Land Degradation Assessment in Drylands Riccardo Biancalani, FAO Technical Advisor Beijing, 16 April 2008

Land Degradation Assessment in Drylands National Level Assessment

National level 30 arcsec mapping (~900 meters) Based on national datasets Compiled by national experts Focus

To provide an insight of the type, extent and intensity of land degradation and its spatial location within a country Aim To give a picture of the measures taken to combat degradation

The main direct drivers of land degradation Land Use Land Cover + Management + Inputs Land Use Change Land Cover change and/or Intensification Ecosystem Land degradation should be described/mapped in Land Use Systems Units

The LADA/WOCAT Questionnaire

Land Use System (LUS) –Type –Area trend –Intensity trends Degradation (per Land Use System LUS) –Type (including vegetation and water) –Relative extent (area) –Degree –Rate –Impact on ecosystem services (type and level) –Trend in provision of ecosystem services (productivity, water, biodiverstity, carbon…) –Direct causes (crop manag., deforestation, over-exploitation, overgrazing, …) –Indirect causes (population pressure, tenure, poverty, labour availability, road access, education, Conservation per LUS –Name / SWC category –Relative extent (area) –Effectiveness –Effectiveness trend –Period of implementation –Reference to QT (local level assessment) –Impact on ecosystem services (type and level) –Trend in provision of ecosystem services (prod., water, bio-divers, carbon…)

Degradation types: W: Soil erosion by water Wt loss of topsoil by water Wg gully erosion Wm mass movements Wr riverbank erosion Wc coastal erosion Wo offsite effects: deposition of sediments, downstream flooding, siltation of reservoirs and waterways, and pollution of water bodies with eroded sediments E: Wind erosion Et loss of topsoil by wind Ed deflation and deposition Eo offsite effects of wind erosion: Covering of the terrain with windborne sand particles from distant sources ("overblowing") C: Chemical deterioration Cn fertility decline and reduced organic matter content not caused by erosion, eg leaching, fertility mining, nutrient oxidation and volatisation (N) Caacidification: lowering of the soil pH Cpsoil pollution: contamination of the soil with toxic materials Cssalinisation/alkalinisation: a net increase of the salt content of the (top)soil leading to a productivity decline P: Physical deterioration Pccompaction: deterioration of soil structure by trampling or the weight and/or frequent use of machinery Pksealing and crusting: clogging of pores with fine soil material and development of a thin impervious layer at the soil surface obstructing the infiltration of rainwater, water-repellent layer (eg ashes after forest fire) Pwwaterlogging: effects of human induced hydromorphism (excluding paddy fields) Pssubsidence of organic soils, settling of soil Puloss of bio-productive function due to other activities (eg construction, mining) V: Vegetation degradation Vrreduction of vegetation cover Vsquality and species composition decline Vqquantity decline (loss of vegetative production); eg through clear felling, forest fire, etc H: Water degradation Haaridification / soil moisture problem Hpwater quality decline (pollution) Hqwater quantity decline (groundwater, surface water)

Conclusions – Summary based on three set of data: natural resources land use socio-economic assessed through a guided expert opinion

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