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Pastures and rangelands underpin global meat and milk production and are a critical resource for millions of people dependent on livestock for food security1,2. Forage growth, which is highly climate dependent3,4, is potentially vulnerable to climate change, although precisely where and to what extent remains relatively unexplored. In this study, we assess climate-based threats to global pastures, with a specific focus on changes in within- and between-year precipitation variability (precipitation concentration index (PCI) and coefficient of variation of precipitation (CVP), respectively). Relating global satellite measures of vegetation greenness (such as the Normalized Difference Vegetation Index; NDVI) to key climatic factors reveals that CVP is a significant, yet often overlooked, constraint on vegetation productivity across global pastures. Using independent stocking data, we found that areas with high CVP support lower livestock densities than less-variable regions. Globally, pastures experience about a 25% greater year-to-year precipitation variation (CVP = 0.27) than the average global land surface area (0.21). Over the past century, CVP has generally increased across pasture areas, although both positive (49% of pasture area) and negative (31% of pasture area) trends exist. We identify regions in which livestock grazing is important for local food access and economies, and discuss the potential for pasture intensification in the context of long-term regional trends in precipitation variability. Satellite measures of vegetation greenness, together with animal stocking data and key climatic factors, reveal interannual precipitation variability to be a significant constraint on global pasture productivity.

Despite a growing body of research about rangeland degradation and the effects of policies implemented to address it on the Tibetan Plateau, little in-depth research has been conducted on how pastoralists make decisions. Based on qualitative research in Gouli Township, Qinghai province, China, we analyze the context in which Tibetan herders make decisions, and their decisions about livestock and pastures. We refute three fundamental assumptions upon which current policy is premised: that pastoralists aim to increase livestock numbers without limit; that, blindly following tradition, they do not actively manage livestock and rangelands; and that they lack environmental knowledge. We demonstrate that pastoralists carefully assess limits to livestock holdings based on land and labor availability; that they increasingly manage their livestock and rangelands through contracting; and that herding knowledge is a form of embodied practical skill. We further discuss points of convergence and contradiction between herders’ observations and results of a vegetation analysis.

The southern highlands of Ethiopia are home to some of the planet’s oldest agricultural systems, dating back 10,000 years (Brandt et al. 1997), and are considered a global center of crop diversity (Vavilov and Chester 1951). The highland landscape is made up of a patchwork of small, diverse subsistence farms, grasslands, and forests where the lines between ‘human’ and ‘natural’ are indistinct, and the actions of farmers are a driving force in the distribution of biodiversity. Crop diversity serves both to buffer the global food supply against environmental change and pest and disease outbreaks, and to maintain the sustainability of traditional small-scale agricultural systems (Gepts 2006). These diverse crops and varieties are created and maintained through seed exchange among farmers, and the scales and strengths of these pathways have enormous influence on agricultural biodiversity. In order to understand patterns of diversity, it is therefore useful to explore the patterns of farmer seed exchange that influence farmers’ use of and access to agricultural biodiversity, and the ways in which cultural, demographic, and agricultural changes have the potential to enhance or erode that diversity. Our research focuses on four related questions: 1) How the scales and mechanisms of seed exchange affect diversity; 2) How those practices differ among locations, agroecological zones, and individual farms; 3) How and why those practices are changing; and 4) What the effects of those changes on diversity in this agroecosystem may be.

Interventions to improve crop yields in rural China through collaboration between researchers and farmers illustrate how the goal of increasing global food production can be approached locally. See Letter p.671 Closing the gap between realized and potential crop yields is key to sustainably feeding the world's growing population. Fusuo Zhang and colleagues report on attempts to increase wheat and maize yields of smallholder farms in four villages in Quzhou County in the North China Plain, using ten practices recommended by the Science and Technology Backyard, a co-operative research project involving agricultural scientists, local extension officers and smallholder farmers. Adoption of these practices—including alternative seed varieties, sowing times and other crop management practices—raised five-year-average yields from 68% to 97% of the attainable level on target farms, and 63% to 80% countywide. The authors suggest that this approach could be adopted in other parts of the world to help smallholder farmers achieve greater yields.