Adjusting agricultural emissions for trade matters for climate change mitigation.

Reducing greenhouse gas emissions in food systems is becoming more challenging as food is increasingly consumed away from producer regions, highlighting the need to consider emissions embodied in trade in agricultural emissions accounting. To address this, our study explores recent trends in trade-adjusted agricultural emissions of food items at the global, regional, and national levels. We find that emissions are largely dependent on a country's consumption patterns and their agricultural emission intensities relative to their trading partners'. The absolute differences between the production-based and trade-adjusted emissions accounting approaches are especially apparent for major agricultural exporters and importers and where large shares of emission-intensive items such as ruminant meat, milk products and rice are involved. In relative terms, some low-income and emerging and developing economies with consumption of high emission intensity food products show large differences between approaches. Similar trends are also found under various specifications that account for trade and re-exports differently. These findings could serve as an important element towards constructing national emissions reduction targets that consider trading partners, leading to more effective emissions reductions overall.

Social-ecological interactions in the Draa River Basin, southern Morocco: Towards nature conservation and human well-being using the IPBES framework.

Water is essential to human societies and a prerequisite for flourishing nature, especially in arid regions. Yet, climate change and socio-economic developments are expected to exacerbate current and future stresses on water resources, demanding innovative approaches to balance water needs for society and nature conservation. In this study, we use the IPBES conceptual framework to combine ecological and socio-economic insights and analyse the connections between people and nature in the water scarce Draa River Basin, southern Morocco. We study the diversity of desert benthic macroinvertebrates as one component of nature using DNA barcoding and their potential to serve as bioindicators of human impact by relating species occurrences to environmental parameters. Furthermore, based on 87 interviews with farmers and key institutional stakeholders, we investigate how farmers perceive water related changes and how water is managed in the basin. Regarding benthic macroinvertebrates, 41 families were identified, 475 DNA barcodes generated and assigned to 118 putative species (Barcode Index Numbers) of which 60 were first records. This indicates a lack of reference sequences for known, but also a potentially high number of undescribed species. Environmental parameters, which are partly influenced by human activities, such as aquatic stages, salinity and intermittency, were the most important variables explaining invertebrate richness and community composition in generalized linear models. We further describe farmers' perceptions of decreasing water quality and quantity. Farmers generally believe that they are able to cope with water related changes, although perceptions are regionally differentiated with farmers downstream being less optimistic. With growing concerns, water policies currently focus on increasing water supply and less on reducing water demands. Based on these findings, the usefulness of the IPBES framework for understanding social-ecological system dynamics is reflected, and recommendations for future freshwater management and research are derived.

Environmental and socioeconomic effects of mosquito control in Europe using the biocide Bacillus thuringiensis subsp. israelensis (Bti).

Bacillus thuringiensis subsp. israelensis (Bti) has been used in mosquito control programs to reduce nuisance in Europe for decades and is generally considered an environmentally-safe, effective and target-specific biocide. However, the use of Bti is not uncontroversial. Target mosquitoes and affected midges represent an important food source for many aquatic and terrestrial predators and reduction of their populations is likely to result in food-web effects at higher trophic levels. In the context of global biodiversity loss, this appears particularly critical since treated wetlands are often representing conservation areas. In this review, we address the current large-scale use of Bti for mosquito nuisance control in Europe, provide a description of its regulation followed by an overview of the available evidence on the parameters that are essential to evaluate Bti use in mosquito control. Bti accumulation and toxin persistence could result in a chronic expose of mosquito populations ultimately affecting their susceptibility, although observed increase in resistance to Bti in mosquito populations is low due to the four toxins involved. A careful independent monitoring of mosquito susceptibility, using sensitive bioassays, is mandatory to detect resistance development timely. Direct Bti effects were documented for non-target chironomids and other invertebrate groups and are discussed for amphibians. Field studies revealed contrasting results on possible impacts on chironomid abundances. Indirect, food-web effects were rarely studied in the environment. Depending on study design and duration, Bti effects on higher trophic levels were demonstrated or not. Further long-term field studies are needed, especially with observations of bird declines in Bti-treated wetland areas. Socio-economic relevance of mosquito control requires considering nuisance, vector-borne diseases and environmental effects jointly. Existing studies indicate that a majority of the population is concerned regarding potential environmental effects of Bti mosquito control and that they are willing to pay for alternative, more environment-friendly techniques.

Salinity impacts on river ecosystem processes: a critical mini-review.

In many dry parts of the world, salinization of water resources threatens freshwater biodiversity and the livelihood of people. However, ecological impact studies remain scarce. Here, we review field-observations of salinity impacts on ecosystem processes such as leaf decomposition, metabolism, biomass production and nutrient cycling, with a special emphasis on dryland ecosystems. In addition, we discuss the potential linkages of these processes to ecosystem service delivery-the benefits that humans derive from ecosystems-as additional nature conservation arguments and the challenges associated with this endeavour.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation?

