Water and Development Research Group, Aalto University, Espoo, Finland.
Department of Bioecology, Baku State University, Baku, Azerbaijan.
Glob Chang Biol. 2022 Jun;28(12):3902-3919. doi: 10.1111/gcb.16174. Epub 2022 Apr 6.
Although the role of livestock in future food systems is debated, animal proteins are unlikely to completely disappear from our diet. Grasslands are a key source of primary productivity for livestock, and feed-food competition is often limited on such land. Previous research on the potential for sustainable grazing has focused on restricted geographical areas or does not consider inter-annual changes in grazing opportunities. Here, we developed a robust method to estimate trends and interannual variability (IV) in global livestock carrying capacity (number of grazing animals a piece of land can support) over 2001-2015, as well as relative stocking density (the reported livestock distribution relative to the estimated carrying capacity [CC]) in 2010. We first estimated the aboveground biomass that is available for grazers on global grasslands based on the MODIS Net Primary Production product. This was then used to calculate livestock carrying capacities using slopes, forest cover, and animal forage requirements as restrictions. We found that globally, CC decreased on 27% of total grasslands area, mostly in Europe and southeastern Brazil, while it increased on 15% of grasslands, particularly in Sudano-Sahel and some parts of South America. In 2010, livestock forage requirements exceeded forage availability in northwestern Europe, and southern and eastern Asia. Although our findings imply some opportunities to increase grazing pressures in cold regions, Central Africa, and Australia, the high IV or low biomass supply might prevent considerable increases in stocking densities. The approach and derived open access data sets can feed into global food system modelling, support conservation efforts to reduce land degradation associated with overgrazing, and help identify undergrazed areas for targeted sustainable intensification efforts or rewilding purposes.
尽管家畜在未来食物系统中的作用存在争议，但动物蛋白不太可能从我们的饮食中完全消失。草原是家畜初级生产力的关键来源，而饲料与食物的竞争通常在这种土地上受到限制。以前关于可持续放牧潜力的研究主要集中在有限的地理区域，或者没有考虑放牧机会的年际变化。在这里，我们开发了一种稳健的方法来估计 2001-2015 年期间全球家畜承载能力（一块土地可以支持的放牧动物数量）的趋势和年际变异性（IV），以及 2010 年相对放养密度（报告的牲畜分布相对于估计的承载能力[CC]）。我们首先根据 MODIS 净初级生产力产品估计全球草原上可供食草动物食用的地上生物量。然后，使用斜率、森林覆盖和动物饲料需求作为限制条件，计算家畜的承载能力。我们发现，在全球范围内，27%的草地总面积的 CC 下降，主要集中在欧洲和巴西南部，而 15%的草地的 CC 增加，特别是在萨赫勒和南美洲的一些地区。2010 年，家畜饲料需求超过了北欧、南亚和东亚的饲料供应。虽然我们的研究结果表明在寒冷地区、中非和澳大利亚增加放牧压力存在一些机会，但高 IV 或低生物量供应可能会阻止放养密度的大幅增加。该方法和派生的开放获取数据集可以用于全球粮食系统建模，支持减少过度放牧相关土地退化的保护工作，并有助于确定目标可持续集约化或重新野生化的未充分放牧地区。
