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Despite recent advances in modeling forest–rainfall relationships, the current understanding of changes in observed rainfall patterns resulting from historical deforestation remains limited. To address this knowledge gap, we analyzed how 40 years of deforestation has altered rainfall patterns in South America as well as how current Amazonian forest cover sustains rainfall. First, we develop a spatiotemporal neural network model to simulate rainfall as a function of vegetation and climate inputs in South America; second, we assess the rainfall effects of observed deforestation in South America during the periods 1982–2020 and 2000–2020; third, we assess the potential rainfall changes in the Amazon biome under two deforestation scenarios. We find that, on average, cumulative deforestation in South America from 1982 to 2020 has reduced rainfall over the period 2016–2020 by 18% over deforested areas, and by 9% over non‐deforested areas across South America. We also find that more recent deforestation, that is, from 2000 to 2020, has reduced rainfall over the period 2016–2020 by 10% over deforested areas and by 5% over non‐deforested areas. Deforestation between 1982 and 2020 has led to a doubling in the area experiencing a minimum dry season of 4 months in the Amazon biome. Similarly, in the Cerrado region, there has been a corresponding doubling in the area with a minimum dry season of 7 months. These changes are compared to a hypothetical scenario where no deforestation occurred. Complete conversion of all Amazon forest land outside protected areas would reduce average annual rainfall in the Amazon by 36% and complete deforestation of all forest cover including protected areas would reduce average annual rainfall in the Amazon by 68%. Our findings emphasize the urgent need for effective conservation measures to safeguard both forest ecosystems and sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

• Deforestation-induced rainfall changes negatively impact soybean and maize yields in Brazil. • Soybean and maize yields could have been 6.6 % and 9.9 % higher per year if rainfall patterns hadn't been altered by deforestation. • Agricultural efficiency improvements insufficient to counteract rainfall-changes effects on yields. • Study underscores the vital role of forest preservation for agricultural resilience and food security. • Forests' critical role in regulating the water cycle highlighted in the face of climate change. Whereas the global demand for food, fiber and energy is increasing, the capacity of ecosystems services to sustain agricultural production is being compromised worldwide. Brazil is a global food supplier that has benefitted from agricultural intensification in the past decades. At the same time, expansion of cropland has led to deforestation that, in turn, is increasingly affecting rainfall patterns thereby influencing crop yields. This study examines how loss in forest cover has impacted agricultural yields through change in rainfall. To do so, we use modelled data on changes in rainfall patterns due to deforestation as input to a crop model. We assess yield changes within the soybean-maize double cropping system, the country's most relevant agricultural system, in five states within the Amazon and Cerrado biomes. Findings revealed that soybean and maize yields would have been respectively 6.6 % and 9.9 % higher per year in the last decade if rainfall patterns hadn't been altered by deforestation from 1982 onwards. Although agricultural efficiency improved between 2011 and 2020, it was insufficient to offset the negative effect of altered rainfall on yields. Our paper reveals the link between deforestation and crop yields, emphasizing the need to preserve forest cover for agricultural resilience and food security. It reinforces the critical role of forests in regulating the water cycle, particularly in the face of climate change-induced warmer and drier conditions that can impact agricultural production and other human activities. [ABSTRACT FROM AUTHOR]

In recent decades, there have been substantial increases in crop production in sub-Saharan Africa (SSA) as a result of higher yields, increased cropping intensity, expansion of irrigated cropping systems, and rainfed cropland expansion. Yet, to date much of the research focus of the impact of climate change on crop production in the coming decades has been on crop yield responses. In this study, we analyse the impact of climate change on the potential for increasing rainfed cropping intensity through sequential cropping and irrigation expansion in central Benin. Our approach combines hydrological modelling and scenario analysis involving two Representative Concentration Pathways (RCPs), two water-use scenarios for the watershed based on the Shared Socioeconomic Pathways (SSPs), and environmental water requirements leading to sustained streamflow. Our analyses show that in Benin, warmer temperatures will severely limit crop production increases achieved through the expansion of sequential cropping. Depending on the climate change scenario, between 50% and 95% of cultivated areas that can currently support sequential cropping or will need to revert to single cropping. The results also show that the irrigation potential of the watershed will be at least halved by mid-century in all scenario combinations. Given the urgent need to increase crop production to meet the demands of a growing population in SSA, our study outlines challenges and the need for planned development that need to be overcome to improve food security in the coming decades. [ABSTRACT FROM AUTHOR]

