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1. Introduction and purpose of the study

The United Nations university programme
Objective of the study
Choice of study areas
Definitions and distribution of arid and semi-arid lands
Benefits of trees-the "4-E Package"
Recent trends in forestry

The United Nations university programme

Through its Programme on the Use and Management of Natural Resources, the United Nations University has been attempting to identify critical problems of resource management that can be alleviated through research, training, and dissemination of knowledge. One of the initial three critical problems chosen was the ineffective application of knowledge to the management and development of arid lands.

A sub-programme on the Assessment of the Application of Knowledge to Arid Lands Problems was established in 1977 with the remit that "the reasons for inadequate and unsuccessful application of knowledge and experience must be identified as a basis for planning and for the optimum use of technology to improve human welfare." This was intended "to facilitate the basic desire of many arid land inhabitants to remain within such areas by providing them with services and enabling them to manage their resources for optimum productivity at the least social, capital and environmental cost."


Objective of the study

Existing knowledge and technology may well be limited within the political boundaries of one country while relevant information is freely available in other countries within the ecological boundaries of the arid zone. Afforestation of arid and semi-arid lands may be considered technically impossible in some areas yet be successfully practiced in others. The objective of the present study was to consider two countries, one with some experience and the other with pressing problems of arid zone development, and to compare and contrast them in terms of environmental, technical, social, and economic factors with a view to identifying constraints to tree planting and to identifying areas in which national institutions and international agencies including the United Nations University could contribute by training and the dissemination of knowledge. In both of the countries chosen there is poor awareness and distribution of relevant literature, and throughout this report an attempt is made to draw attention to published information from these and other countries, particularly the technical and environmental literature.

The study transects two other sets of activities of the United Nations University in addition to the work on arid lands, namely fuelwood and agro-forestry. Fuelwood is a major forest product required in most of the developing world, and especially in the arid zone; agro-forestry, the combination of agricultural and forest crops, is one approach to land use and afforestation in the zone,


Choice of study areas

Two English-speaking countries were chosen, India and Kenya, both of which were known previously to the consultant. They both have large areas of arid and semi-arid lands, but they have different population totals and densities; in both cases there are appreciable demands by their populations for wood products, particularly fuelwood and fodder. Kenya hosts the headquarters of international agencies, including ICRAF (International Council for Research in Agro-forestry) and UNEP (United Nations Environment Programme), but it has no research institute specifically concerned with arid lands development. In contrast, India has ICRISAT (International Crops Research Institute for the Semi-Arid Tropics, Hyderabad) and CAZRI (Central Arid Zone Research Institute, Jodhpur) as well as the long-established FRI (Forest Research Institute, Dehra Dun). Kenya has a new university forestry department with inadequate staff and a curriculum that is not yet well-developed in agro-forestry and arid zone forestry; India has many training establishments and many graduates in agriculture, forestry, and soil and water conservation.

Both countries have long traditions of professional forest management, but until 1980 Kenya has emphasized afforestation by industrial plantations on relatively highly productive sites, while in India considerable attention in the last ten years has been given to social (community) forestry in less desirable environments. The two countries also differ in land use policy and tenure, and the organization of field staff.


Definitions and distribution of arid and semi-arid lands

The growth and yield of trees, as of other plants, in arid areas depend on several limiting factors including low and irregular rainfall with frequent drought periods, high temperature and intense radiation, and poor soil conditions, including low moisture-holding capacity, high infiltration rate, and low content of organic carbon. An integrative discussion of their physiological effects was given in Perry and Goodall (1979), but together these are expressed conveniently in terms of aridity

The bioclimatic aridity of a site depends on the relative amounts of water gained from rainfall and lost by evaporation and transpiration. Various ratios of these climatic measurements have been used, but they will not be reviewed here. On a worldwide scale the most useful representation is that used by UNESCO (1977) in the preparation of a map of the world distribution of arid regions; this used the ratio of mean annual precipitation (P) to the mean annual evapo-transpiration (EPT). Four main classes of aridity were recognized: hyper-arid (P/EPT < 0.03), arid (0.03 < P/EPT < 0.20), semi-arid (0.20 < P/EPT < 0.50), and subhumid (0.50 < P/EPT < 0.75). Temperature and its annual fluctuations were recognized in subdivisions, and rainfall regimes were represented by colours.

Within the hyper-arid zone annual rainfall is less than 100 mm with virtually 100 per cent inter-annual variability; vegetation is either absent or ephemeral; tree planting without irrigation is unlikely to succeed; and the most common land use is for oil and mineral mining (and construction of gambling casinos), unless subterranean water is available.

In the arid zone annual rainfall is approximately in the range 100-400 mm, with an inter-annual variation of 50-100 per cent; vegetation comprises mainly sparse annual grasses with some low shrubs; non-irrigated tree planting is possible. Extensive animal breeding occurs, and rainfed agriculture is increasing, although irrigated agriculture may be considered more logical.

