Are drought‐related crashes in pastoral cattle herds predictable ? — More evidence of equilibrium dynamics from the douthern Ethiopian rangelands
Drought routinely ravages the Greater Horn of Africa, especially rangelands.Drought leads to massive reductions in livestock productivity and increased risk of famine and poverty for people.Traditional pastoral systems were better able to cope with drought, but restoring traditional pastoralism is nearly impossible in many cases.Other strategies focus on helping people deal with drought using market development and opportunities for livelihood diversification.Livestock remain the core economic engine for pastoralism and understanding how risks and returns to livestock vary over time is important to devise tactics to improve the situation.Ellis and Swift (1988) proposed that some East African pastoral systems are non‐equilibrial, meaning that vegetation and herbivore dynamics are controlled by precipitation ; carrying capacity and livestock‐induced ecological degradation lose relevance.Livestock death losses would be unpredictable and vary with rainfall.For the semi‐arid Borana Plateau we posit a different theory based on dynamic equilibrium concepts (Desta and Coppock 2002).In this situation, drought impacts on livestock production are predictable due to interactions between stocking rates and precipitation.When stocking rates are high the regional herd is more likely to crash if annual precipitation is low.Cattle crashes in 1983‐5,1991‐3, and in 1998‐9 lead to the hypothesis that periodicity of crashes is related to time needed for the regional herd to grow to a vulnerable size.Desta and Coppock (2002 ; p.450) predicted that the next cattle crash would occur by 2005.The purpose of this paper is to verify the cattle prediction and illustrate whether ecological change has occurred as a result of pastoral activity (Mesele, 2006).
Equilibrial/non‐equilibrial ecosystems Boran risk management livestock early warning
D.L.Coppock G.Gebru S.Mesele S.Desta
GL-CRS P PA R IMA,Utah State University,Logan,UT,USA 84332-5215 GL-CRS P PA R IMA,c/o IL RI,P.O.Box 5689,Addis Ababa,Ethiop ia OA R I,P.O.Box 81265,Addis Ababa,Ethiopia GL-CRS P PA R IMA,c/o IL R I,P.O.Box 30709,N airobi,Kenya.
国际会议
呼和浩特
英文
2008-06-29（万方平台首次上网日期，不代表论文的发表时间）