Part II

Causes, general extent and physical consequences of land degradation in arid, semi-arid and dry sub-humid areas

- Degradation of rainfed agricultural land, irrigated agricultural lands, ranching and traditional pastoral lands, and forest lands
Presented by : Mr. Wim G. Sombroed, Director, Land and Water Development Division & Mr. El Hadji M. Sene, Chief, Sub-Division of Forest Conservation and Natural Resources, Forest Department, Food and Agricultural Organization (FAO)

- Land Degradation resulting from urbanization, industrialization, mining and tourism
Presented by : Mr. Jochan Eigen, Coordinator, Sustainable Cities Progamme, and Mr. Graham Alabaster, Human Settlements Officer, United Nations Centre for Human Settlements (HABITAT)

DEGRADATION OF RAINFED AGRICULTURAL LAND, IRRIGATED AGRICULTURAL LANDS, RANCHING AND TRADITIONAL PASTORAL LANDS, AND FOREST LANDS

Presented by : Mr. Wim G. Sombroed, Director, Land and Water Development Division & Mr. El Hadji M. Sene, Chief, Sub-Division of Forest Conservation and Natural Resources, Forest Department, Food and Agricultural Organization (FAO)

SUMMARY

This document is a response to the request of the Secretariat of the Inter-Governmental Negotiating committee for a convention to combat Desertification; it analyses the cause, general extent and consequences of land degradation in arid, semi-arid and dry sub-humid areas of the world.

In a first section, some definitions pertinent to land and water resources degradation are given to provide a basic platform of understanding to the document. A second section discusses the components and processes of land degradation and its recovery highlighting the composite nature of land degradation and desertification. The third section of the document introduces and discusses the major degradation processes affecting rainfed and irrigated arable lands, grasslands and woodlands. The underlying and fundamental message is the anthrofic origin of desertification-related processes and the importance of issues relating to poverty, food security and landlessness.

The fourth section elaborates rapidly on some strategic elements, stressing the fact that combating desertification should be envisaged in an integrated approach to Sustainable Agriculture and Rural Development and that knowledge and solutions exist where populations are thoroughly involved and timely action envisages.

DEFINITIONS

In the context of assessment, desertification is defined as:

"Land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities" (Chapter 12 of UNCED's Agenda '21).

The various elements of this definition need to be quantified before one can enter upon a discussion of causes, general extent and physical consequences of the process.

What are Arid, Semi-arid and Dry Sub-Humid Areas?

An early classification and delineation is given in UNESCO's MAB Technical Note 7 of 1977, with an accompanying map at 1:25 million scale of the world distribution of arid regions, prepared as part of UNESCO's "Arid Zone Research" programme. Combinations of two climatic variables, bioclimatic aridity and temperature regime, define the various regions. Degree of bioclimatic aridity was established on the basis of the ratio P/Etp (average total annual rainfall/potential evapotranspiration).

The ratio between mean annual rainfall and potential evapo-transpiration provides only a crude measure of aridity or humidity of climate, and does not have a close relation with agricultural or grazing potential. The potential productivity of arable crops and grazing land, or crop choices or farming or grazing management options, depend more on the length of the period in the year when moisture supply, from rainfall and soil storage, is sufficient for the growth of crops or vegetation. a Length of Growing Period (LGP) concept was developed and used in FAO's Agro-Ecological Zones studies.

A Reference Growing Period starts once rainfall exceeds half of the potential evapotranspiration (Etp); may be interrupted by a period with low temperature during which growth is not permitted; and ends after the date when rainfall falls below half of Etp, plus the period required to evapotranspire 100 mm water assumed stored in the soil from excess rainfall (or less if less excess rainfall during the Growing Period).

Areas with an LGP less than 1 day are hyperarid (true deserts); less than 75 days arid, 75 to less than 120 days (dry) semiarid, 120 to less than 180 days (moist) semiarid. These areas together correspond closely to the areas denominated as Drylands (INCD Secretariat, April 1993). Fig. 1 shows the different dryland areas for the developing world. The overall similarity with the earlier map of annual P/Etp ratios is clear; differences can be seen in southern Africa, for example, where the LGP map more clearly identifies the large extent of arid conditions.

What is Land?

Land in the sense used by FAO's Interdepartmental Working Group on Land Use Planning, is a delineable area of the earth's solid surface, the characteristics of which embrace all attributes of the biosphere vertically above or below this surface, including those of the lower atmosphere, the soil and the underlying geology, the hydrology (including lakes, rivers, marshes and swamps), the plant and animal populations, the human settlement pattern and the physical results of past and present human activity (terracing, water storage or drainage structures, roads, etc.).

In this holistic approach, a unit of land has both a vertical component - from atmospheric climate down to confined aquifers in the deeper substratum, and a horizontal element - an identifiable repetitive sequence of soil, terrain, hydrological and land use elements ("landscape", "land unit" or "terroir" units).

What is Land Degradation?

Degradation of the land involves the reduction of the renewable resource potential by one or a combination of processes acting upon the land. The resource potential relates to agricultural suitability (rainfed or irrigated arable copping, animal husbandry, forestry, inland fishery), primary productivity level, and natural biotic functions.

Such a reduction, leading to an abandonment, or "deserting," of the land (e.g. of parts of the Sahara, populated until some 6000 years ago) can be because of natural processes, such as a natural aridification of atmospheric climate, natural processes of erosion, some processes of soil formation such as primary salinization and hardpan formation, a natural change in the base level of river catchments, or natural invasion by noxious plants or animals.

The reduction in resource potential can also be human-induced, either directly on the terrain or indirectly through man-induced adverse climatic change.

Some aspects related to climate change are discussed below Human activities that can cause drylands degradation include:

i. cultivation of soils that are fragile, or erodible by wind or water;

ii. net export of plant nutrients leading to loss of soil fertility, such as cash cropping without adequate nutrient replenishment;

iii. reduction in fallow periods and lack of organic or mineral fertilizers;

iv. overgrazing - often selectively - of shrubs, herbs and grasses,

v. overexploitation of woody resources, in particular for fuelwood;

vi. uncontrolled use of fire, e.g. for regenerating pasture, or agricultural clearing;

vii. unsuitable agricultural practices or machinery that destroy soil structure.

All these activities derive from two root causes: from poverty and underdevelopment, or from 'modern' development which disregards the impact of the technologies on the land.

Factors typical of poverty and underdevelopment include:

i. undernutrition or malnutrition, leading to physical weakness and vulnerability to disease;

ii. lack of access to credit, thus preventing any chance of investment in tools, seeds or fertilizers;

iii. limited access to basic schooling and technical training;

iv. short-term survival strategies (e.g. annual or seasonal migration);

v. lack of an effective framework to support rural communities with technical advice, infrastructure, energy, training, organisation of barter exchanges or market access;

vi. a lack of basic security.

COMPONENTS AND PROCESSES OF LAND DEGRADATION AND RECOVERY

Components of Degradation

There are different forms of human-induced land degradation, related to the various vertical components of the land units: atmospheric, vegetation, soil, geology and hydrology.

The degradation may be in the sense of a deterioration of atmospheric climate conditions, i.e. human-induced adverse global climatic change. Most of the currently available, rough General Circulation Models do not predict a change-to-the worse for the current arid and semi-arid regions such as the Sahel, which would be irreversible in a "business-as-usual" scenario, but do so for the Mediterranean area.

The degradation of the above-ground vegetational and animal populations (denseness, diversity) is prevalent in many areas, through direct human influence and aggravated by droughts of a more or less cyclic nature (Sahel, Southeastern Africa, Northeastern Brazil). By and large this biotic degradation is providing to be reversible in a few years time after return of the rains and the "resting" of the land from excess human or animal occupation. The reversibility may, however, not extend to the full range of biodiversity.

The degradation of soil conditions is more serious in the sense that it is not easily reversible. This is because soil formation and regeneration processes are predominantly slow. Along GLASOD lines (Oldeman et al. 1991) one can distinguish the following types:

Loss of topsoil through water erosions is the most common type of human- induced soil degradation. It is generally known as surface wash or sheet erosion. It occurs in almost every country, under a great variety of climatic and physical conditions and land use. As the topsoil is normally rich in nutrients, a relatively large amount of nutrients is lost together with the topsoil. Loss of topsoil itself is often preceded by compaction and/or crusting, causing a decrease in infiltration capacity of the soil, and leading to accelerated run-off and soil erosion.

