SURVEY OF THE PRESENT STATUS OF STREET TREE PLANTING IN COLOMBO MUNICIPAL COUNCIL AREA and SOME RECOMMENDATIONS FOR IMPROVEMENTS

Abstract

Urban Forestry embraces parks, avenue planting or street trees, boulevards, cemeteries,parking places etc. It plays an important role by providing aesthetic beauty andenvironmental pollution by absorbing vehicular emission. Colombo, which is thecommercial capital of Sri Lanka, is plaqued with high population density and highcommercial activities. Urban forestry has II significant potential in improving aesthetic &environmental aspects of the city.

Objectives of this research project were to identify the existing situation of the street treeplanting in the 15 sub divisions of the Colombo Municipal Council Area and to give somerecommendations for improvements. 2 trunk roads were selected per division randomlyand the status of trees in these roads was recorded. Measurements of crown size, height,diameter at breast height, height of the first branching, widths of roads, sidewalks, andcenter medians were measured and recorded. Observations done in status of maturity, pestdiseaseattack, root pattern, foliage characteristics such as whether easily decayable ormoderately decayable and small or large leaves, land use patterns such as commercial,service & administration, residential and recreational land use & recorded.

According to the results, a difference in the status of street trees in the 15 sub divisions inthe Colombo Municipal Council Area was identified. The sub divisions can be rankedaccording to the total crown area per kilometer as follows: sub divisions 7, 14, 3, 11, I, 2,5, 10,6, 13, 12, 15,8,9 & 4. The sub divisions can be ranked according to the number oftrees per kilometer as follows: sub divisions 7,10,14,1,13,2,5,6,12,11,3,15,8,9 & 4. The subdivisions can be ranked according to the number of species diversity per kilometer asfollows sub divisions 7,13,12,14,'1,5,2,11,15,8,10,6,3,4 and 9. Terminalia Catappa(Kottang), Polyalthya longifolia (Willow) Samanea Saman (paramara), Delonix regia(Maimara), Casia fistula (Ehala) & Plumer.ya spp. ( Araliya) represent 5 or more than 5 %in the sample survey. 56 tree species were identified in the study area.

Out of 30 selected street SItes, 7 were identified as sites, which need immediate planting programsand another 17 sites needs planting program. <) street sites need immediate pruning operations asthey have trees with first branching height of less than 2.00 meters, which may interrupt the trafficnow. 6 street sites were identified as site" which need immediate removal and replacementoperauons as they have over-matured trees, which may become hazardous trees if necessary actionsare not taken. Out of 15 sub divisions surveyed, 7 were identified as affected with pest-diseaseattack. Further, some recommendations are Identified as to improve the existing situation of thestreet tree planting in the study area and a draft action plan for 5 years was drawn. Further scientificstudies such as species, which can reduce soi' erosion, pollutants absorbers, etc. are needed forbetter management of urban trees.