1 Trees, forests and land use in drylands The first global assessment Preliminary findings FAO/Giulio Napolitano Trees, forests and land use in drylands The first global assessment Preliminary findings Food and Agriculture Organization of the United Nations (FAO). Rome, 2016. Cover photo: FAO/Giulio Napolitano Design and layout: Kate Ferrucci, The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned.
2 The conclusions given in this information product are considered appropriate at the time of its preparation. They may be modified in the light of further knowledge gained at subsequent stages of the initiative. This document has been produced with the financial assistance of the European Union. The views expressed herein can in no way be taken to reflect the official opinion of the European Union. ISBN 978-92-5-109326-9. FAO, 2016. FAO encourages the use, reproduction and dissemination of material in this information product. Except where otherwise indicated, material may be copied, downloaded and printed for private study, research and teaching purposes, or for use in non-commercial products or services, provided that appropriate acknowledgement of FAO as the source and copyright holder is given and that FAO's endorsement of users' views, products or services is not implied in any way.
3 All requests for translation and adaptation rights, and for resale and other commercial use rights should be made via or addressed to FAO information products are available on the FAO website ( ). and can be purchased through FAO/Giulio Napolitano Contents 1 Trees, forests and land use in drylands : why?..1. This 2 Sampling Data Data The implementation Data 3 land use in Forests in Trees in Crown cover Crown cover density by land -use Trees outside 4 Concluding 27. 27. Advantages, caveats, limitations and 28. Global drylands Assessment: the way 29. 30. List of boxes Box 1. What are drylands ?..2. Box 2. The Rome Box 3. Collect Earth: a tool in the Open Foris Box 4. Indicative list of collected Box 5. Hierarchical rule for classifying predominant land List of figures Figure 1. The world's drylands ..4. Figure 2. Illustration of sampling intensity, by aridity Figure 3. Distribution of sample plots, by highest-resolution source of Figure 4.
4 land -use distribution in drylands , by Figure 5. land -use distribution (proportion of total area), by Figure 6. land -use distribution, by Figure 7. forest distribution as a proportion of total forest area, by aridity Figure 8. dryland forest distribution, by crown cover Figure 9. Average crown cover density, by region and aridity 20. Figure 10. land with a presence of trees (million ha), by land use (share of total)..21. Figure 11. Crown cover density as a proportion of total land area, by land Figure 12. Crown cover density as a proportion of cropland (a) and grassland (b), by 22. Figure 13. Distribution of trees outside forests in each of five land -use categories in drylands , by region (million trees).. 24. Figure 14. Distribution of land with tree presence, by land use and aridity zone ('000 ha).. 25. Figure 15. tree density, by cropland 25. List of tables Table 1. land -use categories of the Intergovernmental Panel on Climate Table 2.
5 Regions, partner institutions and participants involved in the first Global drylands Table 3. land -use distribution, by aridity Acknowledgements The first Global drylands Assessment was possible thanks to the contributions of many experts on drylands , assessment and monitoring in the Rome Promise Collaborative Network and FAO. Many thanks are given to the partner organizations that participated directly in the assessment and analysis, as listed in Table 2. Special thanks are due for the financial support provided by: the European Union in the framework of Action Against Desertification, an initiative of the African, Caribbean and the Pacific Group of States (ACP) in support of the Great Green Wall for the Sahara and the Sahel Initiative and the United Nations Convention to Combat Desertification action plans to promote sustainable land management and restore drylands and degraded lands in ACP countries, implemented by FAO with the African Union Commission and other partners; and Germany's Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety in the framework of the Global forest Survey project implemented by FAO in collaboration with Google.
6 FAO/Giulio Napolitano 1. Trees, forests and land use in drylands : why? drylands cover about 41 percent of the Earth's land surface and are characterized by a scarcity of water (Box 1 contains a full definition). About 90 percent of the estimated 2 billion people living in drylands are in developing countries (Millennium Ecosystem Assessment, 2005). The majority of these people depend on forests and other wooded lands, grasslands and trees on farms to meet basic needs for food, medicines, shelter, cooking, heating, wood, and fodder for livestock, and for income. Trees and forests in drylands generate a wealth of such as land degradation and desertification, com- environmental services; for example, they provide bined with drought, hunger and violence, are already habitats for biodiversity, protect against water and leading to forced migration in dryland regions in wind erosion and desertification, help water infiltrate Africa and western Asia.
7 Soils, and contribute to soil fertility. They also help Urgent action is needed, therefore, to improve increase the resilience of landscapes and communi- the management and restoration of drylands . Such ties in the face of global change (FAO, 2015). action requires a comprehensive understanding of Life in the drylands is precarious, and the socioeconomic status of people in drylands is sig- nificantly lower than that of people in many other areas. Water availability in drylands , already (on average) one-third below the threshold for minimum human well-being and sustainable development, is expected to decline further due to changes in climate and land use (Millennium Ecosystem Assess- XXXXXXXXXXXXXXX. ment, 2005). Poor people living in areas remote from public services and markets and dependent on marginal natural resource bases will be most vulner- able to food shortages (World Food Programme and Overseas Development Institute, 2015).
8 Challenges 1. BOX 1. What are drylands ? The United Nations (UNEP, 1992; UN Environment Management Group, 2011) defines drylands as lands where the ratio of annual precipitation and mean annual potential evapotranspiration, also known as the aridity index (see formula below), is less than Under this definition, the world's drylands cover about billion hectares an area more than twice the size of Africa. Aridity index (AI) = MAP/MAE. Where MAP = mean annual precipitation and MAE = mean annual potential evapotranspiration The global drylands can be divided into the following four zones based on the aridity index: 1) hyperarid (AI < ). 2) arid ( AI < ). 3) semiarid ( AI < ). 4) dry subhumid ( AI < ). Figure 1 presents a global map of the drylands , showing the four aridity zones. It also shows areas defined as presumed drylands , which were not included in the Global drylands Assessment (UNEP-WCMC, 2007).
9 The dry subhumid zone the least-dry of the four zones accounts for 22 percent of the total drylands area. Major components of this zone are the Sudanian savanna, forests and grasslands in South America, the tree steppes of eastern Europe and southern Siberia, and the Canadian prairie. Most dryland forests occur in this zone, as do some large, irrigated, intensively farmed areas along perennial rivers. At the other extreme, the hyperarid zone is the driest zone, constituting 16 percent of the total drylands area. Deserts dominate this zone the Sahara alone accounts for 45 percent of it, and the Arabian Desert is another large component. The remaining drylands are made up of the semiarid and arid zones, at 37 percent and 25 percent, respectively, of the total drylands area. The concepts of aridity zones and land -use categories (described later in the text) were used in the Assessment to help encompass the complexity and variability of this very large area of land .
10 The complexity, status and roles of drylands , as well as humid tropical forests. tree cover and land use as context-specific approaches tailored to the unique in drylands are poorly known, even though recent conditions of drylands . But dryland forests and other studies have indicated the need to restore drylands ecosystems have not attracted the same level of to cope with the effects of drought, desertification, interest and investment as other ecosystems, such land degradation and climate change. 2 Trees, forests and land use in drylands : The first global assessment BOX 2. The Rome Promise FAO organized the first drylands Monitoring Week in January 2015 in collaboration with the World Resources Institute, the International Union for Conservation of Nature and the Global Environment Facility. The Week was supported financially by the European Union within the framework of the African, Caribbean and Pacific Group of States (ACP) Action Against Desertification1 initiative in support of the Great Green Wall and south south cooperation in ACP countries.