There are various coniferous species in Bulgaria - pine, fir, alder, white fir, etc. Deciduous species, mainly oak, beech, hornbeam, ash, lime, nut trees can be found in Stara Planina, Sredna Gora and Strandja mountain, the sides of which are covered with young pines.
Poslednja provera i obrada od lilian canale - 22 April 2008 16:05
Hello Mr. Ian, I'm sorry but I've finished my evaluation for Japanese translation.
According to a machine translation, it's like this:
"whose slopes are covered with young pines"
I think it might sound most natural in English as:
...Strandja Mountain, the sides of which are covered with young pines.
If we use "whose" here, it would feel a little like "Strandja Mountain" was being personified.
If we use "the sides of which," it sounds less like Strandja Mountain "owns" its "sides"...
Also, "slopes" give the image of steep sides. (It also conjures up images of ski hills and so on.)
To me, anyway, it is very natural in English to say "the sides of a mountain"...