Terrain deformation/mass movement through water erosion the most common phenomena of this degradation type are rill and gully formation. Rapid incision of gullies, eating away valuable soil is well known and dramatic in may countries. Other phenomena of this degradation type are riverbank destruction and mass movement, and off-site deposition of the eroded material in a negative way (choking of river beds; smothering of riverside crops).

Loss of topsoil through wind erosion as the uniform displacement of topsoil and selective removal of fine particles by wind action, is widespread, particularly in arid and semi-arid climates.

Overblowing, which is defined as the coverage of the land surface by wind-carried particles, is an off-site effect of the wind erosion types mentioned above. Overblowing may occur in the same mapped unit or in adjacent units. It may affect structures like roads, buildings and waterways, but it can also cause damage to agricultural land.

Loss of nutrients is a form of chemical soil degradation which occurs if agriculture is practised on poor or moderately fertile soils, without sufficient application of manure or fertilizer: "nutrient mining". It causes a general depletion of the soil fertility and leads to decreased productivity. Loss of organic matter by clearing the natural vegetation is also included in this type of chemical soil degradation, although it often has a negative influence on the soil physical properties as well. The loss of nutrients by erosion of fertile topsoil is considered to be a side-effect of wind or water erosion, and not distinguished separately.

Human-induced salinization ("secondary salinization") occurs where human activities lead to an increase in evapotranspiration of soil moisture in soils on salt-containing parent material or with saline ground water; it is often the result of poor management of irrigation schemes.

Soil acidification is caused by over-application of some forms of mineral fertilizer. It may lead to reduced agricultural potential, especially in the dry sub-humid areas.

Soil pollution has many types which can be recognized, such as industrial or urban waste accumulation, the excessive use of pesticides, acidification by airborne pollutants, excessive manuring, oil spills, etc.

Compaction, sealing and crusting are important forms of physical soil degradation in dryland areas. Compaction is usually caused by the use of heavy machinery on soils with a low structure stability. Sealing and crusting of the topsoil occur, in particular, if the soil cover does not provide sufficient protection to the impact of raindrops. Soils low in organic matter content with poorly-sorted sand fractions and appreciable amounts of silt are particularly vulnerable. Both compaction and crusting can be caused by cattle trampling. Compaction and crusting will make tillage more costly, impede or delay seedling emergence, and lead to a decrease in water infiltration capacity, causing, in its turn, a higher surface run-off, which may lead to significant water erosion.

The degradation of the surface hydrological conditions is closely related to degradation of the vegetation - from shrub to herbaceous cover or even to bares soil - and soil surface crusting and sealing. The hydrological regime is affected by this modification of the ground surface conditions and results in:

i. a less regular run-off with heavy flash floods followed by low-flow or zero-flow periods;

ii. an increasing soil erosion and sediment transport resulting in serious sedimentation problems in surface reservoirs;

iii. a decreasing infiltration in the soil affecting the soil moisture dependent vegetation and also resulting in a much lower aquifer recharge. As a consequence, the groundwater resources and especially those of the shallow unconfined aquifers are seriously affected.

Land degradation is therefore a self-accelerating phenomenon since it produces itself the conditions for a further soil and water resources degradation.

Geohydrological degradation refers to the reduction in the amount and the quality of freshwater storage in deeper layers, without contact with the surface immediately above: confined aquifers. This reduction can be because of mining of fossil aquifers for large-scale irrigation or town water supply (lowering of the surface of the aquifer, sideways or upward intrusion of saline waters). Overexploitation of active aquifers in relation to their rate of recharge from far-away sources, often several hundred km, is another form of geohydrological degradation. These sources may still provide a sustained inflow, or themselves be subject to one or another form of land degradation reducing inflow. Studies over whole geologic basins are required to define the long-term degradation of the geohydrological conditions of the land.

The degradation of human settlements and infrastructures is still another form of land degradation in its holistic context, often as the result of the other forms, but also on its own, for instance because of rising living requirements of the local population.

HAZARDS AND EXTENT OF PRESENT DAY DEGRADATION OF DRYLANDS

Hazards and Vulnerability

An early global overview of the hazards of "desertification" (i.e. land degradation of drylands in present day terminology) was given in a joint FAO-UNESCO-UNEP-WMO project, in preparation for the UN Conference on Desertification in 1977 in Nairobi (FAO/UNESCO 1977). The map at scale 1:25 M indicates:

i. three qualitative degrees of desertification hazards in respective hyper-arid, arid, semi-arid and sub-humid areas (see UNESCO classification of Chapter 1.1) viz. "very high", "high" and "moderate";

ii. four types of vulnerability of the land to desertification processes, viz. "surfaces subject to sand movement", "stony or rocky surfaces subject to areal stripping by deflation or sheetwash", "alluvial or residual surfaces subject to stripping of topsoil and accelerated run-off", and "surfaces subject to salinization or alkalinization";

iii. two types of pressure on the land, viz. "human pressures, including mechanization", and "animal pressure".

As a follow-up on this activity, FAO in cooperation with UNEP and UNESCO prepared a methodology for soil degradation assessment at a larger scale, accompanied by 1:5 M provisional maps for the Northern half of Africa and the Middle East on the "present degradation rate and present state of soil" and on "soil degradation risks", respectively.

Extent and Severity of Actual Degradation

There is one current global assessment of the present-day status of land degradation, and this relates to soil degradation only: the Global Assessment of Soil Degradation (GLASOD) project of ISRIC-UNEP, in cooperation with FAO and other institutions, including about 300 regional and national resource persons. This undertaking has resulted in a world map of the status of human- induced forms of soil degradation at an average scale of 1:10 M; for Africa there is also unpublished map material at 1:5 M scale.

UNEP/GEMS/GRID subsequently processed the GLASOD information for a series of computer printouts on individual components for the African continent with a delineation of the dryland areas.

As a follow-up of the GLASOD study, at the request of ECOSOC, FAO in cooperation with UNEP and UNDP provided a more detailed report on land degradation in the South Asia region with special attention to socio-economic impacts.

Action-oriented data collection and processing

More quantitative information on the current extent and on the hazards or risks of land degradation in all its forms, awaits better, fully georeferenced data bases on natural resources (climate, topography and land form, vegetation and land use, hydrology) and current socio- economic conditions on a more meaningful scale, say 1:1 M, in the drylands of the world, preferably in GIS-supported digital form and with remote sensing as a tool.

Action-oriented data collection and appraisal, however, needs more than GIS and remote sensing. These are useful tools, but cannot replace district-or village-level detailed ground surveys, in close contact with the local land users, and subsequent people's participation in the design and implementation of desertification control and land rehabilitation programmes. Depending on the severity of the degradation problem and the number of people involved, the investments can then be small or may still have to be very substantial.

TIME SCALES, CYCLES AND REVERSIBILITY OF LAND DEGRADATION

Past Land Degradation

All the above information relates to human-induced soil degradation over the period after the Second World War only. Mapping of human-induced soil degradation that had taken place during early civilizations up to 250 years ago, or during the period of European expansion in the Americas, Asia and Africa, 250 to 50 years ago, proved to be unfeasible in the time frame of the GLASOD project because of insufficient georeferenced information. However, much valuable information on dryland use and degradation in the past is contained in the classic UNESCO publication "A History of Land Use in Arid Regions" (Dudley Stamp 1961) and a large number of subsequent case studies. This information can be collated without undue effort, preferably in combination with georeferenced information on all dryland areas that have actually been improved by mankind in the course of history from their original natural status, or rehabilitated after a period of degradation (terracing, bunding, drainage and salinity control, reforestation, soil organic matter and fertility improvement, etc.).

Cycles of Land Degradation

Land degradation can be a gradual process, but more often it occurs in cycles, of different time spans, alternating with land improvement or recovery.

Large time spans, in the order of centuries, have been associated with rise and fall of civilisations and empires. In the early days of development of a civilisation, the available land is often being reclaimed and improved, providing the basis for rapid urban and cultural growth. Already at the zenith of a civilisation, the exigencies of the wealthy and powerful segments of the society, and the requirements of defence of the empire tend to go beyond the carrying capacity of the land, leading to overexploitation. In the declining phase of a civilisation, care of the land becomes neglected, in some cases hastened by outbreaks of infectious diseases and military incursions from upcoming neighbouring powers. Abandonment of the land - the real meaning of "desertification" - is the result, followed by a very gradual recovery through natural build-up of new soil and associated new land cover and hydrological qualities.

