Evaluation of different thermal conditions based on THI under different kind of tree types – as a specific case in a Ata Botanic Garden in eastern Turkey

Outdoor recreation is an important issue for people living in areas where they face problems caused
by harsh climatic features like the city of Erzurum. The aim of this study was to determine the
favourable features of tree species, which can grow in the city, for human bioclimatic comfort
conditions. For this aim, measurements of climatic elements (temperature, humidity, and wind) were
carried out under different tree canopies in the Ataturk University Ata Botanic Garden in July and
August 2008. For the calculation of bioclimatic conditions, one of the most widely used indices, THI
(Thermo hygrometric Index) was used based solely on the data of clear and calm days during the
measurement period. From the results of the study, it was found that the canopy of Scotch pine trees
can provide the most comfortable environment by increasing human thermal condition by 5.1 %,
followed by Silver birch trees by 3.8 % which increased human thermal condition when compared to
open space while mixed canopy did not give the respective results. Some suggestions about the use
of plant materials in recreational areas are presented.