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Climate change is already negatively affecting Sub Saharan African agriculture. One of the most effective ways to adapt on farm is to switch crop varieties. This technological change depends on the policies and institutions involved in governing the seed systems on which farmers rely for access to suitable seeds. Whilst the need for seed systems to adapt and become more resilient is indisputable, the question of how this is best achieved is debated. The dominant seed system development pathway promoted by international development actors is characterized by formalization and commercialization of the seed sector. In order to assess political and social outcomes of this development agenda, we compare maize seed system development in Ethiopia, Malawi and Tanzania, combining policy analysis with quantitative analysis of farmers' seed use. We show that while the development policies promoted by international donors have similar objectives in the three countries, national policies and the seed systems farmers use differ substantially. National policies are shaped by political and historical factors and established in an interplay between state institutions, international donors and private input suppliers. Drawing on a new livelihood dataset, we show that in all three countries the formalization agenda is most visible in maize seed systems, with 25, 61, and 58% of the maize farmers planting improved maize varieties in the study sites in Ethiopia, Malawi and Tanzania, respectively. The inroads of improved maize, and particularly hybrid maize, in farmers' seed systems reflects these seeds high profitability for private seed companies. The tenuous use of improved varieties in crops such as sorghum reflects the limitation of the private sector-based seed system development approach in other crops and illustrates the need for public research and governance. Comparison of households cultivating improved maize with households cultivating local maize reveals that the first group is significantly wealthier and more food secure than the latter. This suggests that better-off households are likely to benefit first from the commercial formalization agenda. We argue that climate-smart seed policies and seed system development strategies must be sensitive to differences between farming systems and different groups of farmers if they are to deliver socially fair outcomes.

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.