Short time spans, often rather irregular in length, are involved where socio-economic conditions are subject to changing external influences, inducing strong population growth, increased aspirations for the well-being of rural populations, and changing international markets for agricultural products. In the modern context, these external influences extend to successes and failures of worldwide agricultural research, unfair terms of trade, variations in the flow of funds from rich nations to rural development programmes, structural adjustment programmes, increased access to equipment for modern warfare, etc.

Sustainability and Resilience

The reversibility of land degradation has different time spans as well. In the framework of UNCED and INCD, one objective is reversibility in decades, or rather: the complete avoidance of any decline of the productive capacity of the land, i.e. the sustainability of land use. This sustainability can be equated with stability or even, purposely scaling down the intensity of present-day land use in industrialised countries. But this cannot hold good for most developing countries with their strong population growth; there, stability means stagnation at a very low level of intensity and inputs. In such cases, one should aim at a sustained growth of agricultural productivity of the land without negative environmental effects, apparent or hidden, that would cause an ultimate collapse of the land use, on-site or off-site.

Related to sustainability is the concept of resilience of the land, which can be defined as the capacity of an agro-ecosystem on a given unit of land to return to its original equilibrium after a major natural or man-made disturbance. Again, in the case of developing countries' needs, it would be the capacity of an agro-ecosystem to return to a sustained growth of productivity.

When, exactly, an (agro-)ecosystem will break irreversibly through its resilience level is not only a matter of technical assessment of the threshold values of individual elements of soil and water resources, nowadays eagerly discussed at international scientific gatherings. It is also a matter of temporal perspective and financial implications of recuperation, which, on its turn, depends on the local socio-economic conditions, such as for the number of people to be catered for.

The possibilities for economic development and recovery from emergency situations depend on site-specific combinations of prevailing socio-economic and biophysical conditions. If the major disturbance (a social or physical "accident") takes place in a situation of gradual biophysical degradation, then the appropriate type of external intervention is different from the situation where the normal trend is one of gradual biophysical improvement or development. In the first case, the external assistance has to be much more substantial, of a more structural nature and of longer duration.

Climate Change as Cause and Result of Degradation of Dryland Areas.

A distinction should be made between local climate variability and human- induced global climatic change, as reported in the recent Inter Governmental Meeting on the World Climate Programme, April 1993 in Geneva.

Sahelian droughts are a recurrent feature, although the most recent one was particularly strong and recuperation to normal rainfall conditions took many years - which in itself may be a foreboding of global climatic change. El Niño is another example of a natural climatic anomaly of cyclic character. Concentrated studies in the framework of the World climate Programme have now revealed that the phenomenon has its repercussions through changes in the atmospheric jet streams, on weather anomalies elsewhere in the world, such as droughts in northeastern Brazil and southeastern Africa.

As stated before, human-induced global climate change may, or may not negatively affect the climatic conditions of drylands, and hence their degradation. The current Global Circulation Models are yet too rough to come to unequivocal conclusions for regions or local areas. The implications of a coupling between terrestrial and ocean models, and of the direct effect of increased atmospheric CO2 on plant growth are not yet known. In contrast to the situation with methane and nitrous oxide, the increase in the concentration of atmospheric carbon dioxide has a direct positive effect on plant growth through the so-called "CO2-fertilization" and the "CO2-antitranspiration" phenomena. also, a slight increase of the surface temperature of open waters because of any global warming would result in a strong intensification of the global hydrological cycle. This implies more rainfall in many parts, and thus more transpiration-cum-growth of plants, or more run-off to be used on-site or downstream for extra irrigation if stored adequately. FAO well recognizes these potentially positive aspects of human-induced climate change in the field of agriculture and rural development, while also concentrating on how to deal with the potential negative consequences. Among the latter are the potential increase in the frequency and severity of extreme weather events (droughts, floods, hurricanes) because of an intensification of the hydrological cycle.

LAND DEGRADATION BY MAIN TYPE OF RURAL LAND USE IN DRYLAND AREAS

Introduction

There is both competition and complementarity of land uses in a spatial context. Traditional land users in drylands are often versatile; they adapt to the often very local rainfall variability through year-to-year changes in agricultural practices and herding. The current transformation of communal lands into private ownership, especially when absent ownership is involved, creates a rigidity that is detrimental to such versatile land uses.

Land uses in drylands are very complex, for example, cultivated is usually grazed between crops. The description below of land degradation aspects in relation to rainfed farming, irrigated farming, rangeland and woodland use, respectively, is therefore a rather artificial undertaking.

There is an acute need for systematic analysis and georeferencing of the various forms of multiple land use in dryland areas, including aspects such as inputs, labour requirements, local redistribution of soil fertility, as a prerequisite for any well integrated intervention to halt land degradation and rehabilitate rural livelihood systems. Each landscape and each occupational system needs its own solution; there is no panacea.

Land Degradation and Rainfed Agriculture

Rainfed agriculture is practised in drylands all over the world. It is a major cropping system which provides considerable amounts of crops, particularly cereals and legumes. Lands under rainfed agriculture, although often marginal in some areas, are important land resources and provides livelihood for several social groups and are managed traditionally under complex land use systems.

Causes

Rainfed arable lands in arid, semi-arid and subhumid areas have been extensively degraded due to population pressure and to the struggle to produce more in order to satisfy growing food needs. Specific causes of land degradation are inappropriate land-use practices and farming techniques.

i. Encroachment of farming into areas where risk of drought is high or onto other marginal lands.

ii. Shortening of cycles in farming. Reducing the fallow period in shifting cultivation in dry tropics.

iii. Inadequate restitution of plant nutrients to the land.

iv. Monoculture or lack of adequate crop rotation.

v. Clean fallowing and excessive tillage.

vi. Divorce of arable farming from livestock production.

vii. Ploughing and planting of crops down the slopes in sloping lands.

viii Deterioration of terraces and other soil and water conservation structures, (often because of labour shortage, as in areas of strong migration).

Consequences

Rainfed arable land in the drylands is subject to a range of degradation hazards, including erosion by water and wind, sandblasting of crops and emerging seedings on arable land and rangeland, deposition of windblown sand, plant nutrient depletion in the soils, surface sealing or crusting, salinization in some areas. These hazards are generally more severe than in more well- watered regions, for several reasons.

During the long dry season, crop residues are exported from the land or are consumed by livestock belonging to the farmers or to pastoralists, by wildlife or by termites. This leaves the fields essentially bare to the impact of the early rains, and to wind action during the dry season. Traditional defence to these hazards was by adequate fallow periods.

The soil material eroded by wind or water generally is more fine-grained and contains more organic matter, and the coarser grains are left. Most of the plant nutrients are contained int he fractions of the soil that are lost. The amounts of such nutrient losses may even exceed the amount of nutrients removed in the harvest or in the crop residues eaten and in part removed by the animals.

The year-to-year variability of the rainfall in drylands and of its distribution over the rainy season entail a great risk to the farmer, so that inputs applied at the start of the crop season such as fertilizer, or indeed seed or labour for land preparation, might not be repaid by the crop yield in low- rainfall years.

The consequent tendency to low-input, variable-yield farming systems is a sound economic strategy in principle, and this may work well where land is relatively abundant and where dry season grazing is light, recycles plant nutrients and allow some cover to remain until the start of the next rains. Fig. 4 shows plant nutrient dynamics in mixed farming systems, and demonstrates the spatial interaction between grazing land, rainfed arable land and irrigated land in terms of nutrient depletion, transport by various means, intentional (e.g., by manure from livestock) or unintentional (for example through runoff), and concentration of plant nutrients on the more intensively used land.

In the many places where increasing number of people and livestock lead to greater intensity of cultivation and grazing, however, a downward spiral of decreasing soil fertility starts, resulting in low crop yields even in years with good rainfall. The small amounts of crop residues then provide poor cover, and soil erosion aggravates the nutrient losses.

Silty or loamy topsoils are generally liable to seal or crust under rain impact, especially where organic matter contents are low and where there is little soil cover. Such conditions are aggravated, through excessive grazing on crop residues or grazing land, or through plant nutrient mining, low-input arable farming. The resulting runoff may accelerate removal of plant nutrients and decrease the amounts of moisture available to the next crop or the vegetation, aggravating the downward trend in productivity.