The semi-arid zone receives 400-600 (occasionally 800) mm of annual precipitation with 25-50 per cent variation between years; the total differs between areas receiving winter rainfall (e.g., north Africa, 400-500 mm), and those receiving summer rainfall (e.g., east Africa, 700-800 mm). Vegetation is taller and denser with more trees than in the arid zone.

While the UNESCO map provides at small scale a base document for the world, it does not delineate exactly the distribution of arid zones within a given country. Further the systems used by national agencies for site classification do not necessarily agree with those of UNESCO, and in any case no meaningfully precise delimitation is possible because of annual variation in rainfall and temperature.

Various countries consider 300 mm rainfall the upper limit of the arid zone and 500-800 mm the upper limit of the semi-arid zone. For the purpose of this report an exact definition is unnecessary because tree-planting techniques and constraints do not change abruptly. (Ghosh 1977, in his treatment of afforestation techniques in India, grouped all tropical dry forests that occur in areas receiving less than 1,250 mm.) The areas considered here are those recognized as arid (350-500 mm rainfall) and very arid (200-350 mm) in Kenya (Government of Kenya 1979) and as arid in India (less than 500-600 mm, mainly in parts of Gujarat and Rajasthan; e.g., see ICRISAT 1978), but to a large extent the discussion applies equally to the drought prone areas of Andhra Pradesh, Bihar, Gularat, Haryana, Jammu and Kashmir, Karnataka, Madhya Pradesh, Maharashtra, Orissa, Rajasthan, Tamil Nadu, Uttar Pradesh, and West Bengal (Government of India 1978). However, most of the examples are taken from Gujarat, where tree planting is actively pursued. The Kenyan acronym ASAL (arid and semi-arid lands) is adopted as an all-embracing term (Government of Kenya 1979).

These areas are illustrated in figures 1 (India) and 2 (Kenya). Although there are considerable variations in climate, soil, topography, and demography within these areas, many of the obstacles to tree planting are common within a country.


Benefits of trees-the "4-E Package"

Tree planting, even if constraints can be overcome, must take its place in an overall programme of arid zone develop meet. There are four major components (the four E's) of any such development, namely ecology, employment, energy, and economics. All components include a strong human dimension, and it is important to emphasize the potential contribution that local people can make. Development projects are intended to be for people, but they should also be designed to operate with people. Specific instances of local participation are outlined below. Too often schemes that are laudable with respect to one or two of these components fail to consider the others adequately.


If, in ecology, we include the amelioration and protection of the environment for man and his domestic animals, trees can play a significant role in the ASAL.

FIG. 1. Isohyets in India (based on Government of India 1975, ICRISAT 1978, Subrahmanyam et al. 1965)

FIG. 2. Isohyet for 500 mm in Kenya (based on Kamweti 1979)

Climatic Effects

There is still controversy about the effect of forests on rainfall at a continental or regional level but there is little doubt that trees and forests can modify local environment, e.g., individual trees that provide shade, and shelterbelts, which affect windspeed, temperature, and evaporation.

Soil and Water Effects

Trees, through their widespread roots, can stabilize soil in sand dunes and on hillsides thus preventing soil erosion, river pollution, and dam siltation. Deep-rooted trees may reach underground water supplies not accessible to other plants. Trees tap nutrient reserves and recycle them through leaf fall, making them available to other crops; this is particularly important in tropical areas where high temperatures and intense rainfall cause leaching. It is true that clear-felled industrial plantations may themselves cause nutrient loss and require artificial inputs for second and later rotations, but this type of tree planting is not widespread in the ASAL, where agro-forestry systems and coppice cutting are preferable.

Amenity and Recreation Benefits

In more developed countries the inhabitants have the leisure time and sufficient money to enjoy recreational pursuits and appreciate amenity values of trees and forests, but residents of the dry areas have different perceptions. However, trees are widely appreciated for one quality- shade. In the hot season (i.e., for much of the Year) it is a common sight to see a herdsman and his stock resting in the welcome shade of a tree.


For employment in the ASAL, tree planting and harvesting require more individual and group labour per unit area than pastoral or annual crops. Trees can provide employment and income, particularly during slack agricultural periods, through the development of industries processing minor and major products. Employment and income from trees can benefit diverse sectors in the ASAL, particularly the land poor and the landless, but also middle- and upper income households. Guaranteed land tenure and access to trees are essential to encourage tree planting.


Trees have traditionally been regarded as a low-input/ high-output, free energy source, and over half of the wood currently consumed throughout the world is used for fuel, largely for domestic purposes; within the ASAL the proportion is far higher. Some 1.5 x 109 people use wood daily for cooking their food and for maintaining essential levels of warmth in their homes (FAO 1978). (See also Arnold and Jongma 1978; Arnold 1978; IDRC 1979.) Even in developed countries far from the ASAL, with the recognition that reserves of non-renewable energy sources, particularly oil, are finite and diminishing rapidly, wood has recently attained new prominence as a potential source of energy, including its use for fuelwood, charcoal, and chemical feedstock (alcohols).


