Suchergebnisse

When urban areas expand without concomitant increases in wastewater treatment capacity, vast quantities of wastewater are released to surface waters with little or no treatment. Downstream of many urban areas are large areas of irrigated croplands reliant on these same surface water sources. Case studies document the widespread use of untreated wastewater in irrigated agriculture, but due to the practical and political challenges of conducting a true census of this practice, its global extent is not well known except where reuse has been planned. This study used GIS-based modeling methods to develop the first spatially explicit estimate of the global extent of irrigated croplands influenced by urban wastewater flows, including indirect wastewater use. These croplands were further classified by their likelihood of using poor quality water based on the spatial proximity of croplands to urban areas, urban wastewater return flow ratios, and proportion of wastewater treated. This study found that 65 percent (35.9 Mha) of downstream irrigated croplands were located in catchments with high levels of dependence on urban wastewater flows. These same catchments were home to 1.37 billion urban residents. Of these croplands, 29.3 Mha were located in countries with low levels of wastewater treatment and home to 885 million urban residents. These figures provide insight into the key role that water reuse plays in meeting the water and food needs of people around the world, and the need to invest in wastewater treatment to protect public health.

AbstractGlobal trade in niche commodities has increased the influence of consumers' choices on land use change and livelihoods in developing rural areas. New niche commodity markets for fine cocoa—produced by old tree varieties frequently grown in shaded agroforestry systems—create more direct linkages between producers and buyers. We explored the socioeconomic and environmental outcomes for cocoa smallholders that participated in direct trade relations compared with smallholders that sold through mainstream markets. Household interviews were conducted with cocoa smallholders in northern Ecuador. Biodiversity conditions at farm level were monitored for 75% of surveyed households. Using a counterfactual based on genetic matching, we found that smallholders engaged in direct trade (a) captured superior prices for cocoa sales; (b) had greater access to agricultural training, technical assistance, and improved social networks; and (b) applied more nature‐friendly management practices, compared with smallholders selling through mainstream markets. However, a strong overlap between direct trading practices and organic certification made attribution of environmental benefits difficult. This overlap likely explained why farmers engaged in direct trade used more organic fertilizers and less herbicide. Shade level and plant species richness and abundance in plantations were unrelated to market participation. Additional qualitative analyses suggest that certification facilitates engagement in direct trade and that some direct buyers request certification. This study provides insights on the potential of developing value chain innovations for high‐quality commodity trade. The success of value chain innovations hinges on the competitiveness of farmers' cooperatives and involvement of governments, nongovernmental organizations, and private actors.

Overlapping land use allocations, in which one parcel of land is allocated two or more times for different uses, either intentionally or unintentionally, are common globally. We assess how overlapping land use allocations impact forest cover change using Peruvian government data for the lowland Amazon. Results are based on propensity score matched difference-in-differences methods using 1-ha resolution forest loss data for 2000–2014, along with Peruvian government land use allocation data. We find that deforestation is lower in overlapping than in same-type, non-overlapping allocations. This finding is consistent across all types of overlapping land use allocations. These results support the hypothesis that multiple use management decreases deforestation, and provide no evidence indicating that overlapping allocations are a form of tenure insecurity that might increase deforestation. Our findings inform conservation policy related to multiple use management, land tenure security, and conflict avoidance.

Overlapping land use allocations, in which one parcel of land is allocated two or more times for different uses, either intentionally or unintentionally, are common globally. We assess how overlapping land use allocations impact forest cover change using Peruvian government data for the lowland Amazon. Results are based on propensity score matched difference-in-differences methods using 1-ha resolution forest loss data for 2000–2014, along with Peruvian government land use allocation data. We find that deforestation is lower in overlapping than in same-type, non-overlapping allocations. This finding is consistent across all types of overlapping land use allocations. These results support the hypothesis that multiple use management decreases deforestation, and provide no evidence indicating that overlapping allocations are a form of tenure insecurity that might increase deforestation. Our findings inform conservation policy related to multiple use management, land tenure security, and conflict avoidance.

Marginal and unstable environmental conditions force stockbreeders in drylands to develop adaptive strategies to ensure stability of production. In intensive market-oriented pastoral systems, the partial substitution of rangeland forage production by external feed increases the influence of commodity prices in stockbreeders' decisions, which become increasingly decoupled from environmental constraints. In Mediterranean countries of the European Union (EU), Common Agricultural Policy (CAP) subsidies also influence agricultural practices, potentially increasing environmental impacts. By modeling subsidy allocation to sheep and goat breeders in Crete, we showed that livestock subsidies for Less Favoured Areas (LFA) stimulated flock growth up to a point. By linking interviews of farmers to remote-sensing data in four village communities in central Crete, we tested statistically alternative hypotheses explaining the links between CAP subsidies, livestock-husbandry practices, and land degradation at the farm level. The flock growth stimulated by livestock subsidies was accompanied by the intensification of herd management, and decreasing yields and profits, with no statistical association to vegetation degradation. Farms with larger flocks became more sensitive to market fluctuations.

Marginal and unstable environmental conditions force stockbreeders in drylands to develop adaptive strategies to ensure stability of production. In intensive market-oriented pastoral systems, the partial substitution of rangeland forage production by external feed increases the influence of commodity prices in stockbreeders' decisions, which become increasingly decoupled from environmental constraints. In Mediterranean countries of the European Union (EU), Common Agricultural Policy (CAP) subsidies also influence agricultural practices, potentially increasing environmental impacts. By modeling subsidy allocation to sheep and goat breeders in Crete, we showed that livestock subsidies for Less Favoured Areas (LFA) stimulated flock growth up to a point. By linking interviews of farmers to remote-sensing data in four village communities in central Crete, we tested statistically alternative hypotheses explaining the links between CAP subsidies, livestock-husbandry practices, and land degradation at the farm level. The flock growth stimulated by livestock subsidies was accompanied by the intensification of herd management, and decreasing yields and profits, with no statistical association to vegetation degradation. Farms with larger flocks became more sensitive to market fluctuations.