Global Estimates of the Impacts of Grassland Degradation on Livestock Productivity from 2001 to 2011

Global meat and dairy consumption is projected to increase by 173 and 158 % from 2010 to 2050 and an even higher increase in meat and dairy consumption is expected for developing countries. This rapid increase in demand for livestock products would require corresponding increases in demand for animal feeds, which in turn would lead to conversion of high value biomes—such as forest to grazing lands—and overgrazing especially for grassland-based livestock production systems (Asner and Archer 2010). In fact, over the last few decades, grasslands have been degraded due to overgrazing and account for the largest extent of degradation among all major biomes considered. Steinfeld et al. (2006) estimated that about 20 % of global pasture and 73 % of the rangelands in the drylands have been degraded. About 70 % of deforestation in the Amazon was due to expansion of pasture and a large part of the remaining 30 % of cleared forests was due to feed crops expansion (ibid). Other studies also reported severe degradation in grazing biomes. Nabuurs (2004) estimated that about 5 % of soil organic carbon has been lost from overgrazed or moderately degraded temperate and/or boreal grasslands. More recently, Le et al. (2014), Chap.  4, estimated that about 40 % of grasslands experienced degradation between 1982 and 2006 by employing long-term data of remotely sensed Normalized Difference Vegetation Index (NDVI ) as a proxy for global land degradation.

Degradation of grazing biomes poses a big threat to sustain and/or increase global livestock productivity , which serves multiple purposes including economic, social and ecological functions (Nabuurs 2004; Randolph et al. 2007). Livestock plays an especially important role in the livelihoods of the rural poor households, two-thirds of whom keep livestock (Livestock in Development 1999). Low-income rural households also use livestock as living “savings accounts” (Moll 2005) and insurance against risks and shocks (Hoddinott 2006). Additionally, livestock is used to strengthen social bonds (e.g. dowry) and serve as an indicator of social importance (Kitalyi et al. 2005). In Sub-Saharan Africa (SSA), animal and human power account for 80 % of total farm energy (FAO 2011a). The multiple objectives of livestock suggests that the sector has a large potential to contribute to poverty reduction efforts in developing countries. Such potential is amplified by the increasing demand for livestock products as incomes and food tastes and preferences change in middle and low income countries. Currently livestock accounts for about 13 and 28 % of the global caloric and protein intakes, respectively (FAO 2011b). Livestock also plays a vital role in maintaining soil nutrients in cropland , as livestock manure accounts for 54–64 % of total nitrogen applications and 64 % of phosphorus (Sheldrick et al. 2004; Potter and Ramankutty 2010).¹ Given the important role of livestock and the severe land degradation in grasslands, it is necessary to estimate the cost of land degradation in grazing biomes to determine the cost of inaction and to identify cost-effective strategies to address the consequent loss of livestock productivity.

In response to these needs, we developed a modeling framework where global statistics databases and remote sensing data/analyses coupled with empirical/statistical modeling approach are designed to estimate global impacts of land degradation on spatial and temporal changes of agronomic and environmental indicators (e.g. productivity and soil carbon stock) in both croplands and grasslands. In this chapter, we focused to quantify the cost of grassland degradation on a global scale by using this framework. This type of work contributes to literature in two ways. Firstly, our modeling framework employs empirical/statistical models to estimate the loss of grassland biomass productivity. This simple approach allows estimating a complex system (Wainwright and Mulligan 2005). It also utilizes easily available remote-sensing data to estimate changes in biomass productivity so that it could allow building modeling systems for low-cost global and regional monitoring of grazing land degradation and improvement. Secondly, to the best of our knowledge, this is the first global assessment of the cost of grazing land degradation. Many past global studies have largely dwelt on biophysical assessments of grazing land degradation (e.g. Steinfeld et al. 2006). The few past global or regional studies on the cost of grassland degradation have largely been based on review of literature (e.g. Dregne 2002; Requier-Desjardins 2006) or covering a specific area (e.g. Quinlan 1995; Harris 2010).

This chapter detailed procedures included in our modeling framework such as (i) identifying land degradation hotspots where inter-annual mean NDVI over the historical period of 2001 to 2011 has a declining trend, (ii) classifying statistical models to estimate changes in biomass from NDVI based on biome, (iii) developing simple relationships between the NDVI trend and livestock productivity within the hotspots , and iv) estimating changes in livestock productivity. Finally we reported the costs of grassland degradation associated with changes in livestock productivity.