In a small proportion of the drylands, groundwater occurs at depths of only a few meters. there, the natural vegetation has root systems with very different depth distributions, and thus draws moisture from a great range of depths. Salts tend to be distributed throughout the rooting zone, and seasonally fluctuate in depth and concentration. Where such land is cleared and used for arable crops, initially these may use less water, and that mainly from the upper soil layers. In these conditions the groundwater table may rise gradually, until capillary rise brings the groundwater within reach of the crop roots and eventually, within reach of the surface. Then, the upper soil layers rapidly become saline, and crop yields fall or the crop fails.

Traditional defense against this dryland salinization (differing from that under irrigation) has bee the planting of tree lines or groups of trees in sufficient number to keep the groundwater level down by the increased transpiration and water uptake through their deep root systems. Areas with such hydrological characteristics thus provide both a hazard of salinization and the opportunity to combine arable or grazing use with wood production.

Measures for Land Degradation Control in Rainfed Agricultural Areas in Drylands

At a general level, one can distinguish the following measures for controlling land degradation in rainfed, dryland areas:

i. making an inventory of national land resources;

ii. assessing potentials and constraints in dryland farming and identifying agricultural options to safely increase cropping intensity and yields, decrease risks and offering other advantages while reducing land degradation;

iii. studying the reasons behind poor land use, including land tenure-based problems, pricing of agricultural goods, subsidies, taxes, laws and social customs;

iv. encouraging farmers to adopt more sustainable forms of land use, including contingency crop planning in the case of droughts.

Improving agricultural techniques should cover biological (agronomic) techniques and mechanical measures. Biological techniques such as: improved and diversified farming systems with appropriate inclusion of livestock, multipurpose tree and shrub, arboriculture, including adapted fruit trees; improved crop rotation; shelterbelt establishment, revegetation of watersheds, sand dune fixation, supplementary irrigation. Mechanical techniques include improved land preparation methods, soil and water conservation techniques, water harvesting, etc...

Where water is available, even in small amounts, from groundwater or from runoff captures in farm ponds, for example, the irrigation of a small proportion of the land can drastically improve the resilience of farm families against droughts by the increased food and feed security. At the same time, the productivity increase would lower the pressure on the rainfed land from livestock and thus allow some more cover to be retained on the soil. These favourable consequences would only materialize, however, where the increase in productivity is not immediately overtaken by increases in human and livestock populations.

For effective participation of land users in all stages, the role of governments must change from that of implementor to facilitator. The ideal programme for improved land management is one in which land users plan and implement solutions for their own benefit.

National training and research institutions need to be strengthened to support development in rainfed agriculture, in drylands and land use planning.

Legal measures may be needed to adopted to provide a sound framework for land use planning; they should take into account effective traditional land rights and aspects of collective land management. Legal limits may be needed to cultivation by tractors ploughing in marginal lands, which are ecologically better suited for grazing. Land tenure systems which are incompatible with the introduction of improved agriculture and land management need to be reviewed.

Land Degradation and Irrigated Agriculture

Irrigated agriculture represents the most intensive and productive form of primary land use in arid regions and serves as a vital supplement to crop production in arid and semi-arid zones to satisfy the growing food needs of the increasing population

Causes

Many irrigation projects, past and present, are severely affected by secondary salinization or sodication and waterlogging. Secondary salinization of soil is the main degradation process in arid and semi-arid areas.

As soil science develops, the causes and mechanisms of salt accumulation have been better understood. However, in spite of a better knowledge of the phenomenon, the processes of salinization and sodication have not been arrested. Even today, they keep expanding in new irrigated areas and continue to cause considerable damage to the developing world economy. Between 20 and 30 million hectares of irrigated land are today severely affected by salinity with a resulting loss of agricultural production.

The main cause of secondary salinization is inadequate drainage and excessive water application which cause the groundwater table to rise close to the surface and the consequent evaporation of water rising by capillarity. The phenomenon is aggravated by the salinity of the irrigation water: the higher the salt content of the irrigation water the more severe the risk of salinization.

As long as the water table is deep and the moisture cannot come up through capillary flow to the soil profile, even saline groundwater does not cause salinization. But one effect of irrigation in poorly drained areas is to cause the groundwater level to rise so high that it can reach the surface layers and cause salinization even where good quality water is used to irrigate. This rise is often underestimated because the water table may be at great depths (10-20 m below the surface) before the implementation of an irrigation scheme.

The process of upward capillary flow depends on the balance between rainfall and evapotranspiration and on the hydraulic conductivity of the soil which is a function of its structure and texture. The minimum depth at which the water table must be kept so that the velocity of the capillary flow be less than 0.5 mm/day is called the critical depth. This is in the order of 1 m for the loamy or sandy soils and 1.5 m for other soils.

Consequences

Secondary salinization and sodication and waterlogging in irrigated areas in drylands cause many serious environmental and socio-economic problems such as: reduction in crop yield and abandonment of irrigable lands; decreasing income of the farmers; proliferation of water-borne diseases.

Combating Land Degradation of Irrigated Land in Dry Areas

Considering the importance of irrigation in achieving sustainable agriculture and rural development in drylands, it is essential to prevent and control waterlogging, secondary salinization or sodication in irrigation schemes by: improving irrigation and drainage systems; improving irrigated farming systems to increase productivity in a regular and sustained way; and through improvement of the socio-economic and health conditions of people dependent upon irrigated agriculture.

Combating land degradation in irrigated lands should be conceived in an integrated approach to sustainable agriculture and rural development in drylands.

Prevention and reduction of the salinization in connection with irrigation should focus on the following actions:

i. ensure that new or rehabilitated irrigation projects have adequate drainage;

ii. implement groundwater monitoring and water balance studies to predict drainage requirements and implement conjunctive use of ground and surface water, where feasible, to prevent or correct waterlogging;

iii. establish pilot drainage projects in waterlogged and salinized areas to verify design and effectiveness of materials, demonstrate the effect of drainage on productivity, and train personnel in operation and maintenance of drainage systems;

iv. monitor groundwater salinity and improve groundwater management where excessive groundwater abstraction results in salt water intrusion into the aquifers from the sea or from nearby saline aquifers;

v. monitor soil and water salinity in problem areas and adopt appropriate water, soil and crop management practices to overcome the problem.

LAND DEGRADATION AND RANGELAND MANAGEMENT

Main Types of Pastoral Systems in Drylands

The following three main types of pastoral systems are practised in arid and semi-arid areas in the world:

a) The nomadic/transhumant pastoral system. There are two kinds of nomadism: true nomadism (more of less continuous movement of livestock with no set pattern) and transhumance (livestock movement along more predetermined routes leading from the wet season grazing lands in the arid zone to fallow lands in the semi-arid agricultural zone in the dry season). True nomadism usually involves the herding of drought-hardy camels, goats and sheep, in some cases, with a few cattle, a way of insurance against drought.

b) The sedentary livestock raising system. It is practised by farmers who are mainly concerned with rainfed cropping in semi-arid areas, but keep some animals, grazing them on fallow lands and communal village grazing lands. Usually only limited areas of pastures are available within easy reach of villages, so these are used quite intensively and suffer considerable degradation. There is a symbiotic relationship between farmers and nomads, in which meat and milk are exchanged for grains and legumes, and fallow lands are grazed by nomadic herds in return for the fertilizing value of the dung and also for cash and other goods.

c) Cattle and sheep ranching are the typical kinds of cattle pastoral system in the drylands of developed nations such as USA and Australia. The development of lucrative markets in some developing countries such as Nigeria and Ivory Coast has encouraged some trials to establish cattle ranches in the Sudanan and Savanna zone.

Common Features in Rangeland Degradation

The continuing or accelerating course of rangelands degradation shows common features, including:

i. deterioration in the quantity, quality and persistence of native pastures, generally associated with a diminution of plant cover, but also with invasion by shrubs of low pastoral value; frequently unpalatable and of little economic value or practical use.

ii. structural changes in the plant cover, notably the loss of shrubs and trees, partly through browsing, but also through gathering of fuelwood and clearing and burning for agriculture: this increases the exposure of the soil surface to accelerated water and wind erosion, removal of fertile top soils and loss of nutrient and seed stores and may eventually lead to the exposure of barren, locally hard-setting subsoils which resist revegetation. The range rehabilitation in this case becomes critical or impossible, with a definitive loss of many plant species, which could be of great value in the future;

iii. changes in soil surface conditions, notably compaction through trampling by livestock, leading to deterioration in soil - plant -water relationships and reduced germination rates, particularly of the palatable species;

iv. additional processes of sand drift and siltation, leading to further destruction of the vegetation and commonly to deterioration of surface and shallow groundwater supplies.

v. The pattern of such changes varies with the movements and concentration of grazing animals, with seasonal conditions and with the varying vulnerability of the land itself.

