A planetary health innovation for disease, food and water challenges in Africa.

Many communities in low- and middle-income countries globally lack sustainable, cost-effective and mutually beneficial solutions for infectious disease, food, water and poverty challenges, despite their inherent interdependence1-7. Here we provide support for the hypothesis that agricultural development and fertilizer use in West Africa increase the burden of the parasitic disease schistosomiasis by fuelling the growth of submerged aquatic vegetation that chokes out water access points and serves as habitat for freshwater snails that transmit Schistosoma parasites to more than 200 million people globally8-10. In a cluster randomized controlled trial (ClinicalTrials.gov: NCT03187366) in which we removed invasive submerged vegetation from water points at 8 of 16 villages (that is, clusters), control sites had 1.46 times higher intestinal Schistosoma infection rates in schoolchildren and lower open water access than removal sites. Vegetation removal did not have any detectable long-term adverse effects on local water quality or freshwater biodiversity. In feeding trials, the removed vegetation was as effective as traditional livestock feed but 41 to 179 times cheaper and converting the vegetation to compost provided private crop production and total (public health plus crop production benefits) benefit-to-cost ratios as high as 4.0 and 8.8, respectively. Thus, the approach yielded an economic incentive-with important public health co-benefits-to maintain cleared waterways and return nutrients captured in aquatic plants back to agriculture with promise of breaking poverty-disease traps. To facilitate targeting and scaling of the intervention, we lay the foundation for using remote sensing technology to detect snail habitats. By offering a rare, profitable, win-win approach to addressing food and water access, poverty alleviation, infectious disease control and environmental sustainability, we hope to inspire the interdisciplinary search for planetary health solutions11 to the many and formidable, co-dependent global grand challenges of the twenty-first century.

On design-based empirical research and its interpretation and ethics in sustainability science.

Generating credible answers to key policy questions is crucial but difficult in most coupled human and natural systems because complex feedback mechanisms can confound identification of the causal mechanisms behind observed phenomena. By using explicit research designs intended to isolate the causal effects of specific interventions on community monitoring of common property resources, and on the well-being of those resources and their human neighbors, the papers in this Special Feature offer an important advance in empirical sustainability science research. Like earlier advances in my own field of development economics, however, they suffer some avoidable interpretive and ethical errors. This essay celebrates the powerful potential of design-based sustainability science studies, much of it admirably reflected in this set of papers, while simultaneously flagging opportunities to improve future work in this tradition.

From remotely-sensed solar-induced chlorophyll fluorescence to ecosystem structure, function, and service: Part II-Harnessing data.

Although our observing capabilities of solar-induced chlorophyll fluorescence (SIF) have been growing rapidly, the quality and consistency of SIF datasets are still in an active stage of research and development. As a result, there are considerable inconsistencies among diverse SIF datasets at all scales and the widespread applications of them have led to contradictory findings. The present review is the second of the two companion reviews, and data oriented. It aims to (1) synthesize the variety, scale, and uncertainty of existing SIF datasets, (2) synthesize the diverse applications in the sector of ecology, agriculture, hydrology, climate, and socioeconomics, and (3) clarify how such data inconsistency superimposed with the theoretical complexities laid out in (Sun et al., 2023) may impact process interpretation of various applications and contribute to inconsistent findings. We emphasize that accurate interpretation of the functional relationships between SIF and other ecological indicators is contingent upon complete understanding of SIF data quality and uncertainty. Biases and uncertainties in SIF observations can significantly confound interpretation of their relationships and how such relationships respond to environmental variations. Built upon our syntheses, we summarize existing gaps and uncertainties in current SIF observations. Further, we offer our perspectives on innovations needed to help improve informing ecosystem structure, function, and service under climate change, including enhancing in-situ SIF observing capability especially in "data desert" regions, improving cross-instrument data standardization and network coordination, and advancing applications by fully harnessing theory and data.

From remotely sensed solar-induced chlorophyll fluorescence to ecosystem structure, function, and service: Part I-Harnessing theory.

