STUDY OF HIGH SHADE TREES (Gravillea robusta) ON MICRO
CLIMATE OF A TEA FIELD
Ediriweera E.P.S.K. 1 and Anandacoomaraswamy A. 2
1 Department of Forestry & Environmental Science, University
of Sri Jayewardenepura, Nugegoda.
2 Division of Plant Physiology, Tea Research Institute, Talawakelle
Shade trees are widely grown in tea plantations in Sri Lanka to provide
physical shade for tea during the dry weather. It also enriches the soil
fertility by leaf fall. An investigation was carried out to quantify the
radiation and canopy temperature around an eight year old 'high' shade
tree Gravillea robusta. The measurements were made at hourly intervals
from 9.15 am to 3.15 pm on January 13th, 1999. In addition, relative humidity
was measured in the shaded and unshaded area.
The radiation was measured by a tube solarimeter and the canopy temperature
was measured by infra red thermometer. The organic carbon content of the
topsoil between two shade trees were measured at north-south and east-west
directions at 2m intervals.
On a clear day the shaded area ranged from 12-15%, highest during the
early morning and lowest during the noon. The canopy temperature under
shade was 4-60C less than the unshaded area. There was a marginal difference
in relative humidity between shaded and unshaded area. The relative humidity
of the shaded area was marginally higher than the unshaded area in the
afternoon. The organic carbon content ranged from 3-4%. A high value was
found near the base of the tree and a low value was found midway in between
the shade trees. The mean leaf area index of the Grevillea canopy was
6.9 and the canopy extinction coefficient was 0.21.
Department of Forestry and Environmental Science,
of Sri Jayewardenepura,Sri Lanka. 1995-2000. All rights reserved.