Olron , 11-17 May 2014 Pastoralism and water resources in the Sahel - PowerPoint PPT Presentation

International Thematic School ‘Water and society’ Oléron , 11-17 May 2014 Pastoralism and water resources in the Sahel region Pierre Hiernaux agronomist, ecologist, retired CNRS scientist pierre.hiernaux@wanadoo.fr

Intervention outline  The water needs of livestock (individual animal/day-year)  Water provision to pastoral systems (Herd-populations/seasons-years)  Grazing impact on water cycling  Northern Sahel rangelands (Gourma, Mali)  Southern Sahel agro-pastoral system (Fakara, Niger) (local-district scale/seasons-years)  Sahel desertification/greening (local-continental/year-decades)

Water needs of livestock Water intake Water losses  Pulmonary  Drinking evaporation (variable) (<10%)  Ingested in  Evaporative feed (5-85%) cooling: sweating & panting  Metabolic (≈ 80%) water (intracellular Water 60-70% ( Δ <20%)  Urine respiration) a few % (1200-3500 Livestock bodies mOsm/kg)  Respiratory  Feces (≈ 10%) intake (> 45-60 % water)  cutaneous  Lactation (milk exchanges 85-88% water) (insignificant)

Water needs of livestock Unlike feed dry matter intake that is a function of the animal metabolic weight , the daily water intake by livestock drinking is quite variable with: • water ingested in feed • air temperature and relative humidity (sweat, pant, pulmonary exchanges…) • livestock physical activity (distance walked, draft…) • pregnancy and lactation In average for cattle, (3L water/ L milk) • difference between species and sheep and goats: breeds (body size, urine concentration, feces water content, 20-50 l/day/ TLU panting/sweating, cutaneous exchanges…) (i.e. 250 kg LW) Ref.: King J., Liverstock water needs in pastoral Africa …, 1983

Water needs of livestock The drinking frequency do also vary with: Watering distribution herds % (dry season northern frequency Mali) distance water to pasture (km) • 10-19 20-29 30-39 >40 Species and breeds (daily for goats, goats 1-2 54 46 0 0 up to every 3 days for cattle and sheep 3 30 54 16 0 sheep, up to every 15 days for zebu 2-3 19 66 15 0 camels in Sahel breeds) camel 5-6 23 23 39 13 • water ingested in feed source Swift 1979 • air temperature and relative humidity District of Tessékré, Sénégal • livestock physical activity 30 km  The drinking frequency determine the maximum possible grazing distance from the water point (the radius of the « piosphere »)  The drinking frequency modifies the ratio of fodder to water resource  access to water is thus a key of the access to fodder resources. I. Touré, 2010

Water provision to livestock Depending on seasons, geology, geomorphology and investment in infrastructure drinking water is provided to pastoral families and to livestock through a range of possible sources: • Surface water: springs, streams, lakes, ponds of variable size and seasonality. No need of device to fetch water. Most of surface water points are open access. • Shallow wells, wells, boreholes from which water is fetched either manually, or using animal draft, or with pumps (exceptionally artesian boreholes). Some are open access, other are communal access and a few private. • Mobile water tanks filled either from surface water or from deep water. They allow to extend the radius at relatively high labour cost, mostly for small ruminants and young animals

Water provision to livestock  Pastoral systems are breeding systems in which animal nutrition is almost exclusively achieved by grazing rangelands, fallows, stubbles …  In Sahel, pastoral system adapt to the large temporal and spatial variations in fodder availability by different form of livestock mobility: – Daily (or few days ) grazing circuit – Seasonal and regional transhumance – Nomadism In all cases the access to water points structure herd mobility, and the rights to graze

Water provision to livestock  In Sahel, in adaptation to the large seasonal and interannuals variations in grazing resources, pastoral systems are communal: access to rangeland and water points are open either within communities or public, opposite to ranching systems developped in other arid and semi- arid regions (Australia, US, Argentina, Brazil …) where the access to rangeland is privatised. There are dynamics between the two systems (Botswana, Inner Mongolia)  Pastoral development programs have concentrated on providing networks of water points (web of boreholds in Ferlo in the 50’s, recent work funded by AFD in Chad rehabilitation and complementary infrastructures; involving communities).