Solar-induced chlorophyll fluorescence (SIF) is a remotely sensed optical signal emitted during the light reactions of photosynthesis. The past two decades have witnessed an explosion in availability of SIF data at increasingly higher spatial and temporal resolutions, sparking applications in diverse research sectors (e.g., ecology, agriculture, hydrology, climate, and socioeconomics). These applications must deal with complexities caused by tremendous variations in scale and the impacts of interacting and superimposing plant physiology and three-dimensional vegetation structure on the emission and scattering of SIF. At present, these complexities have not been overcome. To advance future research, the two companion reviews aim to (1) develop an analytical framework for inferring terrestrial vegetation structures and function that are tied to SIF emission, (2) synthesize progress and identify challenges in SIF research via the lens of multi-sector applications, and (3) map out actionable solutions to tackle these challenges and offer our vision for research priorities over the next 5-10 years based on the proposed analytical framework. This paper is the first of the two companion reviews, and theory oriented. It introduces a theoretically rigorous yet practically applicable analytical framework. Guided by this framework, we offer theoretical perspectives on three overarching questions: (1) The forward (mechanism) question-How are the dynamics of SIF affected by terrestrial ecosystem structure and function? (2) The inference question: What aspects of terrestrial ecosystem structure, function, and service can be reliably inferred from remotely sensed SIF and how? (3) The innovation question: What innovations are needed to realize the full potential of SIF remote sensing for real-world applications under climate change? The analytical framework elucidates that process complexity must be appreciated in inferring ecosystem structure and function from the observed SIF; this framework can serve as a diagnosis and inference tool for versatile applications across diverse spatial and temporal scales.

Journal submissions, review and editorial decision patterns during initial COVID-19 restrictions.

We use the full administrative records from four leading agricultural economics journals to study the impacts of the COVID-19 pandemic on manuscript submission, editorial desk rejection and reviewer acceptance rates, and time to editorial decision. We also test for gender differences in these impacts. Manuscript submissions increased sharply and equi-proportionately by gender. Desk rejection rates remained stable, leading to increased demand for reviews. Female reviewers became eight percentage points more likely to decline a review invitation during the early stage of the pandemic. First editorial decisions for papers sent out for peer review occurred significantly faster after pandemic lockdowns began. Overall, the initial effects of the pandemic on journal editorial tasks and review patterns appear relatively modest, despite the increased number of submissions handled by editors and reviewers. We find no evidence in agricultural economics of a generalized disruption to near-term, peer-reviewed publication.

The intertemporal evolution of agriculture and labor over a rapid structural transformation: Lessons from Vietnam.

We combine nationally representative household and labor force survey data from 1992 to 2016 to provide a detailed description of rural labor market evolution and how it relates to the structural transformation of rural Vietnam, especially within the agricultural sector. Our study adds to the emerging literature on structural transformation in low-income countries using micro-level data and helps to answer several policy-related questions. We find limited employment creation potential of agriculture, especially for youth. Rural-urban real wage convergence has gone hand-in-hand with increased diversification of the rural economy into the non-farm sector nationwide and rapid advances in educational attainment in all sectors' and regions' workforce. Minimum wage laws seem to have played no significant role in increasing agricultural wages. This enhanced integration also manifests in steady attenuation of the longstanding inverse farm size-yield relationship. Farming has remained securely household-based and the family farmland distribution has remained largely unchanged. Small farm sizes have not obstructed mechanization nor the uptake of labor-saving pesticides, consistent with factor substitution induced by rising real wage rates. As rural households rely more heavily on the labor market, human capital accumulation (rather than land endowments) have become the key correlate of improvements in rural household well-being.

Poverty, disease, and the ecology of complex systems.

Understanding why some human populations remain persistently poor remains a significant challenge for both the social and natural sciences. The extremely poor are generally reliant on their immediate natural resource base for subsistence and suffer high rates of mortality due to parasitic and infectious diseases. Economists have developed a range of models to explain persistent poverty, often characterized as poverty traps, but these rarely account for complex biophysical processes. In this Essay, we argue that by coupling insights from ecology and economics, we can begin to model and understand the complex dynamics that underlie the generation and maintenance of poverty traps, which can then be used to inform analyses and possible intervention policies. To illustrate the utility of this approach, we present a simple coupled model of infectious diseases and economic growth, where poverty traps emerge from nonlinear relationships determined by the number of pathogens in the system. These nonlinearities are comparable to those often incorporated into poverty trap models in the economics literature, but, importantly, here the mechanism is anchored in core ecological principles. Coupled models of this sort could be usefully developed in many economically important biophysical systems--such as agriculture, fisheries, nutrition, and land use change--to serve as foundations for deeper explorations of how fundamental ecological processes influence structural poverty and economic development.

Toward a theory of resilience for international development applications.

We advance a theory of resilience as it applies to the challenges of international development. The conceptualization we advance for development resilience focuses on the stochastic dynamics of individual and collective human well-being, especially on the avoidance of and escape from chronic poverty over time in the face of myriad stressors and shocks. Development resilience clearly nests within it the related but distinct idea of humanitarian resilience and thereby offers a conceptual apparatus to integrate the humanitarian and development ambitions. We discuss the implications for programming, systems integration, and measurement.

