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   Sahel Workshop Abstracts


Evolving Contexts of the Desertification Debate  <back>

A great many debates have grown up around the notion of desertification as a process of degradation that affects the arid, semiarid and subhumid zones of the globe. A fundamental and continuing debate has been over whether desertification actually exists and, if so, how it might be defined, measured and assessed. Rather than simply review the evolution of these debates we examine the contexts in which they take place and how those contexts have contributed to the evolution of our understanding of the intertwined processes that contribute to desertification. The fact that these “contexts” have changed over time, and that some of these contexts are often ignored have helped sustain debate. We consider four “contexts” that frame much of the debate and consider what impact each has had: (1) changes in our understanding of climate variability; (2) changes in our understanding of vegetation responses to perturbation; (3) changes in our understanding of social processes, including household responses to economic perturbation; and (4) changes in our understanding of desertification as a political process or artifact.

Policy implications of the Sahelian recovery  <back>

The Sahelian greening is one phase in a continuous sequence of wet and dry periods. This paper examines policies in the light of these changes. It looks both at policies involved both in other greenings and in the Sahel itself. The others include Sinai, southern Russia, Arizona and the Loess Plateau in northern China. In Sinai, the policies that brought about greening include exclusion, emigration and nature conservation. In Russia, the policy that had impact was the collapse of the Soviet collective farm system. In Arizona, it came after the Taylor Grazing Act of 1934 which allowed the US Forest Service to manage grazing. On the Loess Plateau, it has been the result of irrigation, tree-planting, the extension of responsibility of land users and perhaps aerial seeding and fencing. Most of these policies are inapplicable to the Sahel, with the possible exception of some of the Chinese measures.
In the Sahel, some policies in Burkina Faso, and elsewhere did enable soil and water conservation projects, but the success of these projects is more due to the harnessing of local skills. More generally, policy has had little to do with the greening (as with the earlier browning), even though the Sahel has been a seething cauldron of policy debate for three decades.
Sahelian environmental policies face two main challenges: fast and occasionally extreme fluctuations in rainfall; and changes in the scientific dialectic. There should be less emphasis on the negative policy of controlling land degradation, and more on positive policies that encourage adaptation and allow for rapid deployment to make use of good years and insurance policies against bad ones.

Greening of the Sahel  <back>

For the last four decades there has been sustained scientific interest in contemporary environmental change in the Sahel. It suffered several devastating droughts and famines between the late 1960s and early 1990s. Speculation about the climatology of these droughts is unresolved, as is speculation about the effects of land clearance on rainfall and about land degradation in this zone. However, recent findings suggest a consistent trend of increasing vegetation greenness in much of the region. It is not possible to explain the vegetation trend by rainfall only. The paper presents empirical data and discusses possible other causes of this trend such as land use change, migration and armed conflicts. The policy implications of a positive trend in biophysical conditions are also discussed. One conclusion of the findings is that more site-specific information on the interaction of biophysical dynamics (climate, soils, vegetation) and farming systems (farming practices and risk management strategies) is needed in order to better understand and ultimately support the development challenge in the Sahel.

The impact of soil and water conservation on agriculture and environment on the northern part of the Central Plateau of Burkina Faso between 1980 and 2001  <back>

In the beginning of the 1980s the situation on the northern part of the densely populated Central Plateau was dramatic: drought years succeeded each other, food shortages at household level were endemic and the environment had become degraded. The commonly held view is that the process of environmental degradation continued in the second half of the 1980s as well as in the 1990s.

A study was recently undertaken by a multidisciplinary team of national researchers, who looked at long-term changes in agriculture and environment in this region. Most of their research findings show positive trends. Cereal yields have increased by about 50% since 1984-88; in two of the three provinces studied the cultivated area remained stable during the last 15 years; tree density and species diversity are higher on fields treated with soil and water conservation than on untreated fields; livestock numbers have increased and livestock management is evolving from extensive to semi-intensive and a survey in 59 villages shows that, according to the villagers, local groundwater levels have improved substantially since the start of soil and water conservation. Based on criteria used by villagers, which are mainly related to levels of household food security, rural poverty seems to have decreased significantly (up to 50%) in villages with soil and water conservation.

Much has been achieved, but much more remains to be done. It is urgent to improve soil fertility on cultivated land and to fight against land degradation on uncultivated land, which continues unabated.