MAIN CAUSES OF RANGELAND DEGRADATION IN DRY AREAS

Overgrazing

Overgrazing is a major cause of rangeland degradation in drylands leading to desertification, as has been proved by different studies and observations in the world. Overgrazing results when livestock density becomes excessive and too many animals are grazed on the same area of rangeland, leading to the degradation of vegetation, soil compaction, wind and water erosion. When there is heavy pressure on rangelands, the animals consume palatable vegetation faster than it can regenerates, and eventually only inedible or no vegetation remains. With degraded plant cover, soil erosion becomes serious and any chance of restoring the range becomes remote because of massive top soil loss.

Livestock density can rise in four main ways: first, herd sizes are allowed to grow too large during wet years to be sustained by the limited pasture growth in the dry years. In the dry years, pressure is reduced, although it always remains greater than the carrying capacity of the range. Second, the area available for grazing decreases as nomads are displaced by farmers growing crops. Third, livestock becomes concentrated around villages by nomad resettlement schemes and along herding routes made popular by the sinking of boreholes. Fourth, traditional controls on the grazing of rangelands break down. But the most common cause of overgrazing is the growing of herd sizes within a given area. In the Sahelian rangelands, by 1980 numbers of small livestock have surpassed those of the first-drought years of the late 1960s. Growing markets and marketing systems, linked with rising meat consumption by urban population, are likely to maintain this pressure of livestock numbers on the grazing lands in many of the worse-affected dry rangelands.

The growing size of herd in dry rangelands is caused by many factors:

i. the growing human population in dryland developing countries;

ii. the changes in the economic circumstances of nomads, lead to greater emphasis on the role of livestock. From the nomad point of view, increasing the size of his herd is the only way in which he could save for the future.

iii. market forces at home and overseas causing livestock numbers to rise in many dry rangelands. In response to growing urban market, new commercial forces have linked inappropriately with traditional attitudes to livestock numbers as wealth, prestige or drought insurance, to accentuate further the recent inordinate increases in grazing pressure. Such forces have arisen just when the social structures within which traditional systems are embedded are themselves undergoing change and breakdown through modernization and mobilization of the society;

iv. the introduction of better veterinary care for livestock considerably decreased mortality rate;

v. in some cases, government or provision feed-grains at heavily subsidised prices. This has allowed maintaining stock numbers through the dry season far in excess of the range carrying capacity. Until the heavy subsidization of food-grain ceases, there is little hope of improving range conditions in these cases.

Encroachment of Rainfed Agriculture in Rangelands

At national levels in developing countries, particularly in Africa and Middle East, traditional pastoral societies have commonly lost their relative influence within the new national states of the drylands, where political and economic powers tend to be in the urban and agricultural sectors. It is in this context for example that a marked recent encroachment of rainfed cropping into the better pasture land can be understood as a response to newly created national policies for increased food production and increased emphasis on cash crops as producers of foreign exchange relationships between pastoralists and farmers have broken down.

This type of range degradation is widespread in the Near and Middle East and in Africa, particularly in East and South East Africa where agriculture and pastoralism in the past were in balance with environmental conditions; rangeland degradation seems only to have been considered a serious problem at a few specific cases. The accelerated rangeland degradation should be considered in part as a reflection of unequal economic development and of inequality of access to resources, at national and local levels linked with poverty and inadequate management and poor infrastructure.

In Rajasthan, India, the area of arid land used for rainfed cropping almost doubled from 30% to 60% between 1951 and 1971 at the expense of the grazing lands.

Deforestation also cases a decline in the fodder content of rangelands. Although we might think of shrinking rangelands merely in terms of a reduction in the areas of grass available for grazing, as far as livestock is concerned, rangelands are three dimensional assemblies of fodder, in which grasses, shrubs and small trees are all valuable food sources.

Frequent Drought

Frequent drought in many parts of the world's drylands and notably in Africa is a prominent factor which has contributed to range degradation. The crisis in the pastoral production systems of the Sahel in the early 1970s shows the great repercussion of this sequence of dry years on rangeland degradation.

Drought also hit the herd hardly: 39% of Niger's cattle and 10% of its sheep and goats were lost between 1970 and 1974. In the worst affected areas, mortality was much higher. However no advantage was taken of these losses to reduce livestock numbers to more sustainable levels, which amplified the impact of drought on rangeland degradation.

Sedentarization of Nomads

Many governments are encouraging nomads to settle. Unfortunately, the settlement of nomads, whether voluntary or enforced, breaks up large herds into smaller units which become concentrated around villages and cause degradation of rangelands. Overgrazing around settlements is likely to become a much more serious problem in the future as the inevitable trend towards nomad settlement continues.

Introduction of New Technology

The potentially harmful consequences of the introduction of new technology into traditional rangelands without the support of appropriate management controls is well exemplified by the provision of permanent bore-holes in rangelands which were formerly used only seasonally, or of stock-water supplies beyond the forage capacity of the rangelands.

Large cattle ranches in developed nations can also suffer from degradation. One cause is the coincidence of wet periods with low market prices: this encourages owners to keep cattle until prices improve and therefore to overstock their ranches. In the USA, more than half of the privately owned rangelands are producing forage at half of their potential or less because of overgrazing and consequent soil erosion.

Breakdown of Soil Control

Extensive grazing in rangelands in dry areas, particularly in the Near and Middle East, North Africa and in the Sahel, has been possible for many centuries only because of the rigid social control exerted by the nomads themselves over the movements of their animals. These controls have now broken down, more as a result of outside influences than any other cause (digging of wells; crop cultivation; loss of social control on grazing and growth of a new social class of livestock merchants breaking down the traditional kinship links between nomadic pastoralists; private appropriation of what had previously been communal resources; fencing of rangelands; private boreholes from which water is sold to pastoralists, etc...)

Government-Imposed or Abandoned Policies

Government-imposed policies and actions resulting in the abolition of the traditional administration system without providing effective alternatives, aggravate conflicts between tribes and distort the traditional laws governing communal grazing, thus inflicting drastic deterioration on the rangelands. In some cases, policies imposing northern limit of given commercial agricultural practices have been rendered obsolete through lack of enforcement, thus encouraging further encroachment on pasture lands.

Trend in Rangeland Degradation

The new assessment of the world status of desertification undertaken by UNEP in 1990- 1991 show that the largest area of degraded rangelands lies in Asia, followed by Africa, while the percentage of degraded rangelands is similar in both these continents. About 3,333 million hectares of rangeland or nearly 73 per cent of this total area in the world's drylands (4,55O million hectares) are affected by degradation, mainly by degradation of vegetation, which, on some 757 million hectares, is accompanied by soil degradation, mainly erosion. It shows an increase of some 233 million hectares in comparison with the 1984 assessment, approximately 7,5 per cent. It is safe to assume that the situation has not changed significantly since 1984, but remains very unsatisfactory with a tendency towards worsening.

There is no reliable global data on actual losses of rangelands and their conversion into agricultural land, wasteland/bad land/desert or urban land.

Management of Degraded Rangelands in Drylands

Rehabilitation of degraded rangelands should be based on sound ecological and integrated management of natural resources.

This calls for thorough understanding of the interferences which range ecosystems can tolerate without suffering irreversible degradation and understanding of the exploitation that they can sustain without losing their continuing function of producing the required resources.

However, ecological and integrated management of degraded rangelands should be supported by adapted technology, economic planning, legal, social and financial measures and improved institutions.

In rangelands areas, there is a need for legislation based on traditional land use rights and obligations in order to assign more secure legal land rights to groups of people who have been able, in the past, to manage rangelands without too much irreversible degradation, but who now are under increasing threat from outsiders. In many such areas, "land grabs" by outsiders are proceeding at an alarming rate.

Rehabilitation of degraded rangelands in dry areas cannot be expected to be economically remunerative in the short term. But in terms of stability and security for the immediately affected population, and the effect on regional security, climate change and biodiversity, the social dividends resulting from improved rangelands use are surely positive.

Improving farming in the sedentary zone is as crucial to arresting rangelands degradation as controlling grazing is. Agricultural progress and intensification in irrigated agriculture as well as rainfed farming are essential not only to provide food, employment and income to the increasing populations, but also to halt the uncontrolled spread of cultivation onto pasturelands.

Drought and dry season feed reserves are priority items of livestock production, but can cause overstocking and destruction of rangelands if purchased feed is used to maintain excessive grazing pressure on rangelands. Reserves are therefore best organized on the basis of what can be produced within the one management unit.