Review: Food loss and waste in Sub-Saharan Africa.

The research, development practitioner, and donor community has begun to focus on food loss and waste - often referred to as post-harvest losses (PHL) - in Sub-Saharan Africa. This article reviews the current state of the literature on PHL mitigation. First, we identify explicitly the varied objectives underlying efforts to reduce PHL levels. Second, we summarize the estimated magnitudes of losses, evaluate the methodologies used to generate those estimates, and explore the dearth of thoughtful assessment around "optimal" PHL levels. Third, we synthesize and critique the impact evaluation literature around on-farm and off-farm interventions expected to deliver PHL reduction. Fourth, we suggest a suite of other approaches to advancing these same objectives, some of which may prove more cost-effective. Finally, we conclude with a summary of main points.

Ten striking facts about agricultural input use in Sub-Saharan Africa.

Conventional wisdom holds that Sub-Saharan African farmers use few modern inputs despite the fact that most poverty-reducing agricultural growth in the region is expected to come largely from expanded use of inputs that embody improved technologies, particularly improved seed, fertilizers and other agro-chemicals, machinery, and irrigation. Yet following several years of high food prices, concerted policy efforts to intensify fertilizer and hybrid seed use, and increased public and private investment in agriculture, how low is modern input use in Africa really? This article revisits Africa's agricultural input landscape, exploiting the unique, recently collected, nationally representative, agriculturally intensive, and cross-country comparable Living Standard Measurement Study-Integrated Surveys on Agriculture (LSMS-ISA) covering six countries in the region (Ethiopia, Malawi, Niger, Nigeria, Tanzania, and Uganda). Using data from over 22,000 households and 62,000 agricultural plots, we offer ten potentially surprising facts about modern input use in Africa today.

Agricultural factor markets in Sub-Saharan Africa: An updated view with formal tests for market failure.

This paper uses the recently collected Living Standard Measurement Study-Integrated Surveys on Agriculture Initiative data sets from five countries in Sub-Saharan Africa to provide a comprehensive overview of factor market participation by agrarian households and to formally test for failures in rural markets. Under complete and competitive markets, households can solve their consumption and production problems separately, so that household factor endowments do not predict input demand. This paper implements a simple, theoretically grounded test of this separation hypothesis, which can be interpreted as a reduced form test of market failure. In all five study countries, the analysis finds strong evidence of factor market failure. Moreover, those failures appear general and structural, not specific to subpopulations defined by gender, geography, human capital, or land quality. However, we show that rural markets are not generally missing in an absolute sense, suggesting that market existence is less of a problem than market function.

On biodiversity conservation and poverty traps.

This paper introduces a special feature on biodiversity conservation and poverty traps. We define and explain the core concepts and then identify four distinct classes of mechanisms that define important interlinkages between biodiversity and poverty. The multiplicity of candidate mechanisms underscores a major challenge in designing policy appropriate across settings. This framework is then used to introduce the ensuing set of papers, which empirically explore these various mechanisms linking poverty traps and biodiversity conservation.

Economic and geographic drivers of wildlife consumption in rural Africa.

The harvest of wildlife for human consumption is valued at several billion dollars annually and provides an essential source of meat for hundreds of millions of rural people living in poverty. This harvest is also considered among the greatest threats to biodiversity throughout Africa, Asia, and Latin America. Economic development is often proposed as an essential first step to win-win solutions for poverty alleviation and biodiversity conservation by breaking rural reliance on wildlife. However, increases in wealth may accelerate consumption and extend the scale and efficiency of wildlife harvest. Our ability to assess the likelihood of these two contrasting outcomes and to design approaches that simultaneously consider poverty and biodiversity loss is impeded by a weak understanding of the direction and shape of their interaction. Here, we present results of economic and wildlife use surveys conducted in 2,000 households from 96 settlements in Ghana, Cameroon, Tanzania, and Madagascar. We examine the individual and interactive roles of wealth, relative food prices, market access, and opportunity costs of time spent hunting on household rates of wildlife consumption. Despite great differences in biogeographic, social, and economic aspects of our study sites, we found a consistent relationship between wealth and wildlife consumption. Wealthier households consume more bushmeat in settlements nearer urban areas, but the opposite pattern is observed in more isolated settlements. Wildlife hunting and consumption increase when alternative livelihoods collapse, but this safety net is an option only for those people living near harvestable wildlife.

