Cappa
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Forests is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• genetic gain
• gene diversity
• tree breeding
• genomics
• fertility variation
• background pollination
• seed testing, mass propagation

Title: Fertility variation and gene diversity in forest popualtions
Authors: Kyu-Suk Kang
Affiliation: Department of Agriculture, Forestry and Bioresources, Soul Natiuonal University, South Korea

Title: Fertility variation in seed orchards and their base populations of Pinus nigra
Authors: N. Bilir et al.
Affiliation: Forestry Faculty of Isparta University of Applied Sciences, Turkey

Title: RNA sequencing analysis reveals key pathways and candidate genes related to seed weight and size in oak tree
Authors: Hyemin Lim
Affiliation: National Institure of Foret Science, South Korea

Title: Clonal variation of cone production among clones and estimation of gene diversity in a clonal seed orchard of Pinus koraiensis
Authors: Yeji Kim
Affiliation: Department of Agriculture, Forestry and Bioresources, Soul Natiuonal University, South Korea

Title: Impact of crown closure on cone production and effective number of parents in natural stands of Taurus cedar (Cedrus libani A. Rich.)
Authors: N. Yazici & N. Bilir
Affiliation: Forestry Faculty of Isparta University of Applied Sciences, Turkey

Title: Impact of Sea Mucilage, Algae (Fontinalis antipyretica) and moss (Phylum Bryophyta) in seedling morphology of Pinus brutia, P. nigra and P. sylvestris
Authors: D. Cetinkaya
Affiliation: Forestry Division of Cukurova University, Turkey

Title: The effect of using of ash as a waste material on seedling morphology in Japanese poplar (Brachychiton populneus Schott.) and Scots pine (Pinus sylvestris L.).
Authors: D. Cetinkaya
Affiliation: Forestry Division of Cukurova University, Turkey

Title: Exploration and selection of superior trees for Tilia amurensis tree improvement
Authors: Kyoung-mi Lee
Affiliation: National Institute of Forest Science, South Korea

Title: Selection of superior forest stands of Pinus strobus for designation of seed production stands in Korea
Authors: Il Hwan Lee
Affiliation: National Institute of Forest Science, South Korea

Title: Monitoring of fertility variation by reproduction morphology in Pinus brutia
Authors: G. Ertugrul & N. Bilir
Affiliation: General Directorate of Forestry of Turkey