engleski

Dynamic of fructification and conservation of genetic resources of Pedunculate oak (Quercus robur L.) and European beech (Fagus sylvatica L.) in light of climate changes

Background/Objectives: One of the most pressing problems of the forestry profession nowadays represents a frequent absence of seed crops of forest tree species. In changed ecological conditions, fructification and periodicity of crops are disrupted, and thus the regeneration of forests becomes increasingly questionable. The objective of the project is monitoring seed crops pedunculate oak and european beech in quantity and quality to determine the production potential of stands and new genetic tests will complement the results of the knowledge of genetic diversity, adaptation and use, and circulation forest reproductive material with regard to provenance. Research started in 2015 under the project by Croatian Science Foundation (IP-11- 2013-8131) in four registered european beech seed stands. Now, with the project IP-2018-01-8189, research is carried out in the same beech seed stands (plus additional one) and four pedunculated oak forest stands. Material/Methods: The aim is to apply the same research methodology on both project species. The size of each experimental plot is 60x80 m. Seed yield is estimated based on seed traps, by visual scoring of seeding intensity and from the air with the drone. During autumns the seeds are collected from selected trees. Seed analyses are performed in the Laboratory for Seed Testing of the Croatian Forest Research Institute. In future, procedures for optimum seed storage will be created. Also, field trials for ex situ conservation of their genetic resources will be established. Results: Monitoring of the dynamics and the amount of seed production in the period from 2015 till 2019 was noticed absence and irregularity of beechnuts production. 2016 and 2018 were years with crop in that period. Beechnuts were collected from five selected trees in each plot. Nets for collecting the beechnuts were placed at 1 m above ground covering whole projection area of their crowns. The floor area of nets for the collection of whole seed crop ranges from 40 to 170 m2. The total amount of seed collected at all localities is 245 kg in 2016 and 168 kg in 2018 kg. ISTA (International seed testing association) methods were used for testing seed quality. 1000 seed weight (TSW), moisture content, viability and germination test were assessed. The results showed high variability within and between the populations. Continuous monitoring of the crop of european beach in the coming years will lead to better predictions of the results and recommendations for the use of seeds. Monitoring of the crop of pedunculate oak begun in 2019 and the results are expected during this autumn and winter. Conclusion: Overall, the research results will prescribe the seed manipulation method from the moment of seed collection in forest stands, through seed processing and treatment stages, until storage in the refrigerator. The research will provide a better insight into the genetic diversity of the surveyed species. By establishing new experiments, we will establish the intrapopulation and interpopulation variability of different seed and plant characteristics to improve and ensure the preservation of gene pool. The research will be of great importance for science, the Croatian economy, and implementation in forestry practice. *This work has been fully supported-supported in part by Croatian Science Foundation under the project (IP-11-2013-8131). Research and data processing is continued by the project (IP-01- 2018-8189).

pedunculate oak ; european beech ; seed yield ; seed quality testing ; environmental factors ; adaptive genetic diversity ; provenance trials

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