In economic terms, trees yield products that facilitate monetarization and diversification of the economy and, by encouraging settlement, improve marketing and transport system and encourage enterprise. In the ASAL, in addition to fuelwood, fencing material, poles, and some sawn wood are the major forest products, either from single trees on farms and along edges of canals, railways, and streets or from relatively large plantations in smallholder, community, or government forests. Minor products include directly used material such as animal fodder, roofing and smoking materials, or drugs and indirect products such as honey or wildlife. Overall in the ASAL, timber takes second place to products and services from trees, and conventional timber management systems often conflict with local needs for these other services and goods.

In appraising projects for financial support, national and international institutions have traditionally considered mainly the financial benefits of the projects. Only recently have social benefits been included so that the interactions of the "4-E package" can be examined. Techniques of social cost-benefit analysis and environmental impact analysis now permit approval of some projects that are not financially feasible and the rejection of others that, while financially attractive, have undesirable effects on the ecological or social situations in the project area. Techniques of analysis have advanced in recent years, with the emphasis of USAID, World Bank, and other agencies on social soundness analysis. Such analysis should preferably be made before the project gets under way and should continue during the life of the project. However, even if the analysis is done in good time (which in fact seldom happens), there are many associated problems. These include isolating the effects of one specific action-e.g., afforestation-from other actions, especially as successful development usually requires an integrated plan with many social and economic aspects. Then there is the problem of time-should costs and benefits be estimated for a short period or, more realistically, for the long term? Multiplier effects and indirect effects of projects are often significant, but are also difficult to measure with any precision. Even now there remain considerable problems of quantification and evaluation in the use of social cost-benefit analysis at the subsistence forestry level.


Recent trends in forestry

Professional foresters were traditionally conservationists; indeed, throughout British Commonwealth countries, senior staff are still called Conservators of Forests, In many cases this conservation implied gazetting large areas of natural forest as Government reserves and forbidding access by the public or limiting removal of products; it required a policing function of the Forest Department, often causing the animosity of local populations and lack of awareness both of total forest benefits and of the need for public concern with forest maintenance.

Recent rapid increases in population size and personal expectations have placed great pressures on natural forest throughout the tropics and subtropics, particularly where land is in such short supply that the fallow period of traditional "slash and burn" shifting cultivation is reduced below the limit for site regeneration (e.g., see Kunstadter et al. 1978). Although the effects of population pressure are most commonly experienced in the moist tropical forest (to the extent that in some countries of South-East Asia 30 per cent of officially gazetted Government forest reserves are now under illegal agricultural occupation, and many reserves are being officially relinquished to satisfy the demands of landless rural people), similar trends are now being experienced in more open savannah woodlands of drier areas. In the arid and semi-arid areas, on lands given over mainly to grazing, human populations have remained reasonably constant and small, but animal numbers have increased (for family wealth, for insurance against loss, and for sale to neighbouring towns); natural forests have been reduced to relics by a combination of grazing, fire, and exploitation.

For all these situations the reintroduction of trees is an important step towards rehabilitating degraded sites, protecting soil and water, preventing further desertification, and satisfying population demands.

Throughout the present century there has been an almost exponential increase in plantation forestry (and this is expected to continue in the tropics to the end of the century; Lanly and Clement 1979), particularly with exotic conifers and eucalypts, mainly for saw timber or pulp, and often supported by international agencies' loans and assistance. Although often subject to criticism (frequently unjustified) on the grounds of increased water utilization or soil degradation, this type of plantation will continue to be necessary on economic grounds. Nevertheless, the benefits of such forestry accrue mainly to Government or to large companies and not directly to rural individuals or populations.

Throughout the 1970s there was increasing awareness of the need to benefit rural development more directly by encouraging tree planting at the smallholder and community levels and by using trees that could provide more than one benefit (multipurpose trees, e.g., fodder and fuel), and system that allowed multiple uses of limited land (agro-forestry systems, including agro-pastoral-silvicultural combinations).

This increasing awareness was acknowledged in the theme of the 1978 World Forestry Congress (Jakarta), "Trees for People," and by the creation of the International Council for Research in Agro-forestry (ICRAF, Nairobi) It is reflected in the activities of the United Nations University itself (agro-forestry, fuelwood, arid zone development) and by the revised policies of the FAO (1978), the World Bank (Draper 1977; Keil 1977; Spears 1978; IBRD 1979a), the Asian Development Bank (ADB 1978), and many multilateral and bilateral assistance agencies. (See also Eckholm 1979; King 1978, 1979; Sanger et al. 1977.)

Throughout the tropical and developing world, there is therefore wide interest in tree growing and, for the arid zone in particular, the need for trees is great, but the obstacles to tree planting are also considerable.

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