Impacts of Global Food Systems on Biodiversity and Water: The Vision of Two Reports and Future Aims

Recent reports from the EAT-Lancet Commission and the Intergovernmental Panel on Climate Change have highlighted the environmental impacts of food systems and the means of mitigating these impacts in the future. Here, we reflect upon the reports’ findings on the effects of agricultural production on biodiversity and water resources and present essential areas for future research

Global impacts of nitrogen and phosphorus fertiliser use for major crops on aquatic biodiversity

PURPOSE: The intensive application of nitrogen and phosphorus fertilisers on agricultural land to fertilise crops has caused eutrophication, the nutrient enrichment of waterbodies leading to excessive growth of algae, deoxygenation and loss of aquatic biodiversity. Life cycle impact assessments (LCIA) are often used to determine the environmental impacts of fertiliser use. However, the lack of suitable methodologies to estimate the fate and transport of nutrients from soils makes crop and regional impact comparisons challenging. Using a newly devised, spatially explicit nutrient fate and transport model (fate factor, FF) within an LCIA framework, this study estimates the global spatial-variability of nutrient loss from fertilisation of crops and their relative impact on aquatic biodiversity, specifically species richness. METHOD: The newly devised FFs are based on the global spatially explicit nutrient model IMGE-GNM. The FF’s enable us to assess N and P’s fate and transport from indirect soil emissions (arable land, grassland and natural land) to freshwater environments. Additionally we improve the spatial resolution of existing soil FFs for N within marine environments from basin scale to 5 arcmin resolution. We applied our FF’s within current LCIA methodologies to assess the nutrient loading (midpoint indicator) and final aquatic biodiversity impact (endpoint indicator) from 17 crops. RESULTS AND DISCUSSION: Our results identify strong variability in inputs, loadings and impacts due to differences in the fate, transport and impact of nutrients within the local environmental context. Such variability is translated into large differences between the popularly used nutrient use efficiency (NUE) indicator and final aquatic impacts caused by specific crops. Heavily produced crops (maize, rice, wheat, sugarcane and soybean) with the highest loading rates to receptors did not necessarily have the highest aquatic impacts. We identified rank variability exists at different metric stages (fertiliser inputs, receptor loadings, aquatic impacts) specifically for wheat and sugarcane. Our results showed high global spatial variability in aquatic biodiversity impacts with significant biodiversity loss outside of the highest production regions. CONCLUSION: Our study identified, global hotspots for biodiversity impacts depend on the local context that exist beyond the field (e.g. the fate and transport of nutrients to receptor environments, and the receptor environment's vulnerability). Aquatic impacts from fertiliser use for specific crop commodities should be considered in decision-making for strategic fertiliser pollution control and environmentally sustainable crop-commodity trade sourcing. The development of the improved FFs should be used to aid spatially explicit and site-specific LCIA nutrient studies from soils

A review of the interactions between biodiversity, agriculture, climate change and international trade: Research and policy priorities

Striving to feed a population set to reach almost 10 billion people by 2050 in a sustainable way is high on the research and policy agendas. Further intensification and expansion of agricultural lands would be of major concern for the environment and biodiversity. There is, therefore, a need to understand better the impacts on biodiversity from the global food system. Since biodiversity underpins functions and services that are essential to agriculture, greater consideration of the role of biodiversity in the food system is needed. Here we have generated a conceptual framework separating the environment-agriculture-trade system into its key components, revealing complex interactions and highlighting the role of biodiversity. This process identified components that are well studied, and gaps preventing a better understanding of the interactions, trade-offs, and synergies between biodiversity, agriculture, climate change, and international trade. We highlight eight priorities that will promote a greater understanding of the complexities of the environment-agriculture-trade system

