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"people are entitled to a healthy and productive life in harmony with nature" (Rio declaration)
An integrated approach to planning the use and management of land resources entails the involvement of all stakeholders in the process of decision making on the future of the land, and the identification and evaluation of all biophysical and socio-economic attributes of land units. This requires the identification and establishment of a use or non-use of each land unit that is technically appropriate, economically viable, socially acceptable and environmentally non-degrading.
A purely sectoral approach to the planning of land resources should be avoided, as this may lead to their irreversible degradation. Concern about the environment has been highlighted by the recent rapid growth of the world's human population, the increasing socio-economic interdependence of countries and regions, the growing awareness of the value of natural ecosystems, and the perception that current land use practices may influence the global climatic system. An integrated rather than sectoral approach is a means to prevent or resolve conflicts related to land and water use, as it optimizes the planning process and creates an enabling environment for mediation between, and decision making by, all stakeholders at early stages.
The medium, or most likely, projection of population growth implies a near doubling of world population to about 10 thousand million by the year 2050 (UNFPA, 1992). Most experts agree that through full and judicious application of modern agricultural technology, the world's land resources can, in theory, provide sufficient food, fibre, animal feed, biofuel and timber for such a doubling. In practice, there will be acute land shortages in many countries, especially many developing ones.
A recent FAO study (Alexandratos, 1995) estimates that 92% of the 1800 million ha of land in developing countries (excluding China) with rainfed crop potential, but not yet used for this purpose, is in Sub-Saharan Africa (44%) and in Latin America and the Caribbean (48%). Two-thirds of these 1800 million ha are concentrated in a small number of countries, e.g. 27% in Brazil, 9% in Zaire and 30% in 12 other countries. A good part of this land "reserve" is, however, under forest (at least 45%), or in protected areas, and should therefore not be considered as a readily-available reserve for agricultural production. A significant part (72% in Sub-Saharan Africa and Latin America) suffers from soil and terrain constraints.
Overall some 50% of the 1800 million ha of land "reserve" is classified in the categories "humid" (i.e. too wet for most crops and rather unhealthy for human settlement) or as "marginally suitable for crop production". The possibilities for expansion of land for crop production are therefore limited. Consequently, much of the perceived increased need for food, etc. will have to come from intensification of production with high-yielding crop varieties in high-potential areas. These are lands with good soil and terrain conditions, with favourable temperature and rainfall conditions or a supply of irrigation water, and with easy access to mineral or organic fertilizers.
FAO estimates (Yudelman, 1994) that, though arable land may expand by 90 million ha by the year 2010, the harvested area could increase by 124 million ha because cropping intensities would rise, with irrigated land in developing countries expanding by 23.5 million ha from the present 186 million ha.
More detailed studies are under way on the irrigation potential in developing countries, and Africa in particular. These focus on areas combining suitable soil and terrain conditions that are under command, and with surface and groundwater freshwater resources that can be harnessed without excessive costs or damage to environmental values. At the same time FAO is cooperating with a number of UN Agencies and the Stockholm Environmental institute in assessing the global freshwater resources, with the aim of identifying where water crises may be imminent.
As the result of intensification of land use in areas that are naturally well-endowed, or can be made so by economically-viable human interventions such as irrigation and drainage development, there will in the near future be a significant decrease in the land per rural household. Per caput availability of arable land in developing countries is projected by FAO to nearly halve between the late 1980s and 2010, from 0.65 to about 0.4 ha. This figure is likely to become even smaller toward 2050.
In contrast to this sketched situation in developing countries, the per caput amount of arable land may increase in developed countries with their stagnant population growth. This could lead to the more marginal arable lands being taken out of production as "set-side" lands for nature "development", cultural landscape conservation or recreational purposes (Van de Klundert, et al., 1994). The situation in countries-in-transition is more difficult to project because of the current process of transfer of state-owned arable land to private ownership.
The FAO predictions are limited in time scale to 2010, when any global climatic change is expected to be still of negligible influence. This may be different by the year 2050 or beyond. The consensus among climate change modellers is that in developing countries the effects on food security may be negative rather than positive (Norse and Sombroek, 1995).
The above discussion has concentrated on the amount of land available for the production of food and fibre. Land has, however, many functions (see also ESCAP, 1994):
• It is the basis for many life support systems, through the production of biomass that provides food, fodder, fibre, fuel. timber and other biotic materials for human use, either directly or through animal husbandry including aquaculture and inland and coastal fishery (the production function).
• Land is the basis of terrestrial biodiversity by providing the biological habitats and gene reserves for plants, animals and micro-organisms, above and below ground (the biotic environmental function).
• Land and its use are a source and sink of greenhouse gases and form a co-determinant of the global energy balance - reflection, absorption and transformation of radiative energy of the sun, and of the global hydrological cycle (the climate regulative function).
• Land regulates the storage and flow of surface and groundwater resources, and influences their quality (the hydrologic function)
• Land is a storehouse of raw materials and minerals for human use (the storage function).
• Land has a receptive, filtering, buffering and transforming function of hazardous compounds (the waste and pollution control function).
• Land provides the physical basis for human settlements, industrial plants and social activities such as sports and recreation (the living space function).
• Land is a medium to store and protect the evidence of the cultural history of mankind, and a source of information on past climatic conditions and past land uses (the archive or heritage function).
• Land provides space for the transport of people, inputs and produce, and for the movement of plants and animals between discrete areas of natural ecosystems (the connective space function).
The suitability of the land for these functions varies greatly over the world. Landscape units, as natural resources units, have a dynamism of their own, but human influences affect this dynamism to a great extent, in space and time. The qualities of the land for one or more functions may be improved (for instance, through erosion control measures), but more often than not the land has been or is being degraded by human action.
Human-induced land degradation has taken place all through history, such as during the Mediterranean and Middle East civilizations, around or before O AD, and during the time of European expansion in the Americas, Australia, Asia and Africa. During this century, however, land degradation, including desertification, has increased enormously in extent and severity, by direct action of a strongly growing world population and its increased livelihood expectations and demands (ISRIC, 1990).
The rate of land degradation may continue unabated or even increase under conditions of any human-induced global climatic changes, but this cannot be automatically assumed. Land degradation can be controlled, redressed or even reversed if the land is used wisely, if all the functions of the land are taken into account, and if short-term vested interests of privileged groups are replaced by long-term enlightened interests of all segments of humankind, globally, nationally and locally.
Land degradation has been exacerbated where there has been an absence of any land use planning, or of its orderly execution, or the existence of financial or legal incentives that have led to the wrong land use decisions, or one-sided central planning leading to over-utilization of the land resources - for instance for immediate production at all costs. As a consequence the result has often been misery for large segments of the local population and destruction of valuable ecosystems. Such narrow approaches should be replaced by a technique for the planning and management of land resources that is integrated and holistic and where land users are central. This will ensure the long-term quality of the land for human use, the prevention or resolution of social conflicts related to land use, and the conservation of ecosystems of high biodiversity value.