Meeting the dual objectives of food security and ecosystem protection is a major challenge in sub-Saharan Africa (SSA). To this end agricultural intensification is considered desirable, yet, there remain uncertainties regarding the impact of climate change on opportunities for agricultural intensification and the adequacy of intensification options given the rapid population growth. We quantify trade-offs between levels of yield gap closure, food availability and forest and woodland conservation under different scenarios. Each scenario is made up of a combination of variants of four parameters i.e. (1) climate change based on Representative Concentration Pathways (RCPs); (2) population growth based on Shared Socioeconomic Pathways (SSPs); (3) cropland expansion with varying degrees of deforestation; and (4) different degrees of yield gap closure. We carry out these analyses for three major food crops, i.e. maize, cassava and yam, in Benin. Our analyses show that in most of the scenarios, the required levels of yield gap closures required to maintain the current levels of food availability can be achieved by 2050 by maintaining the average rate of yield increases recorded over the past two and half decades in addition to the current cropping intensity. However, yields will have to increase at a faster rate than has been recorded over the past two and half decades in order to achieve the required levels of yield gap closures by 2100. Our analyses also show that without the stated levels of yield gap closure, the areas under maize, cassava and yam cultivation will have to increase by 95%, 102% and 250% respectively in order to maintain the current levels of per capita food availability. Our study shows that food security outcomes and forest and woodland conservation goals in Benin and likely the larger SSA region are inextricably linked together and require holistic management strategies that considers trade-offs and co-benefits. [ABSTRACT FROM AUTHOR]

Major increases in food production are needed to feed the rapidly growing population of sub-Saharan Africa. Increased application of irrigation has often been identified as one of the main pathways to agricultural intensification. However, water flows, in particular during the dry season, often depend upon the water regulation services provided by forests and woodlands which are increasingly subject to land conversion as well as degradation from the overexploitation of wood resources. Insight in the trade-off between land conversion in sub-Saharan African uplands and sustaining water flows is, therefore, urgently needed. In this paper, we develop a general modelling approach for analysing the effects of deforestation on the availability of water for irrigation at the watershed level, and we apply the approach to the Upper Ouémé watershed in Benin. We use controlled modelling experiments based on the Soil and Water Assessment Tool (SWAT) in addition to copula functions to quantify surface water availability and irrigation potential under prevailing forest and woodland cover as well as varying forest and woodland extents. We undertake these comparative analyses for two irrigation development scenarios that are defined based on different levels of sustained water flows in the Upper Ouémé river network. Our analyses show that conservation of prevailing forests and woodlands in the Upper Ouémé watershed is needed to allow the development of 80% (15,000 ha) or 71% (20,000 ha) of the irrigation potential in the dry season depending on the scenario. At the prevailing forest and woodland extent, the loss of around 40 ha of forest and woodland area reduces the irrigation potential by 1 ha depending on the scenario. Our irrigation potential calculations are based on the water requirements of rice which is the most water intensive crop grown in the study area. For other crops, the ratio will be lower (i.e. less forest and woodland area is required to sustain 1 ha of irrigated crop production). The relation between forest and woodland extent and irrigation potential is, however, not linear, and more hectares of forest and woodland are needed to support 1 ha of irrigated crop production with increasing deforestation. This is relevant for trade-off analysis, where it needs to be noted that the forests and woodlands not only generate water regulation services but also provide other ecosystem services including fuelwood, timber, opportunities for livestock grazing and carbon sequestration. [ABSTRACT FROM AUTHOR]

Rice is one of the major staple foods in sub-Saharan Africa (SSA) and is mainly grown in three environments: rainfed upland and rainfed and irrigated lowlands. In all rice-growing environments, the yield gap (the difference between the potential yield in irrigated lowland or water-limited yield in rainfed lowland and upland and the actual yield obtained by farmers) is largely due to a wide range of constraints including water-related issues. This paper aims to review water management research for rice cultivation in SSA. Major water-related constraints to rice production include drought, flooding, iron toxicity, and soil salinity. A wide range of technologies has been tested by Africa Rice Center (AfricaRice) and its partners for their potential to address some of the water-related challenges across SSA. In the irrigated lowlands, the system of rice intensification and alternate wetting and drying significantly reduced water use, while the pre-conditions to maintain grain yield and quality compared to continuous flooding were identified. Salinity problems caused by the standing water layer could be addressed by flushing and leaching. In the rainfed lowlands, water control structures, Sawah rice production system, and the Smart-Valleys approach for land and water development improved water availability and grain yield compared to traditional water management practices. In the rainfed uplands, supplemental irrigation, mulching, and conservation agriculture mitigated the effects of drought on rice yield. The Participatory Learning and Action Research (PLAR) approach was developed to work with and educate communities to help them implement improved water management technologies. Most of the research assessed a few indicators such as rice yield, water use, water productivity at the field level. There has been limited research on the cost-benefit of water management technologies, enabling conditions and business models for their large-scale adoption, as well as their impact on farmers' livelihoods, particularly on women and youth. Besides, limited research has been conducted on water management design for crop diversification, landscape-level water management, and iron toxicity mitigation, particularly in lowlands. Filling these research gaps could contribute to sustainable water resources management and sustainable intensification of rice-based systems in SSA. • Research on water management for rice cultivation in sub-Saharan Africa was reviewed. • The majority of studies aimed at improving water control in rainfed lowlands. • The studies focused mostly on improving rice yield and water productivity. • Less attention was given to cost-benefits and impact of water control technologies. • Water management was mostly studied at the field- rather than at landscape-level. [ABSTRACT FROM AUTHOR]