Index insurance for pro-poor conservation of hornbills in Thailand.

This study explores the potential of index insurance as a mechanism to finance community-based biodiversity conservation in areas where a strong correlation exists between natural disaster risk, keystone species populations, and the well-being of the local population. We illustrate this potential using the case of hornbill conservation in the Budo-Sungai Padi rainforests of southern Thailand, using 16-y hornbill reproduction data and 5-y household expenditures data reflecting local economic well-being. We show that severe windstorms cause both lower household expenditures and critical nest tree losses that directly constrain nesting capacity and so reduce the number of hornbill chicks recruited in the following breeding season. Forest residents' coping strategies further disturb hornbills and their forest habitats, compounding windstorms' adverse effects on hornbills' recruitment in the following year. The strong statistical relationship between wind speed and both hornbill nest tree losses and household expenditures opens up an opportunity to design wind-based index insurance contracts that could both enhance hornbill conservation and support disaster-affected households in the region. We demonstrate how such contracts could be written and operationalized and then use simulations to show the significant promise of unique insurance-based approaches to address weather-related risk that threatens both biodiversity and poor populations.

Socioenvironmental threats to pastoral livelihoods: risk perceptions in the Altay and Tianshan Mountains of Xinjiang, China.

Subjective risk perceptions give rise to unique policy implications as they reflect both the expectation of risk exposure and the ability to mitigate or cope with the adverse impacts. Based on data collected from semistructured interviews and iterative ranking exercises with 159 households in the Altay and Tianshan Mountains of Xinjiang, China, this study investigates and explains the risks with respect to a seriously understudied population and location. Using both geostatistical and econometric methods, we show that although fear of environmental crisis is prevalent among our respondents, recently implemented pastoral conservation, sedentarization, and development projects are more likely to be ranked as the top concerns among affected households. In order to reduce these concerns, future pastoral policy must be built on the livestock economy, and intervention priority should be given to the geographic areas identified as risk hot spots. In cases where pastoralists have to give up their pastures, the transition to other comparable livelihood strategies must be enabled by creating new opportunities and training pastoralists to acquire the needed skills.

The effect of a political crisis on performance of community forests and protected areas in Madagascar.

Understanding the effectiveness of conservation interventions during times of political instability is important given how much of the world's biodiversity is concentrated in politically fragile nations. Here, we investigate the effect of a political crisis on the relative performance of community managed forests versus protected areas in terms of reducing deforestation in Madagascar, a biodiversity hotspot. We use remotely sensed data and statistical matching within an event study design to isolate the effect of the crisis and post-crisis period on performance. Annual rates of deforestation accelerated at the end of the crisis and were higher in community forests than in protected areas. After controlling for differences in location and other confounding variables, we find no difference in performance during the crisis, but community-managed forests performed worse in post-crisis years. These findings suggest that, as a political crisis subsides and deforestation pressures intensify, community-based conservation may be less resilient than state protection.

Sustainability standards in global agrifood supply chains.

Agrifood supply chains contribute to many environmental and social problems. Sustainability standards-rules that supply chain actors may follow to demonstrate their commitment to social equity and/or environmental protection-aim to mitigate such problems. We provide a narrative review of the effects of many distinct sustainability standards on different supply chain actors spanning multiple crops. Furthermore, we discuss five emerging questions-causality, exclusion, compliance and monitoring, excess supply and emerging country markets-and identify directions for future research. We find that, while sustainability standards can help improve the sustainability of production processes in certain situations, they are insufficient to ensure food system sustainability at scale, nor do they advance equity objectives in agrifood supply chains.

Fishers' response to temperature change reveals the importance of integrating human behavior in climate change analysis.

Climate change will reshape ecological dynamics. Yet, how temperature increases alter the behavior and resource use of people reliant on natural resources remains underexplored. Consequent behavior shifts have the potential to mitigate or accelerate climate impacts on livelihoods and food security. Particularly within the small-scale inland fisheries that support approximately 10% of the global population, temperature changes likely affect both fish and fishers. To analyze how changing temperatures alter households' fishing behavior, we examined fishing effort and fish catch in a major inland fishery. We used longitudinal observational data from households in Cambodia, which has the highest per-capita consumption of inland fish in the world. Higher temperatures caused households to reduce their participation in fishing but had limited net effects on fish catch. Incorporating human behavioral responses to changing environmental conditions will be fundamental to determining how climate change affects rural livelihoods, food production, and food access.