engleski

VARIABILITY AND RANKING OF ACORN CROP SIZE AND PRODUCTION POTENTIAL OF PEDUNCULATE OAK (Quercus robur L.) STANDS OF DIFFERENT AGE

Variability in acorn production strongly affects regeneration of oak forests. It varies among provenances, individual trees, years, stands age and structure, ecological factors and genetic abilities of individual tree for acorn production. Pedunculate oak (Quercus robur L.) is economically and ecologically the most important forest tree species in Croatia. It belongs to the European white oak species which tends to periodically yield at different intervals and quantity. The objective of this study was monitoring of the crop size in oak stands of different age - middle aged, older and old forests - in order to determine the mast index and the production potential of the stands. The acorn-collecting traps method was used. Seed materials were collected three times during the vegetation period. Seed materials were grouped into three different categories according to phenological phases of acorn development. Quantitative analysis and seed quality of fully developed acorns were analysed. Number of acorns per square meter and the amount of acorn crop size of dominant trees per hectare were calculated. According to the amount of the acorns per hectare, the mast index was suggested and production of acorn crop size was estimated. Acorn crop was observed every year in different quantities. The yield in 2015 and 2016 has failed due to some unfavourable climatic and biotic factors in all stands. The yield was ranked as good in the old and middle aged stands in 2014, and it was ranked as very good for all investigated stands of different age in 2017.

Quercus robur, acorn crop size, mast index, stand age, production potential

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