Urban forestry is not a new concept, but it is one which appears to have growing potential. This is particularly true in developing countries,1 where urbanization is increasing at a rapid rate and a demographic switch from a predominantly rural to a predominantly urban society is taking place. Although UN (1991) figures indicate that in 1990 only 37% of the total population of developing countries was urbanized, it is predicted that by the year 2025 the proportion will be 61%. Already rapid and uncontrolled urbanization in many developing countries is having fundamental social and environmental consequences. The role of urban trees in ameliorating this situation might, at first thought, appear to be small. Yet urban forestry may provide Third World town and city dwellers with significant environmental and material benefits. This concept paper outlines the current state of knowledge about urban forestry in developing countries, and the potential for future actions. Where pertinent, it also draws upon examples from developed countries.
The document is divided into eight sections. The first defines the terms ‘urban’ and ‘urban forestry’. In section two the role of trees in Third World urban settlements is set against historical and more recent development of such towns and cities, drawing attention to growing environmental concerns. Section three elaborates upon the various urban locations in which trees may be cultivated, considering this according to biogeographical zonation, land ownership categories, and a simple spatial model. The various benefits to be gained and problems encountered from tree cultivation in an urban environment are outlined in section four. Throughout the discussion, social/cultural aspects are considered as far as they are known, but key issues are highlighted in section five, leading on to tree establishment and management issues in section six. Section seven deals with institutional aspects. The final section draws attention to the information that is currently lacking on urban forestry in developing countries, and some of the most important topics requiring investigation.
It is appropriate to begin with definitions of the terms ‘urban’ and ‘urban’ forestry'.
1 There are of course well known difficulties in distinctions between ‘developing’ and ‘developed’, ‘Third World’ and ‘First World’, or however such differences are phrased. For the purposes of this discussion, the standard UN definition has been adopted, under which middle income or newly industralized countries are considered to be ‘developing’, as are both Hong Kong and Singapore (although if ranked solely according to their per capita income, they both have high income economies). The terms ‘Third World’ and ‘developing’ are used interchangeably throughout the text for convenience. Countries thus classified are, nonetheless, very diverse, and it should not be assumed that they are all experiencing similar development.
When asked to describe an ‘urban settlement’, characteristics that a citizen of an industrialized country might mention include a high density of population, buildings, roads and railways; a centre of commerce, industry and entertainment; a preponderance of concrete and tarmac; atmospheric pollution; and a population which does not engage in agriculture. Perhaps many, but probably not all, of these characteristics would be mentioned by inhabitants of developing countries. They might also think of other characteristics, such as unhygenic conditions (including open sewage and a lack of clean water) and a lack of open space. As far as agriculture is concerned, it would be incorrect to classify urban dwellers in all Third World cities as consumers only, and not producers. A number of studies have shown that a significant number of urban residents in developing countries grow much of what they eat; in Kenya, for example, a study of six towns/cities found that two thirds of all households cultivated at least part of their food (although only 29% did so within the urban area itself) (Lee-Smith, et al. 1987).
Clearly urban areas in developing and developed countries are often very different. Furthermore, although we know intuitively what is ‘urban’ and what is ‘rural’, there is actually no universally accepted criteria for distinguishing between such settlements. The usual mechanism, common in national censuses, is to take population thresholds. Once a nucleated settlement grows beyond a certain threshold, it becomes ‘urban’. However, the threshold used varies widely from country to country, and may even change in successive censuses (Hardoy and Satterthwaite, 1986). The United Nations has attempted to standardize data by defining settlements of over 20,000 people as ‘urban’, over 100,000 as ‘cities’, and over 5 million as ‘big cities’. In contrast, Hardoy and Satterthwaite define any nucleated settlement of more than 5,000 as an urban centre, those having a population of less than 20,000 being ‘small urban centres’, and those having some 20,000 to 100,000 inhabitants being ‘intermediate urban centres’. Whatever the figure used, generalizations are inevitably unsatisfactory (as Hardoy and Satterthwaite fully acknowledge). A small Pacific island whose total population is under 20,000 will obviously have a different perspective on urban settlements from a large, heavily populated country such as India. Different national perspectives may well reflect historical, cultural and political differences. This varied concept of an ‘urban settlement’ should be remembered throughout the ensuing discussion. It is also worth noting that the ‘cut off point’ on the ground for an urban centre is interpreted differently in different countries. An obvious example of this is in China, where cities often ‘annex’ a number of adjacent districts into their administrative areas in order to ensure control over the supply of essential urban services, such as reservoirs or power plants. The official population of many Chinese cities thus includes many rural dwellers (Drakakis-Smith, 1987).2
2 It may also account, at least to a certain extent, for some of the high figures reported for Chinese ‘urban tree planting’.
The discipline of urban forestry
With increasing urbanization in the 20th century, the incorporation of trees into urban settlements has also increased - to the point that the management of all trees within the urban area is considered a distinct discipline of forestry. Urban forestry was conceptualized in the late 1960s in North America, and grew out of what was initially termed environmental forestry. According to a leading authority on the subject, it was at this time that,
“Foresters recognized two things: that they had to deal with urban residents, and that the political power base had shifted to cities.” (Miller, 1988:28).
