Demographic Potential and Problems of the Settlements Network in the Mountains of Bulgaria - Sustainable Development in Mountain Regions: Southeastern Europe - page 167

Migration increase (in ‰)
<

10

− (368)

(66)
(57)

0 −

5

(816)
(9)
(28)

−

10 to − 5

−

5 to 10

−

5 to 0

>

10

Fig. 13.9 Migration increase - 2002-2007

Age structure has a key role in the demographic development of the population.
During the past periods, age structure shaped the general and the regional features of
both - the reproduction and the migration processes. Unlike past periods, nowadays
the age composition of the population in mountainous regions is worse compared
to the national average. This worsening was due to the negative changes in the age
structure of the population of the Rodopi Mountains, Eastern Stara planina and, to
some extent, in Rila and Pirin. There is trend of constant ageing of the population.
This is visible not only at the top, but at the bottom of the sex-age pyramid as well.
The increase of the average life-expectancy affects to a great extent the ageing at
the top of the pyramid, while the lowering birth rates result in ageing at the bottom
of the sex-age pyramid. In both cases, emigration has a major role in the ageing
process.
According to the age structure of their population, Bulgarian mountains can be
divided into two main groups - a group of mountains with extremely old-age struc-
ture of the population and a group of mountains with moderately old-age structure,
while there is no group of mountains with young-age structure of the population.
The first group is composed by Western and Central Stara planina, the Kraishte
region, Sredna Gora, Strandzha and Sakar. The population aged 0-14 years in those
mountains is less than 15% of the total, while the share of population over 60 years
of age is over 25%. The extreme ageing of the population in those areas is a result
only of the intensive emigration of young residents in the past and the extremely
low birth rates nowadays (Fig. 13.10 ).