Collective management on communal grazing lands: Its impact on vegetation attributes and soil erosion in the upper Blue Nile basin,northwestern Ethiopia

Collective action, on communal grazing land, has evolved in the highlands of northwestern Ethiopia to mitigate the problems of feed shortage and land degradation due to overgrazing. The exercise is liked by farmers for improving the availability of natural pasture during the long dry season when other feed sources get depleted. However, large portions of the communal grazing lands are still managed under free grazing throughout the year. This study was undertaken in Maynet village in the upper Blue Nile basin, northwestern Ethiopia, to assess the impacts of three different types of grazing land management (GLM) and two slope gradients (<10%; 15–25%) on aboveground herbaceous biomass yield, ground cover, species richness, runoff, soil loss and soil bulk density of grazing lands. The GLMs include (a) freely open communal GLM, (b) restricted communal GLM – collective management of communal grazing land locally named as ‘yebere sar’ and (c) private holding GLM. Stocking density was more than carrying capacity of grazing lands across all GLMs. However, the extent of overstocking problem was exceptionally severe in freely open communal GLM. The interaction between GLM and slope was significant (P<0.05) for runoff, soil loss and runoff coefficient. The average runoff coefficient was close to 50% in freely open communal GLM on steeper slopes (15–25%). Freely open communal GLM on steeper slopes resulted in consistently highest cumulative runoff and soil loss amounting to 491 mm and 32 t/ha per year, respectively. Polynomial regression analysis showed that quadratic relationship (r²=0.87) existed between soil loss and runoff. But, soil loss was close to nil when runoff did not exceed 2 mm per rainfall event. As expected, restricted communal GLM appeared to reduce surface runoff by more than 40% and curb the rate of soil erosion by more than 50% compared to freely open communal GLM. Its vegetation cover persisted above 70% throughout the year, meeting the threshold level recommended to keep surface runoff and soil loss to minimum. Reducing the problem of overstocking and pasture resting in August–November are important components to improve ground cover and aboveground herbaceous biomass yield, which in turn reduce land degradation on grazing lands.     

海南州实施草畜平衡工程及减畜情况调查报告

为了更好的实施草畜平衡工程 ,采用抽样调查方法 ,对海南州 5县、1 8个乡、6 2个村、1 6 3户牧户进行了畜草平衡调查。结果表明 :1 998年与项目实施之初的 1 994年相比 ,饲草干物质总量增加 1 970 0 .0 7万kg ,理论载畜量增加 44 .97万羊单位 ,实际载畜量减少 90 .0 7万羊单位 ,超载量下降 1 35 .0 4万羊单位     

外购干草是否缓解了天然草原的生态压力?——来自内蒙古的回顾性调查

外购干草在牧民载畜行为及生产方式转型中扮演着重要角色。本文利用内蒙古450户的牧户调研数据,通过核减干草效用计算牧户实际载畜率值,探究核减前后牧户载畜率的变化趋势,剖析核减干草后在新一轮草原补奖政策标准下牧户超载情况。结果表明：三类草原区牧户在核减外购干草效用后的载畜率较核减前均有不同程度下降,其中草甸草原区降幅最大,为35.09%,然后是荒漠草原区和典型草原区,分别下降31.82%,23.23%;依据第二轮草原补奖政策标准,区域内草甸草原区牧户未表现出超载行为,县域内新巴尔虎左旗牧户未呈现超载;区域内典型草原区牧户心理载畜率值最高,为0.86羊单位·hm^-2,较典型草原区牧户核减干草效用后的实际载畜率值高出11.63%;县域内新巴尔虎左旗牧户心理载畜率值最高,为1.28羊单位·hm^-2,较新巴尔虎左旗牧户核减干草效用后的实际载畜率值高出36.72%。