EVAPOTRNSPIRATION DETERMINATION OF SOME FOREST TREE SPECIES AND SEEDLINGS

Weighing method was used to determine actual evapotranspiration of three types of forest trees seedlings Pinus brutia, Cupressus sempervirens var horizontalis and Biota orientalis grown in forestry nursery at College of Agriculture and Forestry during the period from the middle of November 2009 and the end of January 2010 .The effects of various environmental factors on evapotranspiration were studied such as air temperature, relative humidity, dew point, actual vapor pressure, saturation water vapor pressure, saturation deficit and soil moisture. Results showed that the amount of evapotranspiration of the three types of seedlings were 3.3,4.5 ,2.9 ml/hr/seedling, the best equation that gave good agreement are as follow
ETp = 0.5219 ( sd ) 1.339
ETc= 0.860 ( sd ) 2.453
ETt = 0.704 ( sd) 2.406
On the other hand results indicated that the amount of transpiration measured by cut branches of the same species were gave a values of 28.23, 35.7, 34.0 mg H2O/gm/hr respectively.