Government subsidies on feed brought into drylands are especially destructive for the rangelands.

Livestock marketings is an important option for both increasing returns to producers and reducing grazing pressure on rangelands. Special arrangement should be made for marketing animals during drought, ideally before animals loose too much condition and value.

Veterinary services are a necessary adjunct to marketing and, if available where and when required, make it possible for rangelands pastoralists to secure reliable subsistence from a small number of animals.

Technical interventions in livestock and range improvement and management: forage shrub and tree planting, reseeding, breed improvement, water development should go together with establishment of the institutional framework for research and training in range management.

Most projects and national training institutions should devote sufficient time to interact and exchange knowledge with the pastoral communities and avoid approaching these communities as the object of development.

LAND DEGRADATION AND WOODLAND MANAGEMENT

Characteristics of Woodlands in Dry Areas

Woodlands in dry areas are drought-resistant in general and well adapted to the local ecological conditions, where prevail low rainfall and high evaporation and to irregular distribution of rainfall. They are also adapted to recurrent drought.

These woodlands constitute a fundamental natural resource which transform solar energy into biomass and which protects and stabilizes the soil surface. Under natural conditions and through sound management, forest ecosystems in dry areas maintain a balanced exchange of water and energy and conserve their equilibrium. Their exploitation by man induces a certain disturbance in their structure, but they could regenerate and reconstitute their equilibrium after the cessation of the disturbance. A continuous overexploitation of these woodlands provokes however a gradual deterioration and degradation, which lead to the collapse of the ecosystem and desertification.

Dry forest ecosystems disturbed by land uses or stressed by drought, will usually return to what they were. Recovery tends to advance at a slow pace because of the low inherent fertility and productivity of the environment and is usually episodic, with more rapid recovery in years with above-average rainfall. Eventually, former water and energy balances will be restored, with the recovery of the original vegetation. This is a measure of the natural resilience of these dry woodlands.

In the sudano-sahelian zone, it has been observed that despite harsh climatic conditions and the repeated bush fires and fellings, a relatively short fallow period is sufficient for regeneration to start through seed germination, shoots and suckers, the latter representing an effective resistance too.

The drylands plant cover often degrades by a succession of phases manifested by the replacement of the original woodlands by plant communities more and more xerophytic, and of low economic value and of little benefit for soil protection and conservation. At the advanced stage of degradation the plant cover disappears.

Soil degradation follows the plant cover destruction by loss of organic matter, destruction of the structure through water and wind erosion. The soil environment becomes more and more arid.

Where pressure of land use persists through drought, the woodlands in dry areas are shown to be too fragile in certain ecological conditions and processes can be set in motion whereby degradation becomes self-accelerating. This can occur where sand dunes are stripped of their woody vegetation, as near watering points or other places where stock tend to congregate; drifting sands then destroy more vegetation including less damaged woodlands and cover increasing surfaces through the process.

Causes of Woodland Degradation

The causes of woodlands degradation in dry areas are numerous and linked to the multiple services woody plant communities are rendering under these conditions: expansion in cultivated area, pasture, overgrazing, overcutting for fuelwood or charcoal, fire, etc.

Expansion in cultivated area is perhaps the greatest cause of deforestation in the dry tropical areas. The woodlands are threatened by excessive cutting and sluggish programmes of replacement. The rate of deforestation is around 8.5 to 10 times the rate of planting. The depletion of woodlands results form excessive population pressure and poor management of forest-society relationship.

The most frequently cited reason for deforestation was expansion in cultivated area. The demands for domestic firewood or charcoal are also mentioned as responsible of large areas of woodland degradation. The urban demand usually for charcoal leads to the wholesale cutting of woodlands. The commodity status of charcoal makes it an attractive choice for entrepreneurs who can derive incomes form its production and distribution and for this reason the high demand in certain cases could lead to overcutting.

Forest fires can also be responsible for woodland degradation in dry lands because they clear up the woody vegetation, destroy the natural regeneration and young trees, kill the aged trees and lead to the constitution of simplified stands. They also lead to the accumulation of dead trees and intensify the concentration of animals which lead to the degradation of the vegetation by overgrazing in the unburned zones. In the Sahel, forest fires constitute a main factor of desertification.

In the Near East, deforestation is mainly due to expansion of the cultivated lands and to forest fires. Large areas of woodlands in the dry subhumid and the upper semi-arid zones have been cleared illegally for fruit tree plantations in sloping areas, without taking any conservation measures to prevent water erosion.

The woodlands in the dry areas of the Mediterranean region are subject to serious degradation, especially in the eastern and southern part of it, but there are no statistics on the loss of forest lands and on the degree of degradation of these woodlands.

Present Situation of Woodland Degradation

According to the FAO Forest Resources Assessment, 1990, the forest cover in West Sahelian Africa was 43.7 million ha at the end of 1980 and 40.8 million ha at the end of 1990 with a loss of 0.3 million ha (0.7% per annum) in East Sahelian Africa, 71.4 million ha at the end of 1980 and 65.5 million ha at the end of 1990, with a loss of 0.6 million ha (0.9% per annum, and in Tropical South Africa, 159.3 million ha at the end of 1980 and 145.9 million ha at the end of 1990, with a loss of 1,3 million ha (0.9% per annum). In the dry and very dry zone of the whole tropical world, annual deforestation during 1981-1990 was 2.2 million ha (0.9% per annum).

Consequences of Deforestation in Drylands

Woodlands in dry areas represent a stock of biomass of multiple use for the people in the drylands and constitute a major source of useful genetic materials for agriculture, medicine and other pharmaceutical products. The ecological services that woodlands in dry areas provide are many and difficult to assess in terms monetary terms.

Deforestation in drylands leads to increased water erosion with an indirect impact on water resource development, depletion of soil fertility, disappearance of many plant and animal species, local aridification, etc. In addition, flooding, accelerated runoff, droughts, more sedimentation in rivers and reservoirs and depleted groundwater become more severe because of deforestation, with adverse consequences for agricultural production and human life. Wind erosion takes place in the denuded dry plain engendering dust.

Deforestation often, but not always, leads to environmental degradation in the sense of loss of land productivity. The extent of degradation, if any, depends on the use to which the cleared lands are put and its subsequent management. Forest land has often been successfully converted to stable agro-sylvo-pastoral systems which brought high returns. Moreover, there were also cases of unplanned and inappropriate land use, such as slash-and-burn practices which did not allow sufficient time for regeneration. Such degradation was not necessarily related to population pressure and poverty, but was due in a large extent to the absence of sound land use planning and supporting policies, or the lack of physical and institutional infrastructure, necessary for economic exploitation of the cleared lands.

Development of Forestry Resources in Dry Areas

(a) Many national forestry departments are still predominantly concerned with traditional forestry plantations for supplying firewood, building materials, etc. Few resources are devoted to rural afforestation, soil and water conservation and indigenous woodlands. Agricultural services mostly ignore the important role of trees in peasant farming systems both from a biological and economic point of view.

Problems of environmental degradation, deforestation, and fuelwood supply in drylands cannot be solved by tree planting alone. What is needed is a holistic approach to agriculture, livestock, land settlement, forestry and energy policies. Forestry could play an important role in this approach if it is included in integrated rural development aiming at the improvement of the welfare of rural people and at the protection of the environment.

For this reason, forest plantations in arid and semi-arid zones may have little beneficial effects unless they are closely related to the needs and priorities of the people living there. Thus, the integration of trees into the farming systems should arise from the objective not only of growing trees but of improving the rural families welfare, which involve, among other things, the introduction of some form of woody vegetation with multipurpose use: firewood, fruit, honey, gum, tannin, pharmaceutical products, etc., which is accepted by the farmers in order to take care of it and consider it as an important component of the system. The most promising means of encouraging the practice of arid land forestry for multipurpose use appear in planting multipurpose shrub and trees in cultivating lands, in rehabilitating degraded rangelands, in soil and water conservation, i watershed management. Understood in this manner, forestry will play an important role in achieving sustainable development in arid, semi-arid and dry subhumid areas.

(b) Forestry will then play a crucial role in contributing feed for livestock and supplementing the diet of the rural populations, both directly in the form of fruits, nuts and leaves, and indirectly through honey and wildlife. Opportunities to benefit from this role of forestry need to be explored through an expanded programme of agro-forestry adapted to different climates and farming systems and of wildlife management. Agroforestry should be seen as an integral part of future drylands development in the semi-arid zone where it is relatively easy to establish trees and shrubs and promote full fledged forest food, fuel and fodder systems.