In 1970, the US Forest Service created an Institute for Environmental Forestry Studies which has been a centre for training and research in urban forestry ever since. There are now numerous urban foresters in the United States, and a vast body of literature on the subject. This development is also to be found in Canada, Europe and Australia. In line with environmental concerns in the towns and cities of such countries, the subject has concentrated on trees for landscape and amenity purposes, and, increasingly, on how trees may be used to modify specific aspects of the urban environment (noise, airborne pollution, heat, air currents, etc.).
The definition of urban forestry given by Miller (opp. cit.) is of,
“an integrated, city wide approach to the planting, care and management of trees in the city to secure multiple environmental and social benefits for urban dwellers.”
A rather more detailed definition, which will be adopted for the purposes of the present paper, is as follows:
“Urban forestry is the management of trees for their contribution to the physiological, sociological, and economic well-being of urban society. Urban forestry deals with woodlands, groups of trees, and individual trees, where people live - it is multifaceted, for urban areas include a great variety of habitats (streets, parks, derelict corners, etc) where trees bestow a great variety of benefits and problems.” Denne, pers. comm. (adapted from Grey and Deneke, 1986)
Urban forestry thus includes the management of individual as well as groups of trees, and urban foresters see arboriculture3 as one important component of their subject. Urban forestry is also not restricted to trees that have been planted. Many urban trees may have established naturally, although in an environment in which competition for land is high, they are unlikely to survive long unless actively cultivated and managed. As noted below, urban forestry also includes the management of forests at the urban fringe.
The need for urban forestry to be a planned, integrated, and systematic approach to urban tree management should be stressed (Johnston, pers. comm.). Planning is important because trees are very often considered as an afterthought once development has taken place, rather than being incorporated at the original design phase. An integrated approach implies the participation of many different organizations - local councils, municipal and national planning bodies, departments, etc. Systemmatic management entails regulated tree management; operations such as planting, pruning, and felling must all be conducted in an organized manner, at the appropriate time. This is certainly more theoretical than actual in most urban settlements (in developed as well as developing countries); it also implies a greater degree of control over, or at least information about, all trees on all land types than usually exists. The varied ownership and access to land and trees in urban settlements inevitably renders overall management complex. Regarding legal control, there is generally more detailed, and strongly enforced, legislation concerning the management of trees (including ones growing on private property) in cities of developed than developing countries (Profous and Loeb, 1990). Urban tree databases are well developed in some North American towns and cities, as are inventory techniques and software packages to collate them. Such information has also been collected for some, but by no means all, urban settlements in Europe. It is often not available in developing countries.
In industrialized countries urban forestry is concerned primarily with environmental enhancement. Even in countries (e.g. Germany), where timber is harvested from peri-urban forests, the major management objective is providing recreation/education of the urban dweller, and timber harvesting operations are significantly modified accordingly. Largely having been conceived initially in terms of landscape improvement and amenity provision, urban forestry is now increasingly concerned with other, additional benefits, such as the control of air and noise pollution, and microclimatic modification. In developing countries urban trees have the potential to provide a greater variety of goods and benefits - both in terms of environmental improvement and material production (fuel, timber, fruit, fodder, etc). In many cases there may be considerable potential to increase the range of benefits provided by trees through more imaginative management.
3 Arboriculture is defined as the growing and tending of trees and shrubs, individually or in small groups, generally for ornament and instruction rather than use or profit.
Peri-urban forestry as a separate concept?
Peri-urban forestry is loosely defined as forestry on the fringe of urban settlements, but given the lack of conformity between countries as to what constitutes ‘urban’, a precise definition of ‘peri-urban’ is impossible. To use the simple definition of the area used by urban residents is inadequate, since this may extend far into rural areas; as theories such as that of Von Thunen have shown, the sphere of influence of a city or town may be very wide. To define peri-urban solely in spatial terms is also unsatisfactory, since it can be so variable. Many urban foresters are unwilling to accept peri-urban forestry as a separate concept; they argue that the peri-urban area, or urban fringe, is simply one location for urban forestry (Johnston, pers. comm.). This argument has been accepted in the compilation of this document, so that all further mention of urban forestry may be assumed to include peri-urban locations, unless otherwise indicated.
A new approach to the potential of urban forestry in developing countries
The potential of forestry in and around urban settlements may be approached from one of two broad perspectives. One is to focus upon the trees themselves; the potential benefits and problems that may be expected from their cultivation in an urban environment; how they may be managed to maximize the former; and what threats an urban environment pose to their survival. An alternative perspective, which this paper attempts, is to focus first on the residents of urban areas, their needs and the nature of their invariably diverse living conditions, and then to consider how trees might be of benefit to them. Inevitably, most literature on urban forestry tends to have been written from the former perspective. To learn more about the urban dweller, especially in the developing world, it is necessary to consult geographical or other social science texts. These rarely devote much attention to peoples' use of and perceptions of trees, except, to a certain extent, in the case of fuelwood supplies from peri-urban areas. This paper therefore draws together information from a wide variety of disciplines, including urban forestry, arboriculture, community forestry, landscape architecture, geography, sociology and economics. This is only fitting for a subject which has to be implemented through the cooperation of many people with differing professional expertise. However, the discussion is generally devoid (with a few exceptions) of opinions expressed by Third World urban dwellers (particularly the poor) regarding urban trees, and whether or not they value, use, or would like to use them. The reason is that these views are rarely to be found in the available literature.