23 years of Sahelian vegetation dynamics from NOAA-AVHRR  <back>

Satellite measurements of the global biosphere in the form of the normalized difference vegetation index (NDVI) have generated a 23 year time series appropriate for the studies seasonal to interannual vegetation dynamics of the Sahel region. The close coupling between Sahelian rainfall and the green-up of vegetation has made it possible to utilize this vegetation index data set as a proxy for the land surface response to climate variability. Examination of the this time series principally reveals two major periods: (a) 1982-1993 marked by below average vegetation and persistence of drought with a signature large scale drought during the 1983-1985 period; and (2) 1994-2003, marked by a trend towards “greener” conditions with region-wide above normal vegetation conditions in 1994. Spatial patterns enable us to conclude that is not a footprint of desertification, rather they indicated the variability of green vegetation biomass over the region in response to interannual variations in rainfall. Systematic studies of changes on the landscape at local scales using high spatial resolution satellite data sets such as those from LANDSAT, SPOT and MODIS will allow for an improved documentation of degradation of Sahelian land resources that could lead to desertification.

Using farmers’ responses to change as a guide to policy at the country level  <back>

The dominant narrative influencing Sahelian environmental policy during the past 30 years has been that of ‘desertification’. This narrative is disaggregated into (a) the sub-themes of ‘deforestation’, ‘overstocking’, ‘overcultivation’ and over-use of water, (b) sub-hypotheses, which create expectations about farmers’ NRM as an agent of degradation, and (c) biophysical outcomes which have been measured, mapped or assessed. The expectations created by the sub-hypotheses are compared with evidence from selected districts in three countries (Diourbel Region in Senegal, Maradi Department in Niger, and the Kano region of northern Nigeria). Long-term data sets (1960-2000) collected at district level and ground-truthed with village level investigations (1999) are used. The performance of the production systems in these districts departs in significant ways from hypothetical expectations, giving grounds to query their validity, and to construct a counter-narrative.
The findings of these studies (carried out in collaboration with 30 scientists in the countries concerned) have been synthesised with a view to deriving policy lessons for dryland development. A simple narrative of ‘desertification’ is inadequate for understanding the flexibility, adaptability and diversity of farmers’ responses to change, and fails to identify the potential for productivity increases, income and welfare improvements. NRM as a whole should be understood within a context of livelihood management, and is therefore strongly influenced by macro-economic policy. Generalised properties of a new dryland development policy approach are outlined. Using the lessons learnt from the research and in subsequent dissemination activities, burning issues that have specific application to Sahelian drylands are identified for policy formation at the country level.

UNCCD perspectives on the changes in the Sahel  <back>

The plight of the Sahel was brought squarely on the international arena by the reports on the debilitating drought of the early seventies, after massive loss of life and property. The international community made attempts to address the issues of drought and desertification by the establishment by UNCOD in 1977, of the well-known Plan of Action, but the efforts fell way short of expectation.

The UNCED process and the resultant Chapter 12 of Agenda 21 led to further reflection, but there was felt a strong need for a legally binding instrument. The birth of the UNCCD, the Convention to address the fight against drought and desertification the world over, was the way out. This was a call for paradigm shift, a different way of dealing with the twin problems of drought and desertification.

The “United Nations Convention to Combat Desertification in Those Countries Experiencing Drought and/or Desertification, Particularly in Africa”, with its entry into force in December of 1996, to date has 190 signatories. The thrust of the UNCCD is for concerted local level action, but with international level support and partnership.

The objective of the UNCCD is “to combat desertification and mitigate the effects of drought…..through effective action at all levels, supported by international co-operation and partnership arrangements, in the framework of an integrated approach which is consistent with Agenda 21, with a view to contributing to the achievement of sustainable development in affected areas.
The UNCCD recognizes that achieving this objective will involve long-term integrated strategies that focus simultaneously, in affected areas, on improved productivity of the land and the rehabilitation, conservation, and sustainable management of land and water resources, leading to improved living conditions, in particular at the community level.
The Sahel is a major entry point in understanding and eventually addressing the seemingly complex problems of recurrent droughts and the ever-present desertification and land degradation. The particular attention given to Africa by the UNCCD includes the Sahel, as testimony to the dire need to take concrete action in that region.

Various interacting forces come into the picture, in influencing not only the natural processes, but also the possible remedial measures. Traditional knowledge and coping strategies of the affected peoples, early warning systems, the role of the prescribed tools - the Convention implementation frameworks, climatic factors, ecological factors, anthropogenic factors, are all important components to be taken into consideration when looking at the “Changes in the Sahel”. The combined action of these at local level, national level as well as appropriate international interventions in one way or another hold the key.