Plastic mulching has become a globally applied agricultural practice for its instant economic benefits such as higher yields, earlier harvests, improved fruit quality and increased water-use efficiency. However, knowledge of the sustainability of plastic mulching remains vague in terms of both an environmental and agronomic perspective. This review critically discusses the current understanding of the environmental impact of plastic mulch use by linking knowledge of agricultural benefits and research on the life cycle of plastic mulches with direct and indirect implications for long-term soil quality and ecosystem services. Adverse effects may arise from plastic additives, enhanced pesticide runoff and plastic residues likely to fragment into microplastics but remaining chemically intact and accumulating in soil where they can successively sorb agrochemicals. The quantification of microplastics in soil remains challenging due to the lack of appropriate analytical techniques. The cost and effort of recovering and recycling used mulching films may offset the aforementioned benefits in the long term. However, comparative and long-term agronomic assessments have not yet been conducted. Furthermore, plastic mulches have the potential to alter soil quality by shifting the edaphic biocoenosis (e.g. towards mycotoxigenic fungi), accelerate C/N metabolism eventually depleting soil organic matter stocks, increase soil water repellency and favour the release of greenhouse gases. A substantial process understanding of the interactions between the soil microclimate, water supply and biological activity under plastic mulches is still lacking but required to estimate potential risks for long-term soil quality. Currently, farmers mostly base their decision to apply plastic mulches rather on expected short-term benefits than on the consideration of long-term consequences. Future interdisciplinary research should therefore gain a deeper understanding of the incentives for farmers and public perception from both a psychological and economic perspective in order to develop new support strategies for the transition into a more environment-friendly food production.

Review on environmental alterations propagating from aquatic to terrestrial ecosystems.

Terrestrial inputs into freshwater ecosystems are a classical field of environmental science. Resource fluxes (subsidy) from aquatic to terrestrial systems have been less studied, although they are of high ecological relevance particularly for the receiving ecosystem. These fluxes may, however, be impacted by anthropogenically driven alterations modifying structure and functioning of aquatic ecosystems. In this context, we reviewed the peer-reviewed literature for studies addressing the subsidy of terrestrial by aquatic ecosystems with special emphasis on the role that anthropogenic alterations play in this water-land coupling. Our analysis revealed a continuously increasing interest in the coupling of aquatic to terrestrial ecosystems between 1990 and 2014 (total: 661 studies), while the research domains focusing on abiotic (502 studies) and biotic (159 studies) processes are strongly separated. Approximately 35% (abiotic) and 25% (biotic) of the studies focused on the propagation of anthropogenic alterations from the aquatic to the terrestrial system. Among these studies, hydromorphological and hydrological alterations were predominantly assessed, whereas water pollution and invasive species were less frequently investigated. Less than 5% of these studies considered indirect effects in the terrestrial system e.g. via food web responses, as a result of anthropogenic alterations in aquatic ecosystems. Nonetheless, these very few publications indicate far-reaching consequences in the receiving terrestrial ecosystem. For example, bottom-up mediated responses via soil quality can cascade over plant communities up to the level of herbivorous arthropods, while top-down mediated responses via predatory spiders can cascade down to herbivorous arthropods and even plants. Overall, the current state of knowledge calls for an integrated assessment on how these interactions within terrestrial ecosystems are affected by propagation of aquatic ecosystem alterations. To fill these gaps, we propose a scientific framework, which considers abiotic and biotic aspects based on an interdisciplinary approach.

Replacing rubber plantations by rain forest in Southwest China--who would gain and how much?

The cultivation of rubber trees in Xishuangbanna Prefecture in China's Yunnan Province has triggered an unprecedented economic development but it is also associated with severe environmental problems. Rubber plantations are encroaching the indigenous rain forests at a large scale and a high speed in Xishuangbanna. Many rare plant and animal species are endangered by this development, the natural water management is disturbed, and even the microclimate in this region has changed over the past years. The present study aims at an assessment of the environmental benefits accruing from a reforestation project partly reversing the deforestation that has taken place over the past years. To this end, a Contingent Valuation survey has been conducted in Xishuangbanna to elicit local residents' willingness to pay for this reforestation program that converts existing rubber plantations back into forest. It is shown that local people's awareness of the environmental problems caused by increasing rubber plantation is quite high and that in spite of the economic advantages of rubber plantation there is a positive willingness among the local population to contribute financially to a reduction of existing rubber plantations for the sake of a partial restoration of the local rain forest. These results could be used for the practical implementation of a Payments for Eco-System Services system for reforestation in Xishuangbanna.