Researches of Field Evidence for Late Quaternary Climate Changes in the Highest Mountains of Bulgaria - Sustainable Development in Mountain Regions: Southeastern Europe - page 144

Fig. 12.3 Field evidences for evaluation of environmental change and main methods for their
research
12.3 Types of Indicators and Research Methods
Because of the insufficient amount of data from direct climatic measurements in
spatial as well as in temporal aspect, environmental change studies in high-mountain
areas in regional and local scale are based most of all on the existence of field
evidence that indicates different conditions in the far or near past. According to
research methods that have been used at present, this evidence can be summarized
in several groups (Fig. 12.3 ).
Of course, instrumental measurements also take an important part in the studies.
Climatic changes were recorded in the high-mountain area of Rila dated from 1932,
when a meteorological station at Musala peak was opened. However, as can be
seen in Table 12.1 , the number of climate stations in our country at altitudes above
2,000 m a. s. l. is very small.
12.4 Previous Geographical Studies in Rila and Pirin
High mountains have attracted the interests of naturalists since the beginning of
19th century AD. The first explorer who made natural descriptions of Bulgarian
mountains was Boue ( 1840 ). Cvijic ( 1896 , 1909 ) was the first to mention about