Monitoring vegetation growth and mapping changes in landscape : Senegal case study  <back>

A lack of early warning system in the early 1970s prevented governments and even researchers of having a good appreciation of the droughts occurred, in particular in 1972, in semi-arid zones.
Since this period, developing tools to monitoring vegetation growth and to estimate available feeding for cattle has been a strong concern for decision makers. The Centre de Suivi Ecologique (CSE) has experienced, in such a context, the development of various products. Decadal NDVI information and annual biomass maps using NOAA/AVHRR and Spot/Vegetation data are some of the products successfully elaborated and regularly published since 1987.
More recently, some other indicators like VCI and SPI have been successfully applied to drought monitoring in Senegal.
The process has allowed to set up a NOAA database of well calibrated images. These data have been used to look at the tendency of the vegetation growth at national level.
At a more localized level, several studies based on satellite images and aerial photos from 1960’s until 2000 have been conducted to map changes occurred in landuse and land cover. CSE is still continuing to work on this kind of studies with FAO in the framework of the Land degradation assessment project. It is aiming to identify hot and brigth spots and to document their causes using mapping and and censuses.
Early warning systems are now used in some Sahelian countries on a more operational basis and can be expanded to all Sahelian countries. Detection of changes in Sahel landscape is doable at large and localized areas (access to high resolution data still needs to be improved). Generalization on very large areas should be done carefully.

Long-term precipitation variability in the Sahel  <back>

The Sahel has undergone tremendous fluctuations of rainfall throughout historical times. Extreme and prolonged droughts are an inherent feature of the environment. The fluctuations have been particularly extreme during the last half of the 20th century. The mean rainfall for 30-year periods, the traditional time period for a climatic “normal”, decreased 25% to 40% in the Sahel between 1931 – 1960 and 1968 – 1997. the contrast is even greater when the wettest and driest decades, the 1950s and 1980s, are compared. During those decades, the entire continent was affected. That clearly demonstrates that the main causes of rainfall variability are to be found in the large-scale general atmospheric circulation. These in turn are at least partially driven by sea-surface temperature variability, however El Nino/La Nina does not play a large role.
Most of the change takes place in August. Wet/dry conditions in the Sahel tend to be associated with a northward/southward displacement of the rainbelt over West Africa. In some cases, however, the reduction in rainfall is associated with an overall weakening of the tropical rainbelt. There is little relationship between the amount of rainfall during the season and length of the season or its onset date. These facts have strong implications for both adaptive strategies and predictability.
The persistent dry conditions prevailed from the late 1960s through the mid-1990s. TRMM satellite data that was validated with a dense gauge network showed that the region became markedly wetter in 1998. Relatively good rainfall continued through the next year. As a whole rainfall of the last 6 years has been better than average, but the “wet” conditions of the 1950s were not matched.

Regional variability, local relative degradation; how to manage the scales  <back>

« Desertification » has to be clearly distinguished from « desert encroachment », which is linked with the romantic idea of a desert (erg and reg) encroaching irreversibly upon green areas. Different thresholds of land and soils degradation have been used to assess the lost of natural resources, and differ considerably according to the idea of « irreversibility » of the ultimate stage of degradation (which is the « desertification » on a 25 years basis). We have no evidence to say that the drought period has ended, neither we can say that there is a global trend towards a drier climate since the last century. So that the « greening Sahel », following the « yellowing Sahel » of the 70’s is just an expression of this climate variability : the desert did not (already) encroached upon the arid Sub-Saharian regions.
Are land use changes (towards less range pastures, more fields and fallow fields, less time of fallowing, etc) responsible or not for soil and land degradation cannot be assessed just through a global survey at regional scale: the degradation (loss of soil material, decreasing in production) depends notably upon the way populations are using their space and resources (human density, technology, etc.).
Examples from North Saharian countries, where animal pressure increased during the drought period, due sometimes to national actions taken to mitigate the effect of the drought, show that we have to differentiate between « land degradation and/or desertification » (which correspond to the loss of production capability) and « resources degradation », which express a decreasing in man-useful resources.
Combining bio-physical and socio-economical assessment and monitoring, combining functional models at local scale and structural monitoring at national or regional scale, could help understanding the trends in desertification. These are the objectives of the ROSELT/OSS programme.

Environmental and land cover changes in the Sahel region: lessons learned, Challenges and priority actions  <back>

During the last three decades the Sahel region has been confronted with various forms of environmental and ecological degradation due to climate change and anthropogenic factors. These changes have been described as the most important that the region had ever faced. Recent studies and analysis show spatial and temporal patterns changes and variability in the landscape features, tree-crop patterns and forest cover, with severe degradation of soils and fragile ecosystems.
However, their impacts could have been mitigated or even reversed through conducive policies and concerted and collaborative efforts with focus on priority areas where the conservation and rehabilitation of fragile lands could be the most cost effective.
The FAO LADA team is carrying out, since 2002, studies focused on the assessment of the status and trends of these changes, including their impacts on livelihoods and identification of hotspots. LADA work aims to generate up-to-date information related to ecological and environmental changes, including economical, social and technical aspects, traditional knowledge and practices on land management which have occurred in drylands during these last decades.
The principle objective of the LADA project is to develop methods and tools to assess and quantify the nature, extent, severity and impacts of land degradation on ecosystems, watersheds and river basins, carbon storage and biological diversity in drylands at a range of spatial and temporal scales.
The project will also build national, regional and global assessment capacities to enable the design and planning of interventions to mitigate land degradation and establish sustainable land use and management practices.

