WETTING CHARACTERISTICS OF SOME TROPICAL TREE SPECIES

M B D P Gunawardana*, E R N Gunawardana*, and I R Calder**
* University of Peradeniya; **Institute of Hydrology, Wallingford, UK

Interception is a physical process, which represents a definite loss of rain water since most plants can absorb water only through roots. This loss depends on how the canopy is wetted by the falling rains and the amount of water stored on the vegetation after the rain ceases. This information is needed for modelling studies to estimate the interception loss under varying climatic conditions.

This study was conducted to compare the wetting characteristics of Syzygium rundifolium, Rhododendrons zeylanicum, Eucalyptus microcorys, Hedyotis confertiflora, Artocarpus heterophyllus, Pinus caribeae, Tectona grandis and Acacia decurrens. A rainfall simulator consisting of drip irrigation nozzles and spray heads was used to generate three drop sizes. A branch representing a projected area of about one square meter was used to measure the maximum interception and the interception loss.

The results showed that the interception loss depends on the species and not on the rain drop size. Species with smaller leaves, such as Syzygium, Acacia and Pinus tends to have more interception loss compared to larger leaves. Therefore, planting of these species in low rainfall areas may have serious consequences with regard to water yield. Species with larger leaves such as Jack and Teak which gives the lowest interception loss are far more suitable for drier areas.

Department of Forestry and Environmental Science,
University of Sri Jayewardenepura,Sri Lanka. 1999. All rights reserved.