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  FORESTRY SYMPOSIUM 1996
RESTORATION OF DEGRADED CONSTRUCTION SITES IN THE UPPER MAHAWELI REGION BY SELECTING SUITABLE TREE SPECIES

Ranjan Attygalle
Mahaweli Authority

The Mahaweli headworks include dams, reservoirs and power stations. There was a rapid development of these major works in the mid eighties. This acceleration led to the removal of vegetation, transformation of landscape and degradation of land. Thus many sites in the Upper Mahaweli region need restoration. For some of these it might be possible but for others heavy investment may be needed, which might not be economically feasible.

A site which is on the right of Rantembe reservoir is one of these. A fleet of heavy machinery was used to remove the earth during the construction phase leaving unstable slopes exposed to direct impact of rain drops.

The site is heavily degraded and huge gullies have formed. These lead the water, carrying loads of silt, to the Rantembe reservoir. It is known that Rantembe is already having siltation problems due to the human activities that are taking place in the Uma Oya Catchment.

Several attempts have been made, at the requests of the engineers, to colonize the site with artificial seeding and avenue planting, but none succeeded.

The bottlenecks for colonizing these degraded lands are of three fold. The prolonged drought (March to September) which lasts for about eight months is the prime cause. It is also believed that for the artificial seeding and avenue planting operations species identification was not done properly. Finally the presence of browsing animals was also a setback.

In 1995 three sites were selected, from the Rantembe catchment. Several tree species which were thriving well were marked and their gbh were recorded. Since this was not a plot study five individuals from each species were marked. Subsequently within the three sites 20m x 20m plots (3), 5m x 5m plots (3) and 1m x 1m plots (3) were marked and trees, saplings and seedlings were recorded.

The paper highlights some of the preliminary findings of this study.

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