Mitigation of Impacts of Changes in Sahel  <back>

In the frame of the partnership of weather, climate and environment for development, meteorological applications usefully contribute to mitigate the impacts of climate variability and changes in Sahel.

For this purpose, the products of seasonal and intra-seasonal climate forecast disseminated to end-users (rural communities and others) by RANET multi-media system are currently usefully used in Niger and Mali.

By seasonal and intra-seasonal climate prediction process forecasts, outlooks and climate summary are produced to predict and monitor early or late onset or withdrawal of rainfall, the dry or set spells and outlook of the rainy season. This information is disseminated in due time to end-users to enable them to better manage their socio-economic activities.

These tailored products are carried out through two specific programs on these matters by ACMAD in collaboration with its partners (National Meteorological Services, sub-regional and international specialized center). The interdisciplinary teams use them on the ground.

So for the benefit of Sahelian population the program on seasonal and intra-seasonal climate prediction and the program on dissemination of the products of meteorological application to rural communities in their mother tongue are providing useful tools. These programs should be strengthened and generalized in the Sahel.

A new land cover classification system for desertification assessment, mapping and monitoring  <back>

To date there is no consensus concerning the definition of desertification and as such there is no agreement regarding the current status of desertification in the world as a whole or in its various areas. Lack of consensus is mainly due to the fact that the proposed definitions have no measurable parameters for desertification assessment and mapping. In spite of lack of consensus on the definition of desertification, it is generally recognized that desertification is a marked decline or total loss of the potential ability of the ecosystem in dry lands to sustain the biological productivity of land. According to the World Bank definition, desertification is a process of sustained land (soil and vegetation) degradation in arid, semi-arid and dry sub-humid areas, caused at least partly by man. It reduces production potential to an extent that can neither be readily reversed by removing the cause, nor easily reclaimed without substantial investment (World Bank, 1988). Many studies have shown that changes in vegetation/land cover and land use patterns form important criteria in land degradation/desertification assessment, mapping and monitoring. It has further been demonstrated that changes in land cover over time can be monitored effectively using remotely sensed satellite data. However, due to the existence of numerous and inconsistent land cover classification systems, it is not possible to optimally use new or existing land cover data in land degradation/desertification assessment and monitoring and in planning of sustainable land use systems. To address this problem, there is a need to come up with an internationally accepted land cover classification system. This is particularly important due to increasing availability of vast amount of remotely sensed land cover data that is collected from earth observation satellites on a regular basis. The Food and Agriculture Organisation of the United Nations (FAO)/United Nations Environmental Program (UNEP) Land Cover Classification System (LCCS), which attempts to address this problem, is briefly discussed in this paper as well as its possible use in land degradation/desertification assessment, mapping and monitoring.

The utilization of geoinformation technology for agroenvironmental applications in Egypt  <back>

Remote sensing can provide valuable and timely information about natural resources and environment which are very important for sustainable development. However, in developing countries, the utilization of such advanced technologies differs from one country to another. Egypt, as a developing country, has experience in the utilization of earth observation satellites and aircraft remote sensing data in soil mapping as well as assessment of land degradation.
Agriculture in Egypt depends mainly on artificial irrigation, which has long been practiced since the pre- historic times by the Egyptians, and still used today in nearly the same manner. The main source of irrigation water in Egypt is the Nile water. Despite a number of projects to regulate the Nile having been implemented, much of the Nile water is still in use in a non- scientific way with an efficiency of irrigation of less than 50% and salinization as a consequence. The change from the unwise use of irrigation water to the exactly calculated amounts of different crops requirement of water will save a great amount of water besides conserving soils from rendering saline.
In all the cultivated areas the natural vegetation has been degraded as a result of man’s activities or has been completely removed. Agriculture has long been practiced in the Nile Delta by the ancient Egyptians, and so natural vegetation can only be found in the northern part of the Delta and the desert. The rest of the Delta and Wadies are grown with different economic crops in a recurrent succession (grain crops, fiber crops, legumes, sugar cane ... etc.).

Sahel Workshop Contact:

Stefanie Herrmann, ICRSE Workshop Secretariat
stefanie@email.arizona.edu -- (520) 626-8064 Voice -- (520) 621-3816 FAX

Food & Agriculture Organization
of the United Nations
United Nations Convention
to Combat Desertification
United Nations
Environment Programme

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