Loss of milk production contributes 99 % of the total cost of grazing biomass degradation mainly due to its high sensitivity to the loss of grazing biomass. For example, loss of one DM ton of grazing biomass in North America leads to a loss of 909 kg of milk but only about 42 kg of meat respectively worth US$435 and US$79 (Table 8.8). As noted above, the low offtake rate of meat also contributes to its low contribution to the total loss.

Overall, the cost of land degradation is small compared to the area covered by grazing biomass . The low productivity of livestock in developing countries is part of the reason for the low cost. Additionally, other sources of dry matter consumption are not taken into account. These include animal feeds and crop-based DMI. And, as discussed in the methods section, it is only a third of the grassland biomass that is included in the computation of the cost of grazing biomass degradation due to the overlay of degradation and grazing areas. In addition, the loss of carbon sequestration and other ecosystem services are not considered. The livestock population in the grassland considered is also low as it accounts for only 28 % of the total livestock population (Table 8.5), though it covers 20 % of the ice-free global land area (Steinfeld et al. 2006).

Figure 8.3 reports the cost of land degradation and illustrates the high cost in North America, Latin America and SSA.

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This study used innovative approaches that could be used to conduct regular global assessment of grassland degradation or improvement. The approach considers only on-farm cost and ignores off-site costs —such as loss of carbon sequestration. The results reported have important implications on taking action on addressing grazing land degradation but they should be interpreted bearing in mind the weaknesses and gaps of the study.

The on-farm cost of grassland degradation is about 2007 US$6.8 billion. North America accounts for more than 50 % of the loss due to the severe land degradation and the high livestock productivity. The cost of land degradation is not reflected in the loss of productivity due to the ability of farmers in North America to use improved production technologies to maintain or increase livestock productivity. Additionally, the impact of changes in grazing land productivity on human welfare in North America is minimal given the farmers’ ability to cushion such shocks using insurance, government programs, credit and other programs. Although the grazing land degradation is much more widespread in SSA, its actual cost is small due to the low livestock productivity. However, the impact on human welfare is much more severe—especially in the drylands where majority of the livestock is located and where majority of the population is below the poverty line. This implies that efforts to address grassland degradation is even more urgent in SSA. This is especially urgent given the increasing demand of livestock products and the potential to contribute to poverty reduction. Addressing grassland degradation could simultaneously reduce poverty, contribute to carbon sequestration, increase productivity of crops, provide more draft power, and other socio-economic, cultural, and ecological benefits that livestock provide. The large cost of grassland degradation, the increasing demand for livestock products, and the multiple benefits of livestock provide opportunities to take action.

Among the actions that could be taken to increase livestock productivity is to increase public budget allocation to livestock production in developing countries. For example, in SSA public budget allocation to livestock is only about 5 %. Investments in livestock productivity need to be directed to both cost-effective and amenable pasture management practices and breeding programs. Some developing countries can serve as success stories since they have successfully increased livestock productivity, which in turn have contributed to poverty reduction. The Kenyan dairy programs and Botswana’s beef production demonstrate such success stories. Both countries have developed the livestock sector due to long-term policies for livestock development, which aimed at genetic improvement, disease control, strengthening domestic and international markets to allow farmers to address highly seasonal supplies, and health and safety standards (Hazell 2007). Efforts to improve grassland through controlled grazing, planting legumes, and other amenable practices will increase both livestock productivity and carbon sequestration (Henderson et al. 2015). This means the international community has the responsibility to support livestock development programs in low income countries due to large potential of carbon sequestration for improved grasslands management. For example, Henderson et al. (2015) show that improved grassland management could sequester up to 33.3 Tg CO₂ year⁻¹ in SSA. Such support could be done by giving aid specifically aimed at grassland improvement .

Access to market in largely pastoral areas is low and this contributes to the low livestock productivity. Improvement of market access in grazing areas has also been shown to improve livestock productivity (Barrett 2008). Improvement of market access will have multiplier effects on rural development as it will have favorable impacts on poverty reduction, access to health and other rural services.