Species Selection in Urban Forestry—Towards Urban Metabolism

Abstract

With increasing urbanization in the twentieth century, the incorporation of trees into urban settlements has increased and management of trees within the urban area is considered as a distinct discipline of forestry. Urban plantations have many positive effects on urban metabolism like reducing urban runoff, heat islands, energy requirements, effects of climate change and to accelerate urban metabolism. Selection of species with array of considerations, e.g., capacity to sequester more carbon, control of air, noise and water pollution, wastewater treatment through phytoremediation, etc., is an important part of urban forestry. Planting of trees and shrubs in an urbanized area involves the selection of species, planting site, planting activities, maintenance, surgery of trees, etc. Several types of planting sites are unique to urban areas including street lawn, undulating areas, avenue and cluster planting, etc. These sites may require special considerations when selecting a species and choosing a proper planting technique. The choice of species should synchronize with the type of habitation, building patterns, the colour of the country side, the nature of the terrain (rocky, undulating, plains, etc.) and its texture (broken, gently sloped, smooth or with abrupt transitions, etc.). These landforms are the guiding factors to finalize the planting plan so that the trees grow well and synchronize with the city conditions. Species characteristic’s includes grandeur of the size, gracefulness of the branching patterns, tree form and stem character, the harmony of line and symmetry of form, density or pattern of foliage in relation to shade, the elegance of foliage, spectacular foliage colour, spectacular floral display colour, attractive fruits, the luxury of fragrance, etc. In addition, trees and other species in the urban environment are subjected to a number of stresses which are very different from those suffered by trees in typical rural conditions. Hence, in selecting the species for planting in urban areas, the basic properties of species like climatic adaptation, disease resistance, large phenotypic plasticity, etc., should be given more weightage during plantation in these areas.