Water provision in pastoral systems  Concentrations of livestock at main water points are spectacular, yet in numbers the volume of water drinked by livestock per unit area grazed is minimal: fodder is the limiting resource of pastoral systems  This is confirmed by the minimal impact of livestock drinking in the drying up of surface water points during dry seasons example Agoufou Mali (Gardelle et al. 2010) and pounds in Fakara (Desconet et al. 1997 )  This does not contradict the very low Drinking water (l/m²/yr) /Stocking rate (TLU/km²) performance of livestock products in terms of water use (e.g. 15000l virtual water/kg meat; TLU/km² 5 10 20 40 1500l of drinking water). However the same figure could be interpreted as ingenious ways to L/m²/yr 0,09 0,18 0,36 0,73 tap water resources that are not available to grow crops and yet produce high quality feed to humanity and a living for pastoralist families. Evolution saisonnière de la hauteur de l'eau de la mare d'agoufou en 2010-2011 Hauteur (m) 3,90 y = -0,0058x + 234,06 3,40 R² = 0,9628 2,90 2,40 decrue= 0,58cm/j 1,90 1,40 /6/09 4/7/09 /7/09 1/8/09 /8/09 /8/09 /9/09 /9/09 /10/09 /10/09 11/09 1/09 12/09 /12/09 2/1/10 /1/10 /1/10 /2/10 /2/10 /3/10

Grasing impact on water cycling In addition to the direct intake and offtake of water grazing livestock indirectly affect water cycling through: • The short term effect of trampling on soil surface (crust, litter burying) and sub-surface (compaction) • The short and long term effects of fodder intake on herbage cover, species composition… • The long term effects of nutrient cycling (fodder uptake and excretion deposition) on soil biological activity and fertility that contribute to vegetation production and species composition

Grazing Impact on water cycling The processes of impact:  During the wet season • At short term herbage growth altered by grazing- trampling (grass tillering, regrowth function of timing and intensity of grazing, at worth 50% loss in production • Trampling remove crust on sandy soils, compact loamy soils.. • At longer term selective grazing, trampling, organic matter recycling lead to species changes  During the dry season • At short term straws transfered to litter by trampling • Crust and litter fragmented and litter buryed by trampling  All year round • Fertilization by excretion feces (1/2 of intake) and urines, biological activation, rise soil pH • Seed dispersion (particular species) Multi ways impact, globaly mild, althoug could be determining at long term in sedentary grazing systems

Grazing Impact on water cycling Large seasonal and interannual dynamics Large year to year Seasonal states: variations in herbaceous 30-09-2008 27-08-2007 herbaceous cover, vegetation cover, production, mass, woody plant species composition, leaf mass mostly driven by driven by soil rainfall distribution: moisture regime, Largely reversible rainfall, climate 26-09-2007 15-09-2009 Site 17, Agoufou, Avril 2007 - Sept 2010 Kg/ha % plant/m² 2500 40 d 2000 e 30 n… 1500 20 1000 10 500 28-05-2008 13-09-2010 0 0 amj j aasond j fmamj j asond j fmamj j asond j fmamj j asond Daily rains (mm) at Agoufou 2007-2010 80 514,5 mm 329 mm 60 324,5 270 mm 40 20 0 07-06-2008 26-08-2011 aa mj j asonnd j fm a mj j jasond j fm m a mj j asonnd j fm a mj j j asond

Grazing Impact on water cycling Standing herbaceous mass, site 17 2004  In average 85% of the 2005 2500 herbaceous growth is 2006 2000 achieved in a ‘rapid 2007 growth’ period of 45 1500 2008 days, from grass 50 kg/ha/d 2009 1000 tillering to heading. 2010 • 500 The timing is controlled 2011 by the rainfall pattern 0 1/5 31/5 30/6 30/7 29/8 28/9 28/10 and the productivity by soil fertility. • The short term effect of Mean (180 site x year) growth rates on vegetated grazing on herbaceous patches during rapid growth by soil and grazing production during wet pressure type kg/ha/d season is moderate and 100 local, because to the 80 rapid speed of the 60 growth, yet it differs 40 with soil types. 20 0 A L R S1 S2 S3