Reduced Population Control of an Insect Pest in Managed Willow Monocultures

BACKGROUND: There is a general belief that insect outbreak risk is higher in plant monocultures than in natural and more diverse habitats, although empirical studies investigating this relationship are lacking. In this study, using density data collected over seven years at 40 study sites, we compare the temporal population variability of the leaf beetle Phratora vulgatissima between willow plantations and natural willow habitats. METHODOLOGY/PRINCIPAL FINDINGS: The study was conducted in 1999-2005. The density of adult P. vulgatissima was estimated in the spring every year by a knock-down sampling technique. We used two measures of population variability, CV and PV, to compare temporal variations in leaf beetle density between plantation and natural habitat. Relationships between density and variability were also analyzed to discern potential underlying processes behind stability in the two systems. The results showed that the leaf beetle P. vulgatissima had a greater temporal population variability and outbreak risk in willow plantations than in natural willow habitats. We hypothesize that the greater population stability observed in the natural habitat was due to two separate processes operating at different levels of beetle density. First, stable low population equilibrium can be achieved by the relatively high density of generalist predators observed in natural stands. Second, stable equilibrium can also be imposed at higher beetle density due to competition, which occurs through depletion of resources (plant foliage) in the natural habitat. In willow plantations, competition is reduced mainly because plants grow close enough for beetle larvae to move to another plant when foliage is consumed. CONCLUSION/SIGNIFICANCE: To our knowledge, this is the first empirical study confirming that insect pest outbreak risk is higher in monocultures. The study suggests that comparative studies of insect population dynamics in different habitats may improve our ability to predict insect pest outbreaks and could facilitate the development of sustainable pest control in managed systems

International food trade contributes to dietary risks and mortality at global, regional and national levels

Food trade is generally perceived to increase the availability and diversity of foods available to consumers, but there is little empirical evidence on its implications for human health. Here we show that a substantial proportion of dietary risks and diet-related mortality worldwide is attributable to international food trade and that whether the contributions of food trade are positive or negative depends on the types of food traded. Using bilateral trade data for 2019 and food-specific risk–disease relationships, we estimate that imports of fruits, vegetables, legumes and nuts improved dietary risks in the importing countries and were associated with a reduction in mortality from non-communicable diseases of ~1.4 million deaths globally. By contrast, imports of red meat aggravated dietary risks in the importing countries and were associated with an increase of ~150,000 deaths. The magnitude of our findings suggests that considering impacts on dietary risks will become an important aspect of health-sensitive trade and agriculture policies, and of policy responses to disruptions in food chains

Water Quality and Pollution Trading: A Sustainable Solution for Future Food Production

Nitrogen, an essential nutrient for plant growth, is commonly added to food crops in the form of manure and synthetic fertilizers. Fertilizer use has significantly increased in the past decades to meet the food demands from a rising population. Although this has boosted food production, it has come at a cost to the environment. Indeed, excess fertilizer ends up in water bodies, a pollution that causes losses in aquatic biodiversity. Better fertilizer management is therefore essential to maintaining water sustainability. Here, we develop and evaluate a nitrogen water quality trading scheme to address this challenge. Nitrogen trading incentivizes farmers to work together to invest in pollution reduction measures in order to keep nitrogen water pollution levels within a standardized limit. We build a mathematical model to represent the nitrogen trading and use it to assess the pollution reduction, the effect on the crop yield, and economical outcomes. The model is applied among local farms in the agricultural county of Suffolk, eastern England. We calculate the nitrogen load to the river from each farm and incorporate the abatement cost into the model. The results show how nitrogen water pollution could be reduced cost-effectively while simultaneously increasing the benefit for the whole catchment. Although the benefit does not increase for all the farms, the increase in benefit for the whole catchment is enough to compensate for this loss. The surplus benefit is equally distributed between all the farms, thus increasing their overall benefit. We discuss how the proposed trading model can create a platform for farmers to participate and reduce their water pollution

Groundwater depletion embedded in international food trade

Recent hydrological modelling1 and Earth observations2,3 have located and quantified alarming rates of groundwater depletion worldwide. This depletion is primarily due to water withdrawals for irrigation1,2,4, but its connection with the main driver of irrigation, global food consumption, has not yet been explored. Here we show that approximately eleven per cent of non-renewable groundwater use for irrigation is embedded in international food trade, of which two-thirds are exported by Pakistan, the USA and India alone. Our quantification of groundwater depletion embedded in the world’s food trade is based on a combination of global, cropspecific estimates of non-renewable groundwater abstraction and international food trade data. A vast majority of the world’s population lives in countries sourcing nearly all their staple crop imports from partners who deplete groundwater to produce these crops, highlighting risks for global food and water security. Some countries, such as the USA, Mexico, Iran and China, are particularly exposed to these risks because they both produce and import food irrigated from rapidly depleting aquifers. Our results could help to improve the sustainability of global food production and groundwater resource management by identifying priority regions and agricultural products at risk as well as the end consumers of these products

Multi-criteria suitability analysis for neglected and underutilised crop species in South Africa

