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ŠUMARSKI LIST 13/2011 str. 60     <-- 60 -->        PDF

M. Ivanković, M. Popović, S. Bogdan: VARIJABILNOST MORFOMETRIJSKIH SVOJSTAVAŽIREVAI ... Šumarski list – Posebni broj (2011), 46-58

SUMMARY: Seed zone delineation of pedunculate oak in Croatia was done according
to ecological differences, stand productivity and administrative borders of
Forest Range Offices (NN 107/08). Oak forests are divided into three seed zones
and it is recommended to transfer reproductive material only within zones. Seed delineation
was preformed due to Croatian Forest Reproductive Material Transfer
Law (NN 75/09) that was aligned with EU Directive on forests reproductive material
(1999/105/EC). Seed delineation should be done according to genetic differences
between various zones i.e. provenance regions. Aiming at verification of current
seed zones in Croatia, and on the basis of general knowledge on pedunculate oak
genetic variation, research on genetic variation of the species in Croatia has been
started. Due to that, seeds were collected within so called registrated seed stands
which are normally used as a seed sources for regeneration of managed oak stands.

Results of the study of seed morphometric analyses are presented in this paper.
Seed were collected during autumn 2006 below 25 trees within each of 17 seed
stands that represented whole distribution range of the species in Croatia (Table 1).
30 acorn from each tree were sampled for morphometric analysis and measured the
height of seedlings. Acorn length, widths and masses and seedlings height were
measured and acorn volumes were calculated according to formula for cylinder volume
(Figure 1, 2).

ANOVA was performed by MIXED procedure in SAS, in order to analyze significance
of various effects. Results showed that current seed zones were not statistically
significant effect (there were no significant differences between them), but
there were significant differences between populations within zones, as well as between
trees within populations (Table 2). Table 3 shows Type 3 significance F-test
for fixed effect of populations within seed zones for studied acorn traits and for one-
year seedling height.

Determined populations differences did not match current seed delineation i.e.
there were no obvious geographic pattern in between population variability for studied
acorn traits as well as analyzed seedlings traits. Tukey-Kramer’s test was performed
to determine the form and the differentiation which populations are
separated statistically significantly. Test did not give results from which we could
observe regularity in the geographical separation of populations for analyzed seedlings
traits (Table 5). Population HR 88 (Lacići-Gložđe, Koška) was significantly
differed from the geographically closed population HR HR 58 (Darda),
HR 577 (Poljadijske šume, Požega) and HR 627 (Repaš), while at the same time did
not differ from the distant population (HR 387 – Karlovac, Rečićki lugovi and
HR 609 – Buzet).

Statistically significant differences between populations for all analyzed traits
clearly indicate the genetic differentiation of oak populations. However interpopulation
differentiation did not correspond to the geographical pattern. Specific character
of differentiation indicates ecotypic pattern of genetic differences between
oak populations in Croatia, i.e. differentiation that are caused by adaptation to specific
micro-enviromental conditions (e.g. humidity, temperature and edaphic features).
To confirm the hypothesis of ecotype pattern of genetic diversity is necessary
to conduct additional research in genetic tests (provenance and progeny tests). Differences
between currently seed zones were not statistically significant for any of
the analyzed traits, which has not confirmed valid justification of current seed delineation.
Nevertheless, it should be noted that the analysis of seed morphometric
traits are not adaptively valuable properties, while the results of the one-year seedling
heights are not sufficiently reliable due to a very early age of plants. Therefore
these results should be regarded only as a stimulus for further research of oak genetic
diversity in Croatia.

Key words: seed delineation, provenance region, morphometric traits,
acorn, seedling heights, seed zones