TITLE:
Comparative Study of Transpiration in Cooling Effect of Tree Species in the Atmosphere
AUTHORS:
S. K. Gupta, Jeet Ram, Hukum Singh
KEYWORDS:
Rate of Transpiration, Ambient Temperature, Cooling, Stomata, Microclimate, Water Conductance, Root Pressure
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.6 No.8,
August
29,
2018
ABSTRACT: Trees create microclimate under their crowns in comparison to the outside
ambient atmosphere, which is a result of physical as well as physiological
functions of the tree. The cooling produced by trees varies with species due to
variation in several anatomical, structural and physiological attributes of the
species. Transpiration is one of the most significant physiological functions
performed by plants, which affects cooling produced by a tree under its
shade. When solar energy impinges on the leaf, water emerges from its surface
through transpiration taking the latent heat to convert it into water vapour.
This leads to a rise in humidity of the atmosphere and reduction in
temperature of the leaf. To remain leaf in equilibrium, it takes heat from the
surrounding atmosphere resulting in reduction in temperature of surroundings.
Since, transpiration takes place through stomata which are normally located
on the ventral side of the leaf, this reduction in temperature is more
experienced beneath the crown of the tree. Therefore, the present study was
carried out to analyze the role of transpiration in cooling effect of five forestry
tree species. The cooling produced by tree species under their shades has been
found positively correlated to the transpiration rate whereas the rate of transpiration
has responded positively to the ambient temperature and water
conductance. However, no definite relationship has been found between frequency
of open stomata and the rate of transpiration.