Training of foresters and technicians in drylands should cover agroforestry and wildlife, and training institutes should include programmes relevant to particular needs of drylands.

(c) Experience shows in various arid lands of the world that forestry can neither develop nor survive without active involvement of the local community, hence community participation is one of the most important ingredients of forest development.

(d) The scope of national forest policy should accord special emphasis to the role of woodlands and trees and shrubs in dry areas in providing support services to agriculture, contributing to appropriate agroforestry systems, specifically promoting the welfare of the rural poor, contributing to the fuel and energy needs of both rural and urban people and rehabilitating marginal land. Special attention should be paid to the involvement of women working in agriculture. Our endeavour should turn these working women into growers of trees, instead of mere collector. Women extension workers could help in the use of more efficient fuel stores or alternative energy sources such as solar cookers and to encourage local manufacture as an additional local industry. Legislation facilitating community forestry activities should be available in every country in order to carry out effectively extension programmes and developing forestry under its different aspects in drylands.

INTEGRATED RESPONSES FOR LAND REHABILITATION AND SUSTAINABLE DEVELOPMENT IN ARID, SEMI-ARID AND DRY SUBHUMID AREAS

(a) The fight against desertification is a fight for survival. It is an integral part of socio-economic development programmes which should aim at

sustainable agricultural and rural development (SARD).

According to the definition of Sustainable Agricultural and Rural Development approved by the FAO Council in 1988, sustainable development is the management and conservation of the resource base, and the orientation of technological and industrial change in such a manner as to ensure the attainment and continued satisfaction of human needs for present and future generations. Such sustainable development conserves land, water, plant and animal genetic resources, is environmentally non degrading, technically appropriate, economically viable and socially acceptable.

Combating desertification in drylands needs a holistic approach to agriculture, livestock, pastures, woodlands, land settlement and energy policies, taking into account the rehabilitation of the entire affected area, where integration of soil, water, pastures, woodland and wildlife has to be considered, and preferably at a watershed scale, in giving priority to socio-economic and cultural aspects of the inhabitants of the drylands.

More specific to the strategic objective of combating desertification, the sustainable development of arid, semi-arid and dry subhumid zones must confront three challenges:

i. to check or prevent desertification on land slightly or not degraded by preventive measures;

ii. to regenerate the productivity of moderately degraded land by corrective measures;

iii. to restore the productivity of seriously degraded land by rehabilitation and repair measures.

(b) Although the situation and degree of gravity vary substantially by country, it seems that land in the seriously degraded category is fortunately limited in surface area. As a result, the first two categories, where the majority of people affected by desertification live should be the subject of special care and priority. However, the severely degraded lands should not be neglected.

If, in the future, human requirements in drylands are to be met in a sustainable manner, it is now essential to move towards more efficient use of land and its natural resources. Integrated land use planning and management is a compulsory way to achieve this.

(c) As human activity is the reason for degradation of drylands in most cases, it is absolutely essential to question the general policies that allow and sometimes cause these actions and operate needed reorientations incorporating sustainability concerns.

In this context, approaches to sustainable agriculture and rural development should be inspired by considerations of human needs, poverty alleviation and the creation of production incentives.

Development should ensure the attainment of three essential goals:

i. food security, by ensuring an appropriate and sustainable balance between self-sufficiency and self-reliance;

ii. employment and income generation in rural areas, particularly to eradicate poverty; and

iii. natural resources conservation (soil, water, natural vegetation) and environmental protection.

(d) At the national level different pathways can be chosen for the attainment of SARD, depending on the resource endowments of a country, the existing environmental constraints, the demographic situation and trends, the needs, traditions, the available technologies and human skills. But the first prerequisite is to create a policy framework at national and international levels which is favourable to SARD.

Three major objectives should guide the choice of options for appropriate sector policy development plans and programmes:

i. improving efficiency in agriculture and rural development.

ii. increasing resilience and minimizing risks in order to reduce the vulnerability of the agriculture sector and the producer to adverse external factors (environmental and socio-economic); and in particular, provide a steady income to the producer and regular supply to the consumer.

iii. promoting diversity which generally increase the resilience of production systems and minimize risks and provide opportunities for the more efficient use of the diversity of the environment, local resources and cultures.

The attainment of the above-mentioned objectives requires a number of parallel actions at government, rural community, and production unit levels. The main elements which may compose the national strategies are the following:

i. people's participation and development of human resources;

ii. integrated production system management and diversification of rural incomes;

iii. improving efficiency and reducing the risks in the use of natural resources:

- land-use planning and soil conservation;

- improved water management;

- conservation and use of genetic resources (plant and animal).

iv. ensuring a balanced development and conservation through the use of key inputs for SARD by:

- integrated plant nutrition systems;

- integrated pest management;

- integrated rural energy development and utilization.

v. focusing on critical areas such as: drylands and other areas of uncertain rainfall, irrigated lands; mountain and hilly areas.

(e) Political will for sustainable rural development in drylands is a prerequisite.

(f) The challenge of overcoming poverty and translating the SARD concept into an operational reality is a common responsibility that should be met at local, national, regional and international levels. Consequently:

i. Improvement of information and monitoring should concern data acquisition systems as well as analysis of communication methods of the final product, information needs are greatest and more urgent at national and local level.

ii. The village-based approach (living area of a rural community)is best suited to the necessity of undertaking global actions on the lands (instead of sectorial activities often doomed to failure) with the full participation of the local people.

iii. Desertification control can only be successful if the social, economic, cultural and political development adopted aims principally at solving problems brought about by insufficient food, accommodation, employment, income, health, education and population pressure.

iv. Within the framework of an integrated rural development policy desertification could be combated. This requires a review of the agricultural development policies and planning in order to integrate anti-desertification programmes at national level in the framework of policy formulation and strategic planning. The required strengthening of institutional capacities needed in the rural sector should take account of this integration rather than support the setting-up of new institutions and structures.

v. Food security is one of the basic strategies of sustainable rural and agricultural development policy, especially in arid, semi-arid and dry subhumid zones.

vi. The main guiding principle in sustainable development and combating desertification is the promotion of voluntary and responsible popular participation through legislative, economic and institutional measures.

SEE FIGURES 1 - 4

Annex I

SPECIFIC FACETS OF SUSTAINABLE DRY LAND DEVELOPMENT

Water and Land Use Improvement for Sustainable Agriculture

It is recognized that sustainability of food production increasingly depends on sound and efficient water use and conservation practices, consisting primarily of sound irrigation development and water management in rainfed areas.

The International Action Programme on Water and Sustainable Agriculture (IAP-WASAS) which has been initiated in cooperation with other international organizations reflects the strategy in water and sustainable agriculture. The main objective of this programme is to assist Member nations in planning, developing and managing water resources in an integrated manner to meet their present and future needs for agricultural development on a sustainable basis in a flexible approach compatible with the policies and needs of national governments. This action programme framework focuses on five priority areas as follows: water use efficiency; waterlogging, salinity and drainage; water quality management; small scale water programmes; scarce water resources management and national capacity building.

The IAP-WASAD recognizes the importance of a holistic approach to water resources management in order to meet global agricultural and rural development needs. It calls for integrated development of irrigated and rainfed farming, livestock, fisheries and agroforestry and emphasizes the importance of water and soil conservation and environmental protection. An important component of the action programme that is relevant to desertification is the control of waterlogging and salinity, which has rendered about 30 million ha of irrigated lands unproductive and some severely salinized lands abandoned and desertified. The Action Programme proposes to rejuvenate those salinized lands that could be economically reclaimed and prevent further sanitization through the provision of artificial drainage and adoption of improved water management practices.

Range Resources Development

Focus relating to range resources development aims at the following:

i. increased and improved use of feed resources, particularly at the level of the small holder with special emphasis on feed produced on the farm;

ii. nitrogen-fixing forage legumes, and fodder trees and shrubs in the semi-arid and arid zones such as the semi-arid region of South America, the Middle East and North Africa and the arid region of Patagonia, etc.;

iii. adaptation of local management systems to changing conditions, and to maximum exploitation of the local technical knowledge;

iv. improvement of fodder conservation, fodder trees and shrubs and grazing systems. Networks or regional working groups are used to ensure sharing knowledge between national institutions and countries with similar ecological conditions.