Several neglected and underutilised species (NUS) provide solutions to climate change and creating a Zero Hunger world, the Sustainable Development Goal 2. Several NUS are drought and heat stress-tolerant, making them ideal for improving marginalised cropping systems in drought-prone areas. However, owing to their status as NUS, current crop suitability maps do not include them as part of the crop choices. This study aimed to develop land suitability maps for selected NUS [sorghum, (Sorghum bicolor), cowpea (Vigna unguiculata), amaranth and taro (Colocasia esculenta)] using Analytic Hierarchy Process (AHP) in ArcGIS. Multidisciplinary factors from climatic, soil and landscape, socio-economic and technical indicators overlaid using Weighted Overlay Analysis. Validation was done through field visits, and area under the curve (AUC) was used to measure AHP model performance. The results indicated that sorghum was highly suitable (S1) = 2%, moderately suitable (S2) = 61%, marginally suitable (S3) = 33%, and unsuitable (N1) = 4%, cowpea S1 = 3%, S2 = 56%, S3 = 39%, N1 = 2%, amaranth S1 = 8%, S2 = 81%, S3 = 11%, and taro S1 = 0.4%, S2 = 28%, S3 = 64%, N1 = 7%, of calculated arable land of SA (12 655 859 ha). Overall, the validation showed that the mapping exercises exhibited a high degree of accuracies (i.e. sorghum AUC = 0.87, cowpea AUC = 0.88, amaranth AUC = 0.95 and taro AUC = 0.82). Rainfall was the most critical variable and criteria with the highest impact on land suitability of the NUS. Results of this study suggest that South Africa has a huge potential for NUS production. The maps developed can contribute to evidence-based and site-specific recommendations for NUS and their mainstreaming. Also, the maps can be used to design appropriate production guidelines and to support existing policy frameworks which advocate for sustainable intensification of marginalised cropping systems through increased crop diversity and the use of stress-tolerant food crops

Brushing the surface: cascade reactions between immobilized nanoreactors

Functionalization of hard or soft surfaces with, for example, ligands, enzymes or proteins, is an effective and practical methodology for the development of new applications. We report the assembly of two types of nanoreactors based upon poly(dimethylsiloxane)-block-poly(2-methyl-2-oxazoline) (PDMS-b-PMOXA) diblock copolymers as scaffold, uricase and lactoperoxidase as bio-catalysts located within the nanoreactors, and melittin as the biopores inserted into the hydrophobic shell. The nanoreactors were immobilized on poly(2-hydroxyethyl methacrylate)-co-poly(2-aminoethyl methacrylate hydrochloride) (PHEMA-co-P(2-AEMA·HCl) brushes-grafted wafer surfaces by utilizing the strong supramolecular interactions between biotin and streptavidin. The (PHEMA-co-P(2-AEMA·HCl) brushes on silicon surfaces were prepared by a surface initiating atom transfer radical polymerization (ATRP) "graft-from" technique. Cascade reactions between different surface-anchored nanoreactors were demonstrated by converting Amplex Red to the fluorescent probe resorufin by using the H2O2 produced from uric acid and H2O. The detailed properties of the nanoreactors on the functionalized surface including the binding behaviours and cascade reactions were investigated using emission spectroscopy, transmission electron microscopy (TEM), light scattering (LS), atomic force microscopy (AFM) and a quartz crystal microbalance (QCM-D). The results are proof-of-principle for the preparation of catalytically functional engineered surface materials and lay the foundation for applying this advanced functional surface material in biosensing, implanting and antimicrobial materials preparation

Identifying therapeutic targets by combining transcriptional data with ordinal clinical measurements

The immense and growing repositories of transcriptional data may contain critical insights for developing new therapies. Current approaches to mining these data largely rely on binary classifications of disease vs. control, and are not able to incorporate measures of disease severity. We report an analytical approach to integrate ordinal clinical information with transcriptomics. We apply this method to public data for a large cohort of Huntington's disease patients and controls, identifying and prioritizing phenotype-associated genes. We verify the role of a high-ranked gene in dysregulation of sphingolipid metabolism in the disease and demonstrate that inhibiting the enzyme, sphingosine-1-phosphate lyase 1 (SPL), has neuroprotective effects in Huntington's disease models. Finally, we show that one consequence of inhibiting SPL is intracellular inhibition of histone deacetylases, thus linking our observations in sphingolipid metabolism to a well-characterized Huntington's disease pathway. Our approach is easily applied to any data with ordinal clinical measurements, and may deepen our understanding of disease processes