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ŠUMARSKI LIST 7-8/2014 str. 23     <-- 23 -->        PDF

climate conditions are more favorable (it is warmer and with more precipitation), which could initiate earlier flowering in this locality, although it started earlier in the location of "Bojčinska šuma." This provides a basis for the assumtion that the pedunculate oak in the location of "Bojčinska šuma" belongs to a "early" oak form. Based on the analysis of the phenological pattern of the analyzed populations, according to which during the years of observation most trees did not change the group or changed only for one level, it could be assumed that the genetic influence on the expression of this trait was very evident, which would represent objective of future research. Among the trees that, over the years of observation, have not changed its phenological group in the "Ada Ciganlija" location, have mostly been late flowering, while in the "Bojčinska šuma" location have not been any trees that did not change its group.
Phenological asynchronization among individuals affects the flexibility and throuh adaptability helps its survival (Figueiredo Goulart et al., 2005). Bacilieri et al. (1994) emphasize that there is great individual variability in the initiation and duration of the pedunculate oak flowering. In this study they report that 49% of the trees remain in the same phenological group as the last year, 45% shift into the next group and only 6% of the trees change the group for two levels. Among those that did not change the group 26% belonged to the early flowering group, 26% to the late flowering, and the rest (48%) to an intermediate one. Since about 50% of the trees shift from one phenological group to another, quoted authors conclude that the ecological impact is also very strong, especially on the size and stability of populations, and that genetic differentiation among phenological groups is not possible. According to Matziris (1994), the beginning of flowering is under high genetic control, while the duration of flowering is more influenced by environmental factors. As mentioned author further states, it justifies an individual selection of the phenological characteristics, since they are synchronized with the seed production. The stronger effect of the flowering duration by enivornmetal factors is pointed out by Gomez-Casero et al. (2007) in a phenological analysis of three oak species (Quercus ilex L. ssp. ballota (Desf.) Samp., Q. coccifera L., Q. suber L.). The analysing the Q. suber L. in the region of Spain Elena-Rossello et al. (1993) concluded that the intrapopulation variability was the consequence of different ratio of the presence of male and female flowers, on which basis can be distinguished: –trees mostly with male flowers, –trees mostly with female flowers, –trees with both male and female flowers, and –trees without flowers but with a abundant biomass. In the study results of the pedunculate oak flowering in the area of Belgrade, a wealth of flowering was one of the criteria for the selection of trees for the observation of flowering, so that those results can be considered reliable for the assessment of genetic and environmental impact and analyzed variability.
During three years of observation, flowering phenopase of the pedunculate oak in the analyzed locations in the area of Belgrade takes place from 7th April to 2nd May, indicating very pronounced individual variability of the species. Analyzed locations have similar ecological conditions, so that the differences between them are the result of the population phenological pattern, which gives rise to the assumption of the presence of "early" and "late" varieties of the pedunculate oak. Population in the location of "Bojčinska šuma" develops in somewhat more humid conditions as a result of more humid climate and more hydromorphic soil type, although they have no significant effect on the analyzed traits. The results indicate the existence of individuals who maintain the same level in the beginning of flowering phenophase each year, which means its stability regardless the changes in climatic factors between years. As such, those results could be applied in modeling the response of the plant organisms to the micro and macro changes in the ecosystem, as well as in an individual selection for the establishment of plantations for various purposes (Valladares et al., 2006 and references therein).
This paper was realized as part of the project III "Studying climate change and its influence on the environment: impacts, adaptation and mitigation" (43007) financed by the Ministry of Education and Science of the Republic of Serbia within the framework of integrated and interdisciplinary research for the period 2011–2014.
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