There is an established long-term programme based on improvement of grazing resources in arid and semi-arid regions of the world, with major emphasis on Africa and the Near East known as EMASAR (Ecological Management of Arid and Semi-Arid Rangeland). Strategies include an integrated approach to grazing-land development that involves all components in the agriculture sector subject to periodic drought, with emphasis on the participation of the local population.

Forest Resources Development

Programmes should emphasize the role of trees and forests as a renewable natural resource and aim at promoting the understanding of their contribution to rural development, food security, conservation of genetic resources, wildlife management, wind erosion control and watershed management.

An integrated approach to tree and forest management in drylands, and a strategy, have emerged, particularly after the incidence of drought in a number of areas which is based on:

i. a recognition of the role of forestry in arid areas with due consideration of the different ecological, social and economic factors;

ii. a framework of principles (integration, diversification of activities, the return of forest benefits to the local communities, etc...), objectives and areas for action. Many national and international programmes, among which the TFAP, have confirmed these objectives and approaches in their respective components for the control of desertification, the conservation of watersheds in arid areas, the production of wood-based energy and agro-silvo-pastoral integration.

The recent programme, "Conservation and Rehabilitation of African Lands", recognizes the impact of deforestation and degradation of tree and shrub cover in arid areas on the degradation of African lands and prioritizes actions for the management of forest resources and plant rehabilitation to control desertification.

Like tropical forests, Mediterranean forests are under serious threat and the causes are the same. For this reason, a Mediterranean Forest Action Programme (MED-FAP) is being launched and will address the major problems linked to sustainable management of plant formations, and promotion of the role of forestry in desertification control in the mediterranean regions.

In all these activities, the question of biological as well as financial and institutional sustainability, the elimination of rural poverty and the management of forests as a renewable natural resource for present and future generation are accepted as primary objectives.

Energy for Sustainable Rural Development

It is recognized that agriculture and forestry can play a unique role as producers of renewable energy, which is an important pillar for sustainability in drylands, that nations must move fast in this direction and that international cooperation needs to be mobilized to support these efforts. It is necessary for each country to formulate energy policies for agriculture and rural development. Only in this manner will energy technologies related to irrigation, harvesting, transport, processing and rural services realize their full potential. Making available alternative new and renewable sources of energy to increase energy inputs for rural household and agro-industrial needs and to improve energy efficiencies are among the objectives of SARD. They are all the more critical in dry areas.

Conservation and Sustainable Use of Plant and Animal Genetic Resources

It has become increasingly clear that the conservation of plant and animal genetic resources is a logical component of the sustainable development of all biological resources used in agriculture. In this regard, the improved use and preservation of plant and animal genetic resources in drylands will contribute to the on-going endeavour to promote sustainable development and the conservation of biological diversity.

Considering the importance of genetic resources in agricultural development, FAO has, since 1983, developed a global system on plant genetic resources. The objectives of this global system are to ensure the safe conservation and promote the availability and sustainable utilization of plant genetic resources for present and future generations, by providing a flexible framework for sharing the benefits and burdens.

A comprehensive programme for the conservation of animal genetic resources has been launched including the characterization and enumeration of animal genetic resources, the identification of breeds at risk and the conservation and utilization of indigenous breeds to guarantee their survival.

People's Participation in Sustainable Agriculture and Rural Development

SARD can best be achieved with active participation of rural people through local self-help organizations of their own choice. Technological solutions of a scientific nature or other externally designed innovations cannot be sustained on a long-term basis without the active support and participation of rural people.

This fact has been long recognized through the development of a number of participatory programmes. The approaches adopted focus on fostering self-reliance and cooperation. Emphasis is on management practices, building agreements for changes in resource utilization, the rights and duties associated with the use of land, water and forests and on equitable access of rural people, particularly women, small farmers, landless people, and indigenous people to land, water and forest resources.

Annex II

The GLASOD map and tables provide combinations of the following:

Four degrees of soil degradation

light: The terrain has somewhat reduced agricultural suitability, but is suitable for use in local farming systems. Restoration to full productivity is possible by modifications of the management system. Original biotic functions are still largely intact.

moderate: The terrain has greatly reduced agricultural productivity, but is still suitable for use in local farming systems. Major improvements are required to restore productivity. Original biotic functions are partially destroyed.

strong: The terrain is non-reclaimable at farm level. Major engineering works are required for terrain restoration. Original biotic functions are largely destroyed.

extreme: The terrain is non-reclaimable and beyond restoration. Original biotic functions are fully destroyed.

Five categories of relative extent

infrequent (up to 5% of the map unit affected); common (6 to 10%); frequent (11 to 25%); very frequent (26 to 50%); dominant (over 50%).

Severity of soil degradation

This is indicated by a weighted combination of the degree and the relative extent of the process.

Recent-past rate of soil degradation

This gives the average rate of human-induced soil degradation over the last 5-10 years, in three quantitative categories: "slow", medium" and "rapid".

Predominant causative factors

Deforestation and removal of the natural vegetation; overgrazing; agricultural activities (arable farming); overexploitation of vegetation for domestic use; and bio-industrial activities.

LAND DEGRADATION RESULTING FROM URBANIZATION, INDUSTRIALIZATION, MINING AND TOURISM

Presented by : Mr. Jochan Eigen, Coordinator, Sustainable Cities Progamme, and Mr. Graham Alabaster, Human Settlements Officer, United Nations Centre for Human Settlements (HABITAT)

URBANIZATION AND LAND DEGRADATION - A DRAFT AGENDA

Desertification or land degradation is one of the environmental issues Habitat addresses in connection with its concern for sustainable development and growth of human settlements. Combating land degradation or desertification may not be as immediate a mandate for Habitat as it is for other agencies such as UNSO or FAO. However, through its unique expertise in strengthening human settlements management capacity in developing countries Habitat can make essential contributions to combating land degradation. Habitat therefore has developed the outlines of an agenda vis-a-vis land degradation so that its possible role in the Convention to Combat Desertification can be explored in view of it's expertise and ongoing programmes in over 100 developing countries.

The draft UNCHS (Habitat) agenda on urbanization and land degradation is based on the following basic propositions (which, incidentally, flow well from the preceding presentation, where FAO identified population pressure as one of the key factors contributing to desertification):

i. urbanization accommodates population growth;

ii. environmental degradation can limit the benefits of urbanization;

iii. land degradation is one environmental concern associated with urbanization; and

iv. strengthening urban management capacity helps combat desertification.

UNCHS AGENDA ON URBANIZATION AND LAND DEGRADATION

Accommodate population growth through sustainable urbanization

i. Cities absorb 2/3 of population growth in developing countries;

ii. Cities offer economies of scale for housing, infrastructure, services, and a variety of productive sectors;

iii. Cities are important motors of socio-economic advancement in developing countries

iv. In 1980 most people lived in rural areas, after 2000 most will live in cities

Realize fully the benefits of urbanization by avoiding environmental degradation

i. Manage natural resources such as water resources*, urban air resources, fuelwood resources*, recreation and tourism resources, fisheries resources, agricultural land resources.

ii. Control environmental hazards such as flooding*, landslides*, environmental health risks.

Avoid land degradation as one environmental concern associated with urbanisation

Combat desertification by strengthening urban management capacity

a. Promote the latest understanding of issues and priorities

i. misuse of land resources;
ii. over-exploitation and pollution of water resources; and
iii. unsustainable use of biomass energies.

b. Support modern urban management approaches

i. recognize the cross-cutting nature of urban environmental issues;
ii. involve all stakeholders in policy formulation/implementation;
iii. employ the full range of policy implementation instruments;
iv. strengthen urban management capacity "system-wide";
v. address issues at technical, institutional, and political levels;
vi. focus on procedures rather than products.

c. Involve all stakeholders in policy formulation/implementation

i. those whose interests are affected;
ii. those who possess relevant information and expertise; and
iii. those who control relevant implementation instruments.

d. Employ full range of policy implementation instruments:

i. education and information campaigns;
ii. regulatory mechanisms;
iii. economic incentive mechanisms;
iv. strategic use of capital improvements.

e. Strengthen urban management capacity "system-wide":

i. public sector;
ii. private sector; and
iii. community sector.

Apply state-of-the-art strategies for the delivery of external support

i. emphasize capacity building at local, national, and regional levels;
ii. employ issue-focused, bottom-up approaches;
iii. rely primarily on local expertise;
iv. promote the exchange of know-how among cities;
v. use demonstration/replication mechanisms to leverage external inputs; and
vi. coordinate with other external support agencies. 43