Page 29 - NZDPM 33/2017

28 Bokotey A., Strus Iu., Dzubenko N.

Selectivity of Black Storks in the case of old forests of different age categories is
statistically significant when comparing forest age structure in 500 m buffers around nests
2
with such in buffers around random points (χ =16,59, p=0,005, df=5). In comparison with
general forest age structure in the region, the differences in frequencies are not significant
2
(χ =3,34, p=0,65, df=5). Many studies report a strong relation between stork nest locations
and forest age [12, 13, 14, 15, 19]. In our opinion, forest age is not the crucial factor for
storks, but it correlates with the availability of old trees suitable for nest building. The older
forest stand is, the bigger a possibility to find old trees there. On several occasions we have
found nests in relatively young forest stands with only several old trees or even just one tree
(usually old oak or pine).
From the frequency distribution of Black Stork nets in relation to forest soil-humidity
types (classification by P.S. Pogrebniak [18]) we can assume that the most preferable types
for Black Storks are forests which grow on humid and wet soils (B3, B4, C3, C4; fig. 5).
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However, the differences are not statistically significant (comp. with rand. points.: χ =9,78,
2
p=0,78, df=14 and with the entire area: χ =6,73, p=0,94, df=14).

Fig. 5. Distribution (%) of Black Stork nests in forests of different soil-humidity classes
in relation to the general frequency distribution of those classes in the region.

It is quite interesting to note a spatial distribution of Black Stork nests in relation to the
distribution of forests with different productivity (bonitet class) and therefore different
value for the forestry industry. Storks most frequently inhabit forest plots with the highest
productivity – class 1 (1, 1A), which is demonstrated by the occurrence percentage in 500m
buffers around nests (42,3% for 1 and 1A combined). It can be concluded that the forests
with productivity classes 2 and 3 are most suitable for storks (37,1% and 12,3%
respectively, table 3). A very similar situation was observed in the study of R. Treinys and
others [12] where they described distribution of 30, 23, 35, 12% for bonitet classes 1A, 1, 2,
3-4 respectively. The same was also indicated by [4]. In the case of our study, the
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differences with random points and study area are not statistically significant (χ =2,25,
2
p=0,99, df=10 and χ =1,70, p=0,99, df=10). Therefore, Black Storks inhabit mainly forests
of a very high value for forestries producing maximum amount of wood and the highest
income. Conflict of interest is obvious and it is one of